safe-mkstemp.c revision e156adefc1260d31a145df2f5e9b3c82050d4163
/* Copyright (c) 2007-2009 Dovecot authors, see the included COPYING file */
#include "lib.h"
#include "str.h"
#include "hex-binary.h"
#include "randgen.h"
#include "hostpid.h"
#include "eacces-error.h"
#include "safe-mkstemp.h"
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
static int
safe_mkstemp_full(string_t *prefix, mode_t mode, uid_t uid, gid_t gid,
const char *gid_origin)
{
size_t prefix_len;
struct stat st;
unsigned char randbuf[8];
mode_t old_umask;
int fd;
prefix_len = str_len(prefix);
for (;;) {
do {
random_fill_weak(randbuf, sizeof(randbuf));
str_truncate(prefix, prefix_len);
str_append(prefix,
binary_to_hex(randbuf, sizeof(randbuf)));
} while (lstat(str_c(prefix), &st) == 0);
if (errno != ENOENT) {
i_error("stat(%s) failed: %m", str_c(prefix));
return -1;
}
old_umask = umask(0666 ^ mode);
fd = open(str_c(prefix), O_RDWR | O_EXCL | O_CREAT, 0666);
umask(old_umask);
if (fd != -1)
break;
if (errno != EEXIST) {
if (errno != ENOENT && errno != EACCES)
i_error("open(%s) failed: %m", str_c(prefix));
return -1;
}
}
if (uid == (uid_t)-1 && gid == (gid_t)-1)
return fd;
if (fchown(fd, uid, gid) < 0) {
if (errno == EPERM) {
i_error("%s", eperm_error_get_chgrp("fchown",
str_c(prefix), gid, gid_origin));
} else {
i_error("fchown(%s, %ld, %ld) failed: %m",
str_c(prefix),
uid == (uid_t)-1 ? -1L : (long)uid,
gid == (gid_t)-1 ? -1L : (long)gid);
}
(void)close(fd);
(void)unlink(str_c(prefix));
return -1;
}
return fd;
}
int safe_mkstemp(string_t *prefix, mode_t mode, uid_t uid, gid_t gid)
{
return safe_mkstemp_full(prefix, mode, uid, gid, NULL);
}
int safe_mkstemp_group(string_t *prefix, mode_t mode,
gid_t gid, const char *gid_origin)
{
return safe_mkstemp_full(prefix, mode, (uid_t)-1, gid, gid_origin);
}
int safe_mkstemp_hostpid(string_t *prefix, mode_t mode, uid_t uid, gid_t gid)
{
str_printfa(prefix, "%s.%s.", my_hostname, my_pid);
return safe_mkstemp(prefix, mode, uid, gid);
}
int safe_mkstemp_hostpid_group(string_t *prefix, mode_t mode,
gid_t gid, const char *gid_origin)
{
str_printfa(prefix, "%s.%s.", my_hostname, my_pid);
return safe_mkstemp_group(prefix, mode, gid, gid_origin);
}