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100 lines
2.4 KiB
C
100 lines
2.4 KiB
C
/* mkdtemp.c - libc replacement function
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* Copyright (C) 2001 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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/* This is a replacement function for mkdtemp in case the platform
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we're building on (like mine!) doesn't have it. */
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#include <config.h>
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#include <string.h>
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#include <errno.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <gcrypt.h>
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#ifdef MKDIR_TAKES_ONE_ARG
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# undef mkdir
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# define mkdir(a,b) mkdir(a)
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#endif
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char *mkdtemp(char *template)
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{
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int attempts,idx,count=0;
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unsigned char *ch;
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idx=strlen(template);
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/* Walk backwards to count all the Xes */
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while(idx>0 && template[idx-1]=='X')
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{
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count++;
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idx--;
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}
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if(count==0)
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{
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errno=EINVAL;
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return NULL;
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}
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ch=&template[idx];
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/* Try 4 times to make the temp directory */
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for(attempts=0;attempts<4;attempts++)
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{
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int remaining=count;
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char *marker=ch;
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unsigned char *randombits;
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idx=0;
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/* Using really random bits is probably overkill here. The
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worst thing that can happen with a directory name collision
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is that the function will return an error. */
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randombits = gcry_random_bytes (4*remaining, GCRY_WEAK_RANDOM);
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while(remaining>1)
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{
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sprintf(marker,"%02X",randombits[idx++]);
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marker+=2;
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remaining-=2;
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}
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/* Any leftover Xes? get_random_bits rounds up to full bytes,
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so this is safe. */
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if(remaining>0)
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sprintf(marker,"%X",randombits[idx]&0xF);
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gcry_free (randombits);
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if(mkdir(template,0700)==0)
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break;
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}
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if(attempts==4)
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return NULL; /* keeps the errno from mkdir, whatever it is */
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return template;
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}
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