The stat command is a debugging aid for developing the VFS, so it makes
sense to add support for dirfd, so they can be tested interactively.

Signed-off-by: Ahmad Fatoum <a.fat...@pengutronix.de>
---
 commands/Kconfig |  6 ++++--
 commands/stat.c  | 26 +++++++++++++++++++-------
 fs/fs.c          |  5 ++---
 include/fs.h     |  2 +-
 4 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/commands/Kconfig b/commands/Kconfig
index 9df3c67d930d..269d2432b45e 100644
--- a/commands/Kconfig
+++ b/commands/Kconfig
@@ -1011,12 +1011,14 @@ config CMD_STAT
        help
          Display file status
 
-         Usage: stat [-L] [FILEDIR...]
+         Usage: stat [-LcC] [FILEDIR...]
 
          Display status information about the specified files or directories.
 
          Options:
-                 -L    follow symlinks
+                 -L            follow symlinks
+                 -c DIR        lookup file relative to directory DIR
+                 -C DIR        change root to DIR before file lookup
 
 config CMD_MD5SUM
        tristate
diff --git a/commands/stat.c b/commands/stat.c
index 153eac50f1fa..10662005cdda 100644
--- a/commands/stat.c
+++ b/commands/stat.c
@@ -12,15 +12,23 @@
 
 static int do_stat(int argc, char *argv[])
 {
-       int (*statfn)(const char *, struct stat *) = lstat;
-       int ret, opt, exitcode = 0;
+       int (*statfn)(int dirfd, const char *, struct stat *) = lstatat;
+       int ret, opt, dirfd = AT_FDCWD, extra_flags = 0, exitcode = 0;
        char **filename;
        struct stat st;
 
-       while((opt = getopt(argc, argv, "L")) > 0) {
+       while((opt = getopt(argc, argv, "Lc:C:")) > 0) {
                switch(opt) {
                case 'L':
-                       statfn = stat;
+                       statfn = statat;
+                       break;
+               case 'C':
+                       extra_flags |= O_CHROOT;
+                       fallthrough;
+               case 'c':
+                       dirfd = open(optarg, O_PATH | extra_flags);
+                       if (dirfd < 0)
+                               return dirfd;
                        break;
                default:
                        return COMMAND_ERROR_USAGE;
@@ -31,7 +39,7 @@ static int do_stat(int argc, char *argv[])
                return COMMAND_ERROR_USAGE;
 
        for (filename = &argv[optind]; *filename; filename++) {
-               ret = statfn(*filename, &st);
+               ret = statfn(dirfd, *filename, &st);
 
                if (ret) {
                        printf("%s: %s: %m\n", argv[0], *filename);
@@ -39,9 +47,11 @@ static int do_stat(int argc, char *argv[])
                        continue;
                }
 
-               stat_print(*filename, &st);
+               stat_print(dirfd, *filename, &st);
        }
 
+       close(dirfd);
+
        return exitcode;
 }
 
@@ -51,12 +61,14 @@ BAREBOX_CMD_HELP_TEXT("or directories.")
 BAREBOX_CMD_HELP_TEXT("")
 BAREBOX_CMD_HELP_TEXT("Options:")
 BAREBOX_CMD_HELP_OPT ("-L",  "follow links")
+BAREBOX_CMD_HELP_OPT ("-c DIR",  "lookup file relative to directory DIR")
+BAREBOX_CMD_HELP_OPT ("-C DIR",  "change root to DIR before file lookup")
 BAREBOX_CMD_HELP_END
 
 BAREBOX_CMD_START(stat)
        .cmd            = do_stat,
        BAREBOX_CMD_DESC("display file status")
-       BAREBOX_CMD_OPTS("[-L] [FILEDIR...]")
+       BAREBOX_CMD_OPTS("[-LcC] [FILEDIR...]")
        BAREBOX_CMD_GROUP(CMD_GRP_FILE)
        BAREBOX_CMD_HELP(cmd_stat_help)
 BAREBOX_CMD_END
diff --git a/fs/fs.c b/fs/fs.c
index fa1d01d892dc..3bd476713595 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -130,9 +130,8 @@ void cdev_print(const struct cdev *cdev)
 }
 EXPORT_SYMBOL(cdev_print);
 
-void stat_print(const char *filename, const struct stat *st)
+void stat_print(int dirfd, const char *filename, const struct stat *st)
 {
-       int dirfd = AT_FDCWD;
        struct block_device *bdev = NULL;
        struct fs_device *fdev;
        struct cdev *cdev = NULL;
@@ -177,7 +176,7 @@ void stat_print(const char *filename, const struct stat *st)
                char realname[PATH_MAX] = {};
                int ret;
 
-               ret = readlink(filename, realname, PATH_MAX - 1);
+               ret = readlinkat(dirfd, filename, realname, PATH_MAX - 1);
                if (ret)
                        printf(" -> <readlink error %pe>", ERR_PTR(ret));
                else
diff --git a/include/fs.h b/include/fs.h
index 020761692cad..70903142e89b 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -147,7 +147,7 @@ int ls(const char *path, ulong flags);
 
 char *mkmodestr(unsigned long mode, char *str);
 
-void stat_print(const char *filename, const struct stat *st);
+void stat_print(int dirfd, const char *filename, const struct stat *st);
 void cdev_print(const struct cdev *cdev);
 
 char *canonicalize_path(int dirfd, const char *pathname);
-- 
2.39.2


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