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Make the unix VFS tolerant of read() calls that return less than the

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requested number of bytes.

FossilOrigin-Name: a210695abcfa5cb04279edfd04824d881b7c4ada
This commit is contained in:
drh
2011-11-07 18:16:00 +00:00
parent a46739eae0
commit 5802464316
3 changed files with 39 additions and 26 deletions
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51
src/os_unix.c
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@@ -2951,35 +2951,48 @@ static int nfsUnlock(sqlite3_file *id, int eFileLock){
*/
static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
int got;
int prior = 0;
#if (!defined(USE_PREAD) && !defined(USE_PREAD64))
i64 newOffset;
#endif
TIMER_START;
do{
#if defined(USE_PREAD)
do{ got = osPread(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR );
SimulateIOError( got = -1 );
got = osPread(id->h, pBuf, cnt, offset);
SimulateIOError( got = -1 );
#elif defined(USE_PREAD64)
do{ got = osPread64(id->h, pBuf, cnt, offset); }while( got<0 && errno==EINTR);
SimulateIOError( got = -1 );
got = osPread64(id->h, pBuf, cnt, offset);
SimulateIOError( got = -1 );
#else
newOffset = lseek(id->h, offset, SEEK_SET);
SimulateIOError( newOffset-- );
if( newOffset!=offset ){
if( newOffset == -1 ){
((unixFile*)id)->lastErrno = errno;
}else{
((unixFile*)id)->lastErrno = 0;
newOffset = lseek(id->h, offset, SEEK_SET);
SimulateIOError( newOffset-- );
if( newOffset!=offset ){
if( newOffset == -1 ){
((unixFile*)id)->lastErrno = errno;
}else{
((unixFile*)id)->lastErrno = 0;
}
return -1;
}
return -1;
}
do{ got = osRead(id->h, pBuf, cnt); }while( got<0 && errno==EINTR );
got = osRead(id->h, pBuf, cnt);
#endif
if( got==cnt ) break;
if( got<0 ){
if( errno==EINTR ){ got = 1; continue; }
prior = 0;
((unixFile*)id)->lastErrno = errno;
break;
}else if( got>0 ){
cnt -= got;
offset += got;
prior += got;
pBuf = (void*)(got + (char*)pBuf);
}
}while( got>0 );
TIMER_END;
if( got<0 ){
((unixFile*)id)->lastErrno = errno;
}
OSTRACE(("READ %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED));
return got;
OSTRACE(("READ %-3d %5d %7lld %llu\n",
id->h, got+prior, offset-prior, TIMER_ELAPSED));
return got+prior;
}
/*