[libc-commits] [libc] [libc] Add tmpnam implementation (PR #204901)

[Jeff Bailey via libc-commits]

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@@ -0,0 +1,150 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Tests for tmpnam
+/// See: https://pubs.opengroup.org/onlinepubs/9799919799/functions/tmpnam.html
+///
+//===----------------------------------------------------------------------===//
+#include "src/stdio/tmpnam.h"
+
+#include "hdr/stdio_macros.h"
+#include "src/__support/CPP/string_view.h"
+#include "src/__support/macros/config.h"
+#include "test/UnitTest/Test.h"
+
+#include <stddef.h> // size_t
+
+namespace {
+
+using LIBC_NAMESPACE::cpp::string_view;
+
+// The portable filename character set the implementation draws from, plus the
+// '/' that appears in the P_tmpdir prefix. Any byte in a returned name must be
+// one of these.
+constexpr char kAllowed[] = "-._/"
+                            "0123456789"
+                            "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+                            "abcdefghijklmnopqrstuvwxyz";
+
+bool only_allowed_chars(string_view sv) {
+  for (char c : sv) {
+    bool found = false;
+    for (size_t i = 0; kAllowed[i] != '\0'; ++i) {
+      if (c == kAllowed[i]) {
+        found = true;
+        break;
+      }
+    }
+    if (!found)
+      return false;
+  }
+  return true;
+}
+
+} // namespace
+
+// Caller-supplied buffer: the spec requires the return value to be exactly the
+// argument pointer, the string to be null-terminated within L_tmpnam bytes,
+// and the result to begin with the temp-dir prefix.
+TEST(LlvmLibcTmpnamTest, NonNullBufferReturnsSamePointer) {
+  char buf[L_tmpnam];
+  char *result = LIBC_NAMESPACE::tmpnam(buf);
+  ASSERT_EQ(result, buf);
+}
+
+TEST(LlvmLibcTmpnamTest, NonNullBufferIsNullTerminated) {
+  char buf[L_tmpnam];
+  char *result = LIBC_NAMESPACE::tmpnam(buf);
+  ASSERT_NE(result, static_cast<char *>(nullptr));
+  // A NULL must appear within the buffer bounds.
+  bool terminated = false;
+  for (size_t i = 0; i < L_tmpnam; ++i) {
+    if (result[i] == '\0') {
+      terminated = true;
+      break;
+    }
+  }
+  ASSERT_TRUE(terminated);
+}
+
+TEST(LlvmLibcTmpnamTest, ResultHasTempDirPrefix) {
+  char buf[L_tmpnam];
+  char *result = LIBC_NAMESPACE::tmpnam(buf);
+  ASSERT_NE(result, static_cast<char *>(nullptr));
+  string_view sv(result);
+  string_view prefix(P_tmpdir);
+  // P_tmpdir may not carry a trailing slash; the implementation always
+  // emits one separator, so check the directory portion is present at the head.
+  ASSERT_TRUE(sv.starts_with(prefix));
+}
+
+TEST(LlvmLibcTmpnamTest, ResultUsesOnlyPortableChars) {
+  char buf[L_tmpnam];
+  char *result = LIBC_NAMESPACE::tmpnam(buf);
+  ASSERT_NE(result, static_cast<char *>(nullptr));
+  ASSERT_TRUE(only_allowed_chars(string_view(result)));
+}
+
+// Null argument: the result lives in an internal static object; the returned
+// pointer must be non-null and carry the same structural guarantees.
+TEST(LlvmLibcTmpnamTest, NullBufferReturnsInternalObject) {
+  char *result = LIBC_NAMESPACE::tmpnam(nullptr);
+  ASSERT_NE(result, static_cast<char *>(nullptr));
+  string_view sv(result);
+  ASSERT_TRUE(sv.starts_with(string_view(P_tmpdir)));
+  ASSERT_TRUE(only_allowed_chars(sv));
+}
+
+// The core contract: the generated name must not already exist on disk.
+// We re-check existence here via the public access() entry point if available.
----------------
kaladron wrote:

This does not appear to be true =)

https://github.com/llvm/llvm-project/pull/204901