Thanks for your answers.
So this is better (my major mistake was the assumption that fopen implementations
are safe against race condition):
#include <string.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include "bondlog.h" /* here there are all headers needed by the app */
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <pwd.h>
#define MAX_BUF 11
#define RANDOMFILE "/dev/urandom"
FILE *
mytmpfile (void )
{
char appname[] = "/var/spool/bondlog/tmp";
char filename[PATH_MAX];
base64buf b;
unsigned int num = 0;
unsigned int count = 0;
int mypid;
FILE *urand_file;
FILE *tmp;
unsigned char *stream;
struct stat f_stat_info, l_stat_info;
int fd, finfo;
if ((stream = (char *) malloc (MAX_BUF)) == NULL)
{
return NULL;
}
memset (stream, '\0', MAX_BUF);
memset(filename,'\0',sizeof(filename)-1);
urand_file = fopen (RANDOMFILE, "r");
if (urand_file == NULL)
{
/* If I cannot open the random file
i assume that i can't create a safe filename
so I cannot assume that the file creation is safe
*/
free (stream);
return NULL;
}
do
{
count = 0;
while (count < 9)
{
fread (&num, sizeof (unsigned int), 1, urand_file);
stream[count] = (char) num;
count++;
}
base64_encode (&b, stream, 9);
memset (filename, '\0', sizeof (filename)-1);
mypid = (int) getpid();
snprintf (filename, sizeof (filename), "%s-%d-%s", appname, mypid, b.data);
}
while ((finfo = lstat (filename, &l_stat_info)) != -1);
fclose (urand_file);
if (finfo == -1)
{
if (errno != ENOENT)
return NULL;
if ((fd = open (filename, O_CREAT | O_EXCL | O_RDWR, 0600)) == -1)
return NULL;
lstat (filename, &l_stat_info);
}
else
{
free (stream);
return NULL;
}
if ((fstat (fd, &f_stat_info) == -1) ||
(l_stat_info.st_mode != f_stat_info.st_mode) ||
(l_stat_info.st_ino != f_stat_info.st_ino) ||
(l_stat_info.st_dev != f_stat_info.st_dev))
{
free(stream);
close (fd);
return NULL;
}
if ((tmp = fdopen (fd, "r+b")) == NULL)
{
close (fd);
unlink (filename);
free (stream);
return NULL;
}
unlink (filename); // the file will be not delete until closed;
free (stream);
buffer_delete (&b);
return (tmp);
}
---------------end-------------------
This archive was generated by hypermail 2b30 : Thu Jan 03 2002 - 12:08:14 PST