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libblkid: add read() based fallback for char (UBI) devs 

Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2015-09-24 10:35:18 +02:00
parent a674a0ab03
commit 2355dd6a49
1 changed files with 60 additions and 9 deletions
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69
libblkid/src/probe.c
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@ -588,6 +588,8 @@ int __blkid_probe_filter_types(blkid_probe pr, int chain, int flag, char *names[
#define PROBE_MMAP_ENDSIZ (1024 * 1024 * 2) /* end of the device */
#define PROBE_MMAP_MIDSIZ (1024 * 1024) /* middle of the device */
#define probe_is_mmap_wanted(p) (!S_ISCHR((p)->mode))
static struct blkid_bufinfo *mmap_buffer(blkid_probe pr,
blkid_loff_t real_off,
blkid_loff_t len)
@ -660,6 +662,50 @@ static struct blkid_bufinfo *mmap_buffer(blkid_probe pr,
return bf;
}
static struct blkid_bufinfo *read_buffer(blkid_probe pr,
blkid_loff_t real_off,
blkid_loff_t len)
{
ssize_t ret;
struct blkid_bufinfo *bf = NULL;
if (blkid_llseek(pr->fd, real_off, SEEK_SET) < 0) {
errno = 0;
return NULL;
}
/* someone trying to overflow some buffers? */
if (len > ULONG_MAX - sizeof(struct blkid_bufinfo)) {
errno = ENOMEM;
return NULL;
}
/* allocate info and space for data by one malloc call */
bf = calloc(1, sizeof(struct blkid_bufinfo) + len);
if (!bf) {
errno = ENOMEM;
return NULL;
}
bf->data = ((unsigned char *) bf) + sizeof(struct blkid_bufinfo);
bf->len = len;
bf->off = real_off;
INIT_LIST_HEAD(&bf->bufs);
DBG(LOWPROBE, ul_debug("\tread %p: off=%jd len=%jd", bf->data, real_off, len));
ret = read(pr->fd, bf->data, len);
if (ret != (ssize_t) len) {
DBG(LOWPROBE, ul_debug("\tread failed: %m"));
free(bf);
if (ret >= 0)
errno = 0;
return NULL;
}
return bf;
}
/*
* Note that @off is offset within probing area, the probing area is defined by
* pr->off and pr->size.
@ -717,7 +763,10 @@ unsigned char *blkid_probe_get_buffer(blkid_probe pr,
/* not found; read from disk */
if (!bf) {
bf = mmap_buffer(pr, real_off, len);
if (probe_is_mmap_wanted(pr))
bf = mmap_buffer(pr, real_off, len);
else
bf = read_buffer(pr, real_off, len);
if (!bf)
return NULL;
@ -733,7 +782,7 @@ unsigned char *blkid_probe_get_buffer(blkid_probe pr,
static void blkid_probe_reset_buffer(blkid_probe pr)
{
uint64_t mmap_ct = 0, len_ct = 0;
uint64_t ct = 0, len = 0;
if (!pr || list_empty(&pr->buffers))
return;
@ -743,17 +792,19 @@ static void blkid_probe_reset_buffer(blkid_probe pr)
while (!list_empty(&pr->buffers)) {
struct blkid_bufinfo *bf = list_entry(pr->buffers.next,
struct blkid_bufinfo, bufs);
mmap_ct++;
len_ct += bf->len;
ct++;
len += bf->len;
list_del(&bf->bufs);
DBG(BUFFER, ul_debug(" unmap: %p [off=%ju, len=%ju]", bf->data, bf->off, bf->len));
munmap(bf->data, bf->len);
DBG(BUFFER, ul_debug(" remove buffer: %p [off=%ju, len=%ju]", bf->data, bf->off, bf->len));
if (probe_is_mmap_wanted(pr))
munmap(bf->data, bf->len);
free(bf);
}
DBG(LOWPROBE, ul_debug("buffers summary: %ju bytes (%ju pages) by %ju mmap() call(s)",
len_ct, len_ct / pr->mmap_granularity, mmap_ct));
DBG(LOWPROBE, ul_debug(" buffers summary: %ju bytes by %ju read/mmap() calls",
len, ct));
INIT_LIST_HEAD(&pr->buffers);
}
@ -840,7 +891,7 @@ int blkid_probe_set_device(blkid_probe pr, int fd,
goto err;
if (!S_ISBLK(sb.st_mode) && !S_ISCHR(sb.st_mode) && !S_ISREG(sb.st_mode)) {
errno = EINVAL;
errno = EINVAL;
goto err;
}