fix tmpnam to generate better names, not depend on non-ISO-C symbols

diff --git a/src/stdio/tmpnam.c b/src/stdio/tmpnam.c
index 14d5922..6099b74 100644 (file)
--- a/src/stdio/tmpnam.c
+++ b/src/stdio/tmpnam.c
@@ -1,38 +1,30 @@
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
-#include <limits.h>
 #include <unistd.h>
+#include <time.h>
 #include "libc.h"
+#include "syscall.h"
+#include "atomic.h"
+
+#define MAXTRIES 100
 
 char *tmpnam(char *s)
 {
-       static int lock;
        static int index;
-       static char *s2;
-       int pid = getpid();
-       char *dir = getenv("TMPDIR");
-
-       if (!s) {
-               if (!s2) s2 = malloc(L_tmpnam);
-               s = s2;
-       }
+       static char s2[L_tmpnam];
+       struct timespec ts;
+       int try = 0;
+       unsigned n;
 
-       /* this interface is insecure anyway but at least we can try.. */
-       if (!dir || strlen(dir) > L_tmpnam-32)
-               dir = P_tmpdir;
+       if (!s) s = s2;
 
-       if (access(dir, R_OK|W_OK|X_OK) != 0)
+       if (__syscall(SYS_access, P_tmpdir, R_OK|W_OK|X_OK) != 0)
                return NULL;
 
-       LOCK(&lock);
-       for (index++; index < TMP_MAX; index++) {
-               snprintf(s, L_tmpnam, "%s/temp%d-%d", dir, pid, index);
-               if (access(s, F_OK) != 0) {
-                       UNLOCK(&lock);
-                       return s;
-               }
-       }
-       UNLOCK(&lock);
-       return NULL;
+       do {
+               __syscall(SYS_clock_gettime, CLOCK_REALTIME, &ts, 0);
+               n = ts.tv_nsec ^ (unsigned)&s ^ (unsigned)s;
+               snprintf(s, L_tmpnam, "/tmp/t%x-%x", a_fetch_add(&index, 1), n);
+       } while (!__syscall(SYS_access, s, F_OK) && try++<MAXTRIES);
+       return try==MAXTRIES ? 0 : s;
 }