linux-kernel - [PATCH] tools/nolibc: support nanoseconds in stat()

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Message-Id: <20230527-nolibc-stat-nanoseconds-v1-1-3f7825caae68@weissschuh.net>
Date:   Sat, 27 May 2023 14:56:42 +0200
From:   Thomas Weißschuh <linux@...ssschuh.net>
To:     Willy Tarreau <w@....eu>, Shuah Khan <shuah@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH] tools/nolibc: support nanoseconds in stat()

Keep backwards compatibility through unions.

The compatibility macros like

 #define st_atime st_atim.tv_sec

as documented in stat(3type) don't work for nolibc because it would
break with other stat-like structures that contain the field st_atime.

Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 tools/include/nolibc/sys.h                   | 29 +++++++++++++++-------------
 tools/include/nolibc/types.h                 |  6 +++---
 tools/testing/selftests/nolibc/nolibc-test.c | 23 ++++++++++++++++++++++
 3 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index 7874062bea95..11b354e26861 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -1187,19 +1187,22 @@ int sys_stat(const char *path, struct stat *buf)
 #else
 #error Neither __NR_newfstatat nor __NR_stat defined, cannot implement sys_stat()
 #endif
-	buf->st_dev     = stat.st_dev;
-	buf->st_ino     = stat.st_ino;
-	buf->st_mode    = stat.st_mode;
-	buf->st_nlink   = stat.st_nlink;
-	buf->st_uid     = stat.st_uid;
-	buf->st_gid     = stat.st_gid;
-	buf->st_rdev    = stat.st_rdev;
-	buf->st_size    = stat.st_size;
-	buf->st_blksize = stat.st_blksize;
-	buf->st_blocks  = stat.st_blocks;
-	buf->st_atime   = stat.st_atime;
-	buf->st_mtime   = stat.st_mtime;
-	buf->st_ctime   = stat.st_ctime;
+	buf->st_dev          = stat.st_dev;
+	buf->st_ino          = stat.st_ino;
+	buf->st_mode         = stat.st_mode;
+	buf->st_nlink        = stat.st_nlink;
+	buf->st_uid          = stat.st_uid;
+	buf->st_gid          = stat.st_gid;
+	buf->st_rdev         = stat.st_rdev;
+	buf->st_size         = stat.st_size;
+	buf->st_blksize      = stat.st_blksize;
+	buf->st_blocks       = stat.st_blocks;
+	buf->st_atim.tv_sec  = stat.st_atime;
+	buf->st_atim.tv_nsec = stat.st_atime_nsec;
+	buf->st_mtim.tv_sec  = stat.st_mtime;
+	buf->st_mtim.tv_nsec = stat.st_mtime_nsec;
+	buf->st_ctim.tv_sec  = stat.st_ctime;
+	buf->st_ctim.tv_nsec = stat.st_ctime_nsec;
 	return ret;
 }
 #endif
diff --git a/tools/include/nolibc/types.h b/tools/include/nolibc/types.h
index 15b0baffd336..f96e28bff4ba 100644
--- a/tools/include/nolibc/types.h
+++ b/tools/include/nolibc/types.h
@@ -198,9 +198,9 @@ struct stat {
 	off_t     st_size;    /* total size, in bytes */
 	blksize_t st_blksize; /* blocksize for file system I/O */
 	blkcnt_t  st_blocks;  /* number of 512B blocks allocated */
-	time_t    st_atime;   /* time of last access */
-	time_t    st_mtime;   /* time of last modification */
-	time_t    st_ctime;   /* time of last status change */
+	union { time_t st_atime; struct timespec st_atim; }; /* time of last access */
+	union { time_t st_mtime; struct timespec st_mtim; }; /* time of last modification */
+	union { time_t st_ctime; struct timespec st_ctim; }; /* time of last status change */
 };
 
 /* WARNING, it only deals with the 4096 first majors and 256 first minors */
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 6e0a4dbe321e..8de72c87b7b7 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -500,6 +500,28 @@ static int test_fork(void)
 	}
 }
 
+static int test_stat_timestamps(void)
+{
+	struct stat st;
+
+	if (sizeof(st.st_atim.tv_sec) != sizeof(st.st_atime))
+		return 1;
+
+	if (stat("/proc/self/", &st))
+		return 1;
+
+	if (st.st_atim.tv_sec != st.st_atime || st.st_atim.tv_nsec > 1000000000)
+		return 1;
+
+	if (st.st_mtim.tv_sec != st.st_mtime || st.st_mtim.tv_nsec > 1000000000)
+		return 1;
+
+	if (st.st_ctim.tv_sec != st.st_ctime || st.st_ctim.tv_nsec > 1000000000)
+		return 1;
+
+	return 0;
+}
+
 /* Run syscall tests between IDs <min> and <max>.
  * Return 0 on success, non-zero on failure.
  */
@@ -587,6 +609,7 @@ int run_syscall(int min, int max)
 		CASE_TEST(select_fault);      EXPECT_SYSER(1, select(1, (void *)1, NULL, NULL, 0), -1, EFAULT); break;
 		CASE_TEST(stat_blah);         EXPECT_SYSER(1, stat("/proc/self/blah", &stat_buf), -1, ENOENT); break;
 		CASE_TEST(stat_fault);        EXPECT_SYSER(1, stat(NULL, &stat_buf), -1, EFAULT); break;
+		CASE_TEST(stat_timestamps);   EXPECT_SYSZR(1, test_stat_timestamps()); break;
 		CASE_TEST(symlink_root);      EXPECT_SYSER(1, symlink("/", "/"), -1, EEXIST); break;
 		CASE_TEST(unlink_root);       EXPECT_SYSER(1, unlink("/"), -1, EISDIR); break;
 		CASE_TEST(unlink_blah);       EXPECT_SYSER(1, unlink("/proc/self/blah"), -1, ENOENT); break;

---
base-commit: 1974a2b5fd434812b32952b09df7b79fdee8104d
change-id: 20230527-nolibc-stat-nanoseconds-35de1467a430

Best regards,
-- 
Thomas Weißschuh <linux@...ssschuh.net>