Add workaround for bad QoI posix_spawn()

Signed-off-by: Laurent Bercot <ska@appnovation.com>

1 files changed, 99 insertions, 71 deletions

diff --git a/src/libstddjb/child_spawn.c b/src/libstddjb/child_spawn.c
index aa70deb..e5f5115 100644
--- a/src/libstddjb/child_spawn.c
+++ b/src/libstddjb/child_spawn.c
@@ -3,58 +3,48 @@
 /* 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>
+#include <unistd.h>
+
+#include <skalibs/types.h>
+#include <skalibs/djbunix.h>
 
 #ifdef SKALIBS_HASPOSIXSPAWN
 
+#include <signal.h>
 #include <stdlib.h>
 #include <spawn.h>
-#include <skalibs/config.h>
-
-#else
-
-#include <skalibs/sig.h>
-#include <skalibs/strerr.h>
-#include <skalibs/exec.h>
-
-#endif
 
-#include <skalibs/types.h>
-#include <skalibs/allreadwrite.h>
+#include <skalibs/config.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.
- */
+#ifdef SKALIBS_HASPOSIXSPAWNEARLYRETURN
+# include "child_spawn-internal.h"
+#endif
 
 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 ;
+  sigset_t set ;
   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] ;
+#ifdef SKALIBS_HASPOSIXSPAWNEARLYRETURN
+  int syncpipe[2] ;
+  if (pipecoe(syncpipe) == -1) return 0 ;
+#endif
+
   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))
+    if (pipe(p[i]) == -1) goto errpi ;
+    if ((ndelay_on(p[i][i & 1]) == -1) || (coe(p[i][i & 1]) == -1))
     {
       i++ ; goto errpi ;
     }
@@ -66,18 +56,13 @@ pid_t child_spawn (char const *prog, char const *const *argv, char const *const
   }
   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 ;
-  }
+  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])
@@ -110,53 +95,104 @@ pid_t child_spawn (char const *prog, char const *const *argv, char const *const
 
   posix_spawn_file_actions_destroy(&actions) ;
   posix_spawnattr_destroy(&attr) ;
+  for (i = 0 ; i < n ; i++) fd_close(p[i][!(i & 1)]) ;
+
+#ifdef SKALIBS_HASPOSIXSPAWNEARLYRETURN
+  pid = child_spawn_workaround(pid, syncpipe) ;
+  if (!pid)
+  {
+    for (i = 0 ; i < n ; i++) fd_close(p[i][i & 1]) ;
+    return 0 ;
+  }
+#endif
+  for (i = 0 ; i < n ; i++) fds[i] = p[i][i & 1] ;
+  return pid ;
+
+ erractions:
+  posix_spawn_file_actions_destroy(&actions) ;
+ errattr:
+  posix_spawnattr_destroy(&attr) ;
+ erre:
+  errno = e ;
+  i = n ;
+ errpi:
+  while (i--)
+  {
+    fd_close(p[i][1]) ;
+    fd_close(p[i][0]) ;
+  }
+#ifdef SKALIBS_HASPOSIXSPAWNEARLYRETURN
+  fd_close(syncpipe[1]) ;
+  fd_close(syncpipe[0]) ;
+#endif
+  return 0 ;
+}
 
 #else
+
+#include <skalibs/allreadwrite.h>
+#include <skalibs/sig.h>
+#include <skalibs/exec.h>
+
+pid_t child_spawn (char const *prog, char const *const *argv, char const *const *envp, int *fds, unsigned int n)
+{
+  pid_t pid ;
+  int syncpipe[2] ;
+  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] ;
+  char c ;
+
+  memcpy(modifs, SKALIBS_CHILD_SPAWN_FDS_ENVVAR "=", sizeof(SKALIBS_CHILD_SPAWN_FDS_ENVVAR)) ;
+  for (; i < n ; i++)
+  {
+    if (pipe(p[i]) == -1) goto errpi ;
+    if ((ndelay_on(p[i][i & 1]) == -1) || (coe(p[i][i & 1]) == -1))
+    {
+      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 ;
+
   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 ;
+      if (fd_move2(0, p[1][0], 1, p[0][1]) == -1) goto syncdie ;
     }
     else if (n)
     {
-      if (fd_move(1, p[0][1]) < 0) goto syncdie ;
+      if (fd_move(1, p[0][1]) == -1) goto syncdie ;
     }
     sig_blocknone() ;
     mexec_aen(prog, argv, envp, modifs, m, 1) ;
-
   syncdie:
-    {
-      unsigned char c = errno ;
-      fd_write(syncpipe[1], (char *)&c, 1) ;
-    }
+    c = errno ;
+    fd_write(syncpipe[1], &c, 1) ;
     _exit(127) ;
   }
 
   fd_close(syncpipe[1]) ;
+  syncpipe[1] = fd_read(syncpipe[0], &c, 1) ;
+  if (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 ;
-    }
+    int e = (unsigned char)c ;
+    if (syncpipe[1] == -1) e = errno ;
+    if (wait_pid(pid, 0) == -1) e = errno ;
+    errno = e ;
+    goto errsp0 ;
   }
   fd_close(syncpipe[0]) ;
-#endif
 
   for (i = n ; i ; i--)
   {
@@ -165,21 +201,11 @@ pid_t child_spawn (char const *prog, char const *const *argv, char const *const
   }
   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--)
@@ -189,3 +215,5 @@ pid_t child_spawn (char const *prog, char const *const *argv, char const *const
   }
   return 0 ;
 }
+
+#endif