[all-commits] [llvm/llvm-project] b4722c: [libc++][test] Fix infinite loop when mkstemp fails

[Ryan Prichard via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: b4722cc4c96e03cdad3f23b0ba558907e82d95db
      https://github.com/llvm/llvm-project/commit/b4722cc4c96e03cdad3f23b0ba558907e82d95db
  Author: Ryan Prichard <rprichard at google.com>
  Date:   2022-07-22 (Fri, 22 Jul 2022)

  Changed paths:
    M libcxx/test/support/platform_support.h

  Log Message:
  -----------
  [libc++][test] Fix infinite loop when mkstemp fails

mkstemp is guaranteed to make at least TMP_MAX attempts to create the
random file, and if it can't, it fails with EEXIST. get_temp_file_name
shouldn't call mkstemp again if it fails with anything other than
EEXIST. A single mkstemp call seems sufficient.

On Android, I've seen mkstemp fail with:
 - EROFS (because cwd wasn't set to a writable filesystem)
 - EACCES (because cwd pointed to a dir owned by root, but the test
   program was running as the shell user instead)

Previously, get_temp_file_name would run forever in these situations.

See D4962 and "llvm-svn: 229035"

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D130214