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Code

restore overwritten symlinks when the device goes away

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This commit is contained in:
Kay Sievers 2007-03-15 03:54:12 +01:00
parent fbda4babec
commit 27d4bf1817
2 changed files with 73 additions and 56 deletions
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126
udev_node.c
View File

@ -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;
}

3
udev_utils_file.c
View File

@ -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, '/');