windows-spawn: Export an auxiliary function.

* lib/windows-spawn.h (compose_command): New declaration.
* lib/windows-spawn.c (compose_command): New function, extracted from
spawnpvech.
(spawnpvech): Use it.

3 files changed, 60 insertions, 29 deletions

diff --git a/ChangeLog b/ChangeLog
index b716a268a6..ba8a7d9046 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2020-12-24  Bruno Haible  <bruno@clisp.org>
 
+	windows-spawn: Export an auxiliary function.
+	* lib/windows-spawn.h (compose_command): New declaration.
+	* lib/windows-spawn.c (compose_command): New function, extracted from
+	spawnpvech.
+	(spawnpvech): Use it.
+
+2020-12-24  Bruno Haible  <bruno@clisp.org>
+
 	posix_spawn* tests: Add support for native Windows.
 	* tests/test-posix_spawn-open1.c (DATA_FILENAME): Treat native Windows
 	like Cygwin.
diff --git a/lib/windows-spawn.c b/lib/windows-spawn.c
index 0385b1ce1e..cc29196ecf 100644
--- a/lib/windows-spawn.c
+++ b/lib/windows-spawn.c
@@ -203,6 +203,47 @@ prepare_spawn (const char * const *argv, char **mem_to_free)
   return new_argv;
 }
 
+char *
+compose_command (const char * const *argv)
+{
+  /* Just concatenate the argv[] strings, separated by spaces.  */
+  char *command;
+
+  /* Determine the size of the needed block of memory.  */
+  size_t total_size = 0;
+  const char * const *ap;
+  const char *p;
+  for (ap = argv; (p = *ap) != NULL; ap++)
+    total_size += strlen (p) + 1;
+  size_t command_size = (total_size > 0 ? total_size : 1);
+
+  /* Allocate the block of memory.  */
+  command = (char *) malloc (command_size);
+  if (command == NULL)
+    {
+      errno = ENOMEM;
+      return NULL;
+    }
+
+  /* Fill it.  */
+  if (total_size > 0)
+    {
+      char *cp = command;
+      for (ap = argv; (p = *ap) != NULL; ap++)
+        {
+          size_t size = strlen (p) + 1;
+          memcpy (cp, p, size - 1);
+          cp += size;
+          cp[-1] = ' ';
+        }
+      cp[-1] = '\0';
+    }
+  else
+    *command = '\0';
+
+  return command;
+}
+
 intptr_t
 spawnpvech (int mode,
             const char *progname, const char * const *argv,
@@ -227,35 +268,10 @@ spawnpvech (int mode,
   if (resolved_progname == NULL)
     return -1;
 
-  /* Compose the command.
-     Just concatenate the argv[] strings, separated by spaces.  */
-  char *command;
-  {
-    /* Determine the size of the needed block of memory.  */
-    size_t total_size = 0;
-    const char * const *ap;
-    const char *p;
-    for (ap = argv; (p = *ap) != NULL; ap++)
-      total_size += strlen (p) + 1;
-    size_t command_size = (total_size > 0 ? total_size : 1);
-    command = (char *) malloc (command_size);
-    if (command == NULL)
-      goto out_of_memory_1;
-    if (total_size > 0)
-      {
-        char *cp = command;
-        for (ap = argv; (p = *ap) != NULL; ap++)
-          {
-            size_t size = strlen (p) + 1;
-            memcpy (cp, p, size - 1);
-            cp += size;
-            cp[-1] = ' ';
-          }
-        cp[-1] = '\0';
-      }
-    else
-      *command = '\0';
-  }
+  /* Compose the command.  */
+  char *command = compose_command (argv);
+  if (command == NULL)
+    goto out_of_memory_1;
 
   /* Copy *ENVP into a contiguous block of memory.  */
   char *envblock;
diff --git a/lib/windows-spawn.h b/lib/windows-spawn.h
index 77720d5559..cb9d3fab12 100644
--- a/lib/windows-spawn.h
+++ b/lib/windows-spawn.h
@@ -65,6 +65,13 @@
 extern const char ** prepare_spawn (const char * const *argv,
                                     char **mem_to_free);
 
+/* Composes the command to be passed to CreateProcess().
+   ARGV must contain appropriately quoted arguments, as returned by
+   prepare_spawn.
+   Returns a freshly allocated string.  In case of memory allocation failure,
+   NULL is returned, with errno set.  */
+extern char * compose_command (const char * const *argv);
+
 /* Creates a subprocess.
    MODE is either P_WAIT or P_NOWAIT.
    PROGNAME is the program to invoke.