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/* ISC license. */
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <skalibs/random.h>
#include <skalibs/unix-transactional.h>
int atomic_symlink (char const *target, char const *name, char const *suffix)
{
{
int e = errno ;
if (symlink(target, name) == 0) return 1 ;
if (errno != EEXIST) return 0 ;
errno = e ;
}
{
size_t namelen = strlen(name) ;
size_t suffixlen = suffix ? strlen(suffix) : 25 ;
char tmp[namelen + suffixlen + 2] ;
memcpy(tmp, name, namelen) ;
tmp[namelen] = ':' ;
if (suffix)
memcpy(tmp + namelen + 1, suffix, suffixlen + 1) ;
else
{
memcpy(tmp + namelen + 1, "atomic_symlink:", 15) ;
random_name(tmp + namelen + 16, 8) ;
tmp[namelen + 24] = 0 ;
}
{
int e = errno ;
if (unlink(tmp) < 0 && errno != ENOENT) return 0 ;
errno = e ;
}
if (symlink(target, tmp) < 0) return 0 ;
if (rename(tmp, name) < 0)
{
int e = errno ;
unlink(tmp) ;
errno = e ;
return 0 ;
}
}
return 1 ;
}
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