tree-wide: stop using canonicalize_file_name(), use chase_symlinks() instead

Let's use chase_symlinks() everywhere, and stop using GNU
canonicalize_file_name() everywhere. For most cases this should not change
behaviour, however increase exposure of our function to get better tested. Most
importantly in a few cases (most notably nspawn) it can take the correct root
directory into account when chasing symlinks.

8 files changed, 60 insertions, 49 deletions

diff --git a/src/basic/fs-util.c b/src/basic/fs-util.c
index f288848c9..0d96302be 100644
--- a/src/basic/fs-util.c
+++ b/src/basic/fs-util.c
@@ -225,25 +225,25 @@ int readlink_and_make_absolute(const char *p, char **r) {
         return 0;
 }
 
-int readlink_and_canonicalize(const char *p, char **r) {
+int readlink_and_canonicalize(const char *p, const char *root, char **ret) {
         char *t, *s;
-        int j;
+        int r;
 
         assert(p);
-        assert(r);
+        assert(ret);
 
-        j = readlink_and_make_absolute(p, &t);
-        if (j < 0)
-                return j;
+        r = readlink_and_make_absolute(p, &t);
+        if (r < 0)
+                return r;
 
-        s = canonicalize_file_name(t);
-        if (s) {
+        r = chase_symlinks(t, root, &s);
+        if (r < 0)
+                /* If we can't follow up, then let's return the original string, slightly cleaned up. */
+                *ret = path_kill_slashes(t);
+        else {
+                *ret = s;
                 free(t);
-                *r = s;
-        } else
-                *r = t;
-
-        path_kill_slashes(*r);
+        }
 
         return 0;
 }
diff --git a/src/basic/fs-util.h b/src/basic/fs-util.h
index 871f7209f..de4bb861e 100644
--- a/src/basic/fs-util.h
+++ b/src/basic/fs-util.h
@@ -42,7 +42,7 @@ int readlink_malloc(const char *p, char **r);
 #if 0 /// UNNEEDED by elogind
 int readlink_value(const char *p, char **ret);
 int readlink_and_make_absolute(const char *p, char **r);
-int readlink_and_canonicalize(const char *p, char **r);
+int readlink_and_canonicalize(const char *p, const char *root, char **r);
 int readlink_and_make_absolute_root(const char *root, const char *path, char **ret);
 #endif // 0
 
diff --git a/src/basic/mount-util.c b/src/basic/mount-util.c
index 051b14b17..477342e71 100644
--- a/src/basic/mount-util.c
+++ b/src/basic/mount-util.c
@@ -161,7 +161,7 @@ int fd_is_mount_point(int fd, const char *filename, int flags) {
 
 fallback_fdinfo:
         r = fd_fdinfo_mnt_id(fd, filename, flags, &mount_id);
-        if (r == -EOPNOTSUPP)
+        if (IN_SET(r, -EOPNOTSUPP, -EACCES))
                 goto fallback_fstat;
         if (r < 0)
                 return r;
@@ -204,9 +204,10 @@ fallback_fstat:
 }
 
 /* flags can be AT_SYMLINK_FOLLOW or 0 */
-int path_is_mount_point(const char *t, int flags) {
-        _cleanup_close_ int fd = -1;
+int path_is_mount_point(const char *t, const char *root, int flags) {
         _cleanup_free_ char *canonical = NULL, *parent = NULL;
+        _cleanup_close_ int fd = -1;
+        int r;
 
         assert(t);
 
@@ -218,9 +219,9 @@ int path_is_mount_point(const char *t, int flags) {
          * /bin -> /usr/bin/ and /usr is a mount point, then the parent that we
          * look at needs to be /usr, not /. */
         if (flags & AT_SYMLINK_FOLLOW) {
-                canonical = canonicalize_file_name(t);
-                if (!canonical)
-                        return -errno;
+                r = chase_symlinks(t, root, &canonical);
+                if (r < 0)
+                        return r;
 
                 t = canonical;
         }
@@ -473,7 +474,7 @@ int bind_remount_recursive(const char *prefix, bool ro, char **blacklist) {
                                 return r;
 
                         /* Deal with mount points that are obstructed by a later mount */
-                        r = path_is_mount_point(x, 0);
+                        r = path_is_mount_point(x, NULL, 0);
                         if (r == -ENOENT || r == 0)
                                 continue;
                         if (r < 0)
@@ -525,6 +526,7 @@ bool fstype_is_network(const char *fstype) {
                 "glusterfs\0"
                 "pvfs2\0" /* OrangeFS */
                 "ocfs2\0"
+                "lustre\0"
                 ;
 
         const char *x;
diff --git a/src/basic/mount-util.h b/src/basic/mount-util.h
index d538ea953..ea887e162 100644
--- a/src/basic/mount-util.h
+++ b/src/basic/mount-util.h
@@ -30,7 +30,7 @@
 #include "missing.h"
 
 int fd_is_mount_point(int fd, const char *filename, int flags);
-int path_is_mount_point(const char *path, int flags);
+int path_is_mount_point(const char *path, const char *root, int flags);
 
 #if 0 /// UNNEEDED by elogind
 int repeat_unmount(const char *path, int flags);
diff --git a/src/basic/path-util.c b/src/basic/path-util.c
index 25a956e97..9dd073338 100644
--- a/src/basic/path-util.c
+++ b/src/basic/path-util.c
@@ -222,10 +222,11 @@ int path_strv_make_absolute_cwd(char **l) {
 }
 #endif // 0
 
-char **path_strv_resolve(char **l, const char *prefix) {
+char **path_strv_resolve(char **l, const char *root) {
         char **s;
         unsigned k = 0;
         bool enomem = false;
+        int r;
 
         if (strv_isempty(l))
                 return l;
@@ -235,17 +236,17 @@ char **path_strv_resolve(char **l, const char *prefix) {
          * changes on failure. */
 
         STRV_FOREACH(s, l) {
-                char *t, *u;
                 _cleanup_free_ char *orig = NULL;
+                char *t, *u;
 
                 if (!path_is_absolute(*s)) {
                         free(*s);
                         continue;
                 }
 
-                if (prefix) {
+                if (root) {
                         orig = *s;
-                        t = strappend(prefix, orig);
+                        t = prefix_root(root, orig);
                         if (!t) {
                                 enomem = true;
                                 continue;
@@ -253,28 +254,26 @@ char **path_strv_resolve(char **l, const char *prefix) {
                 } else
                         t = *s;
 
-                errno = 0;
-                u = canonicalize_file_name(t);
-                if (!u) {
-                        if (errno == ENOENT) {
-                                if (prefix) {
-                                        u = orig;
-                                        orig = NULL;
-                                        free(t);
-                                } else
-                                        u = t;
-                        } else {
+                r = chase_symlinks(t, root, &u);
+                if (r == -ENOENT) {
+                        if (root) {
+                                u = orig;
+                                orig = NULL;
                                 free(t);
-                                if (errno == ENOMEM || errno == 0)
-                                        enomem = true;
+                        } else
+                                u = t;
+                } else if (r < 0) {
+                        free(t);
 
-                                continue;
-                        }
-                } else if (prefix) {
+                        if (r == -ENOMEM)
+                                enomem = true;
+
+                        continue;
+                } else if (root) {
                         char *x;
 
                         free(t);
-                        x = path_startswith(u, prefix);
+                        x = path_startswith(u, root);
                         if (x) {
                                 /* restore the slash if it was lost */
                                 if (!startswith(x, "/"))
@@ -306,12 +305,12 @@ char **path_strv_resolve(char **l, const char *prefix) {
         return l;
 }
 
-char **path_strv_resolve_uniq(char **l, const char *prefix) {
+char **path_strv_resolve_uniq(char **l, const char *root) {
 
         if (strv_isempty(l))
                 return l;
 
-        if (!path_strv_resolve(l, prefix))
+        if (!path_strv_resolve(l, root))
                 return NULL;
 
         return strv_uniq(l);
@@ -356,6 +355,16 @@ char* path_startswith(const char *path, const char *prefix) {
         assert(path);
         assert(prefix);
 
+        /* Returns a pointer to the start of the first component after the parts matched by
+         * the prefix, iff
+         * - both paths are absolute or both paths are relative,
+         * and
+         * - each component in prefix in turn matches a component in path at the same position.
+         * An empty string will be returned when the prefix and path are equivalent.
+         *
+         * Returns NULL otherwise.
+         */
+
         if ((path[0] == '/') != (prefix[0] == '/'))
                 return NULL;
 
diff --git a/src/basic/path-util.h b/src/basic/path-util.h
index 605485665..4d284d23c 100644
--- a/src/basic/path-util.h
+++ b/src/basic/path-util.h
@@ -76,8 +76,8 @@ static inline bool path_equal_ptr(const char *a, const char *b) {
 #if 0 /// UNNEEDED by elogind
 int path_strv_make_absolute_cwd(char **l);
 #endif // 0
-char** path_strv_resolve(char **l, const char *prefix);
-char** path_strv_resolve_uniq(char **l, const char *prefix);
+char** path_strv_resolve(char **l, const char *root);
+char** path_strv_resolve_uniq(char **l, const char *root);
 
 #if 0 /// UNNEEDED by elogind
 int find_binary(const char *name, char **filename);
diff --git a/src/core/mount-setup.c b/src/core/mount-setup.c
index c551fa62b..7dfaf27df 100644
--- a/src/core/mount-setup.c
+++ b/src/core/mount-setup.c
@@ -174,7 +174,7 @@ static int mount_one(const MountPoint *p, bool relabel) {
         if (relabel)
                 (void) label_fix(p->where, true, true);
 
-        r = path_is_mount_point(p->where, AT_SYMLINK_FOLLOW);
+        r = path_is_mount_point(p->where, NULL, AT_SYMLINK_FOLLOW);
         if (r < 0 && r != -ENOENT) {
                 log_full_errno((p->mode & MNT_FATAL) ? LOG_ERR : LOG_DEBUG, r, "Failed to determine whether %s is a mount point: %m", p->where);
                 return (p->mode & MNT_FATAL) ? r : 0;
diff --git a/src/login/logind-user.c b/src/login/logind-user.c
index c1fd75a82..b8abc6af0 100644
--- a/src/login/logind-user.c
+++ b/src/login/logind-user.c
@@ -347,7 +347,7 @@ static int user_mkdir_runtime_path(User *u) {
         if (r < 0)
                 return log_error_errno(r, "Failed to create /run/user: %m");
 
-        if (path_is_mount_point(u->runtime_path, 0) <= 0) {
+        if (path_is_mount_point(u->runtime_path, NULL, 0) <= 0) {
                 _cleanup_free_ char *t = NULL;
 
                 (void) mkdir_label(u->runtime_path, 0700);