[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, 3 insertions, 9 deletions

diff --git a/llvm/lib/Support/Unix/Process.inc b/llvm/lib/Support/Unix/Process.inc
index 1d0143c6716..2d466209468 100644
--- a/llvm/lib/Support/Unix/Process.inc
+++ b/llvm/lib/Support/Unix/Process.inc
@@ -207,13 +207,10 @@ std::error_code Process::FixupStandardFileDescriptors() {
   for (int StandardFD : StandardFDs) {
     struct stat st;
     errno = 0;
-    while (fstat(StandardFD, &st) < 0) {
+    if (RetryAfterSignal(-1, fstat, StandardFD, &st) < 0) {
       assert(errno && "expected errno to be set if fstat failed!");
       // fstat should return EBADF if the file descriptor is closed.
-      if (errno == EBADF)
-        break;
-      // retry fstat if we got EINTR, otherwise bubble up the failure.
-      if (errno != EINTR)
+      if (errno != EBADF)
         return std::error_code(errno, std::generic_category());
     }
     // if fstat succeeds, move on to the next FD.
@@ -222,11 +219,8 @@ std::error_code Process::FixupStandardFileDescriptors() {
     assert(errno == EBADF && "expected errno to have EBADF at this point!");
 
     if (NullFD < 0) {
-      while ((NullFD = open("/dev/null", O_RDWR)) < 0) {
-        if (errno == EINTR)
-          continue;
+      if ((NullFD = RetryAfterSignal(-1, open, "/dev/null", O_RDWR)) < 0)
         return std::error_code(errno, std::generic_category());
-      }
     }
 
     if (NullFD == StandardFD)