add support for renaming/relocating device nodes

3 files changed, 61 insertions, 5 deletions

diff --git a/docs/mdev.txt b/docs/mdev.txt
index 4a4451b4d..38f1da964 100644
--- a/docs/mdev.txt
+++ b/docs/mdev.txt
@@ -53,6 +53,15 @@ matched, then the default of 0:0 660 is used.  To set your own default, simply
 create your own total match like so:
         .* 1:1 777
 
+You can rename/relocate device nodes by using the next optional field.
+        <device regex> <uid>:<gid> <octal permissions> [>path]
+So if you want to place the device node into a subdirectory, make sure the path
+has a trailing /.  If you want to rename the device node, just place the name.
+        hda 0:3 660 >drives/
+This will relocate "hda" into the drives/ subdirectory.
+        hdb 0:3 660 >cdrom
+This will rename "hdb" to "cdrom".
+
 If you also enable support for executing your own commands, then the file has
 the format:
         <device regex> <uid>:<gid> <octal permissions> [<@|$|*> <command>]
diff --git a/util-linux/Config.in b/util-linux/Config.in
index 8ec466bb8..d236b77b6 100644
--- a/util-linux/Config.in
+++ b/util-linux/Config.in
@@ -301,6 +301,15 @@ config FEATURE_MDEV_CONF
 
           For more information, please see docs/mdev.txt
 
+config FEATURE_MDEV_RENAME
+        bool "Support subdirs/symlinks"
+        default n
+        depends on FEATURE_MDEV_CONF
+        help
+          Add support for renaming devices and creating symlinks.
+
+          For more information, please see docs/mdev.txt
+
 config FEATURE_MDEV_EXEC
         bool "Support command execution at device addition/removal"
         default n
diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index 65b4da4f4..a18fc0916 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -31,6 +31,10 @@ static void make_device(char *path, int delete)
         gid_t gid = 0;
         char *temp = path + strlen(path);
         char *command = NULL;
+        char *alias = NULL;
+
+        /* Force the configuration file settings exactly. */
+        umask(0);
 
         /* 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
@@ -70,7 +74,7 @@ static void make_device(char *path, int delete)
                         ++lineno;
 
                         /* Three fields: regex, uid:gid, mode */
-                        for (field = 0; field < (3 + ENABLE_FEATURE_MDEV_EXEC); ++field) {
+                        for (field = 0; field < (3 + ENABLE_FEATURE_MDEV_RENAME + ENABLE_FEATURE_MDEV_EXEC); ++field) {
 
                                 /* Find a non-empty field */
                                 char *val;
@@ -131,7 +135,16 @@ static void make_device(char *path, int delete)
                                         /* Mode device permissions */
                                         mode = strtoul(val, NULL, 8);
 
-                                } else if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
+                                } else if (ENABLE_FEATURE_MDEV_RENAME && field == 3) {
+
+                                        if (*val != '>')
+                                                ++field;
+                                        else
+                                                alias = xstrdup(val + 1);
+
+                                }
+
+                                if (ENABLE_FEATURE_MDEV_EXEC && field == 3 + ENABLE_FEATURE_MDEV_RENAME) {
 
                                         /* Optional command to run */
                                         const char *s = "@$*";
@@ -167,20 +180,45 @@ static void make_device(char *path, int delete)
  end_parse:     /* nothing */ ;
         }
 
-        umask(0);
         if (!delete) {
                 if (sscanf(temp, "%d:%d", &major, &minor) != 2)
                         return;
+
+                if (ENABLE_FEATURE_MDEV_RENAME)
+                        unlink(device_name);
+
                 if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
                         bb_perror_msg_and_die("mknod %s", device_name);
 
                 if (major == root_major && minor == root_minor)
                         symlink(device_name, "root");
 
-                if (ENABLE_FEATURE_MDEV_CONF)
+                if (ENABLE_FEATURE_MDEV_CONF) {
                         chown(device_name, uid, gid);
+
+                        if (ENABLE_FEATURE_MDEV_RENAME && alias) {
+                                char *dest;
+
+                                temp = strrchr(alias, '/');
+                                if (temp) {
+                                        if (temp[1] != '\0')
+                                                /* given a file name, so rename it */
+                                                *temp = '\0';
+                                        bb_make_directory(alias, 0755, FILEUTILS_RECUR);
+                                        dest = concat_path_file(alias, device_name);
+                                } else
+                                        dest = alias;
+
+                                rename(device_name, dest);
+                                symlink(dest, device_name);
+
+                                if (alias != dest)
+                                        free(alias);
+                                free(dest);
+                        }
+                }
         }
-        if (command) {
+        if (ENABLE_FEATURE_MDEV_EXEC && command) {
                 /* setenv will leak memory, so use putenv */
                 char *s = xasprintf("MDEV=%s", device_name);
                 putenv(s);