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mdev: use $DEVNAME in uevent sysfs file for device node name

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516530c932 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>
This commit is contained in:
Nikolaus Voss 2013-05-13 03:55:11 +02:00 committed by Denys Vlasenko
parent ff463a885d
commit c3cf1e30a3
1 changed files with 35 additions and 12 deletions
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47
util-linux/mdev.c
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@ -295,8 +295,8 @@ struct globals {
/* Prevent infinite loops in /sys symlinks */ /* Prevent infinite loops in /sys symlinks */
#define MAX_SYSFS_DEPTH 3 #define MAX_SYSFS_DEPTH 3
/* We use additional 64+ bytes in make_device() */ /* We use additional bytes in make_device() */
#define SCRATCH_SIZE 80 #define SCRATCH_SIZE 128
#if ENABLE_FEATURE_MDEV_CONF #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" /* mknod in /dev based on a path like "/sys/block/hda/hda1"
* NB1: path parameter needs to have SCRATCH_SIZE scratch bytes * 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. * path string.
* NB2: "mdev -s" may call us many times, do not leak memory/fds! * 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) static void make_device(char *device_name, char *path, int operation)
{ {
int major, minor, type, len; int major, minor, type, len;
char *path_end = path + strlen(path);
/* Try to read major/minor string. Note that the kernel puts \n after /* 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 * 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; major = -1;
if (operation == OP_add) { if (operation == OP_add) {
char *dev_maj_min = path + strlen(path); strcpy(path_end, "/dev");
len = open_read_close(path, path_end + 1, SCRATCH_SIZE - 1);
strcpy(dev_maj_min, "/dev"); *path_end = '\0';
len = open_read_close(path, dev_maj_min + 1, 64);
*dev_maj_min = '\0';
if (len < 1) { if (len < 1) {
if (!ENABLE_FEATURE_MDEV_EXEC) if (!ENABLE_FEATURE_MDEV_EXEC)
return; return;
/* no "dev" file, but we can still run scripts /* no "dev" file, but we can still run scripts
* based on device name */ * 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); dbg1("dev %u,%u", major, minor);
} else { } else {
major = -1; 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 */ /* else: for delete, -1 still deletes the node, but < -1 suppresses that */
/* Determine device name, type, major and minor */ /* Determine device name */
if (!device_name) if (!device_name) {
device_name = (char*) bb_basename(path); /*
* 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 * http://kernel.org/doc/pending/hotplug.txt says that only
* "/sys/block/..." is for block devices. "/sys/bus" etc is not. * "/sys/block/..." is for block devices. "/sys/bus" etc is not.