[PATCH] D124607: Add an error message to the default SIGPIPE handler

[Damian Malarczyk via Phabricator via llvm-commits]

dmcyk updated this revision to Diff 434741.
dmcyk marked 3 inline comments as done.
dmcyk added a comment.

- Move test case to support; update comments


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D124607/new/

https://reviews.llvm.org/D124607

Files:
  llvm/lib/Support/Unix/Signals.inc
  llvm/test/Support/unix03-sigpipe-exit.test


Index: llvm/test/Support/unix03-sigpipe-exit.test
===================================================================
--- /dev/null
+++ llvm/test/Support/unix03-sigpipe-exit.test
@@ -0,0 +1,26 @@
+## Test that when writing to a closed stdout, LLVM tools finish with a non-zero
+## exit code and an error message on stderr. The test uses llvm-cxxfilt, but
+## it's a logic from the default SIGPIPE handler, so it applies to all the tools.
+## This is required for UNIX03 conformance.
+
+# UNSUPPORTED: system-windows
+
+# RUN: not %python %s llvm-cxxfilt 2>&1 | FileCheck %s
+# CHECK: error: write on a pipe with no reader
+
+import subprocess
+import sys
+
+with subprocess.Popen([sys.argv[1]], stdout=subprocess.PIPE, stdin=subprocess.PIPE) as process:
+  process.stdout.close()
+
+  # llvm-cxxfilt with no extra arguments runs interactively and writes input
+  # to output. Writing continuously to stdin should trigger SIGPIPE when the
+  # subprocess attempts to write out bytes to a closed stdout.
+  try:
+    while True:
+      process.stdin.write("foo\n".encode("utf-8"))
+  except BrokenPipeError:
+    # Clear stdin, pipe is broken and closing it on cleanup will raise an exception.
+    process.stdin = None
+sys.exit(process.returncode)
Index: llvm/lib/Support/Unix/Signals.inc
===================================================================
--- llvm/lib/Support/Unix/Signals.inc
+++ llvm/lib/Support/Unix/Signals.inc
@@ -432,6 +432,10 @@
 }
 
 void llvm::sys::DefaultOneShotPipeSignalHandler() {
+  // UNIX03 conformance requires a non-zero exit code and an error message
+  // to stderr when writing to a closed stdout fails.
+  errs() << "error: write on a pipe with no reader\n";
+
   // Send a special return code that drivers can check for, from sysexits.h.
   exit(EX_IOERR);
 }


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