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/* ISC license. */
#include <string.h>
#include <pwd.h>
#include <grp.h>
#include <errno.h>
#include <limits.h>
#include <skalibs/types.h>
#include <skalibs/sgetopt.h>
#include <skalibs/strerr2.h>
#include <skalibs/djbunix.h>
#include <skalibs/exec.h>
#define USAGE "s6-envuidgid [ -i | -D defaultuid:defaultgid:defaultgidlist ] [ -u | -g | -B ] [ -n ] account prog..."
#define dieusage() strerr_dieusage(100, USAGE)
static inline size_t scan_defaults (char const *s, uid_t *uid, gid_t *gid, size_t *n, gid_t *tab)
{
size_t pos = uid_scan(s, uid) ;
if (!pos)
{
if (*s != ':') return 0 ;
*uid = 0 ;
}
s += pos ;
if (!*s) goto zgid ;
if (*s++ != ':') return 0 ;
if (!*s) goto zgid ;
pos = gid_scan(s, gid) ;
if (!pos)
{
if (*s != ':') return 0 ;
*gid = 0 ;
}
s += pos ;
if (!*s) goto zn ;
if (*s++ != ':') return 0 ;
if (!*s) goto zn ;
return gid_scanlist(tab, NGROUPS_MAX, s, n) ;
zgid:
*gid = 0 ;
zn:
*n = 0 ;
return 1 ;
}
static int prot_readgroups (char const *name, gid_t *tab, unsigned int max)
{
unsigned int n = 0 ;
for (;;)
{
struct group *gr ;
char **member ;
errno = 0 ;
if (n >= max) break ;
gr = getgrent() ;
if (!gr) break ;
for (member = gr->gr_mem ; *member ; member++)
if (!strcmp(name, *member)) break ;
if (*member) tab[n++] = gr->gr_gid ;
}
endgrent() ;
return errno ? -1 : n ;
}
int main (int argc, char *const *argv)
{
char const *user = 0 ;
char const *group = 0 ;
unsigned int what = 7 ;
int numfallback = 0 ;
int insist = 1 ;
uid_t uid ;
gid_t gid ;
size_t n ;
gid_t tab[NGROUPS_MAX] ;
PROG = "s6-envuidgid" ;
{
subgetopt l = SUBGETOPT_ZERO ;
for (;;)
{
int opt = subgetopt_r(argc, (char const *const *)argv, "ugBniD:", &l) ;
if (opt == -1) break ;
switch (opt)
{
case 'u' : what = 1 ; break ;
case 'g' : what = 2 ; break ;
case 'B' : what = 3 ; break ;
case 'n' : what &= 3 ; numfallback = 1 ; break ;
case 'i' : insist = 1 ; break ;
case 'D' :
if (!scan_defaults(l.arg, &uid, &gid, &n, tab)) dieusage() ;
insist = 0 ;
break ;
default : dieusage() ;
}
}
argc -= l.ind ; argv += l.ind ;
}
if (argc < 2) dieusage() ;
switch (what)
{
case 7 : /* account */
case 1 : /* user */
user = argv[0] ;
break ;
case 2 : /* group */
group = argv[0] ;
break ;
case 3 : /* both */
{
char *colon = strchr(argv[0], ':') ;
user = argv[0] ;
if (colon)
{
*colon = 0 ;
group = colon + 1 ;
if (colon == argv[0]) user = 0 ;
if (!group[0]) group = 0 ;
}
break ;
}
default : strerr_dief1x(101, "inconsistent option management - please submit a bug-report") ;
}
if (group)
{
struct group *gr = getgrnam(group) ;
if (gr) gid = gr->gr_gid ;
else if (numfallback && gid_scan(group, &gid)) ;
else if (insist) strerr_dief2x(1, "unknown group: ", group) ;
}
if (user)
{
struct passwd *pw = getpwnam(user) ;
if (pw)
{
uid = pw->pw_uid ;
if (what == 7)
{
int r = prot_readgroups(argv[0], tab, NGROUPS_MAX) ;
if (r < 0)
strerr_diefu2sys(111, "get supplementary groups for ", argv[0]) ;
n = r ;
gid = pw->pw_gid ;
}
}
else if (numfallback && uid_scan(user, &uid)) ;
else if (insist) strerr_dief2x(1, "unknown user: ", user) ;
}
{
size_t pos = 0 ;
char fmt[19 + UID_FMT + (NGROUPS_MAX+1) * GID_FMT] ;
if (what & 1)
{
memcpy(fmt + pos, "UID=", 4) ; pos += 4 ;
pos += uid_fmt(fmt + pos, uid) ;
fmt[pos++] = 0 ;
}
if (what & 2)
{
memcpy(fmt + pos, "GID=", 4) ; pos += 4 ;
pos += gid_fmt(fmt + pos, gid) ;
fmt[pos++] = 0 ;
}
if (what & 4)
{
memcpy(fmt + pos, "GIDLIST=", 8) ; pos += 8 ;
pos += gid_fmtlist(fmt + pos, tab, n) ;
fmt[pos++] = 0 ;
}
xmexec_m((char const *const *)argv + 1, fmt, pos) ;
}
}
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