Add IO error test cases for file variants

Author: mleleszi

libc/src/stdio/printf_core/vasprintf_internal.h

@@ -59,12 +59,12 @@ LIBC_INLINE PrintfResult vasprintf_internal(char **ret,
   if (wb.buff == init_buff_on_stack) {
     *ret = static_cast<char *>(malloc(ret_val.value + 1));
     if (ret == nullptr)
-      return -ENOMEM;
+      return {0, ENOMEM};
     inline_memcpy(*ret, wb.buff, ret_val.value);
   } else {
     *ret = wb.buff;
   }
-  (*ret)[ret_val.value] = '\0'; // TODO OK HERE or overflow
+  (*ret)[ret_val.value] = '\0';
   return ret_val;
 }
 } // namespace printf_core

libc/test/src/stdio/CMakeLists.txt

@@ -186,6 +186,8 @@ add_libc_test(
     fprintf_test.cpp
   DEPENDS
     libc.src.stdio.fprintf
+    libc.test.UnitTest.ErrnoCheckingTest
+    libc.test.UnitTest.ErrnoSetterMatcher
     ${fprintf_test_deps}
   COMPILE_OPTIONS
     ${use_system_file}

libc/test/src/stdio/fprintf_test.cpp

@@ -16,6 +16,8 @@
 #include "src/stdio/fprintf.h"
 
 #include "test/UnitTest/Test.h"
+#include "test/UnitTest/ErrnoCheckingTest.h"
+#include "test/UnitTest/ErrnoSetterMatcher.h"
 
 namespace printf_test {
 #ifndef LIBC_COPT_STDIO_USE_SYSTEM_FILE
@@ -31,6 +33,8 @@ using ::fread;
 #endif // LIBC_COPT_STDIO_USE_SYSTEM_FILE
 } // namespace printf_test
 
+using LlvmLibcFPrintfTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
+
 TEST(LlvmLibcFPrintfTest, WriteToFile) {
   const char *FILENAME = APPEND_LIBC_TEST("fprintf_output.test");
   auto FILE_PATH = libc_make_test_file_path(FILENAME);
@@ -78,6 +82,7 @@ TEST(LlvmLibcFPrintfTest, WriteToFile) {
   written =
       LIBC_NAMESPACE::fprintf(file, "Writing to a read only file should fail.");
   EXPECT_LT(written, 0);
+  ASSERT_ERRNO_EQ(EIO);
 
   ASSERT_EQ(printf_test::fclose(file), 0);
 }

libc/test/src/stdio/vfprintf_test.cpp

@@ -20,6 +20,8 @@
 #include "src/stdio/vfprintf.h"
 
 #include "test/UnitTest/Test.h"
+#include "test/UnitTest/ErrnoCheckingTest.h"
+#include "test/UnitTest/ErrnoSetterMatcher.h"
 
 namespace printf_test {
 #ifndef LIBC_COPT_STDIO_USE_SYSTEM_FILE
@@ -44,6 +46,8 @@ int call_vfprintf(::FILE *__restrict stream, const char *__restrict format,
   return ret;
 }
 
+using LlvmLibcVFPrintfTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
+
 TEST(LlvmLibcVFPrintfTest, WriteToFile) {
   const char *FILENAME = APPEND_LIBC_TEST("vfprintf_output.test");
   auto FILE_PATH = libc_make_test_file_path(FILENAME);
@@ -90,6 +94,7 @@ TEST(LlvmLibcVFPrintfTest, WriteToFile) {
 
   written = call_vfprintf(file, "Writing to a read only file should fail.");
   EXPECT_LT(written, 0);
+  ASSERT_ERRNO_EQ(EIO);
 
   ASSERT_EQ(printf_test::fclose(file), 0);
 }