file_utils: add open_at()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/file_utils.c b/src/lxc/file_utils.c
index 5e88cf893bc1e80e654cfbea6345d6a9c626b7a5..8b6d6f16c53c3d7c4be58196685f07b3e3585e8d 100644 (file)
--- a/src/lxc/file_utils.c
+++ b/src/lxc/file_utils.c
@@ -621,22 +621,24 @@ bool exists_file_at(int dir_fd, const char *path)
        return fstatat(dir_fd, path, &sb, 0) == 0;
 }
 
-int open_beneath(int dir_fd, const char *path, unsigned int flags)
+int open_at(int dfd, const char *path, mode_t mode, unsigned int o_flags,
+           unsigned int resolve_flags)
 {
        __do_close int fd = -EBADF;
        struct lxc_open_how how = {
-               .flags          = flags,
-               .resolve        = RESOLVE_NO_XDEV | RESOLVE_NO_SYMLINKS | RESOLVE_NO_MAGICLINKS | RESOLVE_BENEATH,
+               .flags          = o_flags,
+               .mode           = mode,
+               .resolve        = resolve_flags,
        };
 
-       fd = openat2(dir_fd, path, &how, sizeof(how));
+       fd = openat2(dfd, path, &how, sizeof(how));
        if (fd >= 0)
                return move_fd(fd);
 
        if (errno != ENOSYS)
                return -errno;
 
-       return openat(dir_fd, path, O_NOFOLLOW | flags);
+       return openat(dfd, path, O_NOFOLLOW | o_flags);
 }
 
 int fd_make_nonblocking(int fd)

diff --git a/src/lxc/file_utils.h b/src/lxc/file_utils.h
index 2091f7e49a40bf392037f5d49046d5595d733478..b50773dd59d82b1a77eccefea2eec4af4cc161c2 100644 (file)
--- a/src/lxc/file_utils.h
+++ b/src/lxc/file_utils.h
@@ -13,6 +13,7 @@
 #include <unistd.h>
 
 #include "compiler.h"
+#include "syscall_wrappers.h"
 
 /* read and write whole files */
 __hidden extern int lxc_write_to_file(const char *filename, const void *buf, size_t count,
@@ -81,7 +82,16 @@ __hidden extern FILE *fopen_cached(const char *path, const char *mode, void **ca
 __hidden extern int timens_offset_write(clockid_t clk_id, int64_t s_offset, int64_t ns_offset);
 __hidden extern bool exists_dir_at(int dir_fd, const char *path);
 __hidden extern bool exists_file_at(int dir_fd, const char *path);
-__hidden extern int open_beneath(int dir_fd, const char *path, unsigned int flags);
+__hidden extern int open_at(int dfd, const char *path, mode_t mode,
+                            unsigned int o_flags, unsigned int resolve_flags);
+static inline int open_beneath(int dfd, const char *path, unsigned int flags)
+{
+       return open_at(dfd, path, 0, flags,
+                      RESOLVE_NO_XDEV |
+                      RESOLVE_NO_SYMLINKS |
+                      RESOLVE_NO_MAGICLINKS |
+                      RESOLVE_BENEATH);
+}
 __hidden int fd_make_nonblocking(int fd);
 __hidden extern char *read_file_at(int dfd, const char *fnam);