Fossil

** to be entered into the chat history.
**
** On success it responds with an empty response: the new message
** should be fetched via /chat-poll. On error, e.g. login expiry,
** it emits a JSON response in the same form as described for
** /chat-poll errors, but as a standalone object instead of a
** list of objects.
**
** Requests to this page should be POST, not GET.  POST parameters
** include:
**
**    msg        The (Markdown) text of the message to be sent
**
**    file       The content of the file attachment
**
**    lmtime     ISO-8601 formatted date-time string showing the local time
**               of the sender.
**
** At least one of the "msg" or "file" POST parameters must be provided.
*/
void chat_send_webpage(void){
  int nByte;
  const char *zMsg;
  const char *zUserName;
  login_check_credentials();
  if( 0==g.perm.Chat ) {

** Invoking fetch("chat-delete/"+msgid) from javascript in the client
** will delete a chat entry from the CHAT table.
**
** This routine both deletes the identified chat entry and also inserts
** a new entry with the current timestamp and with:
**
**   *  xmsg = NULL
**
**   *  file = NULL
**
**   *  mdel = The msgid of the row that was deleted
**
** This new entry will then be propagated to all listeners so that they
** will know to delete their copies of the message too.
*/
void chat_delete_webpage(void){
  int mdel;

        '#'
    );
    diff_options(&DCfg, 0, 1);
    DCfg.diffFlags |= DIFF_VERBOSE;
    if( g.aCommitFile ){
      FileDirList *diffFiles;
      int i;
      for(i=0; g.aCommitFile[i]!=0; ++i){}
      diffFiles = fossil_malloc_zero((i+1) * sizeof(*diffFiles));
      for(i=0; g.aCommitFile[i]!=0; ++i){
        diffFiles[i].zName  = db_text(0,
         "SELECT pathname FROM vfile WHERE id=%d", g.aCommitFile[i]);
        if( fossil_strcmp(diffFiles[i].zName, "." )==0 ){
          diffFiles[0].zName[0] = '.';
          diffFiles[0].zName[1] = 0;
          break;
        }
        diffFiles[i].nName = strlen(diffFiles[i].zName);
        diffFiles[i].nUsed = 0;
      }
      diff_against_disk(0, &DCfg, diffFiles, &prompt);
      for( i=0; diffFiles[i].zName; ++i ){
        fossil_free(diffFiles[i].zName);
      }
      fossil_free(diffFiles);
    }else{
      diff_against_disk(0, &DCfg, 0, &prompt);
    }

**                                 ("auto" lets Fossil choose it automatically,
**                                  even for private branches)
**    --close                    close the branch being committed
**    --date-override DATETIME   DATE to use instead of 'now'
**    --delta                    use a delta manifest in the commit process
**    --hash                     verify file status using hashing rather
**                               than relying on file mtimes
**    --ignore-clock-skew        If a clock skew is detected, ignore it and
**                               behave as if the user had entered 'yes' to
**                               the question of whether to proceed despite
**                               the skew.
**    --integrate                close all merged-in branches
**    -m|--comment COMMENT-TEXT  use COMMENT-TEXT as commit comment
**    -M|--message-file FILE     read the commit comment from given file
**    --mimetype MIMETYPE        mimetype of check-in comment
**    -n|--dry-run               If given, display instead of run actions
**    -v|--verbose               Show a diff in the commit message prompt
**    --no-prompt                This option disables prompting the user for

  int szB;               /* Size of the baseline manifest */
  int nConflict = 0;     /* Number of unresolved merge conflicts */
  int abortCommit = 0;   /* Abort the commit due to text format conversions */
  Blob ans;              /* Answer to continuation prompts */
  char cReply;           /* First character of ans */
  int bRecheck = 0;      /* Repeat fork and closed-branch checks*/
  int bAutoBrClr = 0;    /* Value of "--branchcolor" is "auto" */
  int bIgnoreSkew = 0;   /* --ignore-clock-skew flag */

  memset(&sCiInfo, 0, sizeof(sCiInfo));
  url_proxy_options();
  /* --sha1sum is an undocumented alias for --hash for backwards compatiblity */
  useHash = find_option("hash",0,0)!=0 || find_option("sha1sum",0,0)!=0;
  noSign = find_option("nosign",0,0)!=0;
  privateFlag = find_option("private",0,0)!=0;

  zComFile = find_option("message-file", "M", 1);
  sCiInfo.zDateOvrd = find_option("date-override",0,1);
  sCiInfo.zUserOvrd = find_option("user-override",0,1);
  db_must_be_within_tree();
  noSign = db_get_boolean("omitsign", 0)|noSign;
  if( db_get_boolean("clearsign", 0)==0 ){ noSign = 1; }
  useCksum = db_get_boolean("repo-cksum", 1);
  bIgnoreSkew = find_option("ignore-clock-skew",0,0)!=0;
  outputManifest = db_get_manifest_setting();
  verify_all_options();

  /* Get the ID of the parent manifest artifact */
  vid = db_lget_int("checkout", 0);
  if( vid==0 ){
    useCksum = 1;

  }


  /* Require confirmation to continue with the check-in if there is
  ** clock skew
  */
  if( g.clockSkewSeen ){
    if( bIgnoreSkew!=0 ){
      cReply = 'y';
      fossil_warning("Clock skew ignored due to --ignore-clock-skew.");
    }else if( !noPrompt ){
      prompt_user("continue in spite of time skew (y/N)? ", &ans);
      cReply = blob_str(&ans)[0];
      blob_reset(&ans);
    }else{
      fossil_print("Abandoning commit due to time skew\n");
      cReply = 'N';
    }

/*
** Returns non-zero if support for symlinks is currently enabled.
*/
int db_allow_symlinks(void){
  return g.allowSymlinks;
}

/*
** Return TRUE if the file in the argument seems like it might be an
** SQLite database file that contains a Fossil repository schema.
*/
int db_looks_like_a_repository(const char *zDbName){
  sqlite3 *db = 0;
  i64 sz;
  int rc;
  int res = 0;
  sqlite3_stmt *pStmt = 0;

  sz = file_size(zDbName, ExtFILE);
  if( sz<16834 ) return 0;
  if( sz & 0x1ff ) return 0;
  rc = sqlite3_open(zDbName, &db);
  if( rc ) goto is_repo_end;
  rc = sqlite3_prepare_v2(db, 
       "SELECT count(*) FROM sqlite_schema"
       " WHERE name COLLATE nocase IN"
       "('blob','delta','rcvfrom','user','config','mlink','plink');",
       -1, &pStmt, 0);
  if( rc ) goto is_repo_end;
  rc = sqlite3_step(pStmt);
  if( rc!=SQLITE_ROW ) goto is_repo_end;
  if( sqlite3_column_int(pStmt, 0)!=7 ) goto is_repo_end;
  res = 1;

is_repo_end:
  sqlite3_finalize(pStmt);
  sqlite3_close(db);
  return res;
}

/*
** COMMAND: test-is-repo
*/
void test_is_repo(void){
  int i;
  for(i=2; i<g.argc; i++){
    fossil_print("%s: %s\n",
       db_looks_like_a_repository(g.argv[i]) ? "yes" : " no",
       g.argv[i]
    );
  }
}


/*
** Open the repository database given by zDbName.  If zDbName==NULL then
** get the name from the already open local database.
*/
void db_open_repository(const char *zDbName){
  i64 sz;
  if( g.repositoryOpen ) return;
  if( zDbName==0 ){
    if( g.localOpen ){
      zDbName = db_repository_filename();
    }
    if( zDbName==0 ){
      db_err("unable to find the name of a repository database");
    }
  }
  if( file_access(zDbName, R_OK) 
   || (sz = file_size(zDbName, ExtFILE))<16384
   || (sz&0x1ff)!=0
  ){
    if( file_access(zDbName, F_OK) ){
#ifdef FOSSIL_ENABLE_JSON
      g.json.resultCode = FSL_JSON_E_DB_NOT_FOUND;
#endif
      fossil_fatal("repository does not exist or"
                   " is in an unreadable directory: %s", zDbName);
    }else if( file_access(zDbName, R_OK) ){

**   --nested          Allow opening a repository inside an opened checkout
**   --nosync          Do not auto-sync the repository prior to opening
**   --repodir DIR     If REPOSITORY is a URI that will be cloned, store
**                     the clone in DIR rather than in "."
**   --setmtime        Set timestamps of all files to match their SCM-side
**                     times (the timestamp of the last checkin which modified
**                     them).
**   --verbose         If passed a URI then this flag is passed on to the clone
**                     operation, otherwise it has no effect.
**   --workdir DIR     Use DIR as the working directory instead of ".". The DIR
**                     directory is created if it does not exist.
**
** See also: [[close]], [[clone]]
*/
void cmd_open(void){
  int emptyFlag;
  int keepFlag;
  int forceMissingFlag;
  int allowNested;
  int setmtimeFlag;              /* --setmtime.  Set mtimes on files */
  int bForce = 0;                /* --force.  Open even if non-empty dir */
  static char *azNewArgv[] = { 0, "checkout", "--prompt", 0, 0, 0, 0 };
  const char *zWorkDir;          /* --workdir value */
  const char *zRepo = 0;         /* Name of the repository file */
  const char *zRepoDir = 0;      /* --repodir value */
  char *zPwd;                    /* Initial working directory */
  int isUri = 0;                 /* True if REPOSITORY is a URI */
  int nLocal;                    /* Number of preexisting files in cwd */
  int bNosync = 0;               /* --nosync.  Omit auto-sync */
  int bVerbose = 0;              /* --verbose option for clone */

  url_proxy_options();
  emptyFlag = find_option("empty",0,0)!=0;
  keepFlag = find_option("keep",0,0)!=0;
  forceMissingFlag = find_option("force-missing",0,0)!=0;
  allowNested = find_option("nested",0,0)!=0;
  setmtimeFlag = find_option("setmtime",0,0)!=0;
  zWorkDir = find_option("workdir",0,1);
  zRepoDir = find_option("repodir",0,1);
  bForce = find_option("force","f",0)!=0;  
  bNosync = find_option("nosync",0,0)!=0;
  bVerbose = find_option("verbose",0,0)!=0;
  zPwd = file_getcwd(0,0);
  

  /* We should be done with options.. */
  verify_all_options();

  if( g.argc!=3 && g.argc!=4 ){

    }
    if( zRepoDir==0 ) zRepoDir = zPwd;
    zRepo = mprintf("%s/%s.fossil", zRepoDir, zNewBase);
    fossil_free(zNewBase);
    blob_init(&cmd, 0, 0);
    blob_append_escaped_arg(&cmd, g.nameOfExe, 1);
    blob_append(&cmd, " clone", -1);
    if(0!=bVerbose){
      blob_append(&cmd, " --verbose", -1);
    }
    blob_append_escaped_arg(&cmd, zUri, 1);
    blob_append_escaped_arg(&cmd, zRepo, 1);
    zCmd = blob_str(&cmd);
    fossil_print("%s\n", zCmd);
    if( zWorkDir ) file_chdir(zPwd, 0);
    rc = fossil_system(zCmd);
    if( rc ){

      if( rc==0 ) transport.isOpen = 1;
#else
      socket_set_errmsg("HTTPS: Fossil has been compiled without SSL support");
      rc = 1;
#endif
    }else if( pUrlData->isFile ){
      sqlite3_uint64 iRandId;
      if( !db_looks_like_a_repository(pUrlData->name) ){
        fossil_fatal("not a fossil repository: \"%s\"", pUrlData->name);
      }
      sqlite3_randomness(sizeof(iRandId), &iRandId);
      transport.zOutFile = mprintf("%s-%llu-out.http",
                                       g.zRepositoryName, iRandId);
      transport.zInFile = mprintf("%s-%llu-in.http",
                                       g.zRepositoryName, iRandId);
      transport.pFile = fossil_fopen(transport.zOutFile, "wb");
      if( transport.pFile==0 ){

    }
    style_submenu_element("Artifact", "%R/artifact/%S", zUuid);
    zMime = mimetype_from_name(zName);
    style_submenu_element("Annotate", "%R/annotate?filename=%T&checkin=%T",
                          zName, zCI);
    style_submenu_element("Blame", "%R/blame?filename=%T&checkin=%T",
                          zName, zCI);
    style_submenu_element("Doc", "%R/doc/%T/%T", zCI, zName);
    blob_init(&downloadName, zName, -1);
    objType = OBJTYPE_CONTENT;
  }else{
    @ <h2>Artifact
    style_copy_button(1, "hash-ar", 0, 2, "%s", zUuid);
    if( g.perm.Setup ){
      @  (%d(rid)):</h2>

**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.37.0"
#define SQLITE_VERSION_NUMBER 3037000
#define SQLITE_SOURCE_ID      "2021-11-15 19:10:13 bd66ab8a1bc3c43a57c7caff5f54545b0feb0177f1f51492f30d308c123c43ba"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros

#define SQLITE_OPEN_SUPER_JOURNAL    0x00004000  /* VFS only */
#define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
#define SQLITE_OPEN_NOFOLLOW         0x01000000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_EXRESCODE        0x02000000  /* Extended result codes */

/* Reserved:                         0x00F00000 */
/* Legacy compatibility: */
#define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */


/*

** the default shared cache setting provided by
** [sqlite3_enable_shared_cache()].)^
**
** ^(<dt>[SQLITE_OPEN_PRIVATECACHE]</dt>
** <dd>The database is opened [shared cache] disabled, overriding
** the default shared cache setting provided by
** [sqlite3_enable_shared_cache()].)^
**
** [[OPEN_EXRESCODE]] ^(<dt>[SQLITE_OPEN_EXRESCODE]</dt>
** <dd>The database connection comes up in "extended result code mode".
** In other words, the database behaves has if
** [sqlite3_extended_result_codes(db,1)] where called on the database
** connection as soon as the connection is created. In addition to setting
** the extended result code mode, this flag also causes [sqlite3_open_v2()]
** to return an extended result code.</dd>
**
** [[OPEN_NOFOLLOW]] ^(<dt>[SQLITE_OPEN_NOFOLLOW]</dt>
** <dd>The database filename is not allowed to be a symbolic link</dd>
** </dl>)^
**
** If the 3rd parameter to sqlite3_open_v2() is not one of the
** required combinations shown above optionally combined with other

#define SQLITE_Defensive      0x10000000  /* Input SQL is likely hostile */
#define SQLITE_DqsDDL         0x20000000  /* dbl-quoted strings allowed in DDL*/
#define SQLITE_DqsDML         0x40000000  /* dbl-quoted strings allowed in DML*/
#define SQLITE_EnableView     0x80000000  /* Enable the use of views */
#define SQLITE_CountRows      HI(0x00001) /* Count rows changed by INSERT, */
                                          /*   DELETE, or UPDATE and return */
                                          /*   the count using a callback. */
#define SQLITE_CorruptRdOnly  HI(0x00002) /* Prohibit writes due to error */

/* Flags used only if debugging */
#ifdef SQLITE_DEBUG
#define SQLITE_SqlTrace       HI(0x0100000) /* Debug print SQL as it executes */
#define SQLITE_VdbeListing    HI(0x0200000) /* Debug listings of VDBE progs */
#define SQLITE_VdbeTrace      HI(0x0400000) /* True to trace VDBE execution */
#define SQLITE_VdbeAddopTrace HI(0x0800000) /* Trace sqlite3VdbeAddOp() calls */

  int walkerDepth;                          /* Number of subqueries */
  u16 eCode;                                /* A small processing code */
  union {                                   /* Extra data for callback */
    NameContext *pNC;                         /* Naming context */
    int n;                                    /* A counter */
    int iCur;                                 /* A cursor number */
    SrcList *pSrcList;                        /* FROM clause */

    struct CCurHint *pCCurHint;               /* Used by codeCursorHint() */
    struct RefSrcList *pRefSrcList;           /* sqlite3ReferencesSrcList() */
    int *aiCol;                               /* array of column indexes */
    struct IdxCover *pIdxCover;               /* Check for index coverage */
    struct IdxExprTrans *pIdxTrans;           /* Convert idxed expr to column */
    ExprList *pGroupBy;                       /* GROUP BY clause */
    Select *pSelect;                          /* HAVING to WHERE clause ctx */
    struct WindowRewrite *pRewrite;           /* Window rewrite context */
    struct WhereConst *pConst;                /* WHERE clause constants */

SQLITE_PRIVATE int sqlite3ExprListCompare(const ExprList*,const ExprList*, int);
SQLITE_PRIVATE int sqlite3ExprImpliesExpr(const Parse*,const Expr*,const Expr*, int);
SQLITE_PRIVATE int sqlite3ExprImpliesNonNullRow(Expr*,int);
SQLITE_PRIVATE void sqlite3AggInfoPersistWalkerInit(Walker*,Parse*);
SQLITE_PRIVATE void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);
SQLITE_PRIVATE void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
SQLITE_PRIVATE int sqlite3ExprCoveredByIndex(Expr*, int iCur, Index *pIdx);
SQLITE_PRIVATE int sqlite3ReferencesSrcList(Parse*, Expr*, SrcList*);
SQLITE_PRIVATE Vdbe *sqlite3GetVdbe(Parse*);
#ifndef SQLITE_UNTESTABLE
SQLITE_PRIVATE void sqlite3PrngSaveState(void);
SQLITE_PRIVATE void sqlite3PrngRestoreState(void);
#endif
SQLITE_PRIVATE void sqlite3RollbackAll(sqlite3*,int);
SQLITE_PRIVATE void sqlite3CodeVerifySchema(Parse*, int);

# define sqlite3VdbeMemSetDouble sqlite3VdbeMemSetInt64
#else
SQLITE_PRIVATE   void sqlite3VdbeMemSetDouble(Mem*, double);
#endif
SQLITE_PRIVATE void sqlite3VdbeMemSetPointer(Mem*, void*, const char*, void(*)(void*));
SQLITE_PRIVATE void sqlite3VdbeMemInit(Mem*,sqlite3*,u16);
SQLITE_PRIVATE void sqlite3VdbeMemSetNull(Mem*);
#ifndef SQLITE_OMIT_INCRBLOB
SQLITE_PRIVATE void sqlite3VdbeMemSetZeroBlob(Mem*,int);
#else
SQLITE_PRIVATE int sqlite3VdbeMemSetZeroBlob(Mem*,int);
#endif
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE int sqlite3VdbeMemIsRowSet(const Mem*);
#endif
SQLITE_PRIVATE int sqlite3VdbeMemSetRowSet(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemMakeWriteable(Mem*);
SQLITE_PRIVATE int sqlite3VdbeMemStringify(Mem*, u8, u8);
SQLITE_PRIVATE int sqlite3IntFloatCompare(i64,double);

** support WAL mode) the truncate() method is only used to reduce
** the size of a file, never to increase the size.
*/
static int memdbTruncate(sqlite3_file *pFile, sqlite_int64 size){
  MemStore *p = ((MemFile*)pFile)->pStore;
  int rc = SQLITE_OK;
  memdbEnter(p);
  if( size>p->sz ){
    /* This can only happen with a corrupt wal mode db */
    rc = SQLITE_CORRUPT;
  }else{
    p->sz = size;
  }
  memdbLeave(p);
  return rc;
}

        }
        if( iFree2 ){
          if( iFree+sz>iFree2 ) return SQLITE_CORRUPT_PAGE(pPage);
          sz2 = get2byte(&data[iFree2+2]);
          if( iFree2+sz2 > usableSize ) return SQLITE_CORRUPT_PAGE(pPage);
          memmove(&data[iFree+sz+sz2], &data[iFree+sz], iFree2-(iFree+sz));
          sz += sz2;
        }else if( NEVER(iFree+sz>usableSize) ){
          return SQLITE_CORRUPT_PAGE(pPage);
        }

        cbrk = top+sz;
        assert( cbrk+(iFree-top) <= usableSize );
        memmove(&data[cbrk], &data[top], iFree-top);
        for(pAddr=&data[cellOffset]; pAddr<pEnd; pAddr+=2){

  u8 *pTmp = sqlite3PagerTempSpace(pPg->pBt->pPager);
  u8 *pData;
  int k;                          /* Current slot in pCArray->apEnd[] */
  u8 *pSrcEnd;                    /* Current pCArray->apEnd[k] value */

  assert( i<iEnd );
  j = get2byte(&aData[hdr+5]);
  if( NEVER(j>(u32)usableSize) ){ j = 0; }
  memcpy(&pTmp[j], &aData[j], usableSize - j);

  for(k=0; pCArray->ixNx[k]<=i && ALWAYS(k<NB*2); k++){}
  pSrcEnd = pCArray->apEnd[k];

  pData = pEnd;
  while( 1/*exit by break*/ ){

  sqlite3VdbeMemSetNull((Mem*)p);
}

/*
** Delete any previous value and set the value to be a BLOB of length
** n containing all zeros.
*/
#ifndef SQLITE_OMIT_INCRBLOB
SQLITE_PRIVATE void sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){
  sqlite3VdbeMemRelease(pMem);
  pMem->flags = MEM_Blob|MEM_Zero;
  pMem->n = 0;
  if( n<0 ) n = 0;
  pMem->u.nZero = n;
  pMem->enc = SQLITE_UTF8;
  pMem->z = 0;
}
#else
SQLITE_PRIVATE int sqlite3VdbeMemSetZeroBlob(Mem *pMem, int n){
  int nByte = n>0?n:1;
  if( sqlite3VdbeMemGrow(pMem, nByte, 0) ){
    return SQLITE_NOMEM_BKPT;
  }
  assert( pMem->z!=0 );
  assert( sqlite3DbMallocSize(pMem->db, pMem->z)>=nByte );
  memset(pMem->z, 0, nByte);
  pMem->n = n>0?n:0;
  pMem->flags = MEM_Blob;
  pMem->enc = SQLITE_UTF8;
  return SQLITE_OK;
}
#endif

/*
** The pMem is known to contain content that needs to be destroyed prior
** to a value change.  So invoke the destructor, then set the value to
** a 64-bit integer.
*/
static SQLITE_NOINLINE void vdbeReleaseAndSetInt64(Mem *pMem, i64 val){

    int eStatementOp = 0;
    int isSpecialError;            /* Set to true if a 'special' error */

    /* Lock all btrees used by the statement */
    sqlite3VdbeEnter(p);

    /* Check for one of the special errors */
    if( p->rc ){
      mrc = p->rc & 0xff;
      isSpecialError = mrc==SQLITE_NOMEM
                    || mrc==SQLITE_IOERR
                    || mrc==SQLITE_INTERRUPT
                    || mrc==SQLITE_FULL;
    }else{
      mrc = isSpecialError = 0;
    }
    if( isSpecialError ){
      /* If the query was read-only and the error code is SQLITE_INTERRUPT,
      ** no rollback is necessary. Otherwise, at least a savepoint
      ** transaction must be rolled back to restore the database to a
      ** consistent state.
      **
      ** Even if the statement is read-only, it is important to perform

        rc = sqlite3VdbeCheckFk(p, 1);
        if( rc!=SQLITE_OK ){
          if( NEVER(p->readOnly) ){
            sqlite3VdbeLeave(p);
            return SQLITE_ERROR;
          }
          rc = SQLITE_CONSTRAINT_FOREIGNKEY;
        }else if( db->flags & SQLITE_CorruptRdOnly ){
          rc = SQLITE_CORRUPT;
          db->flags &= ~SQLITE_CorruptRdOnly;
        }else{
          /* The auto-commit flag is true, the vdbe program was successful
          ** or hit an 'OR FAIL' constraint and there are no deferred foreign
          ** key constraints to hold up the transaction. This means a commit
          ** is required. */
          rc = vdbeCommit(db, p);
        }

    if( op==SQLITE_UPDATE ){
      iKey2 = v->aMem[iReg].u.i;
    }else{
      iKey2 = iKey1;
    }
  }

  assert( pCsr!=0 );
  assert( pCsr->eCurType==CURTYPE_BTREE );
  assert( pCsr->nField==pTab->nCol
       || (pCsr->nField==pTab->nCol+1 && op==SQLITE_DELETE && iReg==-1)
  );

  preupdate.v = v;
  preupdate.pCsr = pCsr;
  preupdate.op = op;

}
SQLITE_API int sqlite3_result_zeroblob64(sqlite3_context *pCtx, u64 n){
  Mem *pOut = pCtx->pOut;
  assert( sqlite3_mutex_held(pOut->db->mutex) );
  if( n>(u64)pOut->db->aLimit[SQLITE_LIMIT_LENGTH] ){
    return SQLITE_TOOBIG;
  }
#ifndef SQLITE_OMIT_INCRBLOB
  sqlite3VdbeMemSetZeroBlob(pCtx->pOut, (int)n);
  return SQLITE_OK;
#else
  return sqlite3VdbeMemSetZeroBlob(pCtx->pOut, (int)n);
#endif
}
SQLITE_API void sqlite3_result_error_code(sqlite3_context *pCtx, int errCode){
  pCtx->isError = errCode ? errCode : -1;
#ifdef SQLITE_DEBUG
  if( pCtx->pVdbe ) pCtx->pVdbe->rcApp = errCode;
#endif
  if( pCtx->pOut->flags & MEM_Null ){

  return rc;
}
SQLITE_API int sqlite3_bind_zeroblob(sqlite3_stmt *pStmt, int i, int n){
  int rc;
  Vdbe *p = (Vdbe *)pStmt;
  rc = vdbeUnbind(p, i);
  if( rc==SQLITE_OK ){
#ifndef SQLITE_OMIT_INCRBLOB
    sqlite3VdbeMemSetZeroBlob(&p->aVar[i-1], n);
#else
    rc = sqlite3VdbeMemSetZeroBlob(&p->aVar[i-1], n);
#endif
    sqlite3_mutex_leave(p->db->mutex);
  }
  return rc;
}
SQLITE_API int sqlite3_bind_zeroblob64(sqlite3_stmt *pStmt, int i, sqlite3_uint64 n){
  int rc;
  Vdbe *p = (Vdbe *)pStmt;

  }

  /* If the old.* record has not yet been loaded into memory, do so now. */
  if( p->pUnpacked==0 ){
    u32 nRec;
    u8 *aRec;

    assert( p->pCsr->eCurType==CURTYPE_BTREE );
    nRec = sqlite3BtreePayloadSize(p->pCsr->uc.pCursor);
    aRec = sqlite3DbMallocRaw(db, nRec);
    if( !aRec ) goto preupdate_old_out;
    rc = sqlite3BtreePayload(p->pCsr->uc.pCursor, 0, nRec, aRec);
    if( rc==SQLITE_OK ){
      p->pUnpacked = vdbeUnpackRecord(&p->keyinfo, nRec, aRec);
      if( !p->pUnpacked ) rc = SQLITE_NOMEM;

  assert( p->bIsReader );
  assert( p->readOnly==0 || pOp->p2==0 );
  assert( pOp->p2>=0 && pOp->p2<=2 );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( DbMaskTest(p->btreeMask, pOp->p1) );
  assert( rc==SQLITE_OK );
  if( pOp->p2 && (db->flags & (SQLITE_QueryOnly|SQLITE_CorruptRdOnly))!=0 ){
    if( db->flags & SQLITE_QueryOnly ){
      /* Writes prohibited by the "PRAGMA query_only=TRUE" statement */
      rc = SQLITE_READONLY;
    }else{
      /* Writes prohibited due to a prior SQLITE_CORRUPT in the current
      ** transaction */
      rc = SQLITE_CORRUPT;
    }
    goto abort_due_to_error;
  }
  pBt = db->aDb[pOp->p1].pBt;

  if( pBt ){
    rc = sqlite3BtreeBeginTrans(pBt, pOp->p2, &iMeta);
    testcase( rc==SQLITE_BUSY_SNAPSHOT );

  Mem **apArg;

  pQuery = &aMem[pOp->p3];
  pArgc = &pQuery[1];
  pCur = p->apCsr[pOp->p1];
  assert( memIsValid(pQuery) );
  REGISTER_TRACE(pOp->p3, pQuery);
  assert( pCur!=0 );
  assert( pCur->eCurType==CURTYPE_VTAB );
  pVCur = pCur->uc.pVCur;
  pVtab = pVCur->pVtab;
  pModule = pVtab->pModule;

  /* Grab the index number and argc parameters */
  assert( (pQuery->flags&MEM_Int)!=0 && pArgc->flags==MEM_Int );

case OP_VColumn: {
  sqlite3_vtab *pVtab;
  const sqlite3_module *pModule;
  Mem *pDest;
  sqlite3_context sContext;

  VdbeCursor *pCur = p->apCsr[pOp->p1];
  assert( pCur!=0 );
  assert( pCur->eCurType==CURTYPE_VTAB );
  assert( pOp->p3>0 && pOp->p3<=(p->nMem+1 - p->nCursor) );
  pDest = &aMem[pOp->p3];
  memAboutToChange(p, pDest);
  if( pCur->nullRow ){
    sqlite3VdbeMemSetNull(pDest);
    break;

case OP_VNext: {   /* jump */
  sqlite3_vtab *pVtab;
  const sqlite3_module *pModule;
  int res;
  VdbeCursor *pCur;

  pCur = p->apCsr[pOp->p1];
  assert( pCur!=0 );
  assert( pCur->eCurType==CURTYPE_VTAB );
  if( pCur->nullRow ){
    break;
  }
  pVtab = pCur->uc.pVCur->pVtab;
  pModule = pVtab->pModule;
  assert( pModule->xNext );

** apply in the case of a constraint failure on an insert or update.
*/
case OP_VUpdate: {
  sqlite3_vtab *pVtab;
  const sqlite3_module *pModule;
  int nArg;
  int i;
  sqlite_int64 rowid = 0;
  Mem **apArg;
  Mem *pX;

  assert( pOp->p2==1        || pOp->p5==OE_Fail   || pOp->p5==OE_Rollback
       || pOp->p5==OE_Abort || pOp->p5==OE_Ignore || pOp->p5==OE_Replace
  );
  assert( p->readOnly==0 );

    rc = SQLITE_NOMEM_BKPT;
  }else if( rc==SQLITE_IOERR_CORRUPTFS ){
    rc = SQLITE_CORRUPT_BKPT;
  }
  assert( rc );
#ifdef SQLITE_DEBUG
  if( db->flags & SQLITE_VdbeTrace ){
    const char *zTrace = p->zSql;
    if( zTrace==0 ){
      if( aOp[0].opcode==OP_Trace ){
        zTrace = aOp[0].p4.z;
      }
      if( zTrace==0 ) zTrace = "???";
    }
    printf("ABORT-due-to-error (rc=%d): %s\n", rc, zTrace);
  }
#endif
  if( p->zErrMsg==0 && rc!=SQLITE_IOERR_NOMEM ){
    sqlite3VdbeError(p, "%s", sqlite3ErrStr(rc));
  }
  p->rc = rc;
  sqlite3SystemError(db, rc);
  testcase( sqlite3GlobalConfig.xLog!=0 );
  sqlite3_log(rc, "statement aborts at %d: [%s] %s",
                   (int)(pOp - aOp), p->zSql, p->zErrMsg);
  sqlite3VdbeHalt(p);
  if( rc==SQLITE_IOERR_NOMEM ) sqlite3OomFault(db);
  if( rc==SQLITE_CORRUPT && db->autoCommit==0 ){
    db->flags |= SQLITE_CorruptRdOnly;
  }
  rc = SQLITE_ERROR;
  if( resetSchemaOnFault>0 ){
    sqlite3ResetOneSchema(db, resetSchemaOnFault-1);
  }

  /* This is the only way out of this procedure.  We have to
  ** release the mutexes on btrees that were acquired at the

    assert( v->aOp[v->pc].opcode==OP_NotExists );
    rc = sqlite3VdbeExec(v);
  }else{
    rc = sqlite3_step(p->pStmt);
  }
  if( rc==SQLITE_ROW ){
    VdbeCursor *pC = v->apCsr[0];
    u32 type;
    assert( pC!=0 );
    assert( pC->eCurType==CURTYPE_BTREE );
    type = pC->nHdrParsed>p->iCol ? pC->aType[p->iCol] : 0;
    testcase( pC->nHdrParsed==p->iCol );
    testcase( pC->nHdrParsed==p->iCol+1 );
    if( type<12 ){
      zErr = sqlite3MPrintf(p->db, "cannot open value of type %s",
          type==0?"null": type==7?"real": "integer"
      );
      rc = SQLITE_ERROR;

      ** same way as an SQLITE_DELETE (the SQLITE_DELETE code is actually
      ** slightly more efficient). Since you cannot write to a PK column
      ** using the incremental-blob API, this works. For the sessions module
      ** anyhow.
      */
      sqlite3_int64 iKey;
      iKey = sqlite3BtreeIntegerKey(p->pCsr);
      assert( v->apCsr[0]!=0 );
      assert( v->apCsr[0]->eCurType==CURTYPE_BTREE );
      sqlite3VdbePreUpdateHook(
          v, v->apCsr[0], SQLITE_DELETE, p->zDb, p->pTab, iKey, -1, p->iCol
      );
    }
#endif

    rc = xCall(p->pCsr, iOffset+p->iOffset, n, z);

          sqlite3WalkExprList(pWalker, pWin->pOrderBy);
          sqlite3WalkExpr(pWalker, pWin->pFilter);
          sqlite3WindowLink(pSel, pWin);
          pNC->ncFlags |= NC_HasWin;
        }else
#endif /* SQLITE_OMIT_WINDOWFUNC */
        {
          NameContext *pNC2;          /* For looping up thru outer contexts */
          pExpr->op = TK_AGG_FUNCTION;
          pExpr->op2 = 0;
#ifndef SQLITE_OMIT_WINDOWFUNC
          if( ExprHasProperty(pExpr, EP_WinFunc) ){
            sqlite3WalkExpr(pWalker, pExpr->y.pWin->pFilter);
          }
#endif
          pNC2 = pNC;
          while( pNC2
              && sqlite3ReferencesSrcList(pParse, pExpr, pNC2->pSrcList)==0
          ){
            pExpr->op2++;
            pNC2 = pNC2->pNext;
          }
          assert( pDef!=0 || IN_RENAME_OBJECT );
          if( pNC2 && pDef ){
            assert( SQLITE_FUNC_MINMAX==NC_MinMaxAgg );
            assert( SQLITE_FUNC_ANYORDER==NC_OrderAgg );

static void exprCodeBetween(Parse*,Expr*,int,void(*)(Parse*,Expr*,int,int),int);
static int exprCodeVector(Parse *pParse, Expr *p, int *piToFree);

/*
** Return the affinity character for a single column of a table.
*/
SQLITE_PRIVATE char sqlite3TableColumnAffinity(const Table *pTab, int iCol){
  if( iCol<0 || NEVER(iCol>=pTab->nCol) ) return SQLITE_AFF_INTEGER;
  return pTab->aCol[iCol].affinity;
}

/*
** Return the 'affinity' of the expression pExpr if any.
**
** If pExpr is a column, a reference to a column via an 'AS' alias,
** or a sub-select with a column as the return value, then the

          colUsed = 0;   /* Columns of index used so far */
          for(i=0; i<nExpr; i++){
            Expr *pLhs = sqlite3VectorFieldSubexpr(pX->pLeft, i);
            Expr *pRhs = pEList->a[i].pExpr;
            CollSeq *pReq = sqlite3BinaryCompareCollSeq(pParse, pLhs, pRhs);
            int j;

            assert( pReq!=0 || pRhs->iColumn==XN_ROWID
                   || pParse->nErr || db->mallocFailed );
            for(j=0; j<nExpr; j++){
              if( pIdx->aiColumn[j]!=pRhs->iColumn ) continue;
              assert( pIdx->azColl[j] );
              if( pReq!=0 && sqlite3StrICmp(pReq->zName, pIdx->azColl[j])!=0 ){
                continue;
              }
              break;

  w.xExprCallback = exprIdxCover;
  w.u.pIdxCover = &xcov;
  sqlite3WalkExpr(&w, pExpr);
  return !w.eCode;
}



/* Structure used to pass information throught the Walker in order to

** implement sqlite3ReferencesSrcList().

*/
struct RefSrcList {
  sqlite3 *db;         /* Database connection used for sqlite3DbRealloc() */
  SrcList *pRef;       /* Looking for references to these tables */

  int nExclude;        /* Number of tables to exclude from the search */
  int *aiExclude;      /* Cursor IDs for tables to exclude from the search */
};

/*
** Walker SELECT callbacks for sqlite3ReferencesSrcList().
**
** When entering a new subquery on the pExpr argument, add all FROM clause

** entries for that subquery to the exclude list.
**
** When leaving the subquery, remove those entries from the exclude list.
*/
static int selectRefEnter(Walker *pWalker, Select *pSelect){
  struct RefSrcList *p = pWalker->u.pRefSrcList;
  SrcList *pSrc = pSelect->pSrc;
  int i, j, *piNew;
  if( pSrc->nSrc==0 ) return WRC_Continue;
  j = p->nExclude;
  p->nExclude += pSrc->nSrc;
  piNew = sqlite3DbRealloc(p->db, p->aiExclude, p->nExclude*sizeof(int));
  if( piNew==0 ){
    p->nExclude = 0;
    return WRC_Abort;
  }else{
    p->aiExclude = piNew;
  }
  for(i=0; i<pSrc->nSrc; i++, j++){
     p->aiExclude[j] = pSrc->a[i].iCursor;
  }
  return WRC_Continue;
}
static void selectRefLeave(Walker *pWalker, Select *pSelect){
  struct RefSrcList *p = pWalker->u.pRefSrcList;
  SrcList *pSrc = pSelect->pSrc;
  if( p->nExclude ){
    assert( p->nExclude>=pSrc->nSrc );
    p->nExclude -= pSrc->nSrc;
  }
}

/* This is the Walker EXPR callback for sqlite3ReferencesSrcList().
**
** Set the 0x01 bit of pWalker->eCode if there is a reference to any
** of the tables shown in RefSrcList.pRef.
**
** Set the 0x02 bit of pWalker->eCode if there is a reference to a
** table is in neither RefSrcList.pRef nor RefSrcList.aiExclude.
*/
static int exprRefToSrcList(Walker *pWalker, Expr *pExpr){






  if( pExpr->op==TK_COLUMN
   || pExpr->op==TK_AGG_COLUMN
  ){
    int i;
    struct RefSrcList *p = pWalker->u.pRefSrcList;
    SrcList *pSrc = p->pRef;
    int nSrc = pSrc ? pSrc->nSrc : 0;
    for(i=0; i<nSrc; i++){
      if( pExpr->iTable==pSrc->a[i].iCursor ){
        pWalker->eCode |= 1;
        return WRC_Continue;
      }


    }
    for(i=0; i<p->nExclude && p->aiExclude[i]!=pExpr->iTable; i++){}



    if( i>=p->nExclude ){
      pWalker->eCode |= 2;
    }
  }
  return WRC_Continue;
}

/*
** Check to see if pExpr references any tables in pSrcList.
** Possible return values:
**
**    1         pExpr does references a table in pSrcList.
**
**    0         pExpr references some table that is not defined in either
**              pSrcList or in subqueries of pExpr itself.
**
**   -1         pExpr only references no tables at all, or it only
**              references tables defined in subqueries of pExpr itself.
**
** As currently used, pExpr is always an aggregate function call.  That
** fact is exploited for efficiency.
*/
SQLITE_PRIVATE int sqlite3ReferencesSrcList(Parse *pParse, Expr *pExpr, SrcList *pSrcList){
  Walker w;
  struct RefSrcList x;

  memset(&w, 0, sizeof(w));
  memset(&x, 0, sizeof(x));
  w.xExprCallback = exprRefToSrcList;
  w.xSelectCallback = selectRefEnter;
  w.xSelectCallback2 = selectRefLeave;
  w.u.pRefSrcList = &x;
  x.db = pParse->db;
  x.pRef = pSrcList;



  assert( pExpr->op==TK_AGG_FUNCTION );
  assert( ExprUseXList(pExpr) );
  sqlite3WalkExprList(&w, pExpr->x.pList);
#ifndef SQLITE_OMIT_WINDOWFUNC
  if( ExprHasProperty(pExpr, EP_WinFunc) ){
    sqlite3WalkExpr(&w, pExpr->y.pWin->pFilter);
  }
#endif
  sqlite3DbFree(pParse->db, x.aiExclude);
  if( w.eCode & 0x01 ){
    return 1;
  }else if( w.eCode ){
    return 0;
  }else{
    return -1;
  }
}

/*
** This is a Walker expression node callback.
**
** For Expr nodes that contain pAggInfo pointers, make sure the AggInfo
** object that is referenced does not refer directly to the Expr.  If

  Module *pMod;                 /* Module for the virtual table */
  HashElem *k;                  /* For looping through the symbol table */

  assert( IsVirtual(pTab) );
  pMod = (Module*)sqlite3HashFind(&db->aModule, pTab->u.vtab.azArg[0]);
  if( pMod==0 ) return;
  if( NEVER(pMod->pModule==0) ) return;
  if( pMod->pModule->iVersion<3 ) return;
  if( pMod->pModule->xShadowName==0 ) return;
  assert( pTab->zName!=0 );
  nName = sqlite3Strlen30(pTab->zName);
  for(k=sqliteHashFirst(&pTab->pSchema->tblHash); k; k=sqliteHashNext(k)){
    Table *pOther = sqliteHashData(k);
    assert( pOther->zName!=0 );
    if( !IsOrdinaryTable(pOther) ) continue;

  if( sqlite3StrNICmp(pTab->zName, "sqlite_", 7)==0 ){
    if( sqlite3StrNICmp(pTab->zName+7, "stat", 4)==0 ) return 0;
    if( sqlite3StrNICmp(pTab->zName+7, "parameters", 10)==0 ) return 0;
    return 1;
  }
  if( (pTab->tabFlags & TF_Shadow)!=0 && sqlite3ReadOnlyShadowTables(db) ){
    return 1;
  }
  if( pTab->tabFlags & TF_Eponymous ){
    return 1;
  }
  return 0;
}

/*
** This routine is called to do the work of a DROP TABLE statement.
** pName is the name of the table to be dropped.

#define sqlite3_free_filename          sqlite3_api->free_filename
#define sqlite3_database_file_object   sqlite3_api->database_file_object
/* Version 3.34.0 and later */
#define sqlite3_txn_state              sqlite3_api->txn_state
/* Version 3.36.1 and later */
#define sqlite3_changes64              sqlite3_api->changes64
#define sqlite3_total_changes64        sqlite3_api->total_changes64
/* Version 3.37.0 and later */
#define sqlite3_autovacuum_pages       sqlite3_api->autovacuum_pages
#endif /* !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION) */

#if !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION)
  /* This case when the file really is being compiled as a loadable
  ** extension */
# define SQLITE_EXTENSION_INIT1     const sqlite3_api_routines *sqlite3_api=0;

    if( zType ){
      m = sqlite3Strlen30(zType);
      n = sqlite3Strlen30(pCol->zCnName);
      pCol->zCnName = sqlite3DbReallocOrFree(db, pCol->zCnName, n+m+2);
      if( pCol->zCnName ){
        memcpy(&pCol->zCnName[n+1], zType, m+1);
        pCol->colFlags |= COLFLAG_HASTYPE;
      }else{
        testcase( pCol->colFlags & COLFLAG_HASTYPE );
        pCol->colFlags &= ~(COLFLAG_HASTYPE|COLFLAG_HASCOLL);
      }
    }
    if( pCol->affinity<=SQLITE_AFF_NONE ) pCol->affinity = aff;
    pColl = sqlite3ExprCollSeq(pParse, p);
    if( pColl ){
      assert( pTab->pIndex==0 );
      sqlite3ColumnSetColl(db, pCol, pColl->zName);

** The second argument is the associated aggregate-info object. This
** function tests if the SELECT is of the form:
**
**   SELECT count(*) FROM <tbl>
**
** where table is a database table, not a sub-select or view. If the query
** does match this pattern, then a pointer to the Table object representing
** <tbl> is returned. Otherwise, NULL is returned.
**
** This routine a condition for the count optimization.  A correct answer
** is obtained (though perhaps more slowly) if this routine returns NULL when
** it could have returned a table pointer.  But returning the pointer when
** NULL should have been returned can result in incorrect answers and/or
** crashes.  So, when in doubt, return NULL.
*/
static Table *isSimpleCount(Select *p, AggInfo *pAggInfo){
  Table *pTab;
  Expr *pExpr;

  assert( !p->pGroupBy );

  if( p->pWhere
   || p->pEList->nExpr!=1
   || p->pSrc->nSrc!=1
   || p->pSrc->a[0].pSelect
   || pAggInfo->nFunc!=1
  ){
    return 0;
  }
  pTab = p->pSrc->a[0].pTab;

  assert( pTab!=0 );
  assert( !IsView(pTab) );
  if( !IsOrdinaryTable(pTab) ) return 0;
  pExpr = p->pEList->a[0].pExpr;
  assert( pExpr!=0 );
  if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
  if( pExpr->pAggInfo!=pAggInfo ) return 0;
  if( (pAggInfo->aFunc[0].pFunc->funcFlags&SQLITE_FUNC_COUNT)==0 ) return 0;
  assert( pAggInfo->aFunc[0].pFExpr==pExpr );
  testcase( ExprHasProperty(pExpr, EP_Distinct) );
  testcase( ExprHasProperty(pExpr, EP_WinFunc) );
  if( ExprHasProperty(pExpr, EP_Distinct|EP_WinFunc) ) return 0;

  return pTab;
}

/*
** If the source-list item passed as an argument was augmented with an

** This call is a no-op if zTab is not a virtual table.
*/
SQLITE_PRIVATE int sqlite3VtabCallDestroy(sqlite3 *db, int iDb, const char *zTab){
  int rc = SQLITE_OK;
  Table *pTab;

  pTab = sqlite3FindTable(db, zTab, db->aDb[iDb].zDbSName);
  if( ALWAYS(pTab!=0)
   && ALWAYS(IsVirtual(pTab))
   && ALWAYS(pTab->u.vtab.p!=0)
  ){
    VTable *p;
    int (*xDestroy)(sqlite3_vtab *);
    for(p=pTab->u.vtab.p; p; p=p->pNext){
      assert( p->pVtab );
      if( p->pVtab->nRef>0 ){
        return SQLITE_LOCKED;
      }

  /* Generate the code to do the search.  Each iteration of the for
  ** loop below generates code for a single nested loop of the VM
  ** program.
  */
  for(ii=0; ii<nTabList; ii++){
    int addrExplain;
    int wsFlags;
    if( pParse->nErr ) goto whereBeginError;
    pLevel = &pWInfo->a[ii];
    wsFlags = pLevel->pWLoop->wsFlags;
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    if( (pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){
      constructAutomaticIndex(pParse, &pWInfo->sWC,
                &pTabList->a[pLevel->iFrom], notReady, pLevel);
      if( db->mallocFailed ) goto whereBeginError;

        w.xSelectCallback2 = sqlite3WalkerDepthDecrease;
        sqlite3WalkSelect(&w, pSub);
      }
    }else{
      sqlite3SelectDelete(db, pSub);
    }
    if( db->mallocFailed ) rc = SQLITE_NOMEM;

    /* Defer deleting the temporary table pTab because if an error occurred,
    ** there could still be references to that table embedded in the
    ** result-set or ORDER BY clause of the SELECT statement p.  */
    sqlite3ParserAddCleanup(pParse, sqlite3DbFree, pTab);
  }

  if( rc ){
    if( pParse->nErr==0 ){
      assert( pParse->db->mallocFailed );
      sqlite3ErrorToParser(pParse->db, SQLITE_NOMEM);
    }

#else
  yyStackEntry yystack[YYSTACKDEPTH];  /* The parser's stack */
  yyStackEntry *yystackEnd;            /* Last entry in the stack */
#endif
};
typedef struct yyParser yyParser;

/* #include <assert.h> */
#ifndef NDEBUG
/* #include <stdio.h> */

static FILE *yyTraceFILE = 0;
static char *yyTracePrompt = 0;
#endif /* NDEBUG */

#ifndef NDEBUG
/*
** Turn parser tracing on by giving a stream to which to write the trace

  while(1){ /* Exit by "break" */
    assert( yypParser->yytos>=yypParser->yystack );
    assert( yyact==yypParser->yytos->stateno );
    yyact = yy_find_shift_action((YYCODETYPE)yymajor,yyact);
    if( yyact >= YY_MIN_REDUCE ){
      unsigned int yyruleno = yyact - YY_MIN_REDUCE; /* Reduce by this rule */

#ifndef NDEBUG
      assert( yyruleno<(int)(sizeof(yyRuleName)/sizeof(yyRuleName[0])) );
      if( yyTraceFILE ){
        int yysize = yyRuleInfoNRhs[yyruleno];
        if( yysize ){
          fprintf(yyTraceFILE, "%sReduce %d [%s]%s, pop back to state %d.\n",
            yyTracePrompt,
            yyruleno, yyRuleName[yyruleno],
            yyruleno<YYNRULE_WITH_ACTION ? "" : " without external action",

    sqlite3ResetAllSchemasOfConnection(db);
  }
  sqlite3BtreeLeaveAll(db);

  /* Any deferred constraint violations have now been resolved. */
  db->nDeferredCons = 0;
  db->nDeferredImmCons = 0;
  db->flags &= ~(u64)(SQLITE_DeferFKs|SQLITE_CorruptRdOnly);

  /* If one has been configured, invoke the rollback-hook callback */
  if( db->xRollbackCallback && (inTrans || !db->autoCommit) ){
    db->xRollbackCallback(db->pRollbackArg);
  }
}

  /* Remove harmful bits from the flags parameter
  **
  ** The SQLITE_OPEN_NOMUTEX and SQLITE_OPEN_FULLMUTEX flags were
  ** dealt with in the previous code block.  Besides these, the only
  ** valid input flags for sqlite3_open_v2() are SQLITE_OPEN_READONLY,
  ** SQLITE_OPEN_READWRITE, SQLITE_OPEN_CREATE, SQLITE_OPEN_SHAREDCACHE,
  ** SQLITE_OPEN_PRIVATECACHE, SQLITE_OPEN_EXRESCODE, and some reserved
  ** bits.  Silently mask off all other flags.
  */
  flags &=  ~( SQLITE_OPEN_DELETEONCLOSE |
               SQLITE_OPEN_EXCLUSIVE |
               SQLITE_OPEN_MAIN_DB |
               SQLITE_OPEN_TEMP_DB |
               SQLITE_OPEN_TRANSIENT_DB |
               SQLITE_OPEN_MAIN_JOURNAL |

      goto opendb_out;
    }
    if( isThreadsafe==0 ){
      sqlite3MutexWarnOnContention(db->mutex);
    }
  }
  sqlite3_mutex_enter(db->mutex);
  db->errMask = (flags & SQLITE_OPEN_EXRESCODE)!=0 ? 0xffffffff : 0xff;
  db->nDb = 2;
  db->eOpenState = SQLITE_STATE_BUSY;
  db->aDb = db->aDbStatic;
  db->lookaside.bDisable = 1;
  db->lookaside.sz = 0;

  assert( sizeof(db->aLimit)==sizeof(aHardLimit) );

opendb_out:
  if( db ){
    assert( db->mutex!=0 || isThreadsafe==0
           || sqlite3GlobalConfig.bFullMutex==0 );
    sqlite3_mutex_leave(db->mutex);
  }
  rc = sqlite3_errcode(db);
  assert( db!=0 || (rc&0xff)==SQLITE_NOMEM );
  if( (rc&0xff)==SQLITE_NOMEM ){
    sqlite3_close(db);
    db = 0;
  }else if( rc!=SQLITE_OK ){
    db->eOpenState = SQLITE_STATE_SICK;
  }
  *ppDb = db;
#ifdef SQLITE_ENABLE_SQLLOG
  if( sqlite3GlobalConfig.xSqllog ){
    /* Opening a db handle. Fourth parameter is passed 0. */
    void *pArg = sqlite3GlobalConfig.pSqllogArg;
    sqlite3GlobalConfig.xSqllog(pArg, db, zFilename, 0);
  }
#endif
  sqlite3_free_filename(zOpen);
  return rc;
}


/*
** Open a new database handle.
*/
SQLITE_API int sqlite3_open(

      int bEofSave = pNear->bEof;
      fts3EvalRestart(pCsr, pNear, &rc);
      while( rc==SQLITE_OK && !pNear->bEof ){
        fts3EvalNextRow(pCsr, pNear, &rc);
        if( bEofSave==0 && pNear->iDocid==iDocid ) break;
      }
      assert( rc!=SQLITE_OK || pPhrase->bIncr==0 );
      if( rc==SQLITE_OK && pNear->bEof!=bEofSave ){
        rc = FTS_CORRUPT_VTAB;
      }
    }
    if( bTreeEof ){
      while( rc==SQLITE_OK && !pNear->bEof ){
        fts3EvalNextRow(pCsr, pNear, &rc);
      }
    }
    if( rc!=SQLITE_OK ) return rc;

    int NDUMMY = 0;               /* Dummy argument used with xNext() */
    int iStart = 0;
    int iEnd = 0;
    int iCurrent = 0;
    const char *zDoc;
    int nDoc;

    /* Initialize the contents of sCtx.aTerm[] for column iCol. This
    ** operation may fail if the database contains corrupt records.

    */
    sCtx.iCol = iCol;
    sCtx.iTerm = 0;
    rc = fts3ExprIterate(pCsr->pExpr, fts3ExprTermOffsetInit, (void*)&sCtx);
    if( rc!=SQLITE_OK ) goto offsets_out;

    /* Retreive the text stored in column iCol. If an SQL NULL is stored
    ** in column iCol, jump immediately to the next iteration of the loop.
    ** If an OOM occurs while retrieving the data (this can happen if SQLite
    ** needs to transform the data from utf-16 to utf-8), return SQLITE_NOMEM
    ** to the caller.
    */

        if( pPatch[i+1].eType==JSON_NULL ){
          pTarget[j+1].jnFlags |= JNODE_REMOVE;
        }else{
          JsonNode *pNew = jsonMergePatch(pParse, iTarget+j+1, &pPatch[i+1]);
          if( pNew==0 ) return 0;
          pTarget = &pParse->aNode[iTarget];
          if( pNew!=&pTarget[j+1] ){
            assert( pTarget[j+1].eU==0
                 || pTarget[j+1].eU==1
                 || pTarget[j+1].eU==2 );
            testcase( pTarget[j+1].eU==1 );
            testcase( pTarget[j+1].eU==2 );
            VVA( pTarget[j+1].eU = 5 );
            pTarget[j+1].u.pPatch = pNew;
            pTarget[j+1].jnFlags |= JNODE_PATCH;
          }
        }
        break;
      }

/*
** Swap two objects of type TYPE.
*/
#if !defined(SQLITE_AMALGAMATION)
# define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
#endif

/*
** Name of the URI option that causes RBU to take an exclusive lock as
** part of the incremental checkpoint operation.
*/
#define RBU_EXCLUSIVE_CHECKPOINT "rbu_exclusive_checkpoint"


/*
** The rbu_state table is used to save the state of a partially applied
** update so that it can be resumed later. The table consists of integer
** keys mapped to values as follows:
**
** RBU_STATE_STAGE:

  return pRet;
}


/*
** Open the database handle and attach the RBU database as "rbu". If an
** error occurs, leave an error code and message in the RBU handle.
**
** If argument dbMain is not NULL, then it is a database handle already
** open on the target database. Use this handle instead of opening a new
** one.
*/
static void rbuOpenDatabase(sqlite3rbu *p, sqlite3 *dbMain, int *pbRetry){
  assert( p->rc || (p->dbMain==0 && p->dbRbu==0) );
  assert( p->rc || rbuIsVacuum(p) || p->zTarget!=0 );
  assert( dbMain==0 || rbuIsVacuum(p)==0 );

  /* Open the RBU database */
  p->dbRbu = rbuOpenDbhandle(p, p->zRbu, 1);
  p->dbMain = dbMain;

  if( p->rc==SQLITE_OK && rbuIsVacuum(p) ){
    sqlite3_file_control(p->dbRbu, "main", SQLITE_FCNTL_RBUCNT, (void*)p);
    if( p->zState==0 ){
      const char *zFile = sqlite3_db_filename(p->dbRbu, "main");
      p->zState = rbuMPrintf(p, "file://%s-vacuum?modeof=%s", zFile, zFile);
    }

  iOff = (i64)(pFrame->iDbPage-1) * p->pgsz;
  p->rc = pDb->pMethods->xWrite(pDb, p->aBuf, p->pgsz, iOff);
}


/*
** Take an EXCLUSIVE lock on the database file. Return SQLITE_OK if
** successful, or an SQLite error code otherwise.
*/
static int rbuLockDatabase(sqlite3 *db){
  int rc = SQLITE_OK;
  sqlite3_file *fd = 0;
  sqlite3_file_control(db, "main", SQLITE_FCNTL_FILE_POINTER, &fd);

  if( fd->pMethods ){
    rc = fd->pMethods->xLock(fd, SQLITE_LOCK_SHARED);
    if( rc==SQLITE_OK ){
      rc = fd->pMethods->xLock(fd, SQLITE_LOCK_EXCLUSIVE);
    }
  }
  return rc;
}

/*
** Return true if the database handle passed as the only argument
** was opened with the rbu_exclusive_checkpoint=1 URI parameter
** specified. Or false otherwise.
*/
static int rbuExclusiveCheckpoint(sqlite3 *db){
  const char *zUri = sqlite3_db_filename(db, 0);
  return sqlite3_uri_boolean(zUri, RBU_EXCLUSIVE_CHECKPOINT, 0);
}

#if defined(_WIN32_WCE)
static LPWSTR rbuWinUtf8ToUnicode(const char *zFilename){
  int nChar;
  LPWSTR zWideFilename;

    /* Move the *-oal file to *-wal. At this point connection p->db is
    ** holding a SHARED lock on the target database file (because it is
    ** in WAL mode). So no other connection may be writing the db.
    **
    ** In order to ensure that there are no database readers, an EXCLUSIVE
    ** lock is obtained here before the *-oal is moved to *-wal.
    */
    sqlite3 *dbMain = 0;

    rbuFileSuffix3(zBase, zWal);
    rbuFileSuffix3(zBase, zOal);

    /* Re-open the databases. */
    rbuObjIterFinalize(&p->objiter);
    sqlite3_close(p->dbRbu);
    sqlite3_close(p->dbMain);
    p->dbMain = 0;
    p->dbRbu = 0;

    dbMain = rbuOpenDbhandle(p, p->zTarget, 1);
    if( dbMain ){
      assert( p->rc==SQLITE_OK );
      p->rc = rbuLockDatabase(dbMain);
    }

    if( p->rc==SQLITE_OK ){
#if defined(_WIN32_WCE)
      {
        LPWSTR zWideOal;
        LPWSTR zWideWal;

        zWideOal = rbuWinUtf8ToUnicode(zOal);
        if( zWideOal ){

        }else{
          p->rc = SQLITE_IOERR_NOMEM;
        }
      }
#else
      p->rc = rename(zOal, zWal) ? SQLITE_IOERR : SQLITE_OK;
#endif
    }

    if( p->rc!=SQLITE_OK
     || rbuIsVacuum(p)
     || rbuExclusiveCheckpoint(dbMain)==0
    ){
      sqlite3_close(dbMain);
      dbMain = 0;
    }

    if( p->rc==SQLITE_OK ){
      rbuOpenDatabase(p, dbMain, 0);
      rbuSetupCheckpoint(p, 0);

    }
  }

  sqlite3_free(zWal);
  sqlite3_free(zOal);
}

      /* If the first attempt to open the database file fails and the bRetry
      ** flag it set, this means that the db was not opened because it seemed
      ** to be a wal-mode db. But, this may have happened due to an earlier
      ** RBU vacuum operation leaving an old wal file in the directory.
      ** If this is the case, it will have been checkpointed and deleted
      ** when the handle was closed and a second attempt to open the
      ** database may succeed.  */
      rbuOpenDatabase(p, 0, &bRetry);
      if( bRetry ){
        rbuOpenDatabase(p, 0, 0);
      }
    }

    if( p->rc==SQLITE_OK ){
      pState = rbuLoadState(p);
      assert( pState || p->rc!=SQLITE_OK );
      if( p->rc==SQLITE_OK ){

          if( p->rc==SQLITE_OK ){
            rbuSetupOal(p, pState);
          }
        }
      }else if( p->eStage==RBU_STAGE_MOVE ){
        /* no-op */
      }else if( p->eStage==RBU_STAGE_CKPT ){
        if( !rbuIsVacuum(p) && rbuExclusiveCheckpoint(p->dbMain) ){
          /* If the rbu_exclusive_checkpoint=1 URI parameter was specified
          ** and an incremental checkpoint is being resumed, attempt an
          ** exclusive lock on the db file. If this fails, so be it.  */
          p->eStage = RBU_STAGE_DONE;
          rbuLockDatabase(p->dbMain);
          p->eStage = RBU_STAGE_CKPT;
        }
        rbuSetupCheckpoint(p, pState);
      }else if( p->eStage==RBU_STAGE_DONE ){
        p->rc = SQLITE_DONE;
      }else{
        p->rc = SQLITE_CORRUPT;
      }
    }

*/
SQLITE_API sqlite3rbu *sqlite3rbu_open(
  const char *zTarget,
  const char *zRbu,
  const char *zState
){
  if( zTarget==0 || zRbu==0 ){ return rbuMisuseError(); }

  return openRbuHandle(zTarget, zRbu, zState);
}

/*
** Open a handle to begin or resume an RBU VACUUM operation.
*/
SQLITE_API sqlite3rbu *sqlite3rbu_vacuum(

#else
  fts5yyStackEntry fts5yystack[fts5YYSTACKDEPTH];  /* The parser's stack */
  fts5yyStackEntry *fts5yystackEnd;            /* Last entry in the stack */
#endif
};
typedef struct fts5yyParser fts5yyParser;

/* #include <assert.h> */
#ifndef NDEBUG
/* #include <stdio.h> */

static FILE *fts5yyTraceFILE = 0;
static char *fts5yyTracePrompt = 0;
#endif /* NDEBUG */

#ifndef NDEBUG
/*
** Turn parser tracing on by giving a stream to which to write the trace

  while(1){ /* Exit by "break" */
    assert( fts5yypParser->fts5yytos>=fts5yypParser->fts5yystack );
    assert( fts5yyact==fts5yypParser->fts5yytos->stateno );
    fts5yyact = fts5yy_find_shift_action((fts5YYCODETYPE)fts5yymajor,fts5yyact);
    if( fts5yyact >= fts5YY_MIN_REDUCE ){
      unsigned int fts5yyruleno = fts5yyact - fts5YY_MIN_REDUCE; /* Reduce by this rule */

#ifndef NDEBUG
      assert( fts5yyruleno<(int)(sizeof(fts5yyRuleName)/sizeof(fts5yyRuleName[0])) );
      if( fts5yyTraceFILE ){
        int fts5yysize = fts5yyRuleInfoNRhs[fts5yyruleno];
        if( fts5yysize ){
          fprintf(fts5yyTraceFILE, "%sReduce %d [%s]%s, pop back to state %d.\n",
            fts5yyTracePrompt,
            fts5yyruleno, fts5yyRuleName[fts5yyruleno],
            fts5yyruleno<fts5YYNRULE_WITH_ACTION ? "" : " without external action",

static void fts5SourceIdFunc(
  sqlite3_context *pCtx,          /* Function call context */
  int nArg,                       /* Number of args */
  sqlite3_value **apUnused        /* Function arguments */
){
  assert( nArg==0 );
  UNUSED_PARAM2(nArg, apUnused);
  sqlite3_result_text(pCtx, "fts5: 2021-11-15 19:10:13 bd66ab8a1bc3c43a57c7caff5f54545b0feb0177f1f51492f30d308c123c43ba", -1, SQLITE_TRANSIENT);
}

/*
** Return true if zName is the extension on one of the shadow tables used
** by this module.
*/
static int fts5ShadowName(const char *zName){

**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.37.0"
#define SQLITE_VERSION_NUMBER 3037000
#define SQLITE_SOURCE_ID      "2021-11-15 19:10:13 bd66ab8a1bc3c43a57c7caff5f54545b0feb0177f1f51492f30d308c123c43ba"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros

#define SQLITE_OPEN_SUPER_JOURNAL    0x00004000  /* VFS only */
#define SQLITE_OPEN_NOMUTEX          0x00008000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_FULLMUTEX        0x00010000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
#define SQLITE_OPEN_NOFOLLOW         0x01000000  /* Ok for sqlite3_open_v2() */
#define SQLITE_OPEN_EXRESCODE        0x02000000  /* Extended result codes */

/* Reserved:                         0x00F00000 */
/* Legacy compatibility: */
#define SQLITE_OPEN_MASTER_JOURNAL   0x00004000  /* VFS only */


/*

** the default shared cache setting provided by
** [sqlite3_enable_shared_cache()].)^
**
** ^(<dt>[SQLITE_OPEN_PRIVATECACHE]</dt>
** <dd>The database is opened [shared cache] disabled, overriding
** the default shared cache setting provided by
** [sqlite3_enable_shared_cache()].)^
**
** [[OPEN_EXRESCODE]] ^(<dt>[SQLITE_OPEN_EXRESCODE]</dt>
** <dd>The database connection comes up in "extended result code mode".
** In other words, the database behaves has if
** [sqlite3_extended_result_codes(db,1)] where called on the database
** connection as soon as the connection is created. In addition to setting
** the extended result code mode, this flag also causes [sqlite3_open_v2()]
** to return an extended result code.</dd>
**
** [[OPEN_NOFOLLOW]] ^(<dt>[SQLITE_OPEN_NOFOLLOW]</dt>
** <dd>The database filename is not allowed to be a symbolic link</dd>
** </dl>)^
**
** If the 3rd parameter to sqlite3_open_v2() is not one of the
** required combinations shown above optionally combined with other

  int nOther;
  char **azOther;
  int i;
  Stmt q;

  sync_explain(syncFlags);
  nErr = client_sync(syncFlags, configRcvMask, configSendMask, zAltPCode);
  if( nErr==0 ) url_remember();
  if( (syncFlags & SYNC_ALLURL)==0 ) return nErr;
  nOther = 0;
  azOther = 0;
  db_prepare(&q,
    "SELECT substr(name,10) FROM config"
    " WHERE name glob 'sync-url:*'"
    "   AND value<>(SELECT value FROM config WHERE name='last-sync-url')"

  }
  urlFlags &= ~urlOmitFlags;
  if( urlFlags & URL_REMEMBER ){
    clone_ssh_db_set_options();
  }
  url_parse(zUrl, urlFlags);
  remember_or_get_http_auth(zHttpAuth, urlFlags & URL_REMEMBER, zUrl);

  if( g.url.protocol==0 ){
    if( urlOptional ) fossil_exit(0);
    usage("URL");
  }
  user_select();
  url_enable_proxy("via proxy: ");
  *pConfigFlags |= configSync;

    db_begin_write();
    db_unprotect(PROTECT_CONFIG);
    db_multi_exec("DELETE FROM config WHERE name glob 'sync-pw:*'");
    db_multi_exec("DELETE FROM config WHERE name = 'last-sync-pw'");
    db_protect_pop();
    db_commit_transaction();
    return;
  }
  if( strncmp(zArg, "config-data", nArg)==0 ){
    /* Undocumented command:  "fossil remote config-data"
    **
    ** Show the CONFIG table entries that relate to remembering remote URLs
    */
    Stmt q;
    int n;
    n = db_int(13,
       "SELECT max(length(name))"
       "  FROM config"
       " WHERE name GLOB 'sync-*:*' OR name GLOB 'last-sync-*'"
    );
    db_prepare(&q,
       "SELECT name,"
       "       CASE WHEN name LIKE '%%sync-pw%%'"
                  " THEN printf('%%.*c',length(value),'*') ELSE value END"
       "  FROM config"
       " WHERE name GLOB 'sync-*:*' OR name GLOB 'last-sync-*'"
       " ORDER BY name LIKE '%%sync-pw%%', name"
    );
    while( db_step(&q)==SQLITE_ROW ){
      fossil_print("%-*s  %s\n",
        n, db_column_text(&q,0),
        db_column_text(&q,1)
      );
    }
    db_finalize(&q);
    return;
  }
  if( sqlite3_strlike("http://%",zArg,0)==0
   || sqlite3_strlike("https://%",zArg,0)==0
   || sqlite3_strlike("ssh:%",zArg,0)==0
   || sqlite3_strlike("file:%",zArg,0)==0
   || db_exists("SELECT 1 FROM config WHERE name='sync-url:%q'",zArg)
  ){

who performed the deletion, not the author of the deleted
comment). That can potentially lead to odd corner cases where a user
shows up in the list but has no messages which are currently visible
because they were deleted, or an admin user who has not posted
anything but deleted a message. That is a known minor cosmetic-only
bug with a resolution of "will not fix."

### <a id="cli"></a> The `fossil chat` Command

Type [fossil chat](/help?cmd=chat) from within any open check-out
to bring up a chatroom for the project that is in that checkout.
The new chat window will attempt to connect to the default sync
target for that check-out (the server whose URL is shown by the
[fossil remote](/help?cmd=remote) command).

### <a id="robots"></a> Chat Messages From Robots

The [fossil chat send](/help?cmd=chat) can be used by project-specific
robots to send notifications to the chatroom.  For example, on the
[SQLite project](https://sqlite.org/) (for which the Fossil chatroom
feature, and indeed all of Fossil, was invented) there are long-running
fuzz servers that sometimes run across obscure problems.  Whenever this
happens, a message is sent to the SQLite developers chatroom altering
them to the problem.

The recommended way to allow robots to send chat messages is to create
a new user on the server for each robot.  Give each such robot account
the "C" privilege only.  That means that the robot user account will be 
able to send chat messages, but not do anything else.  Then, in the
program or script that runs the robot, when it wants to send a chat
message, have it run a command like this:

> ~~~~
fossil chat send --remote https://robot:PASSWORD@project.org/fossil \
  --message 'MESSAGE TEXT' --file file-to-attach.txt
~~~~

Substitute the appropriate project URL, robot account
name and password, message text and file attachment, of course.

## Implementation Details

*You do not need to understand how Fossil chat works in order to use it.
But many developers prefer to know how their tools work.
This section is provided for the benefit of those curious developers.*

The [/chat](/help?cmd=/chat) webpage downloads a small amount of HTML
and a small amount of javascript to run the chat session.  The
javascript uses XMLHttpRequest (XHR) to download chat content, post
new content, or delete historical messages.  The following web
interfaces are used by the XHR:

  *  [/chat-poll](/help?name=/chat-poll) &rarr;
     Downloads chat content as JSON.
     Chat messages are numbered sequentially.
     The client tells the server the largest chat message it currently
     holds, and the server sends back subsequent messages.  If there
     are no subsequent messages, the /chat-poll page blocks until new
     messages are available.

  *  [/chat-send](/help?name=/chat-send) &rarr;
     Sends a new chat message to the server.

  *  [/chat-delete](/help?name=/chat-delete) &rarr;
     Deletes a chat message.

Fossil chat uses the venerable "hanging GET" or 
"[long polling](wikipedia:/wiki/Push_technology#Long_polling)"
technique to recieve asynchronous notification of new messages.
This is done because long polling works well with CGI and SCGI,
which are the usual mechanisms for setting up a Fossil server.
More advanced notification techniques such as 
[Server-sent events](wikipedia:/wiki/Server-sent_events) and especially
[WebSockets](wikipedia:/wiki/WebSocket) might seem more appropriate for
a chat system, but those technologies are not compatible with CGI.

Downloading of posted files and images uses a separate, non-XHR interface:

  * [/chat-download](/help?name=/chat-download) &rarr;
    Fetches the file content associated with a post (one file per
    post, maximum). In the UI, this is accessed via links to uploaded
    files and via inlined image tags.

Chat messages are stored on the server-side in the CHAT table of
the repository.

> ~~~
CREATE TABLE repository.chat(
  msgid INTEGER PRIMARY KEY AUTOINCREMENT,
  mtime JULIANDAY,  -- Time for this entry - Julianday Zulu
  lmtime TEXT,      -- Client YYYY-MM-DDZHH:MM:SS when message originally sent
  xfrom TEXT,       -- Login of the sender
  xmsg  TEXT,       -- Raw, unformatted text of the message
  fname TEXT,       -- Filename of the uploaded file, or NULL
  fmime TEXT,       -- MIMEType of the upload file, or NULL
  mdel INT,         -- msgid of another message to delete
  file  BLOB        -- Text of the uploaded file, or NULL
);
~~~

The CHAT table is not cross-linked with any other tables in the repository
schema.  An administrator can "DROP TABLE chat;" at any time, without
harm (apart from deleting all chat history, of course).  The CHAT table
is dropped when running [fossil scrub --verily](/help?cmd=scrub).

<h2>2.0 Composition Of A Project</h2>

<verbatim type="pikchr float-right">
R1: cylinder "Remote" "Repository" fill 0xadd8e6 rad 70%
R2: cylinder same "Remote" "Repository" at 2.5*R1.wid right of R1
    spline <-> from R1.e to 0.6<R1.se,R2.sw> then to 0.4<R1.ne,R2.nw> then to R2.w
    text "HTTPS" at .5<R1.ne,R2.nw>
R3: cylinder same "Local" "Repository" fill 0x90ee90 \
    at dist(R1.e,R2.w) below .5<R1,R2>
    spline <-> from .5<R1.s,R1.se> to 0.6<R1.s,R3.w> to 0.5<R1.se,R3.n> to .5<R3.nw,R3.n> \
      "HTTPS" above behind R1
    spline <-> from R2.sw to .6<R2.sw,R3.n> to .5<R2.s,R3.e> to R3.ne "HTTPS" ljust
T1: line from 1.0cm heading 200 from R3.sw go 2.2cm heading 150 then 2.2cm west close \
       fill 0xffff00 "Local" below "Source Tree" below
T2: line from 1.0cm heading 160 from R3.se same "Local" below "Source Tree" below
    line <-> from R3.sw to T1.start
    line <-> from R3.se to T2.start
</verbatim>

remote repository into a local repository.  Or one can do a "sync"
which is a shortcut for doing both a push and a pull at the same time.
Fossil also has the concept of "cloning".  A "clone" is like a "pull",
except that instead of beginning with an existing local repository,
a clone begins with nothing and creates a new local repository that
is a duplicate of a remote repository.

Communication between repositories is normally via HTTPS.  (SSH is also
supported, as is unencrypted HTTP.) Remote
repositories are identified by URL.  You can also point a web browser
at a repository and get human-readable status, history, and tracking
information about the project.

<h3 id="artifacts">2.1 Identification Of Artifacts</h3>

A particular version of a particular file is called an "artifact".  Each

 what a ZIP archive can do.
 <ul>
 <li><p>Fossil does not care what you name your repository files,
     though names ending with ".fossil" are recommended.
 <li><p>A single project typically has multiple, redundant repositories on
 separate machines.
 <li><p>All repositories stay synchronized with one another by exchanging
     information via HTTPS or SSH.
 <li><p>All repos for a single project redundantly store all information
     about that project.  So if any one repo is lost due to a disk
     crash, all content is preserved in the surviving repos.
 <li><p>The usual arrangement is one repository per user.  And since
     most users these days have their own computer, that means one
     repository per computer.  But this is not a requirement.  It is
     ok to have multiple copies of the same repository on the same