mdev: optional support for regex pattern group substitution.

+142 bytes.

3 files changed, 65 insertions, 3 deletions

diff --git a/testsuite/mdev.tests b/testsuite/mdev.tests
index 777c5c540..81c440d1f 100755
--- a/testsuite/mdev.tests
+++ b/testsuite/mdev.tests
@@ -76,6 +76,23 @@ br--r--r-- 1 0 0 sda
 " \
         "" ""
 
+# continuing to use directory structure from prev test
+rm -rf mdev.testdir/dev/*
+# here we complicate things by having non-matching group 1 and using %0
+echo "s([0-9])*d([a-z]+) 0:0 644 >sd/%2_%0" >mdev.testdir/etc/mdev.conf
+testing "mdev regexp substring match + replace" \
+        "env - ACTION=add DEVPATH=/block/sda chroot mdev.testdir /mdev 2>&1;
+        ls -lnR mdev.testdir/dev | $FILTER_LS2" \
+"\
+mdev.testdir/dev:
+drwxr-xr-x 2 0 0 sd
+lrwxrwxrwx 1 0 0 sda -> sd/a_sda
+
+mdev.testdir/dev/sd:
+brw-r--r-- 1 0 0 a_sda
+" \
+        "" ""
+
 # clean up
 rm -rf mdev.testdir
 
diff --git a/util-linux/Config.in b/util-linux/Config.in
index 1f4322bec..869ec61d5 100644
--- a/util-linux/Config.in
+++ b/util-linux/Config.in
@@ -321,6 +321,13 @@ config FEATURE_MDEV_RENAME
 
           For more information, please see docs/mdev.txt
 
+config FEATURE_MDEV_RENAME_REGEXP
+        bool "Support regular expressions substitutions when renaming device"
+        default n
+        depends on FEATURE_MDEV_RENAME
+        help
+          Add support for regular expressions substitutions when renaming device.
+
 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 c8d603bcf..9d77f6a1f 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -84,6 +84,8 @@ static void make_device(char *path, int delete)
                         goto end_parse;
 
                 while ((line = xmalloc_fgetline(fp)) != NULL) {
+                        regmatch_t off[1+9*ENABLE_FEATURE_MDEV_RENAME_REGEXP];
+
                         ++lineno;
                         trim(line);
                         if (!line[0])
@@ -95,16 +97,24 @@ static void make_device(char *path, int delete)
                         next = next_field(line);
                         {
                                 regex_t match;
-                                regmatch_t off;
                                 int result;
 
                                 /* Is this it? */
                                 xregcomp(&match, line, REG_EXTENDED);
-                                result = regexec(&match, device_name, 1, &off, 0);
+                                result = regexec(&match, device_name, ARRAY_SIZE(off), off, 0);
                                 regfree(&match);
 
+                                //bb_error_msg("matches:");
+                                //for (int i = 0; i < ARRAY_SIZE(off); i++) {
+                                //      if (off[i].rm_so < 0) continue;
+                                //      bb_error_msg("match %d: '%.*s'\n", i,
+                                //              (int)(off[i].rm_eo - off[i].rm_so),
+                                //              device_name + off[i].rm_so);
+                                //}
+
                                 /* If not this device, skip rest of line */
-                                if (result || off.rm_so || off.rm_eo != strlen(device_name))
+                                /* (regexec returns whole pattern as "range" 0) */
+                                if (result || off[0].rm_so || off[0].rm_eo != strlen(device_name))
                                         goto next_line;
                         }
 
@@ -152,7 +162,35 @@ static void make_device(char *path, int delete)
                                 val = next;
                                 next = next_field(val);
                                 if (*val == '>') {
+#if ENABLE_FEATURE_MDEV_RENAME_REGEXP
+                                        /* substitute %1..9 with off[1..9], if any */
+                                        char *s, *p;
+                                        unsigned i, n;
+
+                                        n = 0;
+                                        s = val;
+                                        while (*s && *s++ == '%')
+                                                n++;
+                                        
+                                        p = alias = xzalloc(strlen(val) + n * strlen(device_name));
+                                        s = val + 1;
+                                        while (*s) {
+                                                *p = *s;
+                                                if ('%' == *s) {
+                                                        i = (s[1] - '0');
+                                                        if (i <= 9 && off[i].rm_so >= 0) {
+                                                                n = off[i].rm_eo - off[i].rm_so;
+                                                                strncpy(p, device_name + off[i].rm_so, n);
+                                                                p += n - 1;
+                                                                s++;
+                                                        }
+                                                }
+                                                p++;
+                                                s++;
+                                        }
+#else
                                         alias = xstrdup(val + 1);
+#endif
                                 }
                         }