diff options
Diffstat (limited to 'src/os_unix.c')
| -rw-r--r-- | src/os_unix.c | 23 |
1 files changed, 13 insertions, 10 deletions
diff --git a/src/os_unix.c b/src/os_unix.c index 8314e4f67..f802d9cd1 100644 --- a/src/os_unix.c +++ b/src/os_unix.c @@ -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 } |