mdev: add "!" syntax support

Based on the patch by Steve Bennett <steveb@workware.net.au>

function                                             old     new   delta
make_device                                         1640    1673     +33

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/docs/mdev.txt b/docs/mdev.txt
index 7bd00fe1bf0e9c07640e9c394a6cd7eb8e5dbd68..2d03bd8b2f2f29685d519927f1f53eaac4aa50d7 100644 (file)
--- a/docs/mdev.txt
+++ b/docs/mdev.txt
@@ -51,8 +51,8 @@ device nodes if your system needs something more than the default root/root
 660 permissions.
 
 The file has the format:
-    <device regex>       <uid>:<gid> <octal permissions>
- or @<maj[,min1[-min2]]> <uid>:<gid> <octal permissions>
+    <device regex>       <uid>:<gid> <permissions>
+ or @<maj[,min1[-min2]]> <uid>:<gid> <permissions>
 
 For example:
     hd[a-z][0-9]* 0:3 660
@@ -63,7 +63,7 @@ create your own total match like so:
        .* 1:1 777
 
 You can rename/move device nodes by using the next optional field.
-       <device regex> <uid>:<gid> <octal permissions> [=path]
+       <device regex> <uid>:<gid> <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/
@@ -74,11 +74,17 @@ This will rename "hdb" to "cdrom".
 Similarly, ">path" renames/moves the device but it also creates
 a direct symlink /dev/DEVNAME to the renamed/moved device.
 
+You can also prevent creation of device nodes with the 4th field as "!":
+       tty[a-z]. 0:0 660 !
+       pty[a-z]. 0:0 660 !
+
 If you also enable support for executing your own commands, then the file has
 the format:
-       <device regex> <uid>:<gid> <octal permissions> [=path] [@|$|*<command>]
+       <device regex> <uid>:<gid> <permissions> [=path] [@|$|*<command>]
+    or
+       <device regex> <uid>:<gid> <permissions> [>path] [@|$|*<command>]
     or
-       <device regex> <uid>:<gid> <octal permissions> [>path] [@|$|*<command>]
+       <device regex> <uid>:<gid> <permissions> [!] [@|$|*<command>]
 
 For example:
 ---8<---

diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index b0efd98b50cf76698cd95f459be29f3f99c4c70c..21707566031a2c91ea80308d7a6e64cd64f30ea5 100644 (file)
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -204,7 +204,8 @@ static void make_device(char *path, int delete)
                                if (major < 0)
                                        continue; /* no dev, no match */
                                sc = sscanf(val, "@%u,%u-%u", &cmaj, &cmin0, &cmin1);
-                               if (sc < 1 || major != cmaj
+                               if (sc < 1
+                                || major != cmaj
                                 || (sc == 2 && minor != cmin0)
                                 || (sc == 3 && (minor < cmin0 || minor > cmin1))
                                ) {
@@ -243,7 +244,8 @@ static void make_device(char *path, int delete)
 
                                /* If no match, skip rest of line */
                                /* (regexec returns whole pattern as "range" 0) */
-                               if (result || off[0].rm_so
+                               if (result
+                                || off[0].rm_so
                                 || ((int)off[0].rm_eo != (int)strlen(str_to_match))
                                ) {
                                        continue; /* this line doesn't match */
@@ -258,28 +260,34 @@ static void make_device(char *path, int delete)
                                bb_error_msg("unknown user/group %s on line %d", tokens[1], parser->lineno);
 
                        /* 3rd field: mode - device permissions */
-                       /* mode = strtoul(tokens[2], NULL, 8); */
                        bb_parse_mode(tokens[2], &mode);
 
                        val = tokens[3];
-                       /* 4th field (opt): >|=alias */
+                       /* 4th field (opt): ">|=alias" or "!" to not create the node */
 
                        if (ENABLE_FEATURE_MDEV_RENAME && val) {
-                               aliaslink = val[0];
-                               if (aliaslink == '>' || aliaslink == '=') {
-                                       char *a, *s, *st;
-                                       char *p;
-                                       unsigned i, n;
-
-                                       a = val;
-                                       s = strchrnul(val, ' ');
-                                       st = strchrnul(val, '\t');
-                                       if (st < s)
-                                               s = st;
-                                       val = (s[0] && s[1]) ? s+1 : NULL;
+                               char *a, *s, *st;
+
+                               a = val;
+                               s = strchrnul(val, ' ');
+                               st = strchrnul(val, '\t');
+                               if (st < s)
+                                       s = st;
+                               st = (s[0] && s[1]) ? s+1 : NULL;
+
+                               aliaslink = a[0];
+                               if (aliaslink == '!' && s == a+1) {
+                                       val = st;
+                                       /* "!": suppress node creation/deletion */
+                                       major = -1;
+                               }
+                               else if (aliaslink == '>' || aliaslink == '=') {
+                                       val = st;
                                        s[0] = '\0';
-
                                        if (ENABLE_FEATURE_MDEV_RENAME_REGEXP) {
+                                               char *p;
+                                               unsigned i, n;
+
                                                /* substitute %1..9 with off[1..9], if any */
                                                n = 0;
                                                s = a;
@@ -323,8 +331,13 @@ static void make_device(char *path, int delete)
                                /* Are we running this command now?
                                 * Run $cmd on delete, @cmd on create, *cmd on both
                                 */
-                               if (s2-s != delete)
+                               if (s2 - s != delete) {
+                                       /* We are here if: '*',
+                                        * or: '@' and delete = 0,
+                                        * or: '$' and delete = 1
+                                        */
                                        command = xstrdup(val + 1);
+                               }
                        }
                }
 
@@ -368,7 +381,7 @@ static void make_device(char *path, int delete)
                                free(command);
                        }
 
-                       if (delete) {
+                       if (delete && major >= 0) {
                                if (ENABLE_FEATURE_MDEV_RENAME && alias) {
                                        if (aliaslink == '>')
                                                unlink(device_name);