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

This commit is contained in:
Rich Felker 2011-03-29 08:34:47 -04:00
parent 9646e4d024
commit 507a9fa6ff
1 changed files with 17 additions and 25 deletions
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42
src/stdio/tmpnam.c
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@ -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");
static char s2[L_tmpnam];
struct timespec ts;
int try = 0;
unsigned n;
if (!s) {
if (!s2) s2 = malloc(L_tmpnam);
s = s2;
}
if (!s) s = s2;
/* this interface is insecure anyway but at least we can try.. */
if (!dir || strlen(dir) > L_tmpnam-32)
dir = P_tmpdir;
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;
}