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overhaul tmpfile, tmpnam, and tempnam functions

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these all now use the shared __randname function internally, rather
than duplicating logic for producing a random name. incorrect usage of
the access syscall (which works with real uid/gid, not effective) has
been removed, along with unnecessary heavy dependencies like snprintf.
This commit is contained in:
Rich Felker 2014-05-27 00:44:23 -04:00
commit 2fe6579125
3 changed files with 48 additions and 55 deletions
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40
src/stdio/tmpnam.c
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@ -1,31 +1,23 @@
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <time.h>
#include "libc.h"
#include <fcntl.h>
#include <errno.h>
#include <sys/stat.h>
#include "syscall.h"
#include "atomic.h"
#define MAXTRIES 100
char *tmpnam(char *s)
char *__randname(char *);
char *tmpnam(char *buf)
{
static int index;
static char s2[L_tmpnam];
struct timespec ts;
int try = 0;
unsigned n;
if (!s) s = s2;
if (__syscall(SYS_access, P_tmpdir, R_OK|W_OK|X_OK) != 0)
return NULL;
do {
__syscall(SYS_clock_gettime, CLOCK_REALTIME, &ts, 0);
n = ts.tv_nsec ^ (uintptr_t)&s ^ (uintptr_t)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;
static char internal[L_tmpnam];
char s[] = "/tmp/tmpnam_XXXXXX";
int try;
int r;
for (try=0; try<MAXTRIES; try++) {
__randname(s+12);
r = __syscall(SYS_lstat, s, &(struct stat){0});
if (r == -ENOENT) return strcpy(buf ? buf : internal, s);
}
return 0;
}