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/* ISC license. */
#include <unistd.h>
#include <errno.h>
#include <stdio.h> /* for rename() */
#include <skalibs/bytestr.h>
#include <skalibs/stralloc.h>
#include <skalibs/djbunix.h>
#include <skalibs/random.h>
#include <skalibs/unix-transactional.h>
static char const *mybasename (char const *s, unsigned int len)
{
register unsigned int i = len ;
while (i--) if (s[i] == '/') return s + i + 1 ;
return s ;
}
int dd_commit (dirdescriptor_t *dd)
{
dirdescriptor_t zero = DIRDESCRIPTOR_ZERO ;
unsigned int len = str_len(dd->lnkfn) ;
unsigned int oldbase = dd->new.len ;
unsigned int newlnkbase ;
char const *lnkbn = mybasename(dd->lnkfn, len) ;
if (!sadirname(&dd->new, dd->lnkfn, len)) return 0 ;
if (!stralloc_catb(&dd->new, "/", 1)) goto fail ;
if (sareadlink(&dd->new, dd->lnkfn) < 0)
{
unsigned int lnkbnbase = dd->new.len ;
if (errno != EINVAL) goto fail ;
if (!stralloc_cats(&dd->new, lnkbn)) goto fail ;
if (random_sauniquename(&dd->new, 8) < 0) goto fail ;
if (!stralloc_0(&dd->new)) goto fail ;
if (rename(dd->lnkfn, dd->new.s + oldbase) < 0) goto fail ;
/* /!\ race condition right here: there's no lnkfn in the fs */
if (symlink(dd->new.s + lnkbnbase, dd->lnkfn) < 0) /* now that's VERY BAD if it fails */
{
register int e = errno ;
rename(dd->new.s + oldbase, dd->lnkfn) ; /* attempt to revert to initial situation */
errno = e ;
goto fail ; /* and hope for the best */
}
}
if (!stralloc_0(&dd->new)) goto fail ;
newlnkbase = dd->new.len ;
if (!stralloc_catb(&dd->new, dd->lnkfn, len)) goto fail ;
if (random_sauniquename(&dd->new, 8) < 0) goto fail ;
if (!stralloc_0(&dd->new)) goto fail ;
if (symlink(dd->new.s, dd->new.s + newlnkbase) < 0) goto fail ;
if (rename(dd->new.s + newlnkbase, dd->lnkfn) < 0)
{
register int e = errno ;
unlink(dd->new.s + newlnkbase) ;
errno = e ;
goto fail ;
}
fd_close(dd->fd) ;
dd->new.len = newlnkbase ;
rm_rf_in_tmp(&dd->new, oldbase) ;
stralloc_free(&dd->new) ;
*dd = zero ;
return 1 ;
fail:
dd->new.len = oldbase ;
return 0 ;
}
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