From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Tue, 7 Jan 2025 18:23:29 +0000 (+0900)
Subject: sd-device: make sd_device_new_from_path() accept relative path to device node
X-Git-Tag: v258-rc1~1658
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=cdd53cb74b0882ed2a249117c895b94013fa6ea9;p=thirdparty%2Fsystemd.git

sd-device: make sd_device_new_from_path() accept relative path to device node

Even though udevadm accepts relative syspath, previously, udevadm
could not use relative path to device node:
===
$ cd /dev
$ udevadm info sda
Bad argument "sda", expected an absolute path in /dev/ or /sys/ or a unit name: Invalid argument
$ udevadm info /usr/../dev/sda
Unknown device "/usr/../dev/sda": No such device
===
With this change, both the above cases work fine.

Note, still sd_device_new_from_devname() requires absolute path starts
with /dev/, for safety.
---

diff --git a/src/libsystemd/sd-device/sd-device.c b/src/libsystemd/sd-device/sd-device.c
index 9e281597796..a608ae326f4 100644
--- a/src/libsystemd/sd-device/sd-device.c
+++ b/src/libsystemd/sd-device/sd-device.c
@@ -541,10 +541,8 @@ _public_ int sd_device_new_from_stat_rdev(sd_device **ret, const struct stat *st
         return device_new_from_mode_and_devnum(ret, st->st_mode, st->st_rdev);
 }
 
-_public_ int sd_device_new_from_devname(sd_device **ret, const char *devname) {
-        struct stat st;
-        dev_t devnum;
-        mode_t mode;
+static int device_new_from_devname(sd_device **ret, const char *devname, bool strict) {
+        int r;
 
         assert_return(ret, -EINVAL);
         assert_return(devname, -EINVAL);
@@ -552,28 +550,41 @@ _public_ int sd_device_new_from_devname(sd_device **ret, const char *devname) {
         /* This function actually accepts both devlinks and devnames, i.e. both symlinks and device
          * nodes below /dev/. */
 
-        /* Also ignore when the specified path is "/dev". */
-        if (isempty(path_startswith(devname, "/dev")))
+        if (strict && isempty(path_startswith(devname, "/dev/")))
                 return -EINVAL;
 
+        dev_t devnum;
+        mode_t mode;
         if (device_path_parse_major_minor(devname, &mode, &devnum) >= 0)
                 /* Let's shortcut when "/dev/block/maj:min" or "/dev/char/maj:min" is specified.
                  * In that case, we can directly convert the path to syspath, hence it is not necessary
                  * that the specified path exists. So, this works fine without udevd being running. */
                 return device_new_from_mode_and_devnum(ret, mode, devnum);
 
-        if (stat(devname, &st) < 0)
-                return ERRNO_IS_DEVICE_ABSENT(errno) ? -ENODEV : -errno;
+        _cleanup_free_ char *resolved = NULL;
+        struct stat st;
+        r = chase_and_stat(devname, /* root = */ NULL, /* flags = */ 0, &resolved, &st);
+        if (ERRNO_IS_NEG_DEVICE_ABSENT(r))
+                return -ENODEV;
+        if (r < 0)
+                return r;
+
+        if (isempty(path_startswith(resolved, "/dev/")))
+                return -EINVAL;
 
         return sd_device_new_from_stat_rdev(ret, &st);
 }
 
+_public_ int sd_device_new_from_devname(sd_device **ret, const char *devname) {
+        return device_new_from_devname(ret, devname, /* strict = */ true);
+}
+
 _public_ int sd_device_new_from_path(sd_device **ret, const char *path) {
         assert_return(ret, -EINVAL);
         assert_return(path, -EINVAL);
 
-        if (path_startswith(path, "/dev"))
-                return sd_device_new_from_devname(ret, path);
+        if (device_new_from_devname(ret, path, /* strict = */ false) >= 0)
+                return 0;
 
         return device_new_from_syspath(ret, path, /* strict = */ false);
 }
diff --git a/test/units/TEST-17-UDEV.10.sh b/test/units/TEST-17-UDEV.10.sh
index afa05909c40..e38291bdde8 100755
--- a/test/units/TEST-17-UDEV.10.sh
+++ b/test/units/TEST-17-UDEV.10.sh
@@ -103,6 +103,11 @@ udevadm info -e --initialized-nomatch >/dev/null
 # udevadm info -c
 udevadm info -w /sys/class/net/$netdev
 udevadm info --wait-for-initialization=5 /sys/class/net/$netdev
+pushd /dev
+udevadm info null >/dev/null
+udevadm info ./null >/dev/null
+popd
+udevadm info /usr/../dev/null >/dev/null
 udevadm info -h
 
 assert_rc 124 timeout 1 udevadm monitor