[Support] Add RetryAfterSignal helper function

Summary:
This function retries an operation if it was interrupted by a signal
(failed with EINTR). It's inspired by the TEMP_FAILURE_RETRY macro in
glibc, but I've turned that into a template function. I've also added a
fail-value argument, to enable the function to be used with e.g.
fopen(3), which is documented to fail for any reason that open(2) can
fail (which includes EINTR).

The main user of this function will be lldb, but there were also a
couple of uses within llvm that I could simplify using this function.

Reviewers: zturner, silvas, joerg

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D33895

llvm-svn: 305892

1 files changed, 4 insertions, 8 deletions

diff --git a/llvm/lib/Support/Unix/Path.inc b/llvm/lib/Support/Unix/Path.inc
index b677469..45097eb 100644
--- a/llvm/lib/Support/Unix/Path.inc
+++ b/llvm/lib/Support/Unix/Path.inc
@@ -737,10 +737,8 @@ std::error_code openFileForRead(const Twine &Name, int &ResultFD,
 #ifdef O_CLOEXEC
   OpenFlags |= O_CLOEXEC;
 #endif
-  while ((ResultFD = open(P.begin(), OpenFlags)) < 0) {
-    if (errno != EINTR)
-      return std::error_code(errno, std::generic_category());
-  }
+  if ((ResultFD = sys::RetryAfterSignal(-1, open, P.begin(), OpenFlags)) < 0)
+    return std::error_code(errno, std::generic_category());
 #ifndef O_CLOEXEC
   int r = fcntl(ResultFD, F_SETFD, FD_CLOEXEC);
   (void)r;
@@ -800,10 +798,8 @@ std::error_code openFileForWrite(const Twine &Name, int &ResultFD,
 
   SmallString<128> Storage;
   StringRef P = Name.toNullTerminatedStringRef(Storage);
-  while ((ResultFD = open(P.begin(), OpenFlags, Mode)) < 0) {
-    if (errno != EINTR)
-      return std::error_code(errno, std::generic_category());
-  }
+  if ((ResultFD = sys::RetryAfterSignal(-1, open, P.begin(), OpenFlags, Mode)) < 0)
+    return std::error_code(errno, std::generic_category());
 #ifndef O_CLOEXEC
   int r = fcntl(ResultFD, F_SETFD, FD_CLOEXEC);
   (void)r;