Hi Louis,
On 2025-03-02 20:25:23+0000, Louis Taylor wrote:
openat is useful to avoid needing to construct relative paths, so expose a wrapper for using it directly.
Can you say what you are using nolibc for? I'm curious :-)
Signed-off-by: Louis Taylor louis@kragniz.eu
tools/include/nolibc/sys.h | 29 ++++++++++++++++++++ tools/testing/selftests/nolibc/nolibc-test.c | 22 +++++++++++++++ 2 files changed, 51 insertions(+)
diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h index 8f44c33b1213..e5ff34df4aee 100644 --- a/tools/include/nolibc/sys.h +++ b/tools/include/nolibc/sys.h @@ -765,6 +765,35 @@ int mount(const char *src, const char *tgt, return __sysret(sys_mount(src, tgt, fst, flags, data)); } +/*
- int openat(int dirfd, const char *path, int flags[, mode_t mode]);
- */
+static __attribute__((unused)) +int sys_openat(int dirfd, const char *path, int flags, mode_t mode) +{ +#ifdef __NR_openat
- return my_syscall4(__NR_openat, dirfd, path, flags, mode);
+#else
- return __nolibc_enosys(__func__, dirfd, path, flags, mode);
+#endif
All architectures support openat(), so the #else could be dropped.
+}
+static __attribute__((unused)) +int openat(int dirfd, const char *path, int flags, ...) +{
- mode_t mode = 0;
- if (flags & O_CREAT) {
va_list args;va_start(args, flags);mode = va_arg(args, int);
mode_t instead of int?
va_end(args);- }
- return __sysret(sys_openat(dirfd, path, flags, mode));
+} /*
- int open(const char *path, int flags[, mode_t mode]);
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index 79c3e6a845f3..97ded6c76f99 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -1028,6 +1028,26 @@ int test_rlimit(void) return 0; } +int test_openat(void)
static.
+{
- int dev;
- int null;
- dev = openat(AT_FDCWD, "/dev", O_DIRECTORY);
- if (dev < 0)
return -1;- null = openat(dev, "null", 0);
- if (null < 0) {
close(dev);return -1;- }
- close(dev);
- close(null);
- return 0;
+} /* Run syscall tests between IDs <min> and <max>.
- Return 0 on success, non-zero on failure.
@@ -1116,6 +1136,8 @@ int run_syscall(int min, int max) CASE_TEST(mmap_munmap_good); EXPECT_SYSZR(1, test_mmap_munmap()); break; CASE_TEST(open_tty); EXPECT_SYSNE(1, tmp = open("/dev/null", 0), -1); if (tmp != -1) close(tmp); break; CASE_TEST(open_blah); EXPECT_SYSER(1, tmp = open("/proc/self/blah", 0), -1, ENOENT); if (tmp != -1) close(tmp); break;
CASE_TEST(openat_fdcwd); EXPECT_SYSNE(1, tmp = openat(AT_FDCWD, "/dev/null", 0), -1); if (tmp != -1) close(tmp); break;
AT_FDCWD is already used in test_openat(). What additional value does the test above add?
CASE_TEST(openat_dir); EXPECT_SYSNE(1, test_openat(), -1); break;-- 2.45.2