[compiler-rt][rtsan] Fix failing file permissions test

[cjappl]

This reverts:

d8d8d65

This test was failing with the assertion:

/build/buildbot/premerge-monolithic-linux/llvm-project/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors.cpp:198: Failure
Value of: st.st_mode & 0777
Expected: is equal to 420
  Actual: 384

To fix this bug, we need to record the delta between the existing umask and the requested file permissions.

I have repro'd this on my local machine, which you can do by:

$ umask # look at the existing umask
0022 
$ umask 0077 # set it to the more restrictive umask
$ ninja check-rtsan
...
/Users/topher/code/radsan_cjappl/llvm-project/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors.cpp:198
Value of: st.st_mode & 0777
Expected: is equal to 420
  Actual: 384
...
$ git checkout $THIS_BRANCH
$ ninja check-rtsan
CLEAN :)

[cjappl]

CC @davidtrevelyan

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Chris Apple (cjappl)

Changes

This reverts:

d8d8d65

This test was failing with the assertion:

/build/buildbot/premerge-monolithic-linux/llvm-project/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors.cpp:198: Failure
Value of: st.st_mode & 0777
Expected: is equal to 420
  Actual: 384

My thought is that on my local machine, umask starts at 0022 (owner everything, group read, others read) and on the build machine umask starts at 0077 (owner everything, group nothing, others nothing).

To fix this bug, we need to record the delta between the existing umask and the requested file permissions. Does this seem reasonable?

---

Full diff: https://github.com/llvm/llvm-project/pull/106095.diff

1 Files Affected:

• (modified) compiler-rt/lib/rtsan/tests/rtsan_test_interceptors.cpp (+18-19)

diff --git a/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors.cpp b/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors.cpp
index 5b88cf64612942..8e55ccc1116727 100644
--- a/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors.cpp
+++ b/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors.cpp
@@ -184,25 +184,24 @@ TEST_F(RtsanFileTest, OpenatDiesWhenRealtime) {
   ExpectNonRealtimeSurvival(func);
 }
 
-// FIXME: This fails on the build machines, but not locally!
-// see https://github.com/llvm/llvm-project/pull/105732#issuecomment-2310286530
-// Value of: st.st_mode & 0777
-// Expected: is equal to 420
-// Actual: 384
-// TEST_F(RtsanFileTest, OpenCreatesFileWithProperMode) {
-//   const int mode = S_IRGRP | S_IROTH | S_IRUSR | S_IWUSR;
-//
-//   const int fd = open(GetTemporaryFilePath(), O_CREAT | O_WRONLY, mode);
-//   ASSERT_THAT(fd, Ne(-1));
-//   close(fd);
-//
-//   struct stat st;
-//   ASSERT_THAT(stat(GetTemporaryFilePath(), &st), Eq(0));
-//
-//   // Mask st_mode to get permission bits only
-//
-//   //ASSERT_THAT(st.st_mode & 0777, Eq(mode)); FAILED ASSERTION
-// }
+TEST_F(RtsanFileTest, OpenCreatesFileWithProperMode) {
+  const mode_t existing_umask = umask(0);
+  umask(existing_umask);
+
+  const int mode = S_IRGRP | S_IROTH | S_IRUSR | S_IWUSR;
+
+  const int fd = open(GetTemporaryFilePath(), O_CREAT | O_WRONLY, mode);
+  ASSERT_THAT(fd, Ne(-1));
+  close(fd);
+
+  struct stat st;
+  ASSERT_THAT(stat(GetTemporaryFilePath(), &st), Eq(0));
+
+  // Mask st_mode to get permission bits only
+  const mode_t actual_mode = st.st_mode & 0777;
+  const mode_t expected_mode = mode & ~existing_umask;
+  ASSERT_THAT(actual_mode, Eq(expected_mode));
+}
 
 TEST_F(RtsanFileTest, CreatDiesWhenRealtime) {
   auto func = [this]() { creat(GetTemporaryFilePath(), S_IWOTH | S_IROTH); };

[cjappl]

Unrelated test failure:

/var/lib/buildkite-agent/builds/linux-56-59b8f5d88-g9cxr-1/llvm-project/github-pull-requests/llvm/unittests/Analysis/UnrollAnalyzerTest.cpp:249: Failure
Value of: I1 != SimplifiedValuesVector[5].end()
  Actual: false
Expected: true

merging in a second