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volume_id/fat: careful with sector#, it may not fit in 32 bits. +91 bytes

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volume_id/*: a bit of code shrink
This commit is contained in:
Denis Vlasenko
2008-11-30 17:41:31 +00:00
parent a34b8a4d30
commit 1e10afcdfb
3 changed files with 68 additions and 66 deletions
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96
util-linux/volume_id/util.c
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@ -195,70 +195,73 @@ set:
* It's better to ignore such fs and continue. */
void *volume_id_get_buffer(struct volume_id *id, uint64_t off, size_t len)
{
ssize_t buf_len;
uint8_t *dst;
unsigned small_off;
ssize_t read_len;
dbg("get buffer off 0x%llx(%llu), len 0x%zx",
(unsigned long long) off, (unsigned long long) off, len);
dbg("get buffer off 0x%llx(%llu), len 0x%zx", (unsigned long long) off, (unsigned long long) off, len);
/* check if requested area fits in superblock buffer */
if (off + len <= SB_BUFFER_SIZE) {
if (off + len <= SB_BUFFER_SIZE
/* && off <= SB_BUFFER_SIZE - want this paranoid overflow check? */
) {
if (id->sbbuf == NULL) {
id->sbbuf = xmalloc(SB_BUFFER_SIZE);
}
small_off = off;
dst = id->sbbuf;
/* check if we need to read */
if ((off + len) > id->sbbuf_len) {
dbg("read sbbuf len:0x%llx", (unsigned long long) (off + len));
if (lseek(id->fd, 0, SEEK_SET) != 0) {
dbg("seek(0) failed");
return NULL;
}
buf_len = full_read(id->fd, id->sbbuf, off + len);
if (buf_len < 0) {
dbg("read failed (%s)", strerror(errno));
return NULL;
}
dbg("got 0x%zx (%zi) bytes", buf_len, buf_len);
id->sbbuf_len = buf_len;
if ((uint64_t)buf_len < off + len) {
dbg("requested 0x%zx bytes, got only 0x%zx bytes", len, buf_len);
return NULL;
}
}
len += off;
if (len <= id->sbbuf_len)
goto ret; /* we already have it */
return &(id->sbbuf[off]);
dbg("read sbbuf len:0x%x", (unsigned) len);
id->sbbuf_len = len;
off = 0;
goto do_read;
}
if (len > SEEK_BUFFER_SIZE) {
dbg("seek buffer too small %d", SEEK_BUFFER_SIZE);
return NULL;
}
/* get seek buffer */
if (id->seekbuf == NULL) {
id->seekbuf = xmalloc(SEEK_BUFFER_SIZE);
}
dst = id->seekbuf;
/* check if we need to read */
if ((off < id->seekbuf_off) || ((off + len) > (id->seekbuf_off + id->seekbuf_len))) {
dbg("read seekbuf off:0x%llx len:0x%zx", (unsigned long long) off, len);
if (lseek(id->fd, off, SEEK_SET) != off) {
dbg("seek(0x%llx) failed", (unsigned long long) off);
return NULL;
}
buf_len = full_read(id->fd, id->seekbuf, len);
if (buf_len < 0) {
dbg("read failed (%s)", strerror(errno));
return NULL;
}
dbg("got 0x%zx (%zi) bytes", buf_len, buf_len);
id->seekbuf_off = off;
id->seekbuf_len = buf_len;
if ((size_t)buf_len < len) {
dbg("requested 0x%zx bytes, got only 0x%zx bytes", len, buf_len);
return NULL;
}
if ((off >= id->seekbuf_off)
&& ((off + len) <= (id->seekbuf_off + id->seekbuf_len))
) {
small_off = off - id->seekbuf_off; /* can't overflow */
goto ret; /* we already have it */
}
return &(id->seekbuf[off - id->seekbuf_off]);
id->seekbuf_off = off;
id->seekbuf_len = len;
id->seekbuf = xrealloc(id->seekbuf, len);
small_off = 0;
dst = id->seekbuf;
dbg("read seekbuf off:0x%llx len:0x%zx",
(unsigned long long) off, len);
do_read:
if (lseek(id->fd, off, SEEK_SET) != off) {
dbg("seek(0x%llx) failed", (unsigned long long) off);
goto err;
}
read_len = full_read(id->fd, dst, len);
if (read_len != len) {
dbg("requested 0x%x bytes, got 0x%x bytes",
(unsigned) len, (unsigned) read_len);
err:
/* id->seekbuf_len or id->sbbuf_len is wrong now! Fixing.
* Most likely user will not do any additional
* calls anyway, it's a corrupted fs or something. */
volume_id_free_buffer(id);
return NULL;
}
ret:
return dst + small_off;
}
void volume_id_free_buffer(struct volume_id *id)
@ -269,4 +272,5 @@ void volume_id_free_buffer(struct volume_id *id)
free(id->seekbuf);
id->seekbuf = NULL;
id->seekbuf_len = 0;
id->seekbuf_off = 0; /* paranoia */
}