SQLite

static int fts5Corrupt() { return SQLITE_CORRUPT_VTAB; }
# define FTS5_CORRUPT fts5Corrupt()
#else
# define FTS5_CORRUPT SQLITE_CORRUPT_VTAB
#endif


/*
** Each time a blob is read from the %_data table, it is padded with this
** many zero bytes. This makes it easier to decode the various record formats
** without overreading if the records are corrupt.
*/
#define FTS5_DATA_ZERO_PADDING 8

typedef struct Fts5BtreeIter Fts5BtreeIter;
typedef struct Fts5BtreeIterLevel Fts5BtreeIterLevel;
typedef struct Fts5ChunkIter Fts5ChunkIter;
typedef struct Fts5Data Fts5Data;
typedef struct Fts5DlidxIter Fts5DlidxIter;
typedef struct Fts5MultiSegIter Fts5MultiSegIter;
typedef struct Fts5NodeIter Fts5NodeIter;

      int nByte = sqlite3_blob_bytes(p->pReader);
      if( pBuf ){
        fts5BufferZero(pBuf);
        fts5BufferGrow(&rc, pBuf, nByte);
        aOut = pBuf->p;
        pBuf->n = nByte;
      }else{
        int nSpace = nByte + FTS5_DATA_ZERO_PADDING;
        pRet = (Fts5Data*)sqlite3Fts5MallocZero(&rc, nSpace+sizeof(Fts5Data));
        if( pRet ){
          pRet->n = nByte;
          aOut = pRet->p = (u8*)&pRet[1];
          pRet->nRef = 1;
        }
      }

static void fts5DecodeFunction(
  sqlite3_context *pCtx,          /* Function call context */
  int nArg,                       /* Number of args (always 2) */
  sqlite3_value **apVal           /* Function arguments */
){
  i64 iRowid;                     /* Rowid for record being decoded */
  int iIdx,iSegid,iHeight,iPgno;  /* Rowid components */
  const u8 *aBlob; int n;         /* Record to decode */
  u8 *a = 0;
  Fts5Buffer s;                   /* Build up text to return here */
  int rc = SQLITE_OK;             /* Return code */
  int nSpace = 0;

  assert( nArg==2 );
  memset(&s, 0, sizeof(Fts5Buffer));
  iRowid = sqlite3_value_int64(apVal[0]);
  n = sqlite3_value_bytes(apVal[1]);
  aBlob = sqlite3_value_blob(apVal[1]);

  nSpace = n + FTS5_DATA_ZERO_PADDING;
  a = (u8*)sqlite3Fts5MallocZero(&rc, nSpace);
  if( a==0 ) goto decode_out;
  memcpy(a, aBlob, n);
  fts5DecodeRowid(iRowid, &iIdx, &iSegid, &iHeight, &iPgno);

  fts5DebugRowid(&rc, &s, iRowid);
  if( iHeight==FTS5_SEGMENT_MAX_HEIGHT ){
    int i = 0;
    i64 iPrev;
    if( n>0 ){

    if( iHeight==0 ){
      int iTermOff = 0;
      int iRowidOff = 0;
      int iOff;
      int nKeep = 0;

      if( n>=4 ){
        iRowidOff = fts5GetU16(&a[0]);
        iTermOff = fts5GetU16(&a[2]);
      }else{
        sqlite3Fts5BufferSet(&rc, &s, 8, (const u8*)"corrupt");
        goto decode_out;
      }

      if( iRowidOff ){
        iOff = iRowidOff;
      }else if( iTermOff ){
        iOff = iTermOff;
      }else{
        iOff = n;

          );
        }
      }
      fts5NodeIterFree(&ss);
    }
  }
  
 decode_out:
  sqlite3_free(a);
  if( rc==SQLITE_OK ){
    sqlite3_result_text(pCtx, (const char*)s.p, s.n, SQLITE_TRANSIENT);
  }else{
    sqlite3_result_error_code(pCtx, rc);
  }
  fts5BufferFree(&s);
}

        idx = sqlite3_value_int(apVal[1]);
        iRowid = FTS5_SEGMENT_ROWID(idx, 1, 0, 0);
        sqlite3_result_int64(pCtx, iRowid);
      }
    }else {
      sqlite3_result_error(pCtx, 
        "first arg to fts5_rowid() must be 'segment' "
        "or 'start-of-index'"
        , -1
      );
    }
  }
}

/*

#   1: CREATE VIRTUAL TABLE
#   2: INSERT statement
#   3: DELETE statement
#   4: MATCH expressions
#
#

if 0 {

faultsim_save_and_close
do_faultsim_test 1 -prep {
  faultsim_restore_and_reopen
} -body {
  execsql { CREATE VIRTUAL TABLE t1 USING fts5(a, b, prefix='1, 2, 3') }
} -test {

  } -body "
    execsql { SELECT rowid FROM t2 WHERE t2 MATCH '$expr' }
  " -test "
    faultsim_test_result {[list 0 $res]}
  "
}


}

#-------------------------------------------------------------------------
# The following tests use a larger database populated with random data.
#
# The database page size is set to 512 bytes and the FTS5 page size left
# at the default 1000 bytes. This means that reading a node may require
# pulling an overflow page from disk, which is an extra opportunity for
# an error to occur.

  sqlite3 db test.db
} -body {
  execsql { INSERT INTO x1 VALUES('a b c d', 'e f g h') }
} -test {
  faultsim_test_result [list 0 {}]
}

do_faultsim_test 5.5.1 -faults oom* -body {
  execsql { 
    SELECT count(fts5_decode(rowid, block)) FROM x1_data WHERE rowid=1
  }
} -test {
  faultsim_test_result [list 0 1]
}
do_faultsim_test 5.5.2 -faults oom* -body {
  execsql { 
    SELECT count(fts5_decode(rowid, block)) FROM x1_data WHERE rowid=10
  }
} -test {
  faultsim_test_result [list 0 1]
}
do_faultsim_test 5.5.3 -faults oom* -body {
  execsql { 
    SELECT count(fts5_decode(rowid, block)) FROM x1_data WHERE rowid = (
      SELECT min(rowid) FROM x1_data WHERE rowid>20
    )
  }
} -test {
  faultsim_test_result [list 0 1]
}
do_faultsim_test 5.5.4 -faults oom* -body {
  execsql { 
    SELECT count(fts5_decode(rowid, block)) FROM x1_data WHERE rowid = (
      SELECT max(rowid) FROM x1_data 
    )
  }
} -test {
  faultsim_test_result [list 0 1]
}

finish_test

#-------------------------------------------------------------------------
#
reset_db
do_execsql_test 6.0 {
  CREATE VIRTUAL TABLE x1 USING fts5(x);
  INSERT INTO x1(x1, rank) VALUES('automerge', 0);

  INSERT INTO x1 VALUES('a b c'); -- 15

  SELECT count(*) FROM x1_data;
} {17}

faultsim_save_and_close

do_faultsim_test 6.1 -faults oom* -prep {
  faultsim_restore_and_reopen
} -body {
  execsql { INSERT INTO x1 VALUES('d e f') }
} -test {
  faultsim_test_result [list 0 {}]
  if {$testrc==0} {
    set nCnt [db one {SELECT count(*) FROM x1_data}]
    if {$nCnt!=3} { error "expected 3 entries but there are $nCnt" }
  }
}

#-------------------------------------------------------------------------
do_faultsim_test 7.0 -faults oom* -prep {
  catch { db close }
} -body {
  sqlite3 db test.db
} -test {
  faultsim_test_result [list 0 {}] [list 1 {}]
}


finish_test

# 2014 Dec 20
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# Tests of the scalar fts5_rowid() and fts5_decode() functions.
#

source [file join [file dirname [info script]] fts5_common.tcl]
set testprefix fts5rowid

do_catchsql_test 1.1 {
  SELECT fts5_rowid()
} {1 {should be: fts5_rowid(subject, ....)}}

do_catchsql_test 1.2 {
  SELECT fts5_rowid('segment')
} {1 {should be: fts5_rowid('segment', idx, segid, height, pgno))}}

do_execsql_test 1.3 {
  SELECT fts5_rowid('segment', 1, 1, 1, 1)
} {4503670494330881}

do_catchsql_test 1.4 {
  SELECT fts5_rowid('start-of-index');
} {1 {should be: fts5_rowid('start-of-index', idx)}}

do_execsql_test 1.5 {
  SELECT fts5_rowid('start-of-index', 1);
} {4503668346847232}

do_catchsql_test 1.4 {
  SELECT fts5_rowid('nosucharg');
} {1 {first arg to fts5_rowid() must be 'segment' or 'start-of-index'}} 


#-------------------------------------------------------------------------
# Tests of the fts5_decode() function.
#
reset_db
do_execsql_test 2.1 { 
  CREATE VIRTUAL TABLE x1 USING fts5(a, b);
  INSERT INTO x1(x1, rank) VALUES('pgsz', 32);
} {}

proc rnddoc {n} {
  set map [list 0 a  1 b  2 c  3 d  4 e  5 f  6 g  7 h  8 i  9 j]
  set doc [list]
  for {set i 0} {$i < $n} {incr i} {
    lappend doc [string map $map [format %.3d [expr int(rand()*100)]]]
  }
  set doc
}
db func rnddoc rnddoc

do_execsql_test 2.2 {
  WITH r(a, b) AS (
    SELECT rnddoc(6), rnddoc(6) UNION ALL
    SELECT rnddoc(6), rnddoc(6) FROM r
  )
  INSERT INTO x1 SELECT * FROM r LIMIT 10000;
}

set res [db one {SELECT count(*) FROM x1_data}]
do_execsql_test 2.3 {
  SELECT count(fts5_decode(rowid, block)) FROM x1_data;
} $res
do_execsql_test 2.4 {
  UPDATE x1_data SET block = X'';
  SELECT count(fts5_decode(rowid, block)) FROM x1_data;
} $res

do_execsql_test 2.5 {
  INSERT INTO x1(x1, rank) VALUES('pgsz', 1024);
  INSERT INTO x1(x1) VALUES('rebuild');
}

set res [db one {SELECT count(*) FROM x1_data}]
do_execsql_test 2.6 {
  SELECT count(fts5_decode(rowid, block)) FROM x1_data;
} $res
do_execsql_test 2.7 {
  UPDATE x1_data SET block = X'';
  SELECT count(fts5_decode(rowid, block)) FROM x1_data;
} $res

#-------------------------------------------------------------------------
# Tests with very large tokens.
#
set strlist [list \
  "[string repeat x 400]"                       \
  "[string repeat x 300][string repeat w 100]"  \
  "[string repeat x 300][string repeat y 100]"  \
  "[string repeat x 300][string repeat z 600]"  \
]
do_test 3.0 {
  execsql {
    BEGIN;
    CREATE VIRTUAL TABLE x2 USING fts5(a);
  }
  foreach str $strlist { execsql { INSERT INTO x2 VALUES($str) } }
  execsql COMMIT
} {}

for {set tn 0} {$tn<[llength $strlist]} {incr tn} {
  set str [lindex $strlist $tn]
  do_execsql_test 3.1.$tn {
    SELECT rowid FROM x2 WHERE x2 MATCH $str
  } [expr $tn+1]
}

set res [db one {SELECT count(*) FROM x2_data}]
do_execsql_test 3.2 {
  SELECT count(fts5_decode(rowid, block)) FROM x2_data;
} $res

finish_test