refactor common code of 'execute' and 'spawn-pipe'

[Bruno Haible]

This patch refactors common code of 'execute' and 'spawn-pipe', so that
packages that include both modules contain the same code only once.


2020-11-28  Bruno Haible  <bruno@clisp.org>

        windows-spawn: New module.
        * lib/windows-spawn.h: Renamed from lib/w32spawn.h. Remove
        implementations.
        * lib/windows-spawn.c: Renamed from lib/w32spawn.h.
        * modules/windows-spawn: New file.
        * lib/execute.c: Include "windows-spawn.h" instead of "w32spawn.h".
        * lib/spawn-pipe.c: Likewise.
        * modules/execute (Files): Remove lib/w32spawn.h.
        (Depends-on): Add windows-spawn. Remove cloexec, msvc-nothrow, strpbrk,
        xalloc.
        (Makefile.am): Remove w32spawn.h from lib_SOURCES.
        * modules/spawn-pipe (Files): Remove lib/w32spawn.h.
        (Depends-on): Add windows-spawn. Remove cloexec, msvc-nothrow, strpbrk,
        xalloc.
        (Makefile.am): Remove w32spawn.h from lib_SOURCES.

diff --git a/lib/execute.c b/lib/execute.c
index 15d9ba9..41e1e92 100644
--- a/lib/execute.c
+++ b/lib/execute.c
@@ -39,7 +39,7 @@
 
 /* Native Windows API.  */
 # include <process.h>
-# include "w32spawn.h"
+# include "windows-spawn.h"
 
 #else
 
diff --git a/lib/spawn-pipe.c b/lib/spawn-pipe.c
index 947825a..1a7a1e1 100644
--- a/lib/spawn-pipe.c
+++ b/lib/spawn-pipe.c
@@ -44,7 +44,7 @@
 
 /* Native Windows API.  */
 # include <process.h>
-# include "w32spawn.h"
+# include "windows-spawn.h"
 
 #else
 
diff --git a/lib/w32spawn.h b/lib/windows-spawn.c
similarity index 73%
rename from lib/w32spawn.h
rename to lib/windows-spawn.c
index a4b3b1e..eedb7e4 100644
--- a/lib/w32spawn.h
+++ b/lib/windows-spawn.c
@@ -15,6 +15,11 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
 
+#include <config.h>
+
+/* Specification.  */
+#include "windows-spawn.h"
+
 #ifndef __KLIBC__
 /* Get declarations of the native Windows API functions.  */
 # define WIN32_LEAN_AND_MEAN
@@ -25,19 +30,25 @@
 #include <io.h>
 
 #include <stdbool.h>
+#include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
 
 /* Get _get_osfhandle().  */
-# if GNULIB_MSVC_NOTHROW
-#  include "msvc-nothrow.h"
-# else
-#  include <io.h>
-# endif
+#if GNULIB_MSVC_NOTHROW
+# include "msvc-nothrow.h"
+#else
+# include <io.h>
+#endif
 
 #include "cloexec.h"
+#include "error.h"
 #include "xalloc.h"
+#include "gettext.h"
+
+#define _(str) gettext (str)
+
 
 /* Duplicates a file handle, making the copy uninheritable.
    Returns -1 for a file handle that is equivalent to closed.  */
@@ -71,17 +82,13 @@ fd_safer_noinherit (int fd)
   return fd;
 }
 
-/* Duplicates a file handle, making the copy uninheritable and ensuring the
-   result is none of STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO.
-   Returns -1 for a file handle that is equivalent to closed.  */
-static int
+int
 dup_safer_noinherit (int fd)
 {
   return fd_safer_noinherit (dup_noinherit (fd));
 }
 
-/* Undoes the effect of TEMPFD = dup_safer_noinherit (ORIGFD);  */
-static void
+void
 undup_safer_noinherit (int tempfd, int origfd)
 {
   if (tempfd >= 0)
@@ -99,36 +106,6 @@ undup_safer_noinherit (int tempfd, int origfd)
     }
 }
 
-/* Prepares an argument vector before calling spawn().
-   Note that spawn() does not by itself call the command interpreter
-     (getenv ("COMSPEC") != NULL ? getenv ("COMSPEC") :
-      ({ OSVERSIONINFO v; v.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
-         GetVersionEx(&v);
-         v.dwPlatformId == VER_PLATFORM_WIN32_NT;
-      }) ? "cmd.exe" : "command.com").
-   Instead it simply concatenates the arguments, separated by ' ', and calls
-   CreateProcess().  We must quote the arguments since Windows CreateProcess()
-   interprets characters like ' ', '\t', '\\', '"' (but not '<' and '>') in a
-   special way:
-   - Space and tab are interpreted as delimiters. They are not treated as
-     delimiters if they are surrounded by double quotes: "...".
-   - Unescaped double quotes are removed from the input. Their only effect is
-     that within double quotes, space and tab are treated like normal
-     characters.
-   - Backslashes not followed by double quotes are not special.
-   - But 2*n+1 backslashes followed by a double quote become
-     n backslashes followed by a double quote (n >= 0):
-       \" -> "
-       \\\" -> \"
-       \\\\\" -> \\"
-   - '*', '?' characters may get expanded through wildcard expansion in the
-     callee: By default, in the callee, the initialization code before main()
-     takes the result of GetCommandLine(), wildcard-expands it, and passes it
-     to main(). The exceptions to this rule are:
-       - programs that inspect GetCommandLine() and ignore argv,
-       - mingw programs that have a global variable 'int _CRT_glob = 0;',
-       - Cygwin programs, when invoked from a Cygwin program.
- */
 #ifndef __KLIBC__
 # define SHELL_SPECIAL_CHARS "\"\\ 
\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037*?"
 # define SHELL_SPACE_CHARS " 
\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037"
@@ -136,7 +113,7 @@ undup_safer_noinherit (int tempfd, int origfd)
 # define SHELL_SPECIAL_CHARS ""
 # define SHELL_SPACE_CHARS ""
 #endif
-static char **
+char **
 prepare_spawn (char **argv)
 {
   size_t argc;
diff --git a/lib/windows-spawn.h b/lib/windows-spawn.h
new file mode 100644
index 0000000..200f321
--- /dev/null
+++ b/lib/windows-spawn.h
@@ -0,0 +1,61 @@
+/* Auxiliary functions for the creation of subprocesses.  Native Windows API.
+   Copyright (C) 2001, 2003-2020 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2003.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#ifndef _WINDOWS_SPAWN_H
+#define _WINDOWS_SPAWN_H
+
+/* Duplicates a file handle, making the copy uninheritable and ensuring the
+   result is none of STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO.
+   Returns -1 for a file handle that is equivalent to closed.  */
+extern int dup_safer_noinherit (int fd);
+
+/* Undoes the effect of TEMPFD = dup_safer_noinherit (ORIGFD);  */
+extern void undup_safer_noinherit (int tempfd, int origfd);
+
+/* Prepares an argument vector before calling spawn().
+   Note that spawn() does not by itself call the command interpreter
+     (getenv ("COMSPEC") != NULL ? getenv ("COMSPEC") :
+      ({ OSVERSIONINFO v; v.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
+         GetVersionEx(&v);
+         v.dwPlatformId == VER_PLATFORM_WIN32_NT;
+      }) ? "cmd.exe" : "command.com").
+   Instead it simply concatenates the arguments, separated by ' ', and calls
+   CreateProcess().  We must quote the arguments since Windows CreateProcess()
+   interprets characters like ' ', '\t', '\\', '"' (but not '<' and '>') in a
+   special way:
+   - Space and tab are interpreted as delimiters. They are not treated as
+     delimiters if they are surrounded by double quotes: "...".
+   - Unescaped double quotes are removed from the input. Their only effect is
+     that within double quotes, space and tab are treated like normal
+     characters.
+   - Backslashes not followed by double quotes are not special.
+   - But 2*n+1 backslashes followed by a double quote become
+     n backslashes followed by a double quote (n >= 0):
+       \" -> "
+       \\\" -> \"
+       \\\\\" -> \\"
+   - '*', '?' characters may get expanded through wildcard expansion in the
+     callee: By default, in the callee, the initialization code before main()
+     takes the result of GetCommandLine(), wildcard-expands it, and passes it
+     to main(). The exceptions to this rule are:
+       - programs that inspect GetCommandLine() and ignore argv,
+       - mingw programs that have a global variable 'int _CRT_glob = 0;',
+       - Cygwin programs, when invoked from a Cygwin program.
+ */
+extern char ** prepare_spawn (char **argv);
+
+#endif /* _WINDOWS_SPAWN_H */
diff --git a/modules/execute b/modules/execute
index a438fbf..4a7f845 100644
--- a/modules/execute
+++ b/modules/execute
@@ -4,17 +4,14 @@ Creation of autonomous subprocesses.
 Files:
 lib/execute.h
 lib/execute.c
-lib/w32spawn.h
 m4/execute.m4
 
 Depends-on:
-cloexec
 dup2
 error
 fatal-signal
 wait-process
 gettext-h
-msvc-nothrow
 spawn
 posix_spawnp
 posix_spawn_file_actions_init
@@ -26,16 +23,15 @@ posix_spawnattr_setflags
 posix_spawnattr_destroy
 stdbool
 stdlib
-strpbrk
 unistd
 environ
-xalloc
+windows-spawn
 
 configure.ac:
 gl_EXECUTE
 
 Makefile.am:
-lib_SOURCES += execute.h execute.c w32spawn.h
+lib_SOURCES += execute.h execute.c
 
 Include:
 "execute.h"
diff --git a/modules/spawn-pipe b/modules/spawn-pipe
index dd07fef..2c62586 100644
--- a/modules/spawn-pipe
+++ b/modules/spawn-pipe
@@ -4,17 +4,14 @@ Creation of subprocesses, communicating via pipes.
 Files:
 lib/spawn-pipe.h
 lib/spawn-pipe.c
-lib/w32spawn.h
 m4/spawn-pipe.m4
 
 Depends-on:
-cloexec
 dup2
 environ
 error
 fatal-signal
 gettext-h
-msvc-nothrow
 open
 pipe2
 pipe2-safer
@@ -31,17 +28,16 @@ posix_spawnattr_setflags
 posix_spawnattr_destroy
 stdbool
 stdlib
-strpbrk
 unistd
 unistd-safer
 wait-process
-xalloc
+windows-spawn
 
 configure.ac:
 gl_SPAWN_PIPE
 
 Makefile.am:
-lib_SOURCES += spawn-pipe.h spawn-pipe.c w32spawn.h
+lib_SOURCES += spawn-pipe.h spawn-pipe.c
 
 Include:
 "spawn-pipe.h"
diff --git a/modules/windows-spawn b/modules/windows-spawn
new file mode 100644
index 0000000..747f8bb
--- /dev/null
+++ b/modules/windows-spawn
@@ -0,0 +1,37 @@
+Description:
+Auxiliary functions for the creation of subprocesses on native Windows.
+
+Files:
+lib/windows-spawn.h
+lib/windows-spawn.c
+
+Depends-on:
+cloexec
+dup2
+error
+gettext-h
+msvc-nothrow
+stdbool
+stdlib
+strpbrk
+unistd
+xalloc
+
+configure.ac:
+AC_REQUIRE([AC_CANONICAL_HOST])
+case "$host_os" in
+  mingw*)
+    AC_LIBOBJ([windows-spawn])
+    ;;
+esac
+
+Makefile.am:
+
+Include:
+"windows-spawn.h"
+
+License:
+GPL
+
+Maintainer:
+all