From: Kay Sievers Date: Thu, 15 Mar 2007 02:54:12 +0000 (+0100) Subject: restore overwritten symlinks when the device goes away X-Git-Tag: 174~2039 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=27d4bf1817259873b0a1e118d03978f0d2f2595e;p=systemd restore overwritten symlinks when the device goes away --- diff --git a/udev_node.c b/udev_node.c index e1b62293..d069dfc4 100644 --- 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 9bf60696..e4d5802f 100644 --- 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, '/');