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/* ISC license. */
/* MT-unsafe */
#include <skalibs/sysdeps.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/wait.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#ifdef SKALIBS_HASPOSIXSPAWN
#include <stdlib.h>
#include <spawn.h>
#include <skalibs/config.h>
#else
#include <skalibs/sig.h>
#include <skalibs/strerr2.h>
#include <skalibs/exec.h>
#endif
#include <skalibs/types.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/env.h>
#include <skalibs/djbunix.h>
/*
If n = 0 : child's stdin and stdout are the same as the parent's
If n >= 1 : pipes between parent and child.
Parent reads on even ones, writes on odd ones.
*/
pid_t child_spawn (char const *prog, char const *const *argv, char const *const *envp, int *fds, unsigned int n)
{
pid_t pid ;
#ifdef SKALIBS_HASPOSIXSPAWN
posix_spawn_file_actions_t actions ;
posix_spawnattr_t attr ;
int e ;
#else
int syncpipe[2] ;
#endif
int p[n ? n : 1][2] ;
size_t m = sizeof(SKALIBS_CHILD_SPAWN_FDS_ENVVAR) ;
unsigned int i = 0 ;
char modifs[m + 1 + n * UINT_FMT] ;
memcpy(modifs, SKALIBS_CHILD_SPAWN_FDS_ENVVAR "=", sizeof(SKALIBS_CHILD_SPAWN_FDS_ENVVAR)) ;
for (; i < n ; i++)
{
if (pipe(p[i]) < 0) goto errpi ;
if ((ndelay_on(p[i][i & 1]) < 0) || (coe(p[i][i & 1]) < 0))
{
i++ ; goto errpi ;
}
}
for (i = 2 ; i < n ; i++)
{
m += uint_fmt(modifs + m, p[i][!(i & 1)]) ;
if (i+1 < n) modifs[m++] = ',' ;
}
modifs[m++] = 0 ;
#ifdef SKALIBS_HASPOSIXSPAWN
e = posix_spawnattr_init(&attr) ;
if (e) goto erre ;
{
sigset_t set ;
sigemptyset(&set) ;
e = posix_spawnattr_setsigmask(&attr, &set) ;
if (e) goto errattr ;
e = posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSIGMASK) ;
if (e) goto errattr ;
}
e = posix_spawn_file_actions_init(&actions) ;
if (e) goto errattr ;
if (n >= 2 && p[1][0])
{
e = posix_spawn_file_actions_adddup2(&actions, p[1][0], 0) ;
if (e) goto erractions ;
e = posix_spawn_file_actions_addclose(&actions, p[1][0]) ;
if (e) goto erractions ;
}
if (n && p[0][1] != 1)
{
e = posix_spawn_file_actions_adddup2(&actions, p[0][1], 1) ;
if (e) goto erractions ;
e = posix_spawn_file_actions_addclose(&actions, p[0][1]) ;
if (e) goto erractions ;
}
{
int nopath = !getenv("PATH") ;
size_t envlen = env_len(envp) ;
char const *newenv[envlen + 2] ;
if (!env_mergen(newenv, envlen+2, envp, envlen, modifs, m, 1)) goto erractions ;
if (nopath && (setenv("PATH", SKALIBS_DEFAULTPATH, 0) < 0))
{
e = errno ; goto erractions ;
}
e = posix_spawnp(&pid, prog, &actions, &attr, (char *const *)argv, (char *const *)newenv) ;
if (nopath) unsetenv("PATH") ;
if (e) goto erractions ;
}
posix_spawn_file_actions_destroy(&actions) ;
posix_spawnattr_destroy(&attr) ;
#else
if (pipecoe(syncpipe) < 0) goto errp ;
pid = fork() ;
if (pid < 0) goto errsp ;
else if (!pid)
{
size_t len = strlen(PROG) ;
char name[len + 9] ;
memcpy(name, PROG, len) ;
memcpy(name + len, " (child)", 9) ;
PROG = name ;
if (n >= 2)
{
if (fd_move2(0, p[1][0], 1, p[0][1]) < 0) goto syncdie ;
}
else if (n)
{
if (fd_move(1, p[0][1]) < 0) goto syncdie ;
}
sig_blocknone() ;
mexec_aen(prog, argv, envp, modifs, m, 1) ;
syncdie:
{
unsigned char c = errno ;
fd_write(syncpipe[1], (char *)&c, 1) ;
}
_exit(127) ;
}
fd_close(syncpipe[1]) ;
{
unsigned char c ;
syncpipe[1] = fd_read(syncpipe[0], (char *)&c, 1) ;
if (syncpipe[1])
{
int e = c ;
if (syncpipe[1] < 0) e = errno ;
if (wait_pid(pid, &syncpipe[1]) < 0) e = errno ;
errno = e ;
goto errsp0 ;
}
}
fd_close(syncpipe[0]) ;
#endif
for (i = n ; i ; i--)
{
fd_close(p[i-1][i & 1]) ;
fds[i-1] = p[i-1][!(i & 1)] ;
}
return pid ;
#ifdef SKALIBS_HASPOSIXSPAWN
erractions:
posix_spawn_file_actions_destroy(&actions) ;
errattr:
posix_spawnattr_destroy(&attr) ;
erre:
errno = e ;
#endif
#ifndef SKALIBS_HASPOSIXSPAWN
errsp:
fd_close(syncpipe[1]) ;
errsp0:
fd_close(syncpipe[0]) ;
errp:
#endif
i = n ;
errpi:
while (i--)
{
fd_close(p[i][1]) ;
fd_close(p[i][0]) ;
}
return 0 ;
}
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