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gnupg/g10/mkdtemp.c

73 lines
1.5 KiB
C

/* 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"
char *mkdtemp(char *template)
{
int attempts,index,count=0;
byte *ch;
index=strlen(template);
ch=&template[index-1];
/* Walk backwards to count all the Xes */
while(*ch=='X' && count<index)
{
count++;
ch--;
}
ch++;
if(count==0)
{
errno=EINVAL;
return NULL;
}
/* Try 4 times to make the temp directory */
for(attempts=0;attempts<4;attempts++)
{
int index=0,remaining=count;
char *marker=ch;
byte *randombits;
/* 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[index++]);
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[index]&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;
}