Move string-pointer-array handling to posix.c

* libguile/posix.c (free_string_pointers):
(free_string_pointers_on_unwind):
(allocate_string_pointers): Move here from string.c, and use malloc/free
instead of GC facilities. Adapt all users.
* libguile/strings.h:
* libguile/strings.c (scm_i_allocate_string_pointers): Remove.

libguile/posix.c

@@ -1138,6 +1138,55 @@ SCM_DEFINE (scm_tcsetpgrp, "tcsetpgrp", 2, 0, 0,
 #undef FUNC_NAME
 #endif /* HAVE_TCSETPGRP */
 
+/* Return a newly allocated array of char pointers to each of the strings
+   in args, with a terminating NULL pointer.  The strings are encoded using
+   the current locale. */
+
+static void
+free_string_pointers (char **pointers)
+{
+  for (char **walk = pointers; *walk; walk++)
+    free (*walk);
+  free (pointers);
+}
+
+static void
+free_string_pointers_on_unwind (void *data)
+{
+  free_string_pointers (data);
+}
+
+static char **
+allocate_string_pointers (SCM list)
+{
+  int list_len = scm_ilength (list);
+  int i;
+
+  if (list_len < 0)
+    scm_wrong_type_arg_msg (NULL, 0, list, "proper list");
+
+  char **result = scm_calloc ((list_len + 1) * sizeof (char *));
+
+  scm_dynwind_begin (0);
+  scm_dynwind_unwind_handler (free_string_pointers_on_unwind, result, 0);
+
+  for (i = 0; i < list_len; i++, list = scm_cdr (list))
+    {
+      SCM str = scm_car (list);
+      size_t len;  /* String length in bytes */
+      char *c_str = scm_to_locale_stringn (str, &len);
+      result[i] = malloc (len + 1);
+      memcpy (result[i], c_str, len);
+      result[i][len] = '\0';
+      free (c_str);
+    }
+
+  scm_dynwind_end ();
+
+  return result;
+}
+
+
 SCM_DEFINE (scm_execl, "execl", 1, 0, 1, 
             (SCM filename, SCM args),
 	    "Executes the file named by @var{filename} as a new process image.\n"
@@ -1159,7 +1208,7 @@ SCM_DEFINE (scm_execl, "execl", 1, 0, 1,
   exec_file = scm_to_locale_string (filename);
   scm_dynwind_free (exec_file);
 
-  exec_argv = scm_i_allocate_string_pointers (args);
+  exec_argv = allocate_string_pointers (args);
 
 #ifdef __MINGW32__
   execv (exec_file, (const char * const *)exec_argv);
@@ -1192,7 +1241,7 @@ SCM_DEFINE (scm_execlp, "execlp", 1, 0, 1,
   exec_file = scm_to_locale_string (filename);
   scm_dynwind_free (exec_file);
 
-  exec_argv = scm_i_allocate_string_pointers (args);
+  exec_argv = allocate_string_pointers (args);
 
 #ifdef __MINGW32__
   execvp (exec_file, (const char * const *)exec_argv);
@@ -1229,8 +1278,8 @@ SCM_DEFINE (scm_execle, "execle", 2, 0, 1,
   exec_file = scm_to_locale_string (filename);
   scm_dynwind_free (exec_file);
 
-  exec_argv = scm_i_allocate_string_pointers (args);
+  exec_argv = allocate_string_pointers (args);
-  exec_env = scm_i_allocate_string_pointers (env);
+  exec_env = allocate_string_pointers (env);
 
 #ifdef __MINGW32__
   execve (exec_file, (const char * const *) exec_argv, (const char * const *) exec_env);
@@ -1474,12 +1523,18 @@ SCM_DEFINE (scm_spawn_process, "spawn", 2, 0, 1,
   exec_file = scm_to_locale_string (program);
   scm_dynwind_free (exec_file);
 
-  exec_argv = scm_i_allocate_string_pointers (arguments);
+  exec_argv = allocate_string_pointers (arguments);
+  scm_dynwind_unwind_handler (free_string_pointers_on_unwind, exec_argv,
+                              SCM_F_WIND_EXPLICITLY);
 
   if (SCM_UNBNDP (env))
     exec_env = environ;
   else
-    exec_env = scm_i_allocate_string_pointers (env);
+    {
+      exec_env = allocate_string_pointers (env);
+      scm_dynwind_unwind_handler (free_string_pointers_on_unwind, exec_env,
+                                  SCM_F_WIND_EXPLICITLY);
+    }
 
   if (SCM_UNBNDP (in_scm))
     in_scm = scm_current_input_port ();
@@ -1530,7 +1585,7 @@ piped_process (pid_t *pid, SCM prog, SCM args, SCM from, SCM to)
   char **exec_env = environ;
 
   exec_file = scm_to_locale_string (prog);
-  exec_argv = scm_i_allocate_string_pointers (scm_cons (prog, args));
+  exec_argv = allocate_string_pointers (scm_cons (prog, args));
 
   reading = scm_is_pair (from);
   writing = scm_is_pair (to);
@@ -1575,6 +1630,8 @@ piped_process (pid_t *pid, SCM prog, SCM args, SCM from, SCM to)
   *pid = do_spawn (exec_file, exec_argv, exec_env, in, out, err, 1);
   int errno_save = (*pid < 0) ? errno : 0;
 
+  free_string_pointers (exec_argv);
+
   if (reading)
     close (c2p[1]);
   if (writing)

libguile/strings.c

@@ -2430,52 +2430,6 @@ scm_makfromstrs (int argc, char **argv)
   return lst;
 }
 
-/* Return a newly allocated array of char pointers to each of the strings
-   in args, with a terminating NULL pointer.  The strings are encoded using
-   the current locale. */
-
-char **
-scm_i_allocate_string_pointers (SCM list)
-#define FUNC_NAME "scm_i_allocate_string_pointers"
-{
-  char **result;
-  int list_len = scm_ilength (list);
-  int i;
-
-  if (list_len < 0)
-    scm_wrong_type_arg_msg (NULL, 0, list, "proper list");
-
-  result = scm_gc_malloc ((list_len + 1) * sizeof (char *),
-			  "string pointers");
-  result[list_len] = NULL;
-
-  /* The list might have been modified in another thread, so
-     we check LIST before each access.
-   */
-  for (i = 0; i < list_len && scm_is_pair (list); i++)
-    {
-      SCM str = SCM_CAR (list);
-      size_t len;  /* String length in bytes */
-      char *c_str = scm_to_locale_stringn (str, &len);
-
-      /* OPTIMIZE-ME: Right now, scm_to_locale_stringn always uses
-	 scm_malloc to allocate the returned string, which must be
-	 explicitly deallocated.  This forces us to copy the string a
-	 second time into a new buffer.  Ideally there would be variants
-	 of scm_to_*_stringn that can return garbage-collected buffers. */
-
-      result[i] = scm_gc_malloc_pointerless (len + 1, "string");
-      memcpy (result[i], c_str, len);
-      result[i][len] = '\0';
-      free (c_str);
-
-      list = SCM_CDR (list);
-    }
-
-  return result;
-}
-#undef FUNC_NAME
-
 void
 scm_i_get_substring_spec (size_t len,
 			  SCM start, size_t *cstart,

libguile/strings.h

@@ -1,7 +1,7 @@
 #ifndef SCM_STRINGS_H
 #define SCM_STRINGS_H
 
-/* Copyright 1995-1998,2000-2001,2004-2006,2008-2011,2013,2015-2019,2022
+/* Copyright 1995-1998,2000-2001,2004-2006,2008-2011,2013,2015-2019,2022,2025
      Free Software Foundation, Inc.
 
    This file is part of Guile.
@@ -265,7 +265,6 @@ SCM_INTERNAL void scm_decoding_error (const char *subr, int err,
 
 /* internal utility functions. */
 
-SCM_INTERNAL char **scm_i_allocate_string_pointers (SCM list);
 SCM_INTERNAL void scm_i_get_substring_spec (size_t len,
 					    SCM start, size_t *cstart,
 					    SCM end, size_t *cend);