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Ensure that when a file is extended using FCNTL_SIZE_HINT the last page is allocated on disk, even if the file will only use part of it.

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FossilOrigin-Name: c7f84717d61197afa9e0ac607c4b349361e6e2b7
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dan
2014-12-30 19:58:31 +00:00
parent 9486c1b020
commit 592bf7faf5
3 changed files with 21 additions and 18 deletions
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23
src/os_unix.c
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@@ -3709,24 +3709,27 @@ static int fcntlSizeHint(unixFile *pFile, i64 nByte){
}while( err==EINTR );
if( err ) return SQLITE_IOERR_WRITE;
#else
/* If the OS does not have posix_fallocate(), fake it. First use
** ftruncate() to set the file size, then write a single byte to
** the last byte in each block within the extended region. This
** is the same technique used by glibc to implement posix_fallocate()
** on systems that do not have a real fallocate() system call.
/* If the OS does not have posix_fallocate(), fake it. Write a
** single byte to the last byte in each block that falls entirely
** within the extended region. Then, if required, a single byte
** at offset (nSize-1), to set the size of the file correctly.
** This is a similar technique to that used by glibc on systems
** that do not have a real fallocate() call.
*/
int nBlk = buf.st_blksize; /* File-system block size */
i64 iWrite; /* Next offset to write to */
iWrite = ((buf.st_size + 2*nBlk - 1)/nBlk)*nBlk-1;
while( iWrite<nSize ){
assert( iWrite>=buf.st_size );
assert( (iWrite/nBlk)==((buf.st_size+nBlk-1)/nBlk) );
assert( ((iWrite+1)%nBlk)==0 );
for(/*no-op*/; iWrite<nSize; iWrite+=nBlk ){
int nWrite = seekAndWrite(pFile, iWrite, "", 1);
if( nWrite!=1 ) return SQLITE_IOERR_WRITE;
iWrite += nBlk;
}
if( robust_ftruncate(pFile->h, nSize) ){
pFile->lastErrno = errno;
return unixLogError(SQLITE_IOERR_TRUNCATE, "ftruncate", pFile->zPath);
if( nSize%nBlk ){
int nWrite = seekAndWrite(pFile, nSize-1, "", 1);
if( nWrite!=1 ) return SQLITE_IOERR_WRITE;
}
#endif
}