[libc-commits] [libc] [libc] Implement freopen (PR #207837)

[Jeff Bailey via libc-commits]

================
@@ -176,4 +183,103 @@ int get_fileno(File *f) {
   return lf->get_fd();
 }
 
+int reopenfile(File *f, const char *path, const char *mode) {
+  auto modeflags = File::mode_flags(mode);
+  if (modeflags == 0)
+    return EINVAL;
+
+  auto *lf = reinterpret_cast<LinuxFile *>(f);
+
+  if (path != nullptr) {
+    int open_flags = mode_flags_to_open_flags(modeflags);
+
+    constexpr mode_t OPEN_MODE =
+        S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
+
+    ErrorOr<int> new_fd = linux_syscalls::open(path, open_flags, OPEN_MODE);
+    int old_fd = lf->get_fd();
+
+    // If the new file fails to open, POSIX says we still have to close the old
+    // file.
+    if (!new_fd) {
+      if (old_fd >= 0) {
+        auto close_result = linux_syscalls::close(old_fd);
+        if (!close_result) {
+          f->reset_stream_state(modeflags);
+          return close_result.error();
----------------
kaladron wrote:

"Failure to close the file descriptor successfully shall be ignored" - I think this shouldn't return the error here.

https://github.com/llvm/llvm-project/pull/207837