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Revise the layout of filenames in the Pager object so that it is unchanged

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from prior versions.  It turns out that some important 3rd-party software
does questionable pointer manipulations on those filenames that depend on
that legacy layout.  Technical this is a misuse of SQLite by the 3rd-party
software, but we want to avoid unnecessary breakage.

FossilOrigin-Name: 34ab760689fd493eda482e856047708d74e769a01cc90b69da456d79ffe39aea
This commit is contained in:
drh 2020-01-27 14:40:44 +00:00
parent 9a3bdeba3e
commit 532b0d23fd
4 changed files with 86 additions and 61 deletions
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14
manifest
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@ -1,5 +1,5 @@
C Fix\stypos\sin\sthe\ssqlite3ext.h\sheader\sfile\sthat\sprevent\ssome\snewer\sAPIs\sfrom\nbeing\saccessed\sfrom\sloadable\sextensions.
D 2020-01-23T15:00:18.610
C Revise\sthe\slayout\sof\sfilenames\sin\sthe\sPager\sobject\sso\sthat\sit\sis\sunchanged\nfrom\sprior\sversions.\s\sIt\sturns\sout\sthat\ssome\simportant\s3rd-party\ssoftware\ndoes\squestionable\spointer\smanipulations\son\sthose\sfilenames\sthat\sdepend\son\nthat\slegacy\slayout.\s\sTechnical\sthis\sis\sa\smisuse\sof\sSQLite\sby\sthe\s3rd-party\nsoftware,\sbut\swe\swant\sto\savoid\sunnecessary\sbreakage.
D 2020-01-27T14:40:44.978
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@ -495,7 +495,7 @@ F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
F src/insert.c 2fe4d7f67078a68650f16e4efe73207899e21702e6b9d2e8ad1894c76dcad352
F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
F src/loadext.c 8cd803f1747c03a50b32fe87ebfb5851998d0cdafefe02737daa95e0616b42bb
F src/main.c 430db07f140a2455784b504af1a56fe49134a79dd479a203370490031708d48f
F src/main.c ffaa1308ee8ad7cf70bddc9a9fe2d2d66799e534b12ec876562d26a33a30d745
F src/malloc.c eaa4dc9602ce28b077f7de2eb275db2be270c5cc56d7fec5466301bd9b80e2f5
F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
@ -518,7 +518,7 @@ F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
F src/os_unix.c ad7640c04eed946052a3b12856362a773d0a717696707313037186df0e2b59f2
F src/os_win.c 035a813cbd17f355bdcad7ab894af214a9c13a1db8aeac902365350b98cd45a7
F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
F src/pager.c 302a18da8b247881808cd65009e1ac7c8b6e5cefb22ed9a1c330ed47b73e94ab
F src/pager.c c0bca72aa3f7b1cf521a9f350fcf8e5975ebf98da7dbb03492be876b0f053781
F src/pager.h 71fe1d5016ec54d0cc5d344cd474e563450b438c59f535e8c1ec8a13b1373f14
F src/parse.y c8d2de64db469fd56e0fa24da46cd8ec8523eb98626567d2708df371b47fdc3f
F src/pcache.c 385ff064bca69789d199a98e2169445dc16e4291fa807babd61d4890c3b34177
@ -1857,7 +1857,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P 8a6fe3066cf0599fcf2960e8fb3ae39e4e7a61ec81e8ec71d0b5910aee2c16f6
R adbf99f7d511d2f7862e65bcc9604066
P 14331989fcaf6591336290ed1548e9c90f0f153e27f456f4c30c966f9c23aa6e
R 883ff2472492f888f089aeac00d37048
U drh
Z 72d824d23352153c482aa4a2ca7c7d22
Z 470802efe5cd145ed0af48cfd87c7792

2
manifest.uuid
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@ -1 +1 @@
14331989fcaf6591336290ed1548e9c90f0f153e27f456f4c30c966f9c23aa6e
34ab760689fd493eda482e856047708d74e769a01cc90b69da456d79ffe39aea

54
src/main.c
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@ -4243,6 +4243,21 @@ int sqlite3_test_control(int op, ...){
return rc;
}
/*
** The Pager stores the Database filename, Journal filename, and WAL filename
** consecutively in memory, in that order. The database filename is prefixed
** by four zero bytes. Locate the start of the database filename by searching
** backwards for the first byte following four consecutive zero bytes.
**
** This only works if the filename passed in was obtained from the Pager.
*/
static const char *databaseName(const char *zName){
while( zName[-1]!=0 || zName[-2]!=0 || zName[-3]!=0 || zName[-4]!=0 ){
zName--;
}
return zName;
}
/*
** This is a utility routine, useful to VFS implementations, that checks
** to see if a database file was a URI that contained a specific query
@ -4256,6 +4271,7 @@ int sqlite3_test_control(int op, ...){
*/
const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam){
if( zFilename==0 || zParam==0 ) return 0;
zFilename = databaseName(zFilename);
zFilename += sqlite3Strlen30(zFilename) + 1;
while( zFilename[0] ){
int x = strcmp(zFilename, zParam);
@ -4271,6 +4287,7 @@ const char *sqlite3_uri_parameter(const char *zFilename, const char *zParam){
*/
const char *sqlite3_uri_key(const char *zFilename, int N){
if( zFilename==0 || N<0 ) return 0;
zFilename = databaseName(zFilename);
zFilename += sqlite3Strlen30(zFilename) + 1;
while( zFilename[0] && (N--)>0 ){
zFilename += sqlite3Strlen30(zFilename) + 1;
@ -4304,25 +4321,6 @@ sqlite3_int64 sqlite3_uri_int64(
return bDflt;
}
/*
** The Pager stores the Journal filename, WAL filename, and Database filename
** consecutively in memory, in that order, with prefixes \000\001\000,
** \002\000, and \003\000, in that order. Thus the three names look like query
** parameters if you start at the first prefix.
**
** This routine backs up a filename to the start of the first prefix.
**
** This only works if the filenamed passed in was obtained from the Pager.
*/
static const char *startOfNameList(const char *zName){
while( zName[0]!='\001' || zName[1]!=0 ){
zName -= 3;
while( zName[0]!='\000' ){ zName--; }
zName++;
}
return zName-1;
}
/*
** Translate a filename that was handed to a VFS routine into the corresponding
** database, journal, or WAL file.
@ -4334,14 +4332,26 @@ static const char *startOfNameList(const char *zName){
** corruption.
*/
const char *sqlite3_filename_database(const char *zFilename){
return databaseName(zFilename);
return sqlite3_uri_parameter(zFilename - 3, "\003");
}
const char *sqlite3_filename_journal(const char *zFilename){
const char *z = sqlite3_uri_parameter(startOfNameList(zFilename), "\001");
return ALWAYS(z) && z[0] ? z : 0;
zFilename = databaseName(zFilename);
zFilename += sqlite3Strlen30(zFilename) + 1;
while( zFilename[0] ){
zFilename += sqlite3Strlen30(zFilename) + 1;
zFilename += sqlite3Strlen30(zFilename) + 1;
}
return zFilename + 1;
}
const char *sqlite3_filename_wal(const char *zFilename){
return sqlite3_uri_parameter(startOfNameList(zFilename), "\002");
#ifdef SQLITE_OMIT_WAL
return 0;
#else
zFilename = sqlite3_filename_journal(zFilename);
zFilename += sqlite3Strlen30(zFilename) + 1;
return zFilename;
#endif
}
/*

77
src/pager.c
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@ -4838,30 +4838,48 @@ int sqlite3PagerOpen(
** Database file handle (pVfs->szOsFile bytes)
** Sub-journal file handle (journalFileSize bytes)
** Main journal file handle (journalFileSize bytes)
** \0\1\0 journal prefix (3 bytes)
** Journal filename (nPathname+8+1 bytes)
** \2\0 WAL prefix (2 bytes)
** WAL filename (nPathname+4+1 bytes)
** \3\0 database prefix (2 bytes)
** \0\0\0\0 database prefix (4 bytes)
** Database file name (nPathname+1 bytes)
** URI query parameters (nUriByte bytes)
** \0\0 terminator (2 bytes)
** Journal filename (nPathname+8+1 bytes)
** WAL filename (nPathname+4+1 bytes)
** \0\0\0 terminator (3 bytes)
**
** Some 3rd-party software, over which we have no control, depends on
** the specific order of the filenames and the \0 separators between them
** so that it can (for example) find the database filename given the WAL
** filename without using the sqlite3_filename_database() API. This is a
** misuse of SQLite and a bug in the 3rd-party software, but the 3rd-party
** software is in widespread use, so we try to avoid changing the filename
** order and formatting if possible. In particular, the details of the
** filename format expected by 3rd-party software should be as follows:
**
** - Main Database Path
** - \0
** - Multiple URI components consisting of:
** - Key
** - \0
** - Value
** - \0
** - \0
** - Journal Path
** - \0
** - WAL Path (zWALName)
** - \0
*/
pPtr = (u8 *)sqlite3MallocZero(
ROUND8(sizeof(*pPager)) + /* Pager structure */
ROUND8(pcacheSize) + /* PCache object */
ROUND8(pVfs->szOsFile) + /* The main db file */
journalFileSize * 2 + /* The two journal files */
3 + /* Journal prefix */
nPathname + 8 + 1 + /* Journal filename */
#ifndef SQLITE_OMIT_WAL
2 + /* WAL prefix */
nPathname + 4 + 1 + /* WAL filename */
#endif
2 + /* Database prefix */
4 + /* Database prefix */
nPathname + 1 + /* database filename */
nUriByte + /* query parameters */
2 /* Terminator */
nPathname + 8 + 1 + /* Journal filename */
#ifndef SQLITE_OMIT_WAL
nPathname + 4 + 1 + /* WAL filename */
#endif
3 /* Terminator */
);
assert( EIGHT_BYTE_ALIGNMENT(SQLITE_INT_TO_PTR(journalFileSize)) );
if( !pPtr ){
@ -4875,9 +4893,20 @@ int sqlite3PagerOpen(
pPager->jfd = (sqlite3_file*)pPtr; pPtr += journalFileSize;
assert( EIGHT_BYTE_ALIGNMENT(pPager->jfd) );
/* Fill in the Pager.zFilename and pPager.zQueryParam fields */
pPtr += 4; /* Skip zero prefix */
pPager->zFilename = (char*)pPtr;
if( nPathname>0 ){
memcpy(pPtr, zPathname, nPathname); pPtr += nPathname + 1;
if( zUri ){
memcpy(pPtr, zUri, nUriByte); pPtr += nUriByte;
}else{
pPtr++;
}
}
/* Fill in Pager.zJournal */
pPtr[1] = '\001'; pPtr += 3;
if( nPathname>0 ){
pPager->zJournal = (char*)pPtr;
memcpy(pPtr, zPathname, nPathname); pPtr += nPathname;
@ -4888,12 +4917,10 @@ int sqlite3PagerOpen(
#endif
}else{
pPager->zJournal = 0;
pPtr++;
}
#ifndef SQLITE_OMIT_WAL
/* Fill in Pager.zWal */
pPtr[0] = '\002'; pPtr[1] = 0; pPtr += 2;
if( nPathname>0 ){
pPager->zWal = (char*)pPtr;
memcpy(pPtr, zPathname, nPathname); pPtr += nPathname;
@ -4904,21 +4931,9 @@ int sqlite3PagerOpen(
#endif
}else{
pPager->zWal = 0;
pPtr++;
}
#endif
/* Fill in the Pager.zFilename and pPager.zQueryParam fields */
pPtr[0] = '\003'; pPtr[1] = 0; pPtr += 2;
pPager->zFilename = (char*)pPtr;
if( nPathname>0 ){
memcpy(pPtr, zPathname, nPathname); pPtr += nPathname + 1;
if( zUri ){
memcpy(pPtr, zUri, nUriByte); /* pPtr += nUriByte; // not needed */
}
/* Double-zero terminator implied by the sqlite3MallocZero */
}
if( nPathname ) sqlite3DbFree(0, zPathname);
pPager->pVfs = pVfs;
pPager->vfsFlags = vfsFlags;
@ -7038,8 +7053,8 @@ int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint){
** sqlite3_uri_parameter() and sqlite3_filename_database() and friends.
*/
const char *sqlite3PagerFilename(const Pager *pPager, int nullIfMemDb){
static const char zFake[] = { 0x00, 0x01, 0x00, 0x00, 0x00 };
return (nullIfMemDb && pPager->memDb) ? &zFake[3] : pPager->zFilename;
static const char zFake[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
return (nullIfMemDb && pPager->memDb) ? &zFake[4] : pPager->zFilename;
}
/*