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authorNikolaus Voss <n.voss@weinmann.de>2013-05-13 01:55:11 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2013-05-13 01:55:11 (GMT)
commitc3cf1e30a3022453311a7e9fe11d94c7a381640e (patch)
tree0c451c05fd19f50a0b24368201a65e69500d6e8a
parentff463a885d7dbcea5493074cae498d58a5459539 (diff)
downloadbusybox-c3cf1e30a3022453311a7e9fe11d94c7a381640e.tar.gz
busybox-c3cf1e30a3022453311a7e9fe11d94c7a381640e.tar.bz2
mdev: use $DEVNAME in uevent sysfs file for device node name
516530c932bd17d87c9eb4347a490be051e495f4 uses $DEVNAME variable for device node name. This is fine, but only works for hotplugging, "mdev -s" will behave differently when DEVNAME and basename(path) differ. This patch extracts the DEVNAME from the uevent sysfs file in make_device(), thus works for hot- and coldplugging; so using the environment DEVNAME on hotplug events is no longer necessary. Signed-off-by: Nikolaus Voss <n.voss@weinmann.de> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--util-linux/mdev.c47
1 files changed, 35 insertions, 12 deletions
diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index 1d74136..e80b58f 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -295,8 +295,8 @@ struct globals {
/* Prevent infinite loops in /sys symlinks */
#define MAX_SYSFS_DEPTH 3
-/* We use additional 64+ bytes in make_device() */
-#define SCRATCH_SIZE 80
+/* We use additional bytes in make_device() */
+#define SCRATCH_SIZE 128
#if ENABLE_FEATURE_MDEV_CONF
@@ -541,7 +541,7 @@ static char *build_alias(char *alias, const char *device_name)
/* mknod in /dev based on a path like "/sys/block/hda/hda1"
* NB1: path parameter needs to have SCRATCH_SIZE scratch bytes
- * after NUL, but we promise to not mangle (IOW: to restore if needed)
+ * after NUL, but we promise to not mangle (IOW: to restore NUL if needed)
* path string.
* NB2: "mdev -s" may call us many times, do not leak memory/fds!
*
@@ -551,6 +551,7 @@ static char *build_alias(char *alias, const char *device_name)
static void make_device(char *device_name, char *path, int operation)
{
int major, minor, type, len;
+ char *path_end = path + strlen(path);
/* Try to read major/minor string. Note that the kernel puts \n after
* the data, so we don't need to worry about null terminating the string
@@ -559,17 +560,15 @@ static void make_device(char *device_name, char *path, int operation)
*/
major = -1;
if (operation == OP_add) {
- char *dev_maj_min = path + strlen(path);
-
- strcpy(dev_maj_min, "/dev");
- len = open_read_close(path, dev_maj_min + 1, 64);
- *dev_maj_min = '\0';
+ strcpy(path_end, "/dev");
+ len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1);
+ *path_end = '\0';
if (len < 1) {
if (!ENABLE_FEATURE_MDEV_EXEC)
return;
/* no "dev" file, but we can still run scripts
* based on device name */
- } else if (sscanf(++dev_maj_min, "%u:%u", &major, &minor) == 2) {
+ } else if (sscanf(path_end + 1, "%u:%u", &major, &minor) == 2) {
dbg1("dev %u,%u", major, minor);
} else {
major = -1;
@@ -577,9 +576,33 @@ static void make_device(char *device_name, char *path, int operation)
}
/* else: for delete, -1 still deletes the node, but < -1 suppresses that */
- /* Determine device name, type, major and minor */
- if (!device_name)
- device_name = (char*) bb_basename(path);
+ /* Determine device name */
+ if (!device_name) {
+ /*
+ * There was no $DEVNAME envvar (for example, mdev -s never has).
+ * But it is very useful: it contains the *path*, not only basename,
+ * Thankfully, uevent file has it.
+ * Example of .../sound/card0/controlC0/uevent file on Linux-3.7.7:
+ * MAJOR=116
+ * MINOR=7
+ * DEVNAME=snd/controlC0
+ */
+ strcpy(path_end, "/uevent");
+ len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1);
+ if (len < 0)
+ len = 0;
+ *path_end = '\0';
+ path_end[1 + len] = '\0';
+ device_name = strstr(path_end + 1, "\nDEVNAME=");
+ if (device_name) {
+ device_name += sizeof("\nDEVNAME=")-1;
+ strchrnul(device_name, '\n')[0] = '\0';
+ } else {
+ /* Fall back to just basename */
+ device_name = (char*) bb_basename(path);
+ }
+ }
+ /* Determine device type */
/*
* http://kernel.org/doc/pending/hotplug.txt says that only
* "/sys/block/..." is for block devices. "/sys/bus" etc is not.