[libc] [llvm] [libc] Implemented utimes (Issue #133953) (PR #134167)

[Michael Jones via llvm-commits]

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@@ -0,0 +1,80 @@
+//===-- Linux implementation of utimes -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===/
+
+#include "src/sys/time/utimes.h"
+
+#include "hdr/types/struct_timeval.h"
+
+#include "src/__support/OSUtil/syscall.h"
+#include "src/__support/common.h"
+
+#include "src/errno/libc_errno.h"
+
+#include <cerrno>
+#include <sys/syscall.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+namespace LIBC_NAMESPACE_DECL {
+  
+  LLVM_LIBC_FUNCTION(int, utimes, (const char *path, const struct timeval times[2])) {
+    int ret;
+  
+  #ifdef SYS_utimensat
+    //the utimensat syscall requires a timespec struct, not timeval.
+    struct timespec ts[2];
+    struct timespec *ts_ptr = nullptr; // default value if times is NULL
+    
+    // convert the microsec values in timeval struct times 
+    // to nanosecond values in timespec struct ts
+    if (times != NULL) {
+      
+      // ensure consistent values
+      if ((times[0].tv_usec < 0 || times[1].tv_usec < 0) || 
+         (times[0].tv_usec >= 1000000 || times[1].tv_usec >= 1000000)) {
+           libc_errno = EINVAL;
+           return -1;
+      }
+      
+      // set seconds in ts
+      ts[0].tv_sec = times[0].tv_sec; 
+      ts[1].tv_sec = times[1].tv_sec;
+      
+      // convert u-seconds to nanoseconds
+      ts[0].tv_nsec = times[0].tv_usec * 1000;
+      ts[1].tv_nsec = times[1].tv_usec * 1000;
+      
+      ts_ptr = ts;
+    }
+    
+    // If times was NULL, ts_ptr remains NULL, which utimensat interprets
+    // as setting times to the current time.
+  
+    // utimensat syscall. 
+    // flags=0 means don't follow symlinks (like utimes)
+    ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_utimensat, AT_FDCWD, path,
+                                             ts_ptr, 0);
+  
+  #elif defined(SYS_utimes)
+    // No need to define a timespec struct, use the syscall directly.
+    ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_utimes, path, times);
+  #else
+  #error "utimensat and utimes syscalls not available."
+    // To avoid compilation errors when neither is defined, return an error.
+    libc_errno = ENOSYS; // Function not implemented
+    return -1;
----------------
michaelrj-google wrote:

the `#error` already causes a compilation error. This part isn't necessary.

https://github.com/llvm/llvm-project/pull/134167