Shrink the code about 50 bytes, allocate less run-time memory, and add a

comment that null terminating the string we sscanf() shouldn't be required
since the kernel adds \n to the end of it and sscanf will stop there.

1 files changed, 19 insertions, 20 deletions

diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index 5fea1b8e2..73938f8de 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -38,23 +38,25 @@ static void make_device(char *path)
         int mode = 0660;
         uid_t uid = 0;
         gid_t gid = 0;
+        char *temp = path + strlen(path);
 
-        RESERVE_CONFIG_BUFFER(temp, PATH_MAX);
+        /* 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
+         * because sscanf() will stop at the first nondigit, which \n is.  We
+         * also depend on path having writeable space after it. */
 
-        /* Try to read major/minor string */
-
-        snprintf(temp, PATH_MAX, "%s/dev", path);
-        fd = open(temp, O_RDONLY);
-        len = read(fd, temp, PATH_MAX-1);
+        strcat(path, "/dev");
+        fd = open(path, O_RDONLY);
+        len = read(fd, temp + 1, 64);
+        *temp++ = 0;
         close(fd);
-        if (len < 1) goto end;
+        if (len < 1) return;
 
         /* Determine device name, type, major and minor */
 
         device_name = strrchr(path, '/') + 1;
-        type = strncmp(path+5, "block/", 6) ? S_IFCHR : S_IFBLK;
-        if (sscanf(temp, "%d:%d", &major, &minor) != 2)
-                goto end;
+        type = path[5]=='c' ? S_IFCHR : S_IFBLK;
+        if (sscanf(temp, "%d:%d", &major, &minor) != 2) return;
 
         /* If we have a config file, look up permissions for this device */
 
@@ -167,18 +169,14 @@ found_device:
                 }
         }
 
-        sprintf(temp, "%s/%s", DEV_PATH, device_name);
         umask(0);
-        if (mknod(temp, mode | type, makedev(major, minor)) && errno != EEXIST)
-                bb_perror_msg_and_die("mknod %s failed", temp);
+        if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
+                bb_perror_msg_and_die("mknod %s failed", device_name);
 
         if (major==root_major && minor==root_minor)
-                symlink(temp,DEV_PATH "/root");
+                symlink(device_name, "root");
         
-        if (ENABLE_FEATURE_MDEV_CONF) chown(temp,uid,gid);
-
-end:
-        RELEASE_CONFIG_BUFFER(temp);
+        if (ENABLE_FEATURE_MDEV_CONF) chown(device_name, uid, gid);
 }
 
 /* Recursive search of /sys/block or /sys/class.  path must be a writeable
@@ -220,6 +218,8 @@ int mdev_main(int argc, char *argv[])
         char *env_path;
         RESERVE_CONFIG_BUFFER(temp,PATH_MAX);
 
+        bb_xchdir(DEV_PATH);
+
         /* Scan */
 
         if (argc == 2 && !strcmp(argv[1],"-s")) {
@@ -245,8 +245,7 @@ int mdev_main(int argc, char *argv[])
                         sprintf(temp, "/sys%s", env_path);
                         make_device(temp);
                 } else if (!strcmp(action, "remove")) {
-                        sprintf(temp, "%s/%s", DEV_PATH, strrchr(env_path, '/') + 1);
-                        unlink(temp);
+                        unlink(strrchr(env_path, '/') + 1);
                 }
         }