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/* ISC license. */
#include <skalibs/sysdeps.h>
#ifdef SKALIBS_HASLINKAT
#include <skalibs/nonposix.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <skalibs/sgetopt.h>
#include <skalibs/bytestr.h>
#include <skalibs/strerr2.h>
#include <skalibs/stralloc.h>
#include <skalibs/djbunix.h>
#include <skalibs/random.h>
#include <skalibs/skamisc.h>
#define USAGE "s6-ln [ -s ] [ -f ] [ -L ] [ -P ] src... dest"
typedef int linkfunc_t (char const *, char const *) ;
typedef linkfunc_t *linkfunc_t_ref ;
typedef void ln_t (char const *, char const *, linkfunc_t_ref) ;
typedef ln_t *ln_t_ref ;
#ifdef SKALIBS_HASLINKAT
static int linknoderef (char const *old, char const *new)
{
return linkat(AT_FDCWD, old, AT_FDCWD, new, 0) ;
}
static int linkderef (char const *old, char const *new)
{
return linkat(AT_FDCWD, old, AT_FDCWD, new, AT_SYMLINK_FOLLOW) ;
}
#else /* can't implement SUSv4, default to link */
# define linknoderef link
# define linkderef link
#endif
static void force (char const *old, char const *new, linkfunc_t_ref doit)
{
if ((*doit)(old, new) == -1)
{
size_t base = satmp.len ;
if (errno != EEXIST)
strerr_diefu5sys(111, "make a link", " from ", new, " to ", old) ;
if (!stralloc_catb(&satmp, new, str_len(new))
|| !random_sauniquename(&satmp, 8)
|| !stralloc_0(&satmp))
strerr_diefu2sys(111, "make a unique name for ", old) ;
if ((*doit)(old, satmp.s + base) == -1)
strerr_diefu3sys(111, "make a link", " to ", old) ;
if (rename(satmp.s + base, new) == -1)
{
unlink(satmp.s + base) ;
strerr_diefu2sys(111, "atomically replace ", new) ;
}
satmp.len = base ;
}
}
static void noforce (char const *old, char const *new, linkfunc_t_ref doit)
{
if ((*doit)(old, new) == -1)
strerr_diefu5sys(111, "make a link", " from ", new, " to ", old) ;
}
int main (int argc, char const *const *argv)
{
linkfunc_t_ref mylink = &link ; /* default to system behaviour */
ln_t_ref f = &noforce ;
PROG = "s6-ln" ;
{
subgetopt_t l = SUBGETOPT_ZERO ;
for (;;)
{
register int opt = subgetopt_r(argc, argv, "sfLP", &l) ;
if (opt == -1) break ;
switch (opt)
{
case 's': mylink = &symlink ; break ;
case 'f': f = &force ; break ;
case 'L': if (mylink != &symlink) mylink = &linkderef ; break ;
case 'P': if (mylink != &symlink) mylink = &linknoderef ; break ;
default : strerr_dieusage(100, USAGE) ;
}
}
argc -= l.ind ; argv += l.ind ;
}
if (argc < 2) strerr_dieusage(100, USAGE) ;
if (!random_init())
strerr_diefu1sys(111, "init random generator") ;
if (argc > 2)
{
stralloc sa = STRALLOC_ZERO ;
unsigned int i = 0 ;
size_t base ;
if (!stralloc_cats(&sa, argv[argc-1]) || !stralloc_catb(&sa, "/", 1))
strerr_diefu1sys(111, "stralloc_cats") ;
base = sa.len ;
for (; i < (unsigned int)(argc-1) ; i++)
{
sa.len = base ;
if (!sabasename(&sa, argv[i], str_len(argv[i])))
strerr_diefu1sys(111, "sabasename") ;
if (!stralloc_0(&sa)) strerr_diefu1sys(111, "stralloc_0") ;
(*f)(argv[i], sa.s, mylink) ;
}
return 0 ;
}
{
struct stat st ;
if (stat(argv[1], &st) < 0)
{
if (errno != ENOENT) strerr_diefu2sys(111, "stat ", argv[1]) ;
(*f)(argv[0], argv[1], mylink) ;
return 0 ;
}
if (!S_ISDIR(st.st_mode))
{
(*f)(argv[0], argv[1], mylink) ;
return 0 ;
}
}
{
stralloc sa = STRALLOC_ZERO ;
if (!stralloc_cats(&sa, argv[1])
|| !stralloc_catb(&sa, "/", 1)
|| !sabasename(&sa, argv[0], str_len(argv[0]))
|| !stralloc_0(&sa))
strerr_diefu1sys(111, "stralloc_catb") ;
(*f)(argv[0], sa.s, mylink) ;
}
return 0 ;
}
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