Fix deadlock + 100% CPU caused by wrong loop exit condition.

Suspected cause for GH-1709, GH-1732. Inspection revealed another wrong
exit condition (causing preliminary exit in edge-case code), which was
also fixed.

CHANGELOG

@@ -7,6 +7,7 @@ Release 5.0.24
  * Also log HTTP headers to Union Station for HTTP 4xx responses (extends the header logging for HTTP 5xx that was added in 5.0.22)
  * Fixes cases where compilation failure of (optional) native utils was not reported.
  * On Ruby, no longer traps SIGEXIT. This fixes errorneously setting `$ERROR_INFO` in `at_exit` callbacks. Closes GH-1730.
+ * Fixes a wrong loop exit condition that could cause a deadlock with 100% CPU usage by Passenger core. Closes GH-1709, GH-1732.
  * [Standalone] Fixes the default value of the `load_shell_envvars` option. It's supposed to be disabled by default, but due to a typo it was enabled by default.
 
 

src/cxx_supportlib/ServerKit/FdSinkChannel.h

@@ -54,7 +54,7 @@ class FdSinkChannel: protected Channel {
 
 			do {
 				ret = ::write(watcher.fd, buffer.start, buffer.size());
-			} while (ret == -1 && errno == EAGAIN);
+			} while (ret == -1 && errno == EINTR);
 			if (ret == (ssize_t) buffer.size()) {
 				return Result(ret, false);
 			} else if (ret >= 0) {

src/cxx_supportlib/Utils.cpp

@@ -1313,7 +1313,7 @@ getHighestFileDescriptor(bool asyncSignalSafe) {
 
 			do {
 				ret = read(p[0], u.data + bytesRead, sizeof(int) - bytesRead);
-			} while (ret == -1 && ret == EINTR);
+			} while (ret == -1 && errno == EINTR);
 			if (ret == -1) {
 				if (errno != EAGAIN) {
 					goto done;