Index: subversion/include/svn_io.h
===================================================================
--- subversion/include/svn_io.h	(revision 18637)
+++ subversion/include/svn_io.h	(working copy)
@@ -860,6 +860,41 @@
                             apr_file_t *errfile,
                             apr_pool_t *pool);
 
+#ifdef AS400
+/** Alternative to svn_io_start_cmd() and svn_io_wait_for_cmd() for running
+ * unix-type qsh(ell) scripts on OS400.  Overcomes limitation of
+ * apr_proc_wait() on OS400 where child process always appears to exit
+ * successfully.   
+ * 
+ * Invoke @a cmd with @a args.  @a args is a list of utf8-encoded
+ * (<tt>const char *</tt>)'s, terminated by @c NULL.  @c ARGS[0] is the full
+ * path to the program, though it need not be the same as @a cmd.
+ * 
+ * If @a exitcode is not @c NULL, @a *exitcode will contain the exit code
+ * of the process upon return, and if @a exitwhy is not @c NULL, @a
+ * *exitwhy will indicate why the process terminated.  If @a exitwhy is 
+ * @c NULL, and the exit reason is not @c APR_PROC_CHECK_EXIT(), or if 
+ * @a exitcode is @c NULL and the exit code is non-zero, then an
+ * @c SVN_ERR_EXTERNAL_PROGRAM error will be returned.
+ * 
+ * If @a read_stdout is @c TRUE, any stdout from the command is appended
+ * to @a *err_stream.
+ * 
+ * If @a read_stderr is @c TRUE, any stderr from the command is appended
+ * to @a *err_stream.
+ * 
+ * All allocations are done in @a pool. 
+ */
+svn_error_t *svn_io_run_os400_cmd(const char *cmd,
+                                  const char *const *args,
+                                  int *exitcode,
+                                  apr_exit_why_e *exitwhy,
+                                  svn_boolean_t read_stdout,
+                                  svn_boolean_t read_stderr,
+                                  svn_stringbuf_t **err_stream,
+                                  apr_pool_t *pool);
+#endif /* AS400 */
+
 /** Invoke @c the configured diff program, with @a user_args (an array
  * of utf8-encoded @a num_user_args arguments), if they are specified,
  * or "-u" if they are not.
Index: subversion/libsvn_repos/hooks.c
===================================================================
--- subversion/libsvn_repos/hooks.c	(revision 18637)
+++ subversion/libsvn_repos/hooks.c	(working copy)
@@ -60,6 +60,7 @@
   apr_exit_why_e exitwhy;
   apr_proc_t cmd_proc;
 
+#ifndef AS400
   /* Create a pipe to access stderr of the child. */
   apr_err = apr_file_pipe_create(&read_errhandle, &write_errhandle, pool);
   if (apr_err)
@@ -95,7 +96,13 @@
 
   err = svn_io_start_cmd(&cmd_proc, ".", cmd, args, FALSE,
                          stdin_handle, null_handle, write_errhandle, pool);
+#else
+  /* The functionality of svn_io_start_cmd() and svn_io_wait_for_cmd() is
+   * handled in svn_io_run_as400_cmd() on OS400. */
+  err = NULL;
+#endif /* AS400 */
 
+#ifndef AS400
   /* This seems to be done automatically if we pass the third parameter of
      apr_procattr_child_in/out_set(), but svn_io_run_cmd()'s interface does
      not support those parameters. We need to close the write end of the
@@ -104,6 +111,7 @@
   if (!err && apr_err)
     return svn_error_wrap_apr
       (apr_err, _("Error closing write end of stderr pipe"));
+#endif /* AS400 */
 
   if (err)
     {
@@ -116,9 +124,17 @@
       const char *error;
       svn_error_t *err2;
 
+#ifndef AS400
       err2 = svn_stringbuf_from_aprfile(&native_error, read_errhandle, pool);
 
       err = svn_io_wait_for_cmd(&cmd_proc, cmd, &exitcode, &exitwhy, pool);
+#else
+      err2 = SVN_NO_ERROR;
+
+      err = svn_io_run_os400_cmd(cmd, args, &exitcode, &exitwhy, FALSE,
+                                 TRUE, &native_error, pool);
+#endif /* AS400 */
+
       if (! err)
         {
           if (! APR_PROC_CHECK_EXIT(exitwhy) || exitcode != 0)
@@ -150,6 +166,7 @@
         }
     }
 
+#ifndef AS400
   /* Hooks are fallible, and so hook failure is "expected" to occur at
      times.  When such a failure happens we still want to close the pipe
      and null file */
@@ -161,6 +178,7 @@
   apr_err = apr_file_close(null_handle);
   if (!err && apr_err)
     return svn_error_wrap_apr(apr_err, _("Error closing null file"));
+#endif
 
   return err;
 }
Index: subversion/libsvn_subr/io.c
===================================================================
--- subversion/libsvn_subr/io.c	(revision 18637)
+++ subversion/libsvn_subr/io.c	(working copy)
@@ -42,6 +42,10 @@
 #include <apr_portable.h>
 #include <apr_md5.h>
 
+#if AS400
+#include <spawn.h> /* For spawn() and struct inheritance. */
+#endif
+
 #include "svn_types.h"
 #include "svn_path.h"
 #include "svn_string.h"
@@ -54,6 +58,7 @@
 
 #ifdef AS400
 #define SVN_UTF_UTOE_XLATE_HANDLE "svn-utf-utoe-xlate-handle"
+#define SVN_UTF_ETOU_XLATE_HANDLE "svn-utf-etou-xlate-handle"
 #endif
 
 /*
@@ -2058,7 +2063,164 @@
 }
 
 
+#if AS400
 svn_error_t *
+svn_io_run_os400_cmd(const char *cmd,
+                     const char *const *args,
+                     int *exitcode,
+                     apr_exit_why_e *exitwhy,
+                     svn_boolean_t read_stdout,
+                     svn_boolean_t read_stderr,
+                     svn_stringbuf_t **err_stream,
+                     apr_pool_t *pool)
+{
+  int rc, fd_map[3], ignoreFds[2], useFds[2], exitcode_val;
+  char buffer[20];
+  const char **native_args = NULL;
+  struct inheritance xmp_inherit = {0};
+  pid_t child_pid, wait_rv;
+  svn_stringbuf_t *script_output = svn_stringbuf_create("", pool);
+  apr_size_t args_arr_size = 0, i = 0;
+  apr_exit_why_e exitwhy_val;
+#pragma convert(0)
+  /* Even with the UTF support in V5R4 a few functions don't support utf-8
+   * args, including spawn(), which takes this char array. */
+  char *xmp_envp[2] = {"QIBM_USE_DESCRIPTOR_STDIO=Y", NULL};
+#pragma convert(1208)
+  
+  *err_stream = svn_stringbuf_create("", pool);
+
+  /* Find number of elements in args array. */
+  while (args[args_arr_size] != NULL)
+    args_arr_size++;
+
+  /* Allocate memory for the native_args string array plus one for
+   * the ending null element. */
+  native_args = apr_palloc(pool, sizeof(char *) * args_arr_size + 1);
+  
+  /* Convert utf-8 args to ebcdic for use by spawn(). */
+  while(args[i] != NULL)
+    {
+      SVN_ERR(svn_utf_cstring_from_utf8_ex((const char**)(&(native_args[i])),
+                                           args[i++], (const char *)0,
+                                           SVN_UTF_UTOE_XLATE_HANDLE,
+                                           pool));
+    }
+
+  /* Make the last element in the array a NULL pointer as required
+   * by spawn. */
+  native_args[args_arr_size] = NULL;
+
+  /* Get two data pipes, allowing stdout and stderr to be separate. */
+  if (pipe(ignoreFds) != 0 || pipe(useFds) != 0)
+    {
+      return svn_error_createf(SVN_ERR_EXTERNAL_PROGRAM, NULL,
+                               "Error piping hook script %s.", cmd);
+    }
+
+  /* Map stdin, stdout, stderr. */
+  fd_map[0] = ignoreFds[1];
+  fd_map[1] = read_stdout ? useFds[1] : ignoreFds[1];
+  fd_map[2] = read_stderr ? useFds[1] : ignoreFds[1];  
+
+  /* Spawn the command... */
+  if ((child_pid = spawn(native_args[0], 3, fd_map, &xmp_inherit,
+                         native_args, xmp_envp)) == -1)
+    {
+      return svn_error_createf(SVN_ERR_EXTERNAL_PROGRAM, NULL,
+                              "Error spawning process for hook script %s.",
+                               cmd);
+    }
+
+  /* ...and wait for it to finish. */
+  if ((wait_rv = waitpid(child_pid, &exitcode_val, 0)) == -1)
+    {
+      return svn_error_createf(SVN_ERR_EXTERNAL_PROGRAM, NULL,
+                               "Error waiting for process completion of " \
+                               "hook script %s.", cmd);
+    }
+
+  close(ignoreFds[1]);
+  close(useFds[1]);
+
+  /* Create svn_stringbuf containing any messages the script sent to
+   * stderr and/or stdout. */
+  while ((rc = read(useFds[0], buffer, sizeof(buffer))) > 0)
+    {
+      buffer[rc] = '\0';
+      svn_stringbuf_appendcstr(script_output, buffer);
+    }
+
+  if (script_output->len > 1)
+    {
+      const char* script_out_utf8;
+      SVN_ERR(svn_utf_cstring_to_utf8_ex(&script_out_utf8,
+                                         script_output->data,
+                                         (const char*)0,
+                                         SVN_UTF_ETOU_XLATE_HANDLE,
+                                         pool));
+      svn_stringbuf_appendcstr (*err_stream, script_out_utf8);
+    }
+
+  close(ignoreFds[0]);
+  close(useFds[0]);
+
+  if (exitwhy)
+  {
+    /* waitpid() doesn't explicity give us apr_exit_why_e *exitwhy so we do
+     * our best to determine it's value. */     
+    if (WIFEXITED(*exitcode))
+      {
+        exitwhy_val = APR_PROC_EXIT;
+      }
+    else if (WIFSIGNALED(*exitcode))
+      {
+        exitwhy_val = APR_PROC_SIGNAL;
+      }
+    else if (WIFEXCEPTION(*exitcode))
+      {
+        return svn_error_createf
+         (SVN_ERR_EXTERNAL_PROGRAM, NULL,
+          _("Process '%s' failed unexpectedly with OS400 exception %d"),
+            cmd, WEXCEPTNUMBER(*exitcode));
+      }
+    else if (WIFSTOPPED(*exitcode))
+      {
+        return svn_error_createf
+         (SVN_ERR_EXTERNAL_PROGRAM, NULL,
+          _("Process '%s' stopped unexpectedly by signal %d"),
+            cmd, WSTOPSIG(*exitcode));
+      }
+    else
+      {
+        return svn_error_createf
+         (SVN_ERR_EXTERNAL_PROGRAM, NULL,
+          _("Process '%s' failed unexpectedly with %d"),
+            cmd, APR_EGENERAL);
+      }    
+  }
+
+  if (exitwhy)
+    *exitwhy = exitwhy_val;
+  else if (! APR_PROC_CHECK_EXIT(exitwhy_val))
+    return svn_error_createf
+      (SVN_ERR_EXTERNAL_PROGRAM, NULL,
+       _("Process '%s' failed (exitwhy %d)"), cmd, exitwhy_val);
+
+  if (exitcode)
+    *exitcode = exitcode_val;
+  else if (exitcode_val != 0)
+    {
+      return svn_error_createf
+        (SVN_ERR_EXTERNAL_PROGRAM, NULL,
+         _("Process '%s' returned error exitcode %d"), cmd, exitcode_val);
+    }
+  return SVN_NO_ERROR;
+}
+#endif
+
+
+svn_error_t *
 svn_io_run_diff(const char *dir, 
                 const char *const *user_args,
                 int num_user_args,