tests/tr1: Fix sporadic failures caused by tmpnam/_tempnam

tests/tr1/include/temp_file_name.h

@@ -0,0 +1,21 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#pragma once
+
+#include <random>
+#include <string>
+
+[[nodiscard]] inline std::string temp_file_name() {
+    std::string ret{"temp_file_"};
+    std::uniform_int_distribution<int> dist{0, 15};
+    std::random_device rd;
+
+    for (int i = 0; i < 64; ++i) { // 64 hexits = 256 bits of entropy
+        ret.push_back("0123456789ABCDEF"[dist(rd)]);
+    }
+
+    ret += ".tmp";
+
+    return ret;
+}

tests/tr1/tests/cstdio/test.cpp

@@ -5,6 +5,7 @@
 #define TEST_NAMEX "<cstdio>"
 
 #include "tdefs.h"
+#include "temp_file_name.h"
 #include <assert.h>
 #include <cstdio>
 #include <errno.h>
@@ -91,7 +92,8 @@ void test_cpp() { // test C++ header
         int in1;
         long off;
 
-        assert((tn = STDx tmpnam((char*) nullptr)) != nullptr);
+        const auto temp_name = temp_file_name();
+        tn                   = temp_name.c_str();
         assert((pf = STDx fopen(tn, "w+")) != nullptr);
 
         STDx setbuf(pf, (char*) nullptr);
@@ -124,18 +126,17 @@ void test_cpp() { // test C++ header
     }
 
     { // test character I/O
-        const char* tmpbuff;
         char tname[L_tmpnam];
-        char tmpbuf[L_tmpnam];
+        char tn[100];
         STDx FILE* pf;
-        char tn[100] = {0};
 
-        assert(STDx tmpnam(tmpbuf) == tmpbuf);
-        CHECK(CSTD strlen(tmpbuf) < L_tmpnam);
-        assert((tmpbuff = STDx tmpnam((char*) nullptr)) != nullptr);
+        const auto temp_name1 = temp_file_name();
+        CHECK(temp_name1.size() < sizeof(tname));
+        CSTD strcpy_s(tname, sizeof(tname), temp_name1.c_str());
 
-        CSTD strcpy_s(tn, sizeof(tn), tmpbuff);
-        CSTD strcpy_s(tname, sizeof(tname), tmpbuf);
+        const auto temp_name2 = temp_file_name();
+        CHECK(temp_name2.size() < sizeof(tn));
+        CSTD strcpy_s(tn, sizeof(tn), temp_name2.c_str());
 
         CHECK(CSTD strcmp(tn, tname) != 0);
         assert((pf = STDx fopen(tname, "w")) != nullptr);

tests/tr1/tests/cwchar1/test.cpp

@@ -5,6 +5,7 @@
 #define TEST_NAMEX "<cwchar>, part 1"
 
 #include "tdefs.h"
+#include "temp_file_name.h"
 #include <assert.h>
 #include <cwchar>
 #include <stdarg.h>
@@ -13,9 +14,6 @@
 
 #pragma warning(disable : 4793) // function compiled as native
 
-#define NO_TMPNAM_TESTS 1
-#undef tmpnam
-#define tmpnam(x) _tempnam(".", "")
 
 #undef clearerr // tested in stdio2.c
 #undef feof
@@ -101,7 +99,8 @@ void test_cpp() { // test C++ header
         int in1;
         long off;
 
-        assert((tn = CSTD tmpnam((char*) nullptr)) != nullptr);
+        const auto temp_name = temp_file_name();
+        tn                   = temp_name.c_str();
         assert((pf = CSTD fopen(tn, "w+")) != nullptr);
         CHECK_INT(STDx fwide(pf, 0), 0);
         CHECK_INT(STDx fwprintf(pf, L"123\n"), 4);
@@ -141,19 +140,15 @@ void test_cpp() { // test C++ header
 
         CHECK(wmacs[1] < wmacs[0]);
 
-#if NO_TMPNAM_TESTS
-        char *tname, *tn;
-        assert((tn = CSTD tmpnam((char*) nullptr)) != nullptr);
-        tname = (char*) CSTD malloc(CSTD strlen(tn) + 1);
+        char* tname;
+        const char* tn;
+        const auto temp_name1 = temp_file_name();
+        tn                    = temp_name1.c_str();
+        tname                 = (char*) CSTD malloc(CSTD strlen(tn) + 1);
         CSTD strcpy(tname, tn);
 
-#else // NO_TMPNAM_TESTS
-        char tname[L_tmpnam], *tn;
-        CHECK_PTR(CSTD tmpnam(tname), tname);
-        assert(CSTD strlen(tname) < L_tmpnam);
-#endif // NO_TMPNAM_TESTS
-
-        assert((tn = CSTD tmpnam((char*) nullptr)) != nullptr);
+        const auto temp_name2 = temp_file_name();
+        tn                    = temp_name2.c_str();
         CHECK(CSTD strcmp(tn, tname) != 0);
         assert((pf = CSTD fopen(tname, "w")) != nullptr);
         CHECK_INT(STDx fgetwc(pf), wintval);

tests/tr1/tests/fstream1/test.cpp

@@ -5,19 +5,14 @@
 #define TEST_NAME "<fstream>, part 1"
 
 #include "tdefs.h"
+#include "temp_file_name.h"
 #include <assert.h>
 #include <fstream>
 #include <string>
 
-#undef tmpnam
-#define tmpnam(x) _tempnam(".", "")
-
 void test_main() { // test basic workings of char fstream definitions
-    const char* tn = CSTD tmpnam(0);
-
-    assert(tn != nullptr);
-
-    STD string tn_str(tn);
+    STD string tn_str = temp_file_name();
+    const char* tn    = tn_str.c_str();
 
     // test output file opening
     STD ofstream ofs(tn);

tests/tr1/tests/fstream2/test.cpp

@@ -5,17 +5,14 @@
 #define TEST_NAME "<fstream>, part 2"
 
 #include "tdefs.h"
+#include "temp_file_name.h"
 #include <assert.h>
 #include <fstream>
 #include <wchar.h>
 
-#undef tmpnam
-#define tmpnam(x) _tempnam(".", "")
-
 void test_main() { // test basic workings of wide fstream definitions
-    const char* tn = CSTD tmpnam(0);
-
-    assert(tn != nullptr);
+    const auto temp_name = temp_file_name();
+    const char* tn       = temp_name.c_str();
 
     // test output file opening
     STD wofstream ofs(tn);