[test] Fix error handling in swift-reflection-test.

* Fix handling of EINTR return from read().
* Don't print errno after errors that do not set errno.

Author: Greg Parker

tools/swift-reflection-test/swift-reflection-test.c

@@ -51,6 +51,11 @@ typedef struct RemoteReflectionInfo {
 } RemoteReflectionInfo;
 
 static void errorAndExit(const char *message) {
+  fprintf(stderr, "%s\n", message);
+  abort();
+}
+
+static void errnoAndExit(const char *message) {
   fprintf(stderr, "%s: %s\n", message, strerror(errno));
   abort();
 }
@@ -165,10 +170,13 @@ void PipeMemoryReader_collectBytesFromPipe(const PipeMemoryReader *Reader,
   int ReadFD = PipeMemoryReader_getParentReadFD(Reader);
   while (Size) {
     int bytesRead = read(ReadFD, Dest, Size);
-    if (bytesRead == -EINTR)
-      continue;
-    if (bytesRead <= 0)
-      errorAndExit("collectBytesFromPipe");
+    if (bytesRead < 0)
+      if (errno == EINTR)
+        continue;
+      else
+        errnoAndExit("collectBytesFromPipe");
+    else if (bytesRead == 0)
+      errorAndExit("collectBytesFromPipe: Unexpected end of file");
     Size -= bytesRead;
     Dest += bytesRead;
   }
@@ -232,9 +240,9 @@ static
 PipeMemoryReader createPipeMemoryReader() {
   PipeMemoryReader Reader;
   if (pipe(Reader.to_child))
-    errorAndExit("Couldn't create pipes to child process");
+    errnoAndExit("Couldn't create pipes to child process");
   if (pipe(Reader.from_child))
-    errorAndExit("Couldn't create pipes from child process");
+    errnoAndExit("Couldn't create pipes from child process");
   return Reader;
 }
 
@@ -265,7 +273,7 @@ PipeMemoryReader_receiveReflectionInfo(SwiftReflectionContextRef RC,
   RemoteReflectionInfo *RemoteInfos = calloc(NumReflectionInfos,
                                              sizeof(RemoteReflectionInfo));
   if (RemoteInfos == NULL)
-    errorAndExit("malloc failed");
+    errnoAndExit("malloc failed");
 
   for (size_t i = 0; i < NumReflectionInfos; ++i) {
     RemoteInfos[i] = makeRemoteReflectionInfo(
@@ -385,8 +393,7 @@ int doDumpHeapInstance(const char *BinaryFilename) {
   pid_t pid = _fork();
   switch (pid) {
     case -1:
-      errorAndExit("Couldn't fork child process");
-      exit(EXIT_FAILURE);
+      errnoAndExit("Couldn't fork child process");
     case 0: { // Child:
       close(PipeMemoryReader_getParentWriteFD(&Pipe));
       close(PipeMemoryReader_getParentReadFD(&Pipe));