Avoid insecure usage of tmpnam in tests.

Various glibc testcases use tmpnam in ways subject to race conditions
(generate a temporary file name, then later open that file without
O_EXCL).

This patch fixes those tests to use mkstemp - generally a minimal
local fix to use mkstemp instead of tmpnam, rather than a larger fix
to use other testsuite infrastructure for temporary files.  The
unchanged use of tmpnam in posix/wordexp-test.c would fail safe in the
event of a race (it's generating a name for use with mkdir rather than
for a file to be opened for writing).

Tested for x86_64.

	* grp/tst_fgetgrent.c: Include <unistd.h>.
	(main): Use mkstemp instead of tmpnam.
	* io/test-utime.c (main): Likewise.
	* posix/annexc.c (macrofile): Change to modifiable array.
	(get_null_defines): Use mkstemp instead of tmpnam.  Do not remove
	macrofile here.
	* posix/bug-getopt1.c: Include <stdlib.h>.
	(do_test): Use mkstemp instead of tmpnam.
	* posix/bug-getopt2.c: Include <stdlib.h>.
	(do_test): Use mkstemp instead of tmpnam.
	* posix/bug-getopt3.c: Include <stdlib.h>.
	(do_test): Use mkstemp instead of tmpnam.
	* posix/bug-getopt4.c: Include <stdlib.h>.
	(do_test): Use mkstemp instead of tmpnam.
	* posix/bug-getopt5.c: Include <stdlib.h>.
	(do_test): Use mkstemp instead of tmpnam.
	* stdio-common/bug7.c: Include <stdlib.h> and <unistd.h>.
	(main): Use mkstemp instead of tmpnam.
	* stdio-common/tst-fdopen.c: Include <stdlib.h>.
	(main): Use mkstemp instead of tmpnam.
	* stdio-common/tst-ungetc.c: Include <stdlib.h>.
	(main): use mkstemp instead of tmpnam.
	* stdlib/isomac.c (macrofile): Change to modifiable array.
	(get_null_defines): Use mkstemp instead of tmpnam.  Do not remove
	macrofile here.

3 files changed, 33 insertions, 11 deletions

diff --git a/stdio-common/bug7.c b/stdio-common/bug7.c
index 2b1efe3..c9c2ef5 100644
--- a/stdio-common/bug7.c
+++ b/stdio-common/bug7.c
@@ -1,21 +1,25 @@
 /* Regression test for fseek and freopen bugs.  */
 
 #include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
 
 int
 main (int argc, char *argv[])
 {
   int lose = 0;
-  char filename[L_tmpnam];
+  char filename[] = "/tmp/bug7.XXXXXX";
   FILE *fp;
 
-  if (tmpnam (filename) == NULL)
+  int fd = mkstemp (filename);
+  if (fd == -1)
     {
-      printf ("tmpnam failed\n");
+      printf ("mkstemp failed\n");
       lose = 1;
     }
   else
     {
+      close (fd);
       fp = fopen (filename, "w+");
       fprintf (fp, "Hello world!\n");
       fflush (fp);
@@ -32,17 +36,21 @@ main (int argc, char *argv[])
   {
     FILE *file1;
     FILE *file2;
-    char filename1[L_tmpnam];
-    char filename2[L_tmpnam];
+    char filename1[] = "/tmp/bug7.XXXXXX";
+    char filename2[] = "/tmp/bug7.XXXXXX";
     int ch;
 
-    if (tmpnam (filename1) == NULL || tmpnam (filename2) == NULL)
+    int fd1 = mkstemp (filename1);
+    int fd2 = mkstemp (filename2);
+    if (fd1 == -1 || fd2 == -1)
       {
-	printf ("tmpnam failed\n");
+	printf ("mkstemp failed\n");
 	lose = 1;
       }
     else
       {
+	close (fd1);
+	close (fd2);
 
 	file1 = fopen (filename1, "w");
 	fclose (file1);
diff --git a/stdio-common/tst-fdopen.c b/stdio-common/tst-fdopen.c
index e70a0cd..136fff5 100644
--- a/stdio-common/tst-fdopen.c
+++ b/stdio-common/tst-fdopen.c
@@ -1,6 +1,7 @@
 /* Test for fdopen bugs.  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include <fcntl.h>
 
@@ -18,12 +19,18 @@ char buffer[256];
 int
 main (int argc, char *argv[])
 {
-  char *name;
+  char name[] = "/tmp/tst-fdopen.XXXXXX";
   FILE *fp = NULL;
   int retval = 0;
   int fd;
 
-  name = tmpnam (NULL);
+  fd = mkstemp (name);
+  if (fd == -1)
+    {
+      printf ("mkstemp failed: %m\n");
+      return 1;
+    }
+  close (fd);
   fp = fopen (name, "w");
   assert (fp != NULL)
   fputs ("foobar and baz", fp);
diff --git a/stdio-common/tst-ungetc.c b/stdio-common/tst-ungetc.c
index 44cf6a6..1344b2b 100644
--- a/stdio-common/tst-ungetc.c
+++ b/stdio-common/tst-ungetc.c
@@ -1,6 +1,7 @@
 /* Test for ungetc bugs.  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <unistd.h>
 
 #undef assert
@@ -15,13 +16,19 @@
 int
 main (int argc, char *argv[])
 {
-  char *name;
+  char name[] = "/tmp/tst-ungetc.XXXXXX";
   FILE *fp = NULL;
   int retval = 0;
   int c;
   char buffer[64];
 
-  name = tmpnam (NULL);
+  int fd = mkstemp (name);
+  if (fd == -1)
+    {
+      printf ("mkstemp failed: %m\n");
+      return 1;
+    }
+  close (fd);
   fp = fopen (name, "w");
   assert (fp != NULL)
   fputs ("bla", fp);