[libc-commits] [libc] [libc] Migrate filesystem syscall wrappers to syscall_checked (PR #225636)

[Pavel Labath via libc-commits]

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@@ -27,18 +27,15 @@ namespace linux_syscalls {
 
 LIBC_INLINE ErrorOr<int> chmod(const char *path, mode_t mode) {
 #ifdef SYS_fchmodat
-  int ret = syscall_impl<int>(SYS_fchmodat, AT_FDCWD, path, mode, 0);
+  return syscall_checked<int>(SYS_fchmodat, AT_FDCWD, path, mode, 0);
 #elif defined(SYS_fchmodat2)
-  int ret = syscall_impl<int>(SYS_fchmodat2, AT_FDCWD, path, mode, 0,
+  return syscall_checked<int>(SYS_fchmodat2, AT_FDCWD, path, mode, 0,
                               AT_SYMLINK_NOFOLLOW);
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labath wrote:

Good catch. This kind of works because the AT_SYMLINK_NOFOLLOW bug is cancelled out by another bug -- passing too many arguments to the syscall. fchmodat takes three arguments -- not four, which means the last zero is unused. and fchmodat2 takes four arguments -- not five, which means AT_SYMLINK_NOFOLLOW is ignored and zero is passed as flags.

That said, would you be okay, with keeping this as NFC as possible, and addressing the flags thing in a separate PR. I want to actually add a test to validate the behavior on symlinks.

https://github.com/llvm/llvm-project/pull/225636