From d16e2baf35963f6ed2ccd23a3aa3df69cd65dd84 Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Wed, 19 Oct 2016 01:01:38 +0000
Subject:  Add child_spawn2

---
 src/include/skalibs/djbunix.h |   9 +++
 src/libstddjb/child_spawn2.c  | 151 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 160 insertions(+)
 create mode 100644 src/libstddjb/child_spawn2.c

(limited to 'src')

diff --git a/src/include/skalibs/djbunix.h b/src/include/skalibs/djbunix.h
index 0a1a2c4..354ca57 100644
--- a/src/include/skalibs/djbunix.h
+++ b/src/include/skalibs/djbunix.h
@@ -157,6 +157,15 @@ extern pid_t child_spawn1_pipe (char const *, char const *const *, char const *c
 extern pid_t child_spawn1_socket (char const *, char const *const *, char const *const *, int *) ;
 
 
+ /*
+    Spawn function with 2 communicating pipes. The int * points to 2 fds.
+    Input: fds[0] and fds[1] are the fds to move the pipes to in the child.
+    Output: fds[0] and fds[1] contain the pipes to the child.
+ */
+
+extern pid_t child_spawn2 (char const *, char const *const *, char const *const *, int *) ;
+
+
  /*
     Unified function to fork a child with communication canals.
     * uses posix_spawn() if available, else uses fork+exec
diff --git a/src/libstddjb/child_spawn2.c b/src/libstddjb/child_spawn2.c
new file mode 100644
index 0000000..701be26
--- /dev/null
+++ b/src/libstddjb/child_spawn2.c
@@ -0,0 +1,151 @@
+/* ISC license. */
+
+/* MT-unsafe */
+
+#include <skalibs/sysdeps.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <errno.h>
+#include <signal.h>
+#include <skalibs/djbunix.h>
+
+#ifdef SKALIBS_HASPOSIXSPAWN
+
+#include <stdlib.h>
+#include <spawn.h>
+#include <skalibs/config.h>
+#include <skalibs/env.h>
+
+#else
+
+#include <skalibs/bytestr.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/sig.h>
+#include <skalibs/strerr2.h>
+
+#endif
+
+pid_t child_spawn2 (char const *prog, char const *const *argv, char const *const *envp, int *fds)
+{
+#ifdef SKALIBS_HASPOSIXSPAWN
+  posix_spawn_file_actions_t actions ;
+  posix_spawnattr_t attr ;
+#else
+  int syncpipe[2] ;
+#endif
+  int p[2][2] ;
+  pid_t pid ;
+  int e ;
+  if (pipe(p[0]) < 0) return 0 ;
+  if (ndelay_on(p[0][0]) < 0 || coe(p[0][0]) < 0 || pipe(p[1]) < 0) { e = errno ; goto errp ; }
+  if (ndelay_on(p[1][1]) < 0 || coe(p[1][1]) < 0) { e = errno ; goto errsp ; }
+
+#ifdef SKALIBS_HASPOSIXSPAWN
+
+  e = posix_spawnattr_init(&attr) ;
+  if (e) goto errsp ;
+  {
+    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 ;
+  e = posix_spawn_file_actions_adddup2(&actions, p[1][0], fds[0]) ;
+  if (e) goto erractions ;
+  e = posix_spawn_file_actions_addclose(&actions, p[1][0]) ;
+  if (e) goto erractions ;
+  e = posix_spawn_file_actions_adddup2(&actions, p[0][1], fds[1]) ;
+  if (e) goto erractions ;
+  e = posix_spawn_file_actions_addclose(&actions, p[0][1]) ;
+  if (e) goto erractions ;
+  {
+    int haspath = !!env_get("PATH") ;
+    if (!haspath && (setenv("PATH", SKALIBS_DEFAULTPATH, 0) < 0))
+    {
+      e = errno ; goto erractions ;
+    }
+    e = posix_spawnp(&pid, prog, &actions, &attr, (char *const *)argv, (char *const *)envp) ;
+    if (!haspath) unsetenv("PATH") ;
+    if (e) goto erractions ;
+  }
+
+  posix_spawn_file_actions_destroy(&actions) ;
+  posix_spawnattr_destroy(&attr) ;
+
+#else
+  if (pipe(syncpipe) < 0) { e = errno ; goto errp1 ; }
+  if (coe(syncpipe[1]) < 0) { e = errno ; goto errsp ; }
+
+  pid = fork() ;
+  if (pid < 0) { e = errno ; goto errsp ; }
+  else if (!pid)
+  {
+    unsigned int len = str_len(PROG) ;
+    char name[len + 9] ;
+    byte_copy(name, len, PROG) ;
+    byte_copy(name + len, 9, " (child)") ;
+    PROG = name ;
+    fd_close(syncpipe[0]) ;
+    if (fd_move2(fds[0], p[1][0], fds[1], p[0][1]) < 0) goto syncdie ;
+    sig_blocknone() ;
+    pathexec_run(prog, argv, envp) ;
+
+  syncdie:
+    {
+      unsigned char c = errno ;
+      fd_write(syncpipe[1], (char const *)&c, 1) ;
+    }
+    _exit(127) ;
+  }
+
+  fd_close(syncpipe[1]) ;
+  {
+    char c ;
+    syncpipe[1] = fd_read(syncpipe[0], &c, 1) ;
+    if (syncpipe[1])
+    {
+      if (syncpipe[1] < 0) e = errno ;
+      else
+      {
+        kill(pid, SIGKILL) ;
+        e = c ;
+      }
+      wait_pid(pid, &syncpipe[1]) ;
+      goto errsp0 ;
+    }
+  }
+  fd_close(syncpipe[0]) ;
+#endif
+
+  fd_close(p[0][1]) ; fds[0] = p[0][0] ;
+  fd_close(p[1][0]) ; fds[1] = p[1][1] ;
+  return pid ;
+
+#ifdef SKALIBS_HASPOSIXSPAWN
+ erractions:
+  posix_spawn_file_actions_destroy(&actions) ;
+ errattr:
+  posix_spawnattr_destroy(&attr) ;
+#endif
+ errsp:
+#ifndef SKALIBS_HASPOSIXSPAWN
+  fd_close(syncpipe[1]) ;
+ errsp0:
+  fd_close(syncpipe[0]) ;
+ errp1:
+#endif
+  fd_close(p[1][1]) ;
+  fd_close(p[1][0]) ;
+ errp:
+  fd_close(p[0][1]) ;
+  fd_close(p[0][0]) ;
+  errno = e ;
+  return 0 ;
+}
-- 
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