Message ID | 20100504104504.GE6388@lst.de |
---|---|
State | New |
Headers | show |
Am 04.05.2010 12:45, schrieb Christoph Hellwig: > Use pread instead of lseek + read in preparation of using the qemu > block API. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > > Index: qemu-kevin/block/parallels.c > =================================================================== > --- qemu-kevin.orig/block/parallels.c 2010-05-03 13:00:09.711253925 +0200 > +++ qemu-kevin/block/parallels.c 2010-05-03 13:04:15.686033993 +0200 > @@ -83,7 +83,7 @@ static int parallels_open(BlockDriverSta > > s->fd = fd; > > - if (read(fd, &ph, sizeof(ph)) != sizeof(ph)) > + if (pread(fd, &ph, sizeof(ph), 0) != sizeof(ph)) > goto fail; > > if (memcmp(ph.magic, HEADER_MAGIC, 16) || > @@ -93,14 +93,11 @@ static int parallels_open(BlockDriverSta > > bs->total_sectors = le32_to_cpu(ph.nb_sectors); > > - if (lseek(s->fd, 64, SEEK_SET) != 64) > - goto fail; > - > s->tracks = le32_to_cpu(ph.tracks); > > s->catalog_size = le32_to_cpu(ph.catalog_entries); > s->catalog_bitmap = qemu_malloc(s->catalog_size * 4); > - if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) != > + if (pread(s->fd, s->catalog_bitmap, s->catalog_size * 4, 64) != > s->catalog_size * 4) > goto fail; > for (i = 0; i < s->catalog_size; i++) > @@ -114,28 +111,18 @@ fail: > return -1; > } > > -static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num) > +static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) > { > BDRVParallelsState *s = bs->opaque; > uint32_t index, offset; > - uint64_t position; > > index = sector_num / s->tracks; > offset = sector_num % s->tracks; > > - // not allocated > + /* not allocated */ > if ((index > s->catalog_size) || (s->catalog_bitmap[index] == 0)) > return -1; > - > - position = (uint64_t)(s->catalog_bitmap[index] + offset) * 512; > - > -// fprintf(stderr, "sector: %llx index=%x offset=%x pointer=%x position=%x\n", > -// sector_num, index, offset, s->catalog_bitmap[index], position); > - > - if (lseek(s->fd, position, SEEK_SET) != position) > - return -1; > - > - return 0; > + return (uint64_t)(s->catalog_bitmap[index] + offset) * 512; > } > > static int parallels_read(BlockDriverState *bs, int64_t sector_num, > @@ -144,11 +131,13 @@ static int parallels_read(BlockDriverSta > BDRVParallelsState *s = bs->opaque; > > while (nb_sectors > 0) { > - if (!seek_to_sector(bs, sector_num)) { > - if (read(s->fd, buf, 512) != 512) > - return -1; > - } else > + uint64_t position = seek_to_sector(bs, sector_num); > + if (position >= 0) { position should be a signed int64_t, otherwise the condition is always true. Kevin
On Wed, May 05, 2010 at 04:19:30PM +0200, Kevin Wolf wrote:
> position should be a signed int64_t, otherwise the condition is always true.
Indeed, I'll update the patch.
Index: qemu-kevin/block/parallels.c =================================================================== --- qemu-kevin.orig/block/parallels.c 2010-05-03 13:00:09.711253925 +0200 +++ qemu-kevin/block/parallels.c 2010-05-03 13:04:15.686033993 +0200 @@ -83,7 +83,7 @@ static int parallels_open(BlockDriverSta s->fd = fd; - if (read(fd, &ph, sizeof(ph)) != sizeof(ph)) + if (pread(fd, &ph, sizeof(ph), 0) != sizeof(ph)) goto fail; if (memcmp(ph.magic, HEADER_MAGIC, 16) || @@ -93,14 +93,11 @@ static int parallels_open(BlockDriverSta bs->total_sectors = le32_to_cpu(ph.nb_sectors); - if (lseek(s->fd, 64, SEEK_SET) != 64) - goto fail; - s->tracks = le32_to_cpu(ph.tracks); s->catalog_size = le32_to_cpu(ph.catalog_entries); s->catalog_bitmap = qemu_malloc(s->catalog_size * 4); - if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) != + if (pread(s->fd, s->catalog_bitmap, s->catalog_size * 4, 64) != s->catalog_size * 4) goto fail; for (i = 0; i < s->catalog_size; i++) @@ -114,28 +111,18 @@ fail: return -1; } -static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num) +static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) { BDRVParallelsState *s = bs->opaque; uint32_t index, offset; - uint64_t position; index = sector_num / s->tracks; offset = sector_num % s->tracks; - // not allocated + /* not allocated */ if ((index > s->catalog_size) || (s->catalog_bitmap[index] == 0)) return -1; - - position = (uint64_t)(s->catalog_bitmap[index] + offset) * 512; - -// fprintf(stderr, "sector: %llx index=%x offset=%x pointer=%x position=%x\n", -// sector_num, index, offset, s->catalog_bitmap[index], position); - - if (lseek(s->fd, position, SEEK_SET) != position) - return -1; - - return 0; + return (uint64_t)(s->catalog_bitmap[index] + offset) * 512; } static int parallels_read(BlockDriverState *bs, int64_t sector_num, @@ -144,11 +131,13 @@ static int parallels_read(BlockDriverSta BDRVParallelsState *s = bs->opaque; while (nb_sectors > 0) { - if (!seek_to_sector(bs, sector_num)) { - if (read(s->fd, buf, 512) != 512) - return -1; - } else + uint64_t position = seek_to_sector(bs, sector_num); + if (position >= 0) { + if (pread(s->fd, buf, 512, position) != 512) + return -1; + } else { memset(buf, 0, 512); + } nb_sectors--; sector_num++; buf += 512;
Use pread instead of lseek + read in preparation of using the qemu block API. Signed-off-by: Christoph Hellwig <hch@lst.de>