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[Qemu-devel] [PATCH 03/21] cloop: use pread
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 03/21] cloop: use pread |
Date: |
Fri, 14 May 2010 19:10:37 +0200 |
From: Christoph Hellwig <address@hidden>
Use pread instead of lseek + read in preparation of using the qemu
block API.
Signed-off-by: Christoph Hellwig <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
block/cloop.c | 32 +++++++++++++++++---------------
1 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/block/cloop.c b/block/cloop.c
index e4f995b..9fe2a42 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -62,23 +62,22 @@ static int cloop_open(BlockDriverState *bs, const char
*filename, int flags)
bs->read_only = 1;
/* read header */
- if(lseek(s->fd,128,SEEK_SET)<0) {
-cloop_close:
- close(s->fd);
- return -1;
+ if (pread(s->fd, &s->block_size, 4, 128) < 4) {
+ goto cloop_close;
}
- if(read(s->fd,&s->block_size,4)<4)
- goto cloop_close;
- s->block_size=be32_to_cpu(s->block_size);
- if(read(s->fd,&s->n_blocks,4)<4)
- goto cloop_close;
- s->n_blocks=be32_to_cpu(s->n_blocks);
+ s->block_size = be32_to_cpu(s->block_size);
+
+ if (pread(s->fd, &s->n_blocks, 4, 128 + 4) < 4) {
+ goto cloop_close;
+ }
+ s->n_blocks = be32_to_cpu(s->n_blocks);
/* read offsets */
- offsets_size=s->n_blocks*sizeof(uint64_t);
- s->offsets=(uint64_t*)qemu_malloc(offsets_size);
- if(read(s->fd,s->offsets,offsets_size)<offsets_size)
+ offsets_size = s->n_blocks * sizeof(uint64_t);
+ s->offsets = qemu_malloc(offsets_size);
+ if (pread(s->fd, s->offsets, offsets_size, 128 + 4 + 4) < offsets_size) {
goto cloop_close;
+ }
for(i=0;i<s->n_blocks;i++) {
s->offsets[i]=be64_to_cpu(s->offsets[i]);
if(i>0) {
@@ -98,6 +97,10 @@ cloop_close:
s->sectors_per_block = s->block_size/512;
bs->total_sectors = s->n_blocks*s->sectors_per_block;
return 0;
+
+cloop_close:
+ close(s->fd);
+ return -1;
}
static inline int cloop_read_block(BDRVCloopState *s,int block_num)
@@ -106,8 +109,7 @@ static inline int cloop_read_block(BDRVCloopState *s,int
block_num)
int ret;
uint32_t bytes = s->offsets[block_num+1]-s->offsets[block_num];
- lseek(s->fd, s->offsets[block_num], SEEK_SET);
- ret = read(s->fd, s->compressed_block, bytes);
+ ret = pread(s->fd, s->compressed_block, bytes, s->offsets[block_num]);
if (ret != bytes)
return -1;
--
1.6.6.1
- [Qemu-devel] [PULL 00/21] Block patches, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 01/21] block: Remove semicolon in BDRV_SECTOR_MASK macro, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 04/21] cloop: use qemu block API, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 05/21] ide: Fix ide_dma_cancel, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 09/21] block: Fix protocol detection for Windows devices, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 07/21] bochs: use qemu block API, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 03/21] cloop: use pread,
Kevin Wolf <=
- [Qemu-devel] [PATCH 08/21] block: Avoid unchecked casts for AIOCBs, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 06/21] bochs: use pread, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 12/21] parallels: use pread, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 13/21] parallels: use qemu block API, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 11/21] block/vdi: Allow disk images of size 0, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 15/21] dmg: fix reading of uncompressed chunks, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 14/21] block/vpc: Fix conversion from size to disk geometry, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 02/21] qemu-nbd: Improve error reporting, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 16/21] dmg: use pread, Kevin Wolf, 2010/05/14
- [Qemu-devel] [PATCH 17/21] dmg: use qemu block API, Kevin Wolf, 2010/05/14