[libc-commits] [libc] [wip] [libc] Implement vasprintf (PR #98824)

[Joseph Huber via libc-commits]

================
@@ -0,0 +1,92 @@
+//===-- Unittests for vasprintf--------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdio/sprintf.h"
+#include "src/stdio/vasprintf.h"
+#include "src/string/memset.h"
+#include "test/UnitTest/Test.h"
+#include <iostream>
+
+int call_vasprintf(char **__restrict buffer, const char *__restrict format,
+                   ...) {
+  va_list vlist;
+  va_start(vlist, format);
+  int ret = LIBC_NAMESPACE::vasprintf(buffer, format, vlist);
+  va_end(vlist);
+  return ret;
+}
+
+TEST(LlvmLibcVASPrintfTest, SimpleNoConv) {
+  char *buff = nullptr;
+  int written;
+  written = call_vasprintf(&buff, "A simple string with no conversions.");
+  EXPECT_EQ(written, 36);
+  ASSERT_STREQ(buff, "A simple string with no conversions.");
+  free(buff);
+}
+
+TEST(LlvmLibcVASPrintfTest, PercentConv) {
+  char *buff = nullptr;
+  int written;
+
+  written = call_vasprintf(&buff, "%%");
+  EXPECT_EQ(written, 1);
+  ASSERT_STREQ(buff, "%");
+
+  written = call_vasprintf(&buff, "abc %% def");
+  EXPECT_EQ(written, 9);
+  ASSERT_STREQ(buff, "abc % def");
+
+  written = call_vasprintf(&buff, "%%%%%%");
+  EXPECT_EQ(written, 3);
+  ASSERT_STREQ(buff, "%%%");
+  free(buff);
+}
+
+TEST(LlvmLibcVASPrintfTest, CharConv) {
+  char *buff = nullptr;
+  int written;
+
+  written = call_vasprintf(&buff, "%c", 'a');
+  EXPECT_EQ(written, 1);
+  ASSERT_STREQ(buff, "a");
+
+  written = call_vasprintf(&buff, "%3c %-3c", '1', '2');
+  EXPECT_EQ(written, 7);
+  ASSERT_STREQ(buff, "  1 2  ");
+
+  written = call_vasprintf(&buff, "%*c", 2, '3');
+  EXPECT_EQ(written, 2);
+  ASSERT_STREQ(buff, " 3");
+  free(buff);
+}
+
+TEST(LlvmLibcVASPrintfTest, LargeStringNoConv) {
+  char *buff = nullptr;
+  char long_str[1001];
+  LIBC_NAMESPACE::memset(long_str, 'a', 1000);
+  long_str[1000] = '\0';
+  int written;
+  written = call_vasprintf(&buff, long_str);
+  EXPECT_EQ(written, 1000);
+  ASSERT_STREQ(buff, long_str);
+  free(buff);
+}
+
+TEST(LlvmLibcVASPrintfTest, ManyReAlloc) {
+  char *buff = nullptr;
+  char long_str[1001];
+  auto expected_num_chars =
+      LIBC_NAMESPACE::sprintf(long_str, "%200s%200s%200s", "a", "b", "c");
----------------
jhuber6 wrote:

You can just call `vasprintf` directly with this format, no need to copy it to such a large stack buffer.

https://github.com/llvm/llvm-project/pull/98824