SQLite

**
**  (4)  If none of the above apply and the SQLITE_OPEN_CREATE flag is
**       set, then a new database is appended to the already existing file.
**
**  (5)  Otherwise, SQLITE_CANTOPEN is returned.
**
** To avoid unnecessary complications with the PENDING_BYTE, the size of
** the file containing the database is limited to 1GiB. (1073741824 bytes)
** This VFS will not read or write past the 1GiB mark.  This restriction
** might be lifted in future versions.  For now, if you need a larger
** database, then keep it in a separate file.
**
** If the file being opened is a plain database (not an appended one), then
** this shim is a pass-through into the default underlying VFS. (rule 3)
**/
#include "sqlite3ext.h"

#define APND_MARK_FOS_SZ      8
#define APND_MARK_SIZE       (APND_MARK_PREFIX_SZ+APND_MARK_FOS_SZ)

/*
** Maximum size of the combined prefix + database + append-mark.  This
** must be less than 0x40000000 to avoid locking issues on Windows.
*/
#define APND_MAX_SIZE  (0x40000000)

/*
** Try to align the database to an even multiple of APND_ROUNDUP bytes.
*/
#ifndef APND_ROUNDUP
#define APND_ROUNDUP 4096
#endif
#define APND_ALIGN_MASK         ((sqlite3_int64)(APND_ROUNDUP-1))
#define APND_START_ROUNDUP(fsz) (((fsz)+APND_ALIGN_MASK) & ~APND_ALIGN_MASK)

/*
** Forward declaration of objects used by this utility
*/
typedef struct sqlite3_vfs ApndVfs;
typedef struct ApndFile ApndFile;

/* Access to a lower-level VFS that (might) implement dynamic loading,
** access to randomness, etc.
*/
#define ORIGVFS(p)  ((sqlite3_vfs*)((p)->pAppData))
#define ORIGFILE(p) ((sqlite3_file*)(((ApndFile*)(p))+1))

/* An open appendvfs file




**

** An instance of this structure describes the appended database file.
** A separate sqlite3_file object is always appended. The appended
** sqlite3_file object (which can be accessed using ORIGFILE()) describes
** the entire file, including the prefix, the database, and the
** append-mark.
**
** The structure of an AppendVFS database is like this:
**
**   +-------------+---------+----------+-------------+
**   | prefix-file | padding | database | append-mark |
**   +-------------+---------+----------+-------------+
**                           ^          ^
**                           |          |
**                         iPgOne      iMark
**
**
** "prefix file" -  file onto which the database has been appended.
** "padding"     -  zero or more bytes inserted so that "database"
**                  starts on an APND_ROUNDUP boundary
** "database"    -  The SQLite database file
** "append-mark" -  The 25-byte "Start-Of-SQLite3-NNNNNNNN" that indicates
**                  the offset from the start of prefix-file to the start
**                  of "database".
**
** The size of the database is iMark - iPgOne.
**
** The NNNNNNNN in the "Start-Of-SQLite3-NNNNNNNN" suffix is the value

** of iPgOne stored as a big-ending 64-bit integer.
**
** iMark will be the size of the underlying file minus 25 (APND_MARKSIZE).
** Or, iMark is -1 to indicate that it has not yet been written.
*/
struct ApndFile {

  sqlite3_file base;        /* Subclass.  MUST BE FIRST! */

  sqlite3_int64 iPgOne;     /* Offset to the start of the database */

  sqlite3_int64 iMark;      /* Offset of the append mark.  -1 if unwritten */
  /* Always followed by another sqlite3_file that describes the whole file */
};

/*
** Methods for ApndFile
*/
static int apndClose(sqlite3_file*);
static int apndRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);

){
  sqlite_int64 iPgOne = paf->iPgOne;
  unsigned char a[APND_MARK_SIZE];
  int i = APND_MARK_FOS_SZ;
  int rc;
  assert(pFile == ORIGFILE(paf));
  memcpy(a, APND_MARK_PREFIX, APND_MARK_PREFIX_SZ);
  while( --i >= 0 ){
    a[APND_MARK_PREFIX_SZ+i] = (unsigned char)(iPgOne & 0xff);
    iPgOne >>= 8;
  }
  iWriteEnd += paf->iPgOne;
  if( SQLITE_OK==(rc = pFile->pMethods->xWrite
                  (pFile, a, APND_MARK_SIZE, iWriteEnd)) ){
    paf->iMark = iWriteEnd;

  ApndFile *paf = (ApndFile *)pFile;
  sqlite_int64 iWriteEnd = iOfst + iAmt;
  if( iWriteEnd>=APND_MAX_SIZE ) return SQLITE_FULL;
  pFile = ORIGFILE(pFile);
  /* If append-mark is absent or will be overwritten, write it. */
  if( paf->iMark < 0 || paf->iPgOne + iWriteEnd > paf->iMark ){
    int rc = apndWriteMark(paf, pFile, iWriteEnd);
    if( SQLITE_OK!=rc ) return rc;

  }
  return pFile->pMethods->xWrite(pFile, zBuf, iAmt, paf->iPgOne+iOfst);
}

/*
** Truncate an apnd-file.
*/
static int apndTruncate(sqlite3_file *pFile, sqlite_int64 size){
  ApndFile *paf = (ApndFile *)pFile;
  pFile = ORIGFILE(pFile);
  /* The append mark goes out first so truncate failure does not lose it. */
  if( SQLITE_OK!=apndWriteMark(paf, pFile, size) ) return SQLITE_IOERR;

  /* Truncate underlying file just past append mark */
  return pFile->pMethods->xTruncate(pFile, paf->iMark+APND_MARK_SIZE);
}

/*
** Sync an apnd-file.
*/

static int apndFetch(
  sqlite3_file *pFile,
  sqlite3_int64 iOfst,
  int iAmt,
  void **pp
){
  ApndFile *p = (ApndFile *)pFile;
  if( p->iMark < 0 || iOfst+iAmt > p->iMark ){
    return SQLITE_IOERR; /* Cannot read what is not yet there. */
  }
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xFetch(pFile, iOfst+p->iPgOne, iAmt, pp);
}

/* Release a memory-mapped page */
static int apndUnfetch(sqlite3_file *pFile, sqlite3_int64 iOfst, void *pPage){
  ApndFile *p = (ApndFile *)pFile;

** Return true iff it is such. Parameter sz is the file's size.
*/
static int apndIsAppendvfsDatabase(sqlite3_int64 sz, sqlite3_file *pFile){
  int rc;
  char zHdr[16];
  sqlite3_int64 iMark = apndReadMark(sz, pFile);
  if( iMark>=0 ){
    /* If file has the correct end-marker, the expected odd size, and the
    ** SQLite DB type marker where the end-marker puts it, then it
    ** is an appendvfs database.
    */
    rc = pFile->pMethods->xRead(pFile, zHdr, sizeof(zHdr), iMark);
    if( SQLITE_OK==rc
     && memcmp(zHdr, apvfsSqliteHdr, sizeof(zHdr))==0
     && (sz & 0x1ff) == APND_MARK_SIZE
     && sz>=512+APND_MARK_SIZE
    ){
      return 1; /* It's an appendvfs database */
    }
  }
  return 0;
}

/*
** Check to see if the file is an ordinary SQLite database file.
** Return true iff so. Parameter sz is the file's size.

  ){
    return 0;
  }else{
    return 1;
  }
}






/*
** Open an apnd file handle.
*/
static int apndOpen(
  sqlite3_vfs *pApndVfs,
  const char *zName,
  sqlite3_file *pFile,
  int flags,
  int *pOutFlags
){
  ApndFile *pApndFile = (ApndFile*)pFile;
  sqlite3_file *pBaseFile = ORIGFILE(pFile);
  sqlite3_vfs *pBaseVfs = ORIGVFS(pApndVfs);
  int rc;
  sqlite3_int64 sz;

  if( (flags & SQLITE_OPEN_MAIN_DB)==0 ){
    /* The appendvfs is not to be used for transient or temporary databases.
    ** Just use the base VFS open to initialize the given file object and
    ** open the underlying file. (Appendvfs is then unused for this file.)
    */
    return pBaseVfs->xOpen(pBaseVfs, zName, pFile, flags, pOutFlags);
  }

  memset(pApndFile, 0, sizeof(ApndFile));

  pFile->pMethods = &apnd_io_methods;
  pApndFile->iMark = -1;    /* Append mark not yet written */

  rc = pBaseVfs->xOpen(pBaseVfs, zName, pBaseFile, flags, pOutFlags);
  if( rc==SQLITE_OK ){
    rc = pBaseFile->pMethods->xFileSize(pBaseFile, &sz);
  }
  if( rc ){
    pBaseFile->pMethods->xClose(pBaseFile);

    pFile->pMethods = 0;
    return rc;
  }
  if( apndIsOrdinaryDatabaseFile(sz, pBaseFile) ){
    /* The file being opened appears to be just an ordinary DB. Copy
    ** the base dispatch-table so this instance mimics the base VFS. 
    */
    memmove(pApndFile, pBaseFile, pBaseVfs->szOsFile);
    return SQLITE_OK;
  }


  pApndFile->iPgOne = apndReadMark(sz, pFile);
  if( pApndFile->iPgOne>=0 ){
    pApndFile->iMark = sz - APND_MARK_SIZE; /* Append mark found */

    return SQLITE_OK;
  }
  if( (flags & SQLITE_OPEN_CREATE)==0 ){
    pBaseFile->pMethods->xClose(pBaseFile);
    rc = SQLITE_CANTOPEN;
    pFile->pMethods = 0;
  }else{
    /* Round newly added appendvfs location to #define'd page boundary. 
    ** Note that nothing has yet been written to the underlying file.
    ** The append mark will be written along with first content write.
    ** Until then, paf->iMark value indicates it is not yet written.
    */
    pApndFile->iPgOne = APND_START_ROUNDUP(sz);


  }
  return rc;
}

/*
** Delete an apnd file.
** For an appendvfs, this could mean delete the appendvfs portion,
** leaving the appendee as it was before it gained an appendvfs.

# avfs-1.1. Test that the DB can be read with correct content upon reopen.
# avfs-1.2. Test that an appendvfs DB can be added to a simple text file.
# avfs-1.3. Test that the DB can be read with correct content upon reopen.
# avfs-1.4. Test that appended DB is aligned to default page boundary.
# avfs-2.1. Test that the simple text file retains its initial text.
# avfs-3.1. Test that the appendvfs can grow and shrink, remaining intact.
# avfs-3.2. Test that appendvfs is intact after grow/shrink/close/reopen.
# avfs-3.3. Test that appendvfs can grow by many pages and be written.
# avfs-3.4. Test that grown appendvfs can be reopened and appear intact.
# avfs-3.5. Test that much grown appendvfs can shrink and reopen intact.
# avfs-4.1. Test shell's ability to append to a non-appendvfs file.
# avfs-4.2. Test shell's ability to append to empty or nonexistent file.
# avfs-4.3. Test shell's ability to reopen and alter an appendvfs file.
# avfs-5.1. Test appendvfs refusal to open too-tiny DB appended onto ZLF.
# avfs-5.2. Test appendvfs refusal to open too-tiny DB appended on other.
# ...
# (more to come)

    set ::result "Appendee changed."
  } else {
    set ::result "Appendee intact."
  }
} {Appendee intact.}

# Set of repeatable random integers for a couple tests.
set ::nrint 50000
proc rint {v} {
  return [::tcl::mathfunc::int [expr $v * 100000]]
}
array set ::randints [list 0 [rint [::tcl::mathfunc::srand 0]]]
for {set i 1} {$i < $::nrint} {incr i} {
  set ::randints($i) [rint [::tcl::mathfunc::rand]]
}

do_test 3.1 {
  set results {}
  sqlite3 adb "file:$::fa?mode=rw$::vf" -uri 1
  adb eval {
    DROP TABLE t1;
    PRAGMA cache_size=10;
    CREATE TABLE ri (i INTEGER);
    BEGIN;
  }
  for {set i 0} {$i < $::nrint} {incr i} {
    set r $::randints($i)
    set s $::randints([incr i])
    set t $::randints([incr i])
    set u $::randints([incr i])
    set v $::randints([incr i])
    adb eval {
      INSERT INTO ri VALUES ($r),($s),($t),($u),($v)

    VACUUM;
    SELECT integrity_check as ic FROM pragma_integrity_check();
    SELECT count(*) as ic FROM ri;
  } { lappend qr $ic }
  adb close
  set adaSz [file size $::fa]
  set adba [expr ($adbSz + 0.1)/$adaSz]
  # lappend results $adba
  set results [concat $results [lrange $qr 0 2]]
  lappend results [expr {$adba > 10.0}]
  set ::result [join $results " | "]
} "ok | $::nrint | ok | ok | 1"

do_test 3.2 {
  set results {}
  sqlite3 adb "file:$::fa?mode=rw$::vf" -uri 1
  adb eval {
    SELECT integrity_check as ic FROM pragma_integrity_check();
  } { lappend results $ic }
  adb close
  set ::result [join $results " | "]
} {ok}

# avfs-3.3. Test that appendvfs can grow by many pages and be written.
do_test 3.3 {
  set results {}
  sqlite3 adb "file:$::fa?mode=rw$::vf" -uri 1
  set npages 300
  adb eval { BEGIN }
  while {$npages > 0} {
    adb eval { INSERT INTO ri VALUES (randomblob(1500)) }
    incr npages -1
  }
  adb eval { COMMIT }
  adb eval {
    SELECT integrity_check as ic FROM pragma_integrity_check();
  } { lappend results $ic }
  adb close
  set adaSzr [expr [file size $::fa] / 300.0 / 1500 ]
  set okSzr [expr $adaSzr > 1.0 && $adaSzr < 1.3 ]
  lappend results $okSzr
  set ::result [join $results " | "]
} {ok | 1}

# avfs-3.4. Test that grown appendvfs can be reopened and appear intact.
do_test 3.4 {
  set results {}
  sqlite3 adb "file:$::fa?mode=rw$::vf" -uri 1
  adb eval {
    SELECT integrity_check as ic FROM pragma_integrity_check();
  } { lappend results $ic }
  adb close
  set ::result $ic
} {ok}

# avfs-3.5. Test that much grown appendvfs can shrink and reopen intact.
do_test 3.5 {
  set results {}
  set adbsz [file size $::fa]
  sqlite3 adb "file:$::fa?mode=rw$::vf" -uri 1
  adb eval {
    DELETE FROM ri WHERE rowid % 8 <> 0;
    SELECT integrity_check as ic FROM pragma_integrity_check();
    VACUUM;
    SELECT integrity_check as ic FROM pragma_integrity_check();
  } { lappend results $ic }
  adb close
  set adasz [file size $::fa]
  lappend results [expr {$adbsz/$adasz > 5}]
  sqlite3 adb "file:$::fa?mode=rw$::vf" -uri 1
  adb eval {
    SELECT integrity_check as ic FROM pragma_integrity_check();
  } { lappend results $ic }
  adb close
  set ::result [join $results " | "]
} {ok | ok | 1 | ok}

set ::cliDoesAr [shellDoesAr]

do_test 4.1 {
  set shdo "sh_app1.sql"
  set shod "sh_app1.adb"
  forcedelete $shdo $shod

  }
  forcedelete $fake
  set ::result $res
} {Open failed.}

forcedelete $::fa $::fza

unset -nocomplain ::fa ::fza ::tlo ::result ::randints ::nrint ::cliDoesAr

finish_test