Merge pull request #24709 from rootbeer/24380-fstatat-race-fix

Author: alexrp

lib/std/os/linux/mips.zig

@@ -317,14 +317,14 @@ pub const Stat = extern struct {
     uid: uid_t,
     gid: gid_t,
     rdev: dev_t,
-    __pad1: [2]u32, // -1 because our dev_t is u64 (kernel dev_t is really u32).
+    __pad1: [2]u32,
     size: off_t,
     atim: i32,
-    atim_nsec: u32,
+    atim_nsec: i32,
     mtim: i32,
-    mtim_nsec: u32,
+    mtim_nsec: i32,
     ctim: i32,
-    ctim_nsec: u32,
+    ctim_nsec: i32,
     blksize: blksize_t,
     __pad3: u32,
     blocks: blkcnt_t,

lib/std/posix/test.zig

@@ -395,11 +395,27 @@ test "fstatat" {
     // now repeat but using `fstatat` instead
     const statat = try posix.fstatat(tmp.dir.fd, "file.txt", posix.AT.SYMLINK_NOFOLLOW);
 
-    // s390x-linux does not have nanosecond precision for fstat(), but it does for fstatat(). As a
-    // result, comparing the two structures is doomed to fail.
-    if (builtin.cpu.arch == .s390x and builtin.os.tag == .linux) return error.SkipZigTest;
-
-    try expectEqual(stat, statat);
+    try expectEqual(stat.dev, statat.dev);
+    try expectEqual(stat.ino, statat.ino);
+    try expectEqual(stat.nlink, statat.nlink);
+    try expectEqual(stat.mode, statat.mode);
+    try expectEqual(stat.uid, statat.uid);
+    try expectEqual(stat.gid, statat.gid);
+    try expectEqual(stat.rdev, statat.rdev);
+    try expectEqual(stat.size, statat.size);
+    try expectEqual(stat.blksize, statat.blksize);
+
+    // The stat.blocks/statat.blocks count is managed by the filesystem and may
+    // change if the file is stored in a journal or "inline".
+    // try expectEqual(stat.blocks, statat.blocks);
+
+    // s390x-linux does not have nanosecond precision for fstat(), but it does for
+    // fstatat(). As a result, comparing the timestamps isn't worth the effort
+    if (!(builtin.cpu.arch == .s390x and builtin.os.tag == .linux)) {
+        try expectEqual(stat.atime(), statat.atime());
+        try expectEqual(stat.mtime(), statat.mtime());
+        try expectEqual(stat.ctime(), statat.ctime());
+    }
 }
 
 test "readlinkat" {