From 8733687efc5d3b8d2dd1114b0f5af35c019e9093 Mon Sep 17 00:00:00 2001
From: "jan.nijtmans" <nijtmans@users.sourceforge.net>
Date: Tue, 25 Jul 2023 10:35:22 +0000
Subject: Add (back) check for vfork()

---
 unix/configure      |  5 +++--
 unix/tcl.m4         |  4 ++--
 unix/tclConfig.h.in |  3 +++
 unix/tclUnixPipe.c  | 34 ++++++++++++----------------------
 unix/tclUnixPort.h  |  7 +++++++
 5 files changed, 27 insertions(+), 26 deletions(-)

diff --git a/unix/configure b/unix/configure
index bbe8df9..553fc73 100755
--- a/unix/configure
+++ b/unix/configure
@@ -8978,11 +8978,12 @@ echo "${ECHO_T}$ac_cv_nolto" >&6
 	CFLAGS_NOLTO=""
     fi
 
-    # Check for posix_spawnp() and friends unconditionally
+    # Check for vfork, posix_spawnp() and friends unconditionally
 
 
 
-for ac_func in posix_spawnp posix_spawn_file_actions_adddup2 posix_spawnattr_setflags
+
+for ac_func in vfork posix_spawnp posix_spawn_file_actions_adddup2 posix_spawnattr_setflags
 do
 as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
 echo "$as_me:$LINENO: checking for $ac_func" >&5
diff --git a/unix/tcl.m4 b/unix/tcl.m4
index dfa812b..06d31b8 100644
--- a/unix/tcl.m4
+++ b/unix/tcl.m4
@@ -2067,8 +2067,8 @@ dnl # preprocessing tests use only CPPFLAGS.
 	CFLAGS_NOLTO=""
     fi
 
-    # Check for posix_spawnp() and friends unconditionally
-    AC_CHECK_FUNCS(posix_spawnp posix_spawn_file_actions_adddup2 posix_spawnattr_setflags)
+    # Check for vfork, posix_spawnp() and friends unconditionally
+    AC_CHECK_FUNCS(vfork posix_spawnp posix_spawn_file_actions_adddup2 posix_spawnattr_setflags)
 
     # FIXME: This subst was left in only because the TCL_DL_LIBS
     # entry in tclConfig.sh uses it. It is not clear why someone
diff --git a/unix/tclConfig.h.in b/unix/tclConfig.h.in
index 87e3eb9..5a64236 100644
--- a/unix/tclConfig.h.in
+++ b/unix/tclConfig.h.in
@@ -279,6 +279,9 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #undef HAVE_UNISTD_H
 
+/* Define to 1 if you have the `vfork' function. */
+#undef HAVE_VFORK
+
 /* Define to 1 if you have the `waitpid' function. */
 #undef HAVE_WAITPID
 
diff --git a/unix/tclUnixPipe.c b/unix/tclUnixPipe.c
index e040807..b85ffe0 100644
--- a/unix/tclUnixPipe.c
+++ b/unix/tclUnixPipe.c
@@ -14,30 +14,20 @@
 #include "tclInt.h"
 
 #ifdef HAVE_POSIX_SPAWNP
-#ifdef HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2
-#ifdef HAVE_POSIX_SPAWNATTR_SETFLAGS
-#include <unistd.h>
-#include <spawn.h>
-#define USE_POSIX_SPAWN 1
-#endif
-#endif
+#   if defined(HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2) \
+	    && defined(HAVE_POSIX_SPAWNATTR_SETFLAGS)
+#	include <unistd.h>
+#	include <spawn.h>
+#   else
+#	undef HAVE_POSIX_SPAWNP
+#   endif
 #endif
 
-#ifdef USE_VFORK
+#ifdef HAVE_VFORK
 #define fork vfork
 #endif
 
 /*
- * For now, test exec-17.1 fails (I/O setup after closing stdout) with
- * posix_spawnp(), but the classic implementation (based on fork()+execvp())
- * works well under macOS.
- */
-
-#ifdef __APPLE__
-#undef USE_POSIX_SPAWN
-#endif
-
-/*
  * The following macros convert between TclFile's and fd's. The conversion
  * simple involves shifting fd's up by one to ensure that no valid fd is ever
  * the same as NULL.
@@ -431,7 +421,7 @@ TclpCreateProcess(
     Tcl_DString *dsArray;
     char **newArgv;
     int pid, i;
-#if defined(USE_POSIX_SPAWN)
+#if defined(HAVE_POSIX_SPAWNP)
     int childErrno;
     static int use_spawn = -1;
 #endif
@@ -463,7 +453,7 @@ TclpCreateProcess(
 	newArgv[i] = Tcl_UtfToExternalDString(NULL, argv[i], -1, &dsArray[i]);
     }
 
-#if defined(USE_VFORK) || defined(USE_POSIX_SPAWN)
+#if defined(HAVE_VFORK) || defined(HAVE_POSIX_SPAWNP)
     /*
      * After vfork(), do not call code in the child that changes global state,
      * because it is using the parent's memory space at that point and writes
@@ -483,7 +473,7 @@ TclpCreateProcess(
     }
 #endif
 
-#ifdef USE_POSIX_SPAWN
+#ifdef HAVE_POSIX_SPAWNP
 #ifdef _CS_GNU_LIBC_VERSION
     if (use_spawn < 0) {
 	char conf[32], *p;
@@ -599,7 +589,7 @@ TclpCreateProcess(
     TclStackFree(interp, dsArray);
 
     if (pid == -1) {
-#ifdef USE_POSIX_SPAWN
+#ifdef HAVE_POSIX_SPAWNP
 	errno = childErrno;
 #endif
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
diff --git a/unix/tclUnixPort.h b/unix/tclUnixPort.h
index c2115df..486fa23 100644
--- a/unix/tclUnixPort.h
+++ b/unix/tclUnixPort.h
@@ -636,6 +636,13 @@ extern char **		environ;
 	    defined(HAVE_WEAK_IMPORT) && MAC_OS_X_VERSION_MIN_REQUIRED < 1050
 #	warning "Weak import of 64-bit CoreFoundation is not supported, will not run on Mac OS X < 10.5."
 #   endif
+    /*
+     * For now, test exec-17.1 fails (I/O setup after closing stdout) with
+     * posix_spawnp(), but the classic implementation (based on fork()+execvp())
+     * works well under macOS.
+     */
+#   undef HAVE_POSIX_SPAWNP
+#   undef HAVE_VFORK
 #endif /* __APPLE__ */
 
 /*
-- 
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