Merge pull request #13194 from keszybz/chase-symlinks-testing

Chase symlinks testing

4 files changed, 129 insertions, 17 deletions

diff --git a/src/basic/fs-util.c b/src/basic/fs-util.c
index f929db9c23..b2ac648838 100644
--- a/src/basic/fs-util.c
+++ b/src/basic/fs-util.c
@@ -732,7 +732,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
          * process. On each iteration, we move one component from "todo" to "done", processing it's special meaning
          * each time. The "todo" path always starts with at least one slash, the "done" path always ends in no
          * slash. We always keep an O_PATH fd to the component we are currently processing, thus keeping lookup races
-         * at a minimum.
+         * to a minimum.
          *
          * Suggested usage: whenever you want to canonicalize a path, use this function. Pass the absolute path you got
          * as-is: fully qualified and relative to your host's root. Optionally, specify the root parameter to tell this
@@ -742,9 +742,9 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
          * There are three ways to invoke this function:
          *
          * 1. Without CHASE_STEP or CHASE_OPEN: in this case the path is resolved and the normalized path is returned
-         *    in `ret`. The return value is < 0 on error. If CHASE_NONEXISTENT is also set 0 is returned if the file
-         *    doesn't exist, > 0 otherwise. If CHASE_NONEXISTENT is not set >= 0 is returned if the destination was
-         *    found, -ENOENT if it doesn't.
+         *    in `ret`. The return value is < 0 on error. If CHASE_NONEXISTENT is also set, 0 is returned if the file
+         *    doesn't exist, > 0 otherwise. If CHASE_NONEXISTENT is not set, >= 0 is returned if the destination was
+         *    found, -ENOENT if it wasn't.
          *
          * 2. With CHASE_OPEN: in this case the destination is opened after chasing it as O_PATH and this file
          *    descriptor is returned as return value. This is useful to open files relative to some root
@@ -760,13 +760,13 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
          *
          * 4. With CHASE_SAFE: in this case the path must not contain unsafe transitions, i.e. transitions from
          *    unprivileged to privileged files or directories. In such cases the return value is -ENOLINK. If
-         *    CHASE_WARN is also set a warning describing the unsafe transition is emitted.
+         *    CHASE_WARN is also set, a warning describing the unsafe transition is emitted.
          *
-         * 5. With CHASE_NO_AUTOFS: in this case if an autofs mount point is encountered, the path normalization is
-         *    aborted and -EREMOTE is returned. If CHASE_WARN is also set a warning showing the path of the mount point
-         *    is emitted.
+         * 5. With CHASE_NO_AUTOFS: in this case if an autofs mount point is encountered, path normalization
+         *    is aborted and -EREMOTE is returned. If CHASE_WARN is also set, a warning showing the path of
+         *    the mount point is emitted.
          *
-         * */
+         */
 
         /* A root directory of "/" or "" is identical to none */
         if (empty_or_root(original_root))
diff --git a/src/basic/fs-util.h b/src/basic/fs-util.h
index c7c5899815..1f0bdd95b3 100644
--- a/src/basic/fs-util.h
+++ b/src/basic/fs-util.h
@@ -74,14 +74,16 @@ union inotify_event_buffer {
 int inotify_add_watch_fd(int fd, int what, uint32_t mask);
 
 enum {
-        CHASE_PREFIX_ROOT = 1 << 0, /* If set, the specified path will be prefixed by the specified root before beginning the iteration */
-        CHASE_NONEXISTENT = 1 << 1, /* If set, it's OK if the path doesn't actually exist. */
-        CHASE_NO_AUTOFS   = 1 << 2, /* If set, return -EREMOTE if autofs mount point found */
-        CHASE_SAFE        = 1 << 3, /* If set, return EPERM if we ever traverse from unprivileged to privileged files or directories */
-        CHASE_OPEN        = 1 << 4, /* If set, return an O_PATH object to the final component */
-        CHASE_TRAIL_SLASH = 1 << 5, /* If set, any trailing slash will be preserved */
-        CHASE_STEP        = 1 << 6, /* If set, just execute a single step of the normalization */
-        CHASE_NOFOLLOW    = 1 << 7, /* Only valid with CHASE_OPEN: when the path's right-most component refers to symlink return O_PATH fd of the symlink, rather than following it. */
+        CHASE_PREFIX_ROOT = 1 << 0, /* The specified path will be prefixed by the specified root before beginning the iteration */
+        CHASE_NONEXISTENT = 1 << 1, /* It's OK if the path doesn't actually exist. */
+        CHASE_NO_AUTOFS   = 1 << 2, /* Return -EREMOTE if autofs mount point found */
+        CHASE_SAFE        = 1 << 3, /* Return EPERM if we ever traverse from unprivileged to privileged files or directories */
+        CHASE_OPEN        = 1 << 4, /* Return an O_PATH object to the final component */
+        CHASE_TRAIL_SLASH = 1 << 5, /* Any trailing slash will be preserved */
+        CHASE_STEP        = 1 << 6, /* Just execute a single step of the normalization */
+        CHASE_NOFOLLOW    = 1 << 7, /* Do not follow the path's right-most compontent. With CHASE_OPEN, when
+                                     * the path's right-most component refers to symlink, return O_PATH fd of
+                                     * the symlink. */
         CHASE_WARN        = 1 << 8, /* Emit an appropriate warning when an error is encountered */
 };
 
diff --git a/src/test/meson.build b/src/test/meson.build
index e337e50146..0595cfe37a 100644
--- a/src/test/meson.build
+++ b/src/test/meson.build
@@ -627,6 +627,11 @@ tests += [
          [],
          []],
 
+        [['src/test/test-chase-symlinks.c'],
+         [],
+         [],
+         '', 'manual'],
+
         [['src/test/test-path.c',
           'src/test/test-helper.c'],
          [libcore,
diff --git a/src/test/test-chase-symlinks.c b/src/test/test-chase-symlinks.c
new file mode 100644
index 0000000000..3fac6b6bc5
--- /dev/null
+++ b/src/test/test-chase-symlinks.c
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#include <getopt.h>
+
+#include "log.h"
+#include "fs-util.h"
+#include "main-func.h"
+
+static char *arg_root = NULL;
+static int arg_flags = 0;
+
+static int parse_argv(int argc, char *argv[]) {
+        enum {
+                ARG_ROOT = 0x1000,
+        };
+
+        static const struct option options[] = {
+                { "help",                no_argument,       NULL, 'h'                     },
+                { "root",                required_argument, NULL, ARG_ROOT                },
+
+                { "prefix-root",         no_argument,       NULL, CHASE_PREFIX_ROOT       },
+                { "nonexistent",         no_argument,       NULL, CHASE_NONEXISTENT       },
+                { "no_autofs",           no_argument,       NULL, CHASE_NO_AUTOFS         },
+                { "safe",                no_argument,       NULL, CHASE_SAFE              },
+                { "open",                no_argument,       NULL, CHASE_OPEN              },
+                { "trail-slash",         no_argument,       NULL, CHASE_TRAIL_SLASH       },
+                { "step",                no_argument,       NULL, CHASE_STEP              },
+                { "nofollow",            no_argument,       NULL, CHASE_NOFOLLOW          },
+                { "warn",                no_argument,       NULL, CHASE_WARN              },
+                {}
+        };
+
+        int c;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "", options, NULL)) >= 0)
+                switch (c) {
+
+                case 'h':
+                        printf("Syntax:\n"
+                               "  %s [OPTION...] path...\n"
+                               "Options:\n"
+                               , argv[0]);
+                        for (size_t i = 0; i < ELEMENTSOF(options) - 1; i++)
+                                printf("  --%s\n", options[i].name);
+                        return 0;
+
+                case ARG_ROOT:
+                        arg_root = optarg;
+                        break;
+
+                case CHASE_PREFIX_ROOT:
+                case CHASE_NONEXISTENT:
+                case CHASE_NO_AUTOFS:
+                case CHASE_SAFE:
+                case CHASE_OPEN:
+                case CHASE_TRAIL_SLASH:
+                case CHASE_STEP:
+                case CHASE_NOFOLLOW:
+                case CHASE_WARN:
+                        arg_flags |= c;
+                        break;
+
+                case '?':
+                        return -EINVAL;
+
+                default:
+                        assert_not_reached("Unhandled option");
+                }
+
+        if (optind == argc)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "At least one argument is required.");
+
+        return 1;
+}
+
+static int run(int argc, char **argv) {
+        int r;
+
+        log_show_color(true);
+        log_parse_environment();
+        log_open();
+
+        r = parse_argv(argc, argv);
+        if (r <= 0)
+                return r;
+
+        for (int i = optind; i < argc; i++) {
+                _cleanup_free_ char *p = NULL;
+
+                printf("%s ", argv[i]);
+                fflush(stdout);
+
+                r = chase_symlinks(argv[i], arg_root, arg_flags, &p);
+                if (r < 0)
+                        log_error_errno(r, "failed: %m");
+                else
+                        log_info("→ %s", p);
+        }
+
+        return 0;
+}
+
+DEFINE_MAIN_FUNCTION(run);