[PATCH v2 1/5] tools/nolibc: add support for openat(2)

[PATCH v2 1/5] tools/nolibc: add support for openat(2)

[Louis Taylor]

openat is useful to avoid needing to construct relative paths, so expose
a wrapper for using it directly.

Signed-off-by: Louis Taylor <louis@kragniz.eu>
---
 tools/include/nolibc/sys.h                   | 25 ++++++++++++++++++++
 tools/testing/selftests/nolibc/nolibc-test.c | 21 ++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index 8f44c33b1213..3cd938f9abda 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -765,6 +765,31 @@ 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)
+{
+	return my_syscall4(__NR_openat, dirfd, path, flags, mode);
+}
+
+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, mode_t);
+		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..2a1629938dd6 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;
 }
 
+static int test_openat(void)
+{
+	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 +1136,7 @@ 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_dir);        EXPECT_SYSNE(1, test_openat(), -1); break;
 		CASE_TEST(pipe);              EXPECT_SYSZR(1, test_pipe()); break;
 		CASE_TEST(poll_null);         EXPECT_SYSZR(1, poll(NULL, 0, 0)); break;
 		CASE_TEST(poll_stdout);       EXPECT_SYSNE(1, ({ struct pollfd fds = { 1, POLLOUT, 0}; poll(&fds, 1, 0); }), -1); break;
-- 
2.45.2

[PATCH v2 2/5] tools/nolibc: always use openat(2) instead of open(2)

[Louis Taylor]

All architectures support openat, so we don't need to make its use
conditional.

Signed-off-by: Louis Taylor <louis@kragniz.eu>
---
 tools/include/nolibc/sys.h | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index 3cd938f9abda..a8dca5ac6542 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -798,13 +798,7 @@ int openat(int dirfd, const char *path, int flags, ...)
 static __attribute__((unused))
 int sys_open(const char *path, int flags, mode_t mode)
 {
-#ifdef __NR_openat
 	return my_syscall4(__NR_openat, AT_FDCWD, path, flags, mode);
-#elif defined(__NR_open)
-	return my_syscall3(__NR_open, path, flags, mode);
-#else
-	return __nolibc_enosys(__func__, path, flags, mode);
-#endif
 }
 
 static __attribute__((unused))
-- 
2.45.2

Re: [PATCH v2 2/5] tools/nolibc: always use openat(2) instead of open(2)

[Thomas Weißschuh]

On 2025-03-04 07:58:16+0000, Louis Taylor wrote:
> All architectures support openat, so we don't need to make its use
> conditional.
> 
> Signed-off-by: Louis Taylor <louis@kragniz.eu>
> ---
>  tools/include/nolibc/sys.h | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
> index 3cd938f9abda..a8dca5ac6542 100644
> --- a/tools/include/nolibc/sys.h
> +++ b/tools/include/nolibc/sys.h
> @@ -798,13 +798,7 @@ int openat(int dirfd, const char *path, int flags, ...)
>  static __attribute__((unused))
>  int sys_open(const char *path, int flags, mode_t mode)
>  {
> -#ifdef __NR_openat
>  	return my_syscall4(__NR_openat, AT_FDCWD, path, flags, mode);
> -#elif defined(__NR_open)
> -	return my_syscall3(__NR_open, path, flags, mode);
> -#else
> -	return __nolibc_enosys(__func__, path, flags, mode);
> -#endif

Linus at some point was unhappy with usage of the *at() system calls
over the regular ones for perfomance reasons.
But that probably doesn't matter for nolibc and we are preferring
openat() anyways.

So:

Acked-by: Thomas Weißschuh <linux@weissschuh.net>

>  }
>  
>  static __attribute__((unused))
> -- 
> 2.45.2
> 

[PATCH v2 3/5] tools/nolibc: process open() vararg as mode_t

[Louis Taylor]

openat() uses mode_t for this, so also update open() to be consistent.

Signed-off-by: Louis Taylor <louis@kragniz.eu>
---
 tools/include/nolibc/sys.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index a8dca5ac6542..5d8adc778575 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -810,7 +810,7 @@ int open(const char *path, int flags, ...)
 		va_list args;
 
 		va_start(args, flags);
-		mode = va_arg(args, int);
+		mode = va_arg(args, mode_t);
 		va_end(args);
 	}
 
-- 
2.45.2

Re: [PATCH v2 3/5] tools/nolibc: process open() vararg as mode_t

[Thomas Weißschuh]

On 2025-03-04 07:58:17+0000, Louis Taylor wrote:
> openat() uses mode_t for this, so also update open() to be consistent.
> 
> Signed-off-by: Louis Taylor <louis@kragniz.eu>

Acked-by: Thomas Weißschuh <linux@weissschuh.net>

> ---
>  tools/include/nolibc/sys.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
> index a8dca5ac6542..5d8adc778575 100644
> --- a/tools/include/nolibc/sys.h
> +++ b/tools/include/nolibc/sys.h
> @@ -810,7 +810,7 @@ int open(const char *path, int flags, ...)
>  		va_list args;
>  
>  		va_start(args, flags);
> -		mode = va_arg(args, int);
> +		mode = va_arg(args, mode_t);
>  		va_end(args);
>  	}
>  
> -- 
> 2.45.2
> 

[PATCH v2 4/5] tools/nolibc: drop outdated example from overview comment

[Louis Taylor]

This behaviour was changed in commit a7604ba149e7 ("tools/nolibc/sys:
make open() take a vararg on the 3rd argument").

Signed-off-by: Louis Taylor <louis@kragniz.eu>
---
 tools/include/nolibc/nolibc.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h
index 05d92afedb72..70872401aca8 100644
--- a/tools/include/nolibc/nolibc.h
+++ b/tools/include/nolibc/nolibc.h
@@ -31,8 +31,7 @@
  *   - The third level is the libc call definition. It exposes the lower raw
  *     sys_<name>() calls in a way that looks like what a libc usually does,
  *     takes care of specific input values, and of setting errno upon error.
- *     There can be minor variations compared to standard libc calls. For
- *     example the open() call always takes 3 args here.
+ *     There can be minor variations compared to standard libc calls.
  *
  * The errno variable is declared static and unused. This way it can be
  * optimized away if not used. However this means that a program made of
-- 
2.45.2

Re: [PATCH v2 4/5] tools/nolibc: drop outdated example from overview comment

[Thomas Weißschuh]

On 2025-03-04 07:58:18+0000, Louis Taylor wrote:
> This behaviour was changed in commit a7604ba149e7 ("tools/nolibc/sys:
> make open() take a vararg on the 3rd argument").
> 
> Signed-off-by: Louis Taylor <louis@kragniz.eu>

Acked-by : Thomas Weißschuh <linux@weissschuh.net>

> ---
>  tools/include/nolibc/nolibc.h | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h
> index 05d92afedb72..70872401aca8 100644
> --- a/tools/include/nolibc/nolibc.h
> +++ b/tools/include/nolibc/nolibc.h
> @@ -31,8 +31,7 @@
>   *   - The third level is the libc call definition. It exposes the lower raw
>   *     sys_<name>() calls in a way that looks like what a libc usually does,
>   *     takes care of specific input values, and of setting errno upon error.
> - *     There can be minor variations compared to standard libc calls. For
> - *     example the open() call always takes 3 args here.
> + *     There can be minor variations compared to standard libc calls.
>   *
>   * The errno variable is declared static and unused. This way it can be
>   * optimized away if not used. However this means that a program made of
> -- 
> 2.45.2
> 

[PATCH v2 5/5] tools/nolibc: mark more test functions as static

[Louis Taylor]

It was mentioned that a new test_ function should be static, so go back
over existing functions and mark those static as well.

Signed-off-by: Louis Taylor <louis@kragniz.eu>
---
 tools/testing/selftests/nolibc/nolibc-test.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 2a1629938dd6..b5464ca8d050 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -807,7 +807,7 @@ static int test_dirent(void)
 	return 0;
 }
 
-int test_getpagesize(void)
+static int test_getpagesize(void)
 {
 	int x = getpagesize();
 	int c;
@@ -836,7 +836,7 @@ int test_getpagesize(void)
 	return !c;
 }
 
-int test_fork(void)
+static int test_fork(void)
 {
 	int status;
 	pid_t pid;
@@ -861,7 +861,7 @@ int test_fork(void)
 	}
 }
 
-int test_stat_timestamps(void)
+static int test_stat_timestamps(void)
 {
 	struct stat st;
 
@@ -883,7 +883,7 @@ int test_stat_timestamps(void)
 	return 0;
 }
 
-int test_uname(void)
+static int test_uname(void)
 {
 	struct utsname buf;
 	char osrelease[sizeof(buf.release)];
@@ -922,7 +922,7 @@ int test_uname(void)
 	return 0;
 }
 
-int test_mmap_munmap(void)
+static int test_mmap_munmap(void)
 {
 	int ret, fd, i, page_size;
 	void *mem;
@@ -980,7 +980,7 @@ int test_mmap_munmap(void)
 	return !!ret;
 }
 
-int test_pipe(void)
+static int test_pipe(void)
 {
 	const char *const msg = "hello, nolibc";
 	int pipefd[2];
@@ -1001,7 +1001,7 @@ int test_pipe(void)
 	return !!memcmp(buf, msg, len);
 }
 
-int test_rlimit(void)
+static int test_rlimit(void)
 {
 	struct rlimit rlim = {
 		.rlim_cur = 1 << 20,
-- 
2.45.2

Re: [PATCH v2 5/5] tools/nolibc: mark more test functions as static

[Thomas Weißschuh]

On 2025-03-04 07:58:19+0000, Louis Taylor wrote:
> It was mentioned that a new test_ function should be static, so go back
> over existing functions and mark those static as well.

Actually Willy wants these non-static for debugging purposes.
I can't seem to get that into my head -.-
Let's drop this one.

> Signed-off-by: Louis Taylor <louis@kragniz.eu>
> ---
>  tools/testing/selftests/nolibc/nolibc-test.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
> index 2a1629938dd6..b5464ca8d050 100644
> --- a/tools/testing/selftests/nolibc/nolibc-test.c
> +++ b/tools/testing/selftests/nolibc/nolibc-test.c
> @@ -807,7 +807,7 @@ static int test_dirent(void)
>  	return 0;
>  }
>  
> -int test_getpagesize(void)
> +static int test_getpagesize(void)
>  {
>  	int x = getpagesize();
>  	int c;
> @@ -836,7 +836,7 @@ int test_getpagesize(void)
>  	return !c;
>  }
>  
> -int test_fork(void)
> +static int test_fork(void)
>  {
>  	int status;
>  	pid_t pid;
> @@ -861,7 +861,7 @@ int test_fork(void)
>  	}
>  }
>  
> -int test_stat_timestamps(void)
> +static int test_stat_timestamps(void)
>  {
>  	struct stat st;
>  
> @@ -883,7 +883,7 @@ int test_stat_timestamps(void)
>  	return 0;
>  }
>  
> -int test_uname(void)
> +static int test_uname(void)
>  {
>  	struct utsname buf;
>  	char osrelease[sizeof(buf.release)];
> @@ -922,7 +922,7 @@ int test_uname(void)
>  	return 0;
>  }
>  
> -int test_mmap_munmap(void)
> +static int test_mmap_munmap(void)
>  {
>  	int ret, fd, i, page_size;
>  	void *mem;
> @@ -980,7 +980,7 @@ int test_mmap_munmap(void)
>  	return !!ret;
>  }
>  
> -int test_pipe(void)
> +static int test_pipe(void)
>  {
>  	const char *const msg = "hello, nolibc";
>  	int pipefd[2];
> @@ -1001,7 +1001,7 @@ int test_pipe(void)
>  	return !!memcmp(buf, msg, len);
>  }
>  
> -int test_rlimit(void)
> +static int test_rlimit(void)
>  {
>  	struct rlimit rlim = {
>  		.rlim_cur = 1 << 20,
> -- 
> 2.45.2
> 

Re: [PATCH v2 5/5] tools/nolibc: mark more test functions as static

[Willy Tarreau]

On Thu, Mar 06, 2025 at 06:00:17PM +0100, Thomas Weißschuh wrote:
> On 2025-03-04 07:58:19+0000, Louis Taylor wrote:
> > It was mentioned that a new test_ function should be static, so go back
> > over existing functions and mark those static as well.
> 
> Actually Willy wants these non-static for debugging purposes.
> I can't seem to get that into my head -.-
> Let's drop this one.

I don't remember but it was probably to be able to break into them with
gdb and/or to check the disassembled code when in doubt about anything.

Willy

Re: [PATCH v2 1/5] tools/nolibc: add support for openat(2)

[Willy Tarreau]

Hi Louis,

On Tue, Mar 04, 2025 at 07:58:15AM +0000, Louis Taylor wrote:
> openat is useful to avoid needing to construct relative paths, so expose
> a wrapper for using it directly.

Reviewed the whole series, no comments from me. Let's wait for Thomas
to double-check but for me it's OK:

Acked-by: Willy Tarreau <w@1wt.eu>

Thomas, since you already have plenty of changes in queue, do you mind
if I let you pick this series ?

Thanks!
Willy

Re: [PATCH v2 1/5] tools/nolibc: add support for openat(2)

[Thomas Weißschuh]

Hi Willy,

On 2025-03-04 09:11:16+0100, Willy Tarreau wrote:
> On Tue, Mar 04, 2025 at 07:58:15AM +0000, Louis Taylor wrote:
> > openat is useful to avoid needing to construct relative paths, so expose
> > a wrapper for using it directly.
> 
> Reviewed the whole series, no comments from me. Let's wait for Thomas
> to double-check but for me it's OK:
> 
> Acked-by: Willy Tarreau <w@1wt.eu>

Fairly happy with it, only some tiny nitpicks.

> Thomas, since you already have plenty of changes in queue, do you mind
> if I let you pick this series ?

Sure.

Also we need to send a PR to Shuah soon.
I have some patches I want to get into it.
In case you missed it:
https://lore.kernel.org/lkml/20250305-nolibc-asm-headers-v1-1-f2053def2ee7@linutronix.de/
Also the removal of the constructor order validation.
Will you send a patch or should I?


Thomas

Re: [PATCH v2 1/5] tools/nolibc: add support for openat(2)

[Willy Tarreau]

Hi Thomas,

On Thu, Mar 06, 2025 at 06:22:45PM +0100, Thomas Weißschuh wrote:
> Hi Willy,
> 
> On 2025-03-04 09:11:16+0100, Willy Tarreau wrote:
> > On Tue, Mar 04, 2025 at 07:58:15AM +0000, Louis Taylor wrote:
> > > openat is useful to avoid needing to construct relative paths, so expose
> > > a wrapper for using it directly.
> > 
> > Reviewed the whole series, no comments from me. Let's wait for Thomas
> > to double-check but for me it's OK:
> > 
> > Acked-by: Willy Tarreau <w@1wt.eu>
> 
> Fairly happy with it, only some tiny nitpicks.

Thanks for double-checking, you caught way more things than me!

> > Thomas, since you already have plenty of changes in queue, do you mind
> > if I let you pick this series ?
> 
> Sure.
> 
> Also we need to send a PR to Shuah soon.
> I have some patches I want to get into it.
> In case you missed it:
> https://lore.kernel.org/lkml/20250305-nolibc-asm-headers-v1-1-f2053def2ee7@linutronix.de/

Yes I noticed them, these days I'm totally overwhelmed and tend to only
be able to have a look at them during my week-ends :-(

> Also the removal of the constructor order validation.

Yes, not sure I'll have time for it yet :-( I can try, though!

> Will you send a patch or should I?

As last time it will greatly help me if you take care of it. I
feel like I'm leaving you with all the work these days :-/

Cheers,
Willy

Re: [PATCH v2 1/5] tools/nolibc: add support for openat(2)

[Thomas Weißschuh]

On 2025-03-04 07:58:15+0000, Louis Taylor wrote:
> openat is useful to avoid needing to construct relative paths, so expose
> a wrapper for using it directly.
> 
> Signed-off-by: Louis Taylor <louis@kragniz.eu>

Looks good. I have some tiny nitpicks inline,
but if you prefer I can also pick it up as-is.

Acked-by: Thomas Weißschuh <linux@weissschuh.net>

> ---
>  tools/include/nolibc/sys.h                   | 25 ++++++++++++++++++++
>  tools/testing/selftests/nolibc/nolibc-test.c | 21 ++++++++++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
> index 8f44c33b1213..3cd938f9abda 100644
> --- a/tools/include/nolibc/sys.h
> +++ b/tools/include/nolibc/sys.h
> @@ -765,6 +765,31 @@ 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)
> +{
> +	return my_syscall4(__NR_openat, dirfd, path, flags, mode);
> +}
> +
> +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, mode_t);
> +		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..2a1629938dd6 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;
>  }
>  
> +static int test_openat(void)

As mentioned in my other mail, this in fact should not be static.
Sorry for the back and forth.

> +{
> +	int dev;
> +	int null;

Can be on a single line.

> +
> +	dev = openat(AT_FDCWD, "/dev", O_DIRECTORY);
> +	if (dev < 0)
> +		return -1;
> +
> +	null = openat(dev, "null", 0);

As per the standard:

	The argument flags must include one of the following access modes:
	O_RDONLY, O_WRONLY, or O_RDWR.

The other tests don't do it either and on Linux it doesn't matter
because O_RDONLY == 0. But if we are here anyways.

close(dev) could be moved here for some saved lines.

> +	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 +1136,7 @@ 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_dir);        EXPECT_SYSNE(1, test_openat(), -1); break;

EXPECT_SYSZR() should work here.

>  		CASE_TEST(pipe);              EXPECT_SYSZR(1, test_pipe()); break;
>  		CASE_TEST(poll_null);         EXPECT_SYSZR(1, poll(NULL, 0, 0)); break;
>  		CASE_TEST(poll_stdout);       EXPECT_SYSNE(1, ({ struct pollfd fds = { 1, POLLOUT, 0}; poll(&fds, 1, 0); }), -1); break;
> -- 
> 2.45.2
> 

Re: [PATCH v2 1/5] tools/nolibc: add support for openat(2)

[Louis Taylor]

On Thu Mar 6, 2025 at 5:10 PM GMT, Thomas Weißschuh wrote:
> On 2025-03-04 07:58:15+0000, Louis Taylor wrote:
> > openat is useful to avoid needing to construct relative paths, so expose
> > a wrapper for using it directly.
> > 
> > Signed-off-by: Louis Taylor <louis@kragniz.eu>
>
> Looks good. I have some tiny nitpicks inline,
> but if you prefer I can also pick it up as-is.
>
> Acked-by: Thomas Weißschuh <linux@weissschuh.net>

No problem, I'll send another version.

> > ---
> >  tools/include/nolibc/sys.h                   | 25 ++++++++++++++++++++
> >  tools/testing/selftests/nolibc/nolibc-test.c | 21 ++++++++++++++++
> >  2 files changed, 46 insertions(+)
> > 
> > diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
> > index 8f44c33b1213..3cd938f9abda 100644
> > --- a/tools/include/nolibc/sys.h
> > +++ b/tools/include/nolibc/sys.h
> > @@ -765,6 +765,31 @@ 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)
> > +{
> > +	return my_syscall4(__NR_openat, dirfd, path, flags, mode);
> > +}
> > +
> > +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, mode_t);
> > +		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..2a1629938dd6 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;
> >  }
> >  
> > +static int test_openat(void)
>
> As mentioned in my other mail, this in fact should not be static.
> Sorry for the back and forth.

Ah that's fine, I'll drop the other patch as well.

> > +{
> > +	int dev;
> > +	int null;
>
> Can be on a single line.
>
> > +
> > +	dev = openat(AT_FDCWD, "/dev", O_DIRECTORY);
> > +	if (dev < 0)
> > +		return -1;
> > +
> > +	null = openat(dev, "null", 0);
>
> As per the standard:
>
> 	The argument flags must include one of the following access modes:
> 	O_RDONLY, O_WRONLY, or O_RDWR.
>
> The other tests don't do it either and on Linux it doesn't matter
> because O_RDONLY == 0. But if we are here anyways.
>
> close(dev) could be moved here for some saved lines.
>
> > +	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 +1136,7 @@ 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_dir);        EXPECT_SYSNE(1, test_openat(), -1); break;
>
> EXPECT_SYSZR() should work here.
>
> >  		CASE_TEST(pipe);              EXPECT_SYSZR(1, test_pipe()); break;
> >  		CASE_TEST(poll_null);         EXPECT_SYSZR(1, poll(NULL, 0, 0)); break;
> >  		CASE_TEST(poll_stdout);       EXPECT_SYSNE(1, ({ struct pollfd fds = { 1, POLLOUT, 0}; poll(&fds, 1, 0); }), -1); break;
> > -- 
> > 2.45.2
> >