initial commit with rc for skalibs-2.0.0.0

1 files changed, 228 insertions, 0 deletions

diff --git a/src/libstddjb/child_spawn.c b/src/libstddjb/child_spawn.c
new file mode 100644
index 0000000..aa937fd
--- /dev/null
+++ b/src/libstddjb/child_spawn.c
@@ -0,0 +1,228 @@
+/* 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/allreadwrite.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/env.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/uint.h>
+#include <skalibs/webipc.h>
+
+#ifdef SKALIBS_HASPOSIXSPAWN
+
+#include <stdlib.h>
+#include <spawn.h>
+#include <skalibs/config.h>
+
+#else
+
+#include <skalibs/sig.h>
+#include <skalibs/strerr2.h>
+
+#endif
+
+#define NOFDVAR "SKALIBS_CHILD_SPAWN_FDS"
+
+
+ /*
+    If n = 0 : child's stdin and stdout are the same as the parent's
+    If n = 1 : Unix socket between parent and child.
+               Additional canals, if needed, may be fd-passed through it.
+    If n >= 2 : 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)
+{
+#ifdef SKALIBS_HASPOSIXSPAWN
+  posix_spawn_file_actions_t actions ;
+  posix_spawnattr_t attr ;
+#endif
+  int p[n ? n : 1][2] ;
+  int syncpipe[2] ;
+  pid_t pid ;
+  int e ;
+  unsigned int m = sizeof(NOFDVAR) ;
+  unsigned int i ;
+  char modifs[m + 1 + n * UINT_FMT] ;
+  byte_copy(modifs, sizeof(NOFDVAR), NOFDVAR "=") ;
+  if (n == 1)
+  {
+    if (ipc_pair_b(p[0]) < 0) return 0 ;
+  }
+  else if (n >= 2)
+  {
+    for (i = 0 ; i < n ; i++) if (pipe(p[i]) < 0) { e = errno ; goto errp ; }
+  }
+  if (pipe(syncpipe) < 0) { e = errno ; goto errp ; }
+  if (coe(syncpipe[1]) < 0) { e = errno ; goto errsp ; }
+  for (i = 0 ; i < n ; i++)
+    if ((ndelay_on(p[i][i & 1]) < 0) || (coe(p[i][i & 1]) < 0))
+    {
+      e = errno ; goto errsp ;
+    }
+  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 errsp ;
+  {
+    sigset_t set ;
+    sigemptyset(&set) ;
+    e = posix_spawnattr_setsigmask(&attr, &set) ;
+  }
+  if (e) goto errattr ;
+  e = posix_spawn_file_actions_init(&actions) ;
+  if (e) goto errattr ;
+  e = posix_spawn_file_actions_addclose(&actions, syncpipe[0]) ;
+  if (e) goto erractions ;
+  switch (n)
+  {
+    case 0 :
+       break ;
+    case 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 ;
+      e = posix_spawn_file_actions_adddup2(&actions, 1, 0) ;
+      if (e) goto erractions ;
+      break ;
+    default : 
+      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 ;
+      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 ;
+      break ;
+  }
+  {
+    int haspath = !!env_get("PATH") ;
+    unsigned int envlen = env_len(envp) ;
+    char const *newenv[envlen + 2] ;
+    if (!env_merge(newenv, envlen+2, envp, envlen, modifs, m)) goto errsp ;
+    if (!haspath && (setenv("PATH", SKALIBS_DEFAULTPATH, 0) < 0))
+    {
+      e = errno ; goto erractions ;
+    }
+    e = posix_spawnp(&pid, prog, &actions, &attr, (char *const *)argv, (char *const *)newenv) ;
+    if (!haspath) unsetenv("PATH") ;
+    if (e) goto erractions ;
+  }
+
+  posix_spawn_file_actions_destroy(&actions) ;
+  posix_spawnattr_destroy(&attr) ;
+
+#else
+
+  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]) ;
+    switch (n)
+    {
+      case 0 :
+      {
+        int fd = open2("/dev/null", O_RDONLY) ;
+        if (fd < 0) goto syncdie ;
+        if (fd_move(0, fd) < 0) goto syncdie ;
+        fd = open2("/dev/null", O_WRONLY) ;
+        if (fd < 0) goto syncdie ;
+        if (fd_move(1, fd) < 0) goto syncdie ;
+        break ;
+      }
+      case 1 :
+        if (fd_move(1, p[0][1]) < 0) goto syncdie ;
+        if (fd_copy(0, 1) < 0) goto syncdie ;
+        break ;
+      default :
+        if (fd_move2(0, p[1][0], 1, p[0][1]) < 0) goto syncdie ;
+        break ;
+    }
+    sig_blocknone() ;
+    pathexec_r_name(prog, argv, envp, env_len(envp), modifs, m) ;
+
+  syncdie:
+    {
+      char c = errno ;
+      fd_write(syncpipe[1], &c, 1) ;
+    }
+    _exit(127) ;
+  }
+
+#endif
+
+  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 ;
+    }
+  }
+  if (waitpid_nointr(pid, &e, WNOHANG))
+  {
+    e = WEXITSTATUS(e) == 127 ? EIO : 0 ;
+    goto errsp0 ;
+  }
+
+  fd_close(syncpipe[0]) ;
+  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) ;
+#endif
+ errsp:
+  fd_close(syncpipe[1]) ;
+ errsp0:
+  fd_close(syncpipe[0]) ;
+  i = n ;
+ errp:
+  while (i--)
+  {
+    fd_close(p[i][1]) ;
+    fd_close(p[i][0]) ;
+  }
+  errno = e ;
+  return 0 ;
+}