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gnupg/util/mkdtemp.c

100 lines
2.4 KiB
C

/* mkdtemp.c - libc replacement function
* Copyright (C) 2001 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*/
/* This is a replacement function for mkdtemp in case the platform
we're building on (like mine!) doesn't have it. */
#include <config.h>
#include <string.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include "types.h"
#include "cipher.h"
#ifdef MKDIR_TAKES_ONE_ARG
# undef mkdir
# define mkdir(a,b) mkdir(a)
#endif
char *mkdtemp(char *template)
{
unsigned int attempts,idx,count=0;
byte *ch;
idx=strlen(template);
/* Walk backwards to count all the Xes */
while(idx>0 && template[idx-1]=='X')
{
count++;
idx--;
}
if(count==0)
{
errno=EINVAL;
return NULL;
}
ch=&template[idx];
/* Try 4 times to make the temp directory */
for(attempts=0;attempts<4;attempts++)
{
unsigned int remaining=count;
char *marker=ch;
byte *randombits;
idx=0;
/* Using really random bits is probably overkill here. The
worst thing that can happen with a directory name collision
is that the function will return an error. */
randombits=get_random_bits(4*remaining,0,0);
while(remaining>1)
{
sprintf(marker,"%02X",randombits[idx++]);
marker+=2;
remaining-=2;
}
/* Any leftover Xes? get_random_bits rounds up to full bytes,
so this is safe. */
if(remaining>0)
sprintf(marker,"%X",randombits[idx]&0xF);
m_free(randombits);
if(mkdir(template,0700)==0)
break;
}
if(attempts==4)
return NULL; /* keeps the errno from mkdir, whatever it is */
return template;
}