restore overwritten symlinks when the device goes away

diff --git a/udev_node.c b/udev_node.c
index e1b62293bb08b932f3218834f1a542f0f3c3ab19..d069dfc4aada7ab57596be9a6281db431d8c3252 100644 (file)
--- a/udev_node.c
+++ b/udev_node.c
@@ -88,30 +88,45 @@ exit:
        return retval;
 }
 
-static int udev_node_symlink(struct udevice *udev, const char *linktarget, const char *filename)
+static int node_symlink(const char *node, const char *slink)
 {
-       char target[PATH_SIZE];
+       char target[PATH_SIZE] = "";
+       char buf[PATH_SIZE];
+       int i = 0;
+       int tail = 0;
        int len;
 
+       /* use relative link */
+       while (node[i] && (node[i] == slink[i])) {
+               if (node[i] == '/')
+                       tail = i+1;
+               i++;
+       }
+       while (slink[i] != '\0') {
+               if (slink[i] == '/')
+                       strlcat(target, "../", sizeof(target));
+               i++;
+       }
+       strlcat(target, &node[tail], sizeof(target));
+
        /* look if symlink already exists */
-       len = readlink(filename, target, sizeof(target));
+       len = readlink(slink, buf, sizeof(buf));
        if (len > 0) {
-               target[len] = '\0';
-               if (strcmp(linktarget, target) == 0) {
-                       info("preserving symlink '%s' to '%s'", filename, linktarget);
-                       selinux_setfilecon(filename, NULL, S_IFLNK);
+               buf[len] = '\0';
+               if (strcmp(target, buf) == 0) {
+                       info("preserving symlink '%s' to '%s'", slink, target);
+                       selinux_setfilecon(slink, NULL, S_IFLNK);
                        goto exit;
-               } else {
-                       info("link '%s' points to different target '%s', delete it", filename, target);
-                       unlink(filename);
                }
+               info("link '%s' points to different target '%s', delete it", slink, buf);
+               unlink(slink);
        }
 
        /* create link */
-       info("creating symlink '%s' to '%s'", filename, linktarget);
-       selinux_setfscreatecon(filename, NULL, S_IFLNK);
-       if (symlink(linktarget, filename) != 0)
-               err("symlink(%s, %s) failed: %s", linktarget, filename, strerror(errno));
+       info("creating symlink '%s' to '%s'", slink, target);
+       selinux_setfscreatecon(slink, NULL, S_IFLNK);
+       if (symlink(target, slink) != 0)
+               err("symlink(%s, %s) failed: %s", target, slink, strerror(errno));
        selinux_resetfscreatecon();
 
 exit:
@@ -121,10 +136,8 @@ exit:
 int udev_node_add(struct udevice *udev, struct udevice *udev_old)
 {
        char filename[PATH_SIZE];
-       struct name_entry *name_loop;
        uid_t uid;
        gid_t gid;
-       int tail;
        int i;
        int retval = 0;
 
@@ -132,8 +145,7 @@ int udev_node_add(struct udevice *udev, struct udevice *udev_old)
        filename[sizeof(filename)-1] = '\0';
 
        /* create parent directories if needed */
-       if (strchr(udev->name, '/'))
-               create_path(filename);
+       create_path(filename);
 
        if (strcmp(udev->owner, "root") == 0)
                uid = 0;
@@ -200,41 +212,23 @@ int udev_node_add(struct udevice *udev, struct udevice *udev_old)
 
        /* create symlink(s) if requested */
        if (!list_empty(&udev->symlink_list)) {
-               char symlinks[512] = "";
+               struct name_entry *name_loop;
+               char symlinks[PATH_SIZE] = "";
 
                list_for_each_entry(name_loop, &udev->symlink_list, node) {
-                       char linktarget[PATH_SIZE];
+                       char slink[PATH_SIZE];
 
-                       snprintf(filename, sizeof(filename), "%s/%s", udev_root, name_loop->name);
-                       filename[sizeof(filename)-1] = '\0';
+                       strlcpy(slink, udev_root, sizeof(slink));
+                       strlcat(slink, "/", sizeof(slink));
+                       strlcat(slink, name_loop->name, sizeof(slink));
 
-                       dbg("symlink '%s' to node '%s' requested", filename, udev->name);
-                       if (!udev->test_run)
-                               if (strchr(filename, '/'))
-                                       create_path(filename);
-
-                       /* optimize relative link */
-                       linktarget[0] = '\0';
-                       i = 0;
-                       tail = 0;
-                       while (udev->name[i] && (udev->name[i] == name_loop->name[i])) {
-                               if (udev->name[i] == '/')
-                                       tail = i+1;
-                               i++;
-                       }
-                       while (name_loop->name[i] != '\0') {
-                               if (name_loop->name[i] == '/')
-                                       strlcat(linktarget, "../", sizeof(linktarget));
-                               i++;
+                       info("creating symlink '%s' to node '%s'", slink, filename);
+                       if (!udev->test_run) {
+                               create_path(slink);
+                               node_symlink(filename, slink);
                        }
 
-                       strlcat(linktarget, &udev->name[tail], sizeof(linktarget));
-
-                       info("creating symlink '%s' to '%s'", filename, linktarget);
-                       if (!udev->test_run)
-                               udev_node_symlink(udev, linktarget, filename);
-
-                       strlcat(symlinks, filename, sizeof(symlinks));
+                       strlcat(symlinks, slink, sizeof(symlinks));
                        strlcat(symlinks, " ", sizeof(symlinks));
                }
 
@@ -254,9 +248,11 @@ void udev_node_remove_symlinks(struct udevice *udev)
        struct stat stats;
 
        if (!list_empty(&udev->symlink_list)) {
-               char symlinks[512] = "";
+               char symlinks[PATH_SIZE] = "";
 
                list_for_each_entry(name_loop, &udev->symlink_list, node) {
+                       char devpath[PATH_SIZE];
+
                        snprintf(filename, sizeof(filename), "%s/%s", udev_root, name_loop->name);
                        filename[sizeof(filename)-1] = '\0';
 
@@ -272,9 +268,32 @@ void udev_node_remove_symlinks(struct udevice *udev)
                        info("removing symlink '%s'", filename);
                        if (!udev->test_run) {
                                unlink(filename);
+                               delete_path(filename);
+                       }
 
-                               if (strchr(filename, '/'))
-                                       delete_path(filename);
+                       /* see if another device wants this symlink */
+                       if (udev_db_lookup_name(name_loop->name, devpath, sizeof(devpath)) == 0) {
+                               struct udevice *old;
+
+                               info("found overwritten symlink '%s' of '%s'", name_loop->name, devpath);
+                               old = udev_device_init();
+                               if (old != NULL) {
+                                       if (udev_db_get_device(old, devpath) == 0) {
+                                               char slink[PATH_SIZE];
+                                               char node[PATH_SIZE];
+
+                                               strlcpy(slink, udev_root, sizeof(slink));
+                                               strlcat(slink, "/", sizeof(slink));
+                                               strlcat(slink, name_loop->name, sizeof(slink));
+                                               strlcpy(node, udev_root, sizeof(node));
+                                               strlcat(node, "/", sizeof(node));
+                                               strlcat(node, old->name, sizeof(node));
+                                               info("restore symlink '%s' to '%s'", slink, node);
+                                               if (!udev->test_run)
+                                                       node_symlink(node, slink);
+                                       }
+                                       udev_device_cleanup(old);
+                               }
                        }
 
                        strlcat(symlinks, filename, sizeof(symlinks));
@@ -299,7 +318,6 @@ int udev_node_remove(struct udevice *udev)
 
        snprintf(filename, sizeof(filename), "%s/%s", udev_root, udev->name);
        filename[sizeof(filename)-1] = '\0';
-
        if (stat(filename, &stats) != 0) {
                dbg("device node '%s' not found", filename);
                return -1;
@@ -315,7 +333,6 @@ int udev_node_remove(struct udevice *udev)
                return retval;
 
        setenv("DEVNAME", filename, 1);
-
        num = udev->partitions;
        if (num > 0) {
                int i;
@@ -331,9 +348,6 @@ int udev_node_remove(struct udevice *udev)
                        unlink_secure(partitionname);
                }
        }
-
-       if (strchr(udev->name, '/'))
-               delete_path(filename);
-
+       delete_path(filename);
        return retval;
 }

diff --git a/udev_utils_file.c b/udev_utils_file.c
index 9bf60696d94ed74d9ddd79d5b854e918154dc1c2..e4d5802ff899824b6960a7369e150108c6d66dd9 100644 (file)
--- a/udev_utils_file.c
+++ b/udev_utils_file.c
@@ -65,6 +65,9 @@ int delete_path(const char *path)
 
        strcpy (p, path);
        pos = strrchr(p, '/');
+       if (pos == p || pos == NULL)
+               return 0;
+
        while (1) {
                *pos = '\0';
                pos = strrchr(p, '/');