Re: --with-installed-readline breaks tilde-expansion

[Eric Blake]

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According to Eric Blake on 7/8/2005 6:48 AM:
> On the cygwin list, a difference was pointed out between compilations of
> bash that avoid or use --with-installed-readline:
> 
> static_bash$ echo $HOME ~
> /home/eblake /home/eblake
> static_bash$ HOME=/tmp; echo $HOME ~
> /tmp /tmp
> 
> dynamic_bash$ echo $HOME ~
> /home/eblake /home/eblake
> dynamic_bash$ HOME=/tmp; echo $HOME ~
> /tmp /home/eblake

The following patch, to both readline and bash, allows readline to export
a hook (rather than trying to import a function, which doesn't work in
dynamic libraries for at least cygwin), so that bash can then override
getenv() even within the context of a dynamic readline library.  It fixes
not only tilde expansion (HOME), but also other uses of sh_get_env_value,
where readline needs to read environment variables from bash, rather than
the original program environ: INPUTRC, LC_ALL, LANG, EMACS, TERM, COLUMNS,
and LINES.

- --
Life is short - so eat dessert first!

Eric Blake             ebb9@byu.net
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--- bash-3.0-orig/bashline.c    2005-07-22 07:39:35.654625000 -0600
+++ bash-3.0/bashline.c 2005-07-22 07:24:06.170250000 -0600
@@ -1,6 +1,6 @@
 /* bashline.c -- Bash's interface to the readline library. */
 
-/* Copyright (C) 1987-2004 Free Software Foundation, Inc.
+/* Copyright (C) 1987-2005 Free Software Foundation, Inc.
 
    This file is part of GNU Bash, the Bourne Again SHell.
 
@@ -485,7 +485,11 @@
   rl_filename_dequoting_function = bash_dequote_filename;
   rl_char_is_quoted_p = char_is_quoted;
 
+  /* On cygwin, dynamically linked readline can't see bash's environment
+     without this hook. */
+  rl_getenv_hook = sh_get_env_value;
+
 #if 0
   /* This is superfluous and makes it impossible to use tab completion in
      vi mode even when explicitly binding it in ~/.inputrc.  sv_strict_posix()
--- bash-3.0-orig/lib/readline/readline.c       2003-09-18 09:04:18.000000000 
-0600
+++ bash-3.0/lib/readline/readline.c    2005-07-22 07:24:19.967125000 -0600
@@ -996,4 +996,8 @@
 
   return (0);
 }
+
+/* Hook to allow application (such as bash) to override getenv() when
+   readline is dynamically linked.  */
+rl_getenv_func_t *rl_getenv_hook = (rl_getenv_func_t *)NULL;
--- bash-3.0-orig/lib/readline/readline.h       2004-07-13 08:54:27.000000000 
-0600
+++ bash-3.0/lib/readline/readline.h    2005-07-22 07:24:20.029625000 -0600
@@ -829,7 +829,10 @@
 extern int rl_save_state PARAMS((struct readline_state *));
 extern int rl_restore_state PARAMS((struct readline_state *));
 
+/* If non-null, the address of a replacement to getenv.  */
+extern rl_getenv_func_t *rl_getenv_hook;
+
 #ifdef __cplusplus
 }
 #endif
--- bash-3.0-orig/lib/readline/rltypedefs.h     2004-01-28 11:31:26.000000000 
-0700
+++ bash-3.0/lib/readline/rltypedefs.h  2005-07-22 07:24:20.232750000 -0600
@@ -85,7 +85,9 @@
 typedef char *rl_cpcpfunc_t PARAMS((char  *));
 typedef char *rl_cpcppfunc_t PARAMS((char  **));
 
+typedef char *rl_getenv_func_t PARAMS((const char *));
+
 #endif /* _RL_FUNCTION_TYPEDEF */
 
 #ifdef __cplusplus
--- bash-3.0-orig/lib/readline/shell.c    2005-07-19 06:26:28.828000000 -0600
+++ bash-3.0/lib/readline/shell.c        2005-07-19 20:50:12.374875000 -0600
@@ -53,0 +53,0 @@

 #include <stdio.h>

+#include "readline.h"
 #include "rlstdc.h"
 #include "rlshell.h"
 #include "xmalloc.h"
@@ -149,5 +150,7 @@
 sh_get_env_value (varname)
      const char *varname;
 {
+  if (rl_getenv_hook)
+    return (rl_getenv_hook) (varname);
   return ((char *)getenv (varname));
 }