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udev-builtin-blkid: add support for --hint offsets

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The next libblkid v2.37 is going to support session offsets for
multi-session CD/DVDs. This feature is implemented by "hint offsets".

These offsets are optional and prober specific (e.g., iso, udf, ...).
For this purpose, the library provides a new function
blkid_probe_set_hint(), and blkid(8) provides a new command-line
option --hint <name>=<offset>. For CD/DVD, the offset name is
"session_offset".

The difference between classic --offset and the new --hint is that
--offset is very restrictive and defines the probing area and the rest
of the device is invisible to the library. The new --hint works
like a suggestion, it provides a hint where the user assumes the
filesystem, but the rest of the device is still readable for the
library (for example, to get some additional superblock information
etc.).

If the --hint is without a value then it defaults to zero.

The option --hint implementation in udev-builtin-blkid.c is backwardly
compatible. If compiled against old libblkid, then the option is used in
the same way as --offset.

Addresses: https://github.com/karelzak/util-linux/issues/1161
Addresses: https://github.com/systemd/systemd/pull/17424
This commit is contained in:
Karel Zak 2020-11-30 11:38:21 +01:00 committed by Yu Watanabe
parent 885598f36c
commit 4fcc033b54
4 changed files with 30 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
meson.build
View File

@ -1003,6 +1003,9 @@ want_blkid = get_option('blkid')
if want_blkid != 'false' and not skip_deps
libblkid = dependency('blkid', required : want_blkid == 'true')
have = libblkid.found()
conf.set10('HAVE_BLKID_PROBE_SET_HINT',
have and cc.has_function('blkid_probe_set_hint', dependencies : libblkid))
else
have = false
libblkid = []

2
rules.d/60-persistent-storage.rules
View File

@ -104,7 +104,7 @@ KERNEL=="vd*[0-9]", ENV{ID_PATH}=="pci-*", SYMLINK+="disk/by-path/virtio-$env{ID
# probe filesystem metadata of optical drives which have a media inserted
KERNEL=="sr*", ENV{DISK_EJECT_REQUEST}!="?*", ENV{ID_CDROM_MEDIA_TRACK_COUNT_DATA}=="?*", ENV{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}=="?*", \
IMPORT{builtin}="blkid --offset=$env{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}"
IMPORT{builtin}="blkid --hint=session_offset=$env{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}"
# single-session CDs do not have ID_CDROM_MEDIA_SESSION_LAST_OFFSET
KERNEL=="sr*", ENV{DISK_EJECT_REQUEST}!="?*", ENV{ID_CDROM_MEDIA_TRACK_COUNT_DATA}=="?*", ENV{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}=="", \
IMPORT{builtin}="blkid --noraid"

33
src/udev/udev-builtin-blkid.c
View File

@ -238,10 +238,16 @@ static int builtin_blkid(sd_device *dev, int argc, char *argv[], bool test) {
static const struct option options[] = {
{ "offset", required_argument, NULL, 'o' },
{ "hint", required_argument, NULL, 'H' },
{ "noraid", no_argument, NULL, 'R' },
{}
};
errno = 0;
pr = blkid_new_probe();
if (!pr)
return log_device_debug_errno(dev, errno_or_else(ENOMEM), "Failed to create blkid prober: %m");
for (;;) {
int option;
@ -250,12 +256,28 @@ static int builtin_blkid(sd_device *dev, int argc, char *argv[], bool test) {
break;
switch (option) {
case 'H':
#if HAVE_BLKID_PROBE_SET_HINT
errno = 0;
r = blkid_probe_set_hint(pr, optarg, 0);
if (r < 0)
return log_device_error_errno(dev, errno_or_else(ENOMEM), "Failed to use '%s' probing hint: %m", optarg);
break;
#else
/* Use the hint <name>=<offset> as probing offset for old versions */
optarg = strchr(optarg, '=');
if (!optarg)
/* no value means 0, do nothing for old versions */
break;
++optarg;
_fallthrough_;
#endif
case 'o':
r = safe_atoi64(optarg, &offset);
if (r < 0)
return log_device_error_errno(dev, r, "Failed to parse '%s' as an integer: %m", optarg);
if (offset < 0)
return log_device_error_errno(dev, SYNTHETIC_ERRNO(ERANGE), "Invalid offset %"PRIi64": %m", offset);
return log_device_error_errno(dev, SYNTHETIC_ERRNO(EINVAL), "Invalid offset %"PRIi64": %m", offset);
break;
case 'R':
noraid = true;
@ -263,11 +285,6 @@ static int builtin_blkid(sd_device *dev, int argc, char *argv[], bool test) {
}
}
errno = 0;
pr = blkid_new_probe();
if (!pr)
return log_device_debug_errno(dev, errno > 0 ? errno : ENOMEM, "Failed to create blkid prober: %m");
blkid_probe_set_superblocks_flags(pr,
BLKID_SUBLKS_LABEL | BLKID_SUBLKS_UUID |
BLKID_SUBLKS_TYPE | BLKID_SUBLKS_SECTYPE |
@ -287,7 +304,7 @@ static int builtin_blkid(sd_device *dev, int argc, char *argv[], bool test) {
errno = 0;
r = blkid_probe_set_device(pr, fd, offset, 0);
if (r < 0)
return log_device_debug_errno(dev, errno > 0 ? errno : ENOMEM, "Failed to set device to blkid prober: %m");
return log_device_debug_errno(dev, errno_or_else(ENOMEM), "Failed to set device to blkid prober: %m");
log_device_debug(dev, "Probe %s with %sraid and offset=%"PRIi64, devnode, noraid ? "no" : "", offset);
@ -301,7 +318,7 @@ static int builtin_blkid(sd_device *dev, int argc, char *argv[], bool test) {
errno = 0;
nvals = blkid_probe_numof_values(pr);
if (nvals < 0)
return log_device_debug_errno(dev, errno > 0 ? errno : ENOMEM, "Failed to get number of probed values: %m");
return log_device_debug_errno(dev, errno_or_else(ENOMEM), "Failed to get number of probed values: %m");
for (i = 0; i < nvals; i++) {
if (blkid_probe_get_value(pr, i, &name, &data, NULL) < 0)

2
test/fuzz/fuzz-udev-rules/60-persistent-storage.rules
View File

@ -86,7 +86,7 @@ KERNEL=="vd*[0-9]", ENV{ID_PATH}=="pci-*", SYMLINK+="disk/by-path/virtio-$env{ID
# probe filesystem metadata of optical drives which have a media inserted
KERNEL=="sr*", ENV{DISK_EJECT_REQUEST}!="?*", ENV{ID_CDROM_MEDIA_TRACK_COUNT_DATA}=="?*", ENV{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}=="?*", \
IMPORT{builtin}="blkid --offset=$env{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}"
IMPORT{builtin}="blkid --hint=session_offset=$env{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}"
# single-session CDs do not have ID_CDROM_MEDIA_SESSION_LAST_OFFSET
KERNEL=="sr*", ENV{DISK_EJECT_REQUEST}!="?*", ENV{ID_CDROM_MEDIA_TRACK_COUNT_DATA}=="?*", ENV{ID_CDROM_MEDIA_SESSION_LAST_OFFSET}=="", \
IMPORT{builtin}="blkid --noraid"