Remove STL use from platform/assert.cc

runtime/platform/assert.cc

Index: runtime/platform/assert.cc
diff --git a/runtime/platform/assert.cc b/runtime/platform/assert.cc
index e9d1c4fa301e66db915f676132275b292b21a5c6..c5b91e714f3bbb6c4a1ea6c73c56b562a38ffab4 100644
--- a/runtime/platform/assert.cc
+++ b/runtime/platform/assert.cc
@@ -4,9 +4,6 @@
 
 #include "platform/assert.h"
 
-#include <sstream>
-#include <string>
-
 #include "platform/globals.h"
 #include "vm/os.h"
 
@@ -18,19 +15,27 @@ static void failed_exit(void) {
 }
 
 void DynamicAssertionHelper::Fail(const char* format, ...) {
-  std::ostringstream stream;
-  stream << file_ << ":" << line_ << ": error: ";
+  // Take only the last 1KB of the file name if it is longer.
+  const intptr_t file_len = strlen(file_);
+  const intptr_t file_offset = (file_len > (1 * KB)) ? file_len - (1 * KB) : 0;
+  const char* file = file_ + file_offset;
+
+  // Print the file and line number into the buffer.
+  char buffer[4 * KB];
+  intptr_t file_and_line_length =
+      snprintf(buffer, sizeof(buffer), "%s: %d: error: ", file, line_);
 
+  // Print the error message into the buffer.
   va_list arguments;
   va_start(arguments, format);
-  char buffer[4 * KB];
-  vsnprintf(buffer, sizeof(buffer), format, arguments);
+  vsnprintf(buffer + file_and_line_length,
+            sizeof(buffer) - file_and_line_length,
+            format,
+            arguments);
   va_end(arguments);
-  stream << buffer << std::endl;
 
-  // Get the message from the string stream and dump it on stderr.
-  std::string message = stream.str();
-  fprintf(stderr, "%s", message.c_str());
+  // Print the buffer on stderr.
+  fprintf(stderr, "%s\n", buffer);
   fflush(stderr);
 
   // In case of failed assertions, abort right away. Otherwise, wait