[Bug-readline] Add the rl_free(void *buff) function to the readline library

[Borut Razem]

I suggest to add the rl_free(void *buff) function to the readline library.

The function rl_free() should be used instead of free() to deallocate 
the buffer returned by readline(), the buffer passed as the parameter to 
lhandler function installed by rl_callback_handler_install() and buffers 
allocated by readline library functions (history_expand(), 
remove_history(), ...)

Rationale:

It is always recommended to free the memory by the same module that 
allocated it. This fact becomes more evident when the module is 
dynamically linked: the main program and the shared library may use 
different memory allocation libraries, which might be problematic if the 
memory is allocated by the shared library and deallocated by the main 
program.

I  came across this problem when dynamically linking readline.dll, 
generated by mingw gcc compiler, from the main program compiled with 
Visual Studio .NET: the memory allocation is done by msvcrt.dll called 
from readline.dll, while the deallocation is done by msvcr80.dll (or the 
statically linked equivalent) called from the main program, which seems 
to be incompatible.

I attached the patch which adds the rl_free() function to readline 
library and changes free() to rl_free() in examples directory. The 
documentation in doc directory should be updated accordingly.

I'm the developer and maintainer of WIN32 port on sdcc 
http://sdcc.sourceforge.net/ and gpsimWin32 
http://gpsim.sourceforge.net/gpsimWin32/gpsimWin32.html projects, both 
using the readline library.
The WIN32 port of readline 5.1 library is available at 
http://gpsim.sourceforge.net/gpsimWin32/packages/.

P.S.: The http://directory.fsf.org/readline.html page is not updated 
with the latest readline 5.2 version.

Borut




diff -ubr readline-5.2-orig/examples/excallback.c 
readline-5.2/examples/excallback.c
--- readline-5.2-orig/examples/excallback.c     2006-03-21 16:07:52.000000000 
+0100
+++ readline-5.2/examples/excallback.c  2006-11-01 11:18:13.343750000 +0100
@@ -157,7 +157,7 @@
     fprintf(stderr, "|%s|\n", line);
   }
 
-  free (line);
+  rl_free (line);
 }
 
 int
diff -ubr readline-5.2-orig/examples/fileman.c readline-5.2/examples/fileman.c
--- readline-5.2-orig/examples/fileman.c        2002-04-16 23:50:56.000000000 
+0200
+++ readline-5.2/examples/fileman.c     2006-11-01 11:18:45.203125000 +0100
@@ -145,7 +145,7 @@
           execute_line (s);
         }
 
-      free (line);
+      rl_free (line);
     }
   exit (0);
 }
diff -ubr readline-5.2-orig/examples/histexamp.c 
readline-5.2/examples/histexamp.c
--- readline-5.2-orig/examples/histexamp.c      2005-08-02 23:21:36.000000000 
+0200
+++ readline-5.2/examples/histexamp.c   2006-11-01 11:35:02.484375000 +0100
@@ -67,13 +67,13 @@
 
          if (result < 0 || result == 2)
            {
-             free (expansion);
+             rl_free (expansion);
              continue;
            }
 
          add_history (expansion);
          strncpy (line, expansion, sizeof (line) - 1);
-         free (expansion);
+         rl_free (expansion);
        }
 
       if (strcmp (line, "quit") == 0)
@@ -111,8 +111,8 @@
                fprintf (stderr, "No such entry %d\n", which);
              else
                {
-                 free (entry->line);
-                 free (entry);
+                 rl_free (entry->line);
+                 rl_free (entry);
                }
            }
          else
diff -ubr readline-5.2-orig/examples/manexamp.c readline-5.2/examples/manexamp.c
--- readline-5.2-orig/examples/manexamp.c       2002-04-16 23:53:02.000000000 
+0200
+++ readline-5.2/examples/manexamp.c    2006-11-01 11:36:21.875000000 +0100
@@ -40,7 +40,7 @@
      to the free pool. */
   if (line_read)
     {
-      free (line_read);
+      rl_free (line_read);
       line_read = (char *)NULL;
     }
 
diff -ubr readline-5.2-orig/examples/readlinebuf.h 
readline-5.2/examples/readlinebuf.h
--- readline-5.2-orig/examples/readlinebuf.h    2001-09-24 15:39:34.000000000 
+0200
+++ readline-5.2/examples/readlinebuf.h 2006-11-01 11:37:17.234375000 +0100
@@ -72,7 +72,7 @@
                        
                if ( rd < n ) {
                        low_ = high_ = 0;
-                       free( line_ ); // free( NULL ) is a noop
+                       rl_free( line_ ); // free( NULL ) is a noop
                        line_ = readline( prompt_ );
                        if ( line_ ) {
                                high_ = strlen( line_ );
@@ -87,7 +87,7 @@
        virtual int_type underflow() {
                if ( high_ == low_ ) {
                        low_ = high_ = 0;
-                       free( line_ ); // free( NULL ) is a noop
+                       rl_free( line_ ); // free( NULL ) is a noop
                        line_ = readline( prompt_ );
                        if ( line_ ) {
                                high_ = strlen( line_ );
diff -ubr readline-5.2-orig/examples/rl-fgets.c readline-5.2/examples/rl-fgets.c
--- readline-5.2-orig/examples/rl-fgets.c       2004-04-22 23:52:18.000000000 
+0200
+++ readline-5.2/examples/rl-fgets.c    2006-11-01 11:44:27.296875000 +0100
@@ -336,26 +336,26 @@
     ) ;
     if ( ! strncmp(my_fgets_line, "_fgets_reset_", 13) ) {
       my_fgets_reset () ;
-      free ( my_fgets_line ) ;
+      rl_free ( my_fgets_line ) ;
       strcpy ( s, "\n" ) ;
       return ( s ) ;
     }
     if ( ! strncmp(my_fgets_line, "_fgets_dump_", 12) ) {
       my_fgets_dump () ;
-      free ( my_fgets_line ) ;
+      rl_free ( my_fgets_line ) ;
       strcpy ( s, "\n" ) ;
       return ( s ) ;
     }
     if ( ! strncmp(my_fgets_line, "_fgets_debug_", 13) ) {
       my_fgets_debug_toggle () ;
-      free ( my_fgets_line ) ;
+      rl_free ( my_fgets_line ) ;
       strcpy ( s, "\n" ) ;
       return ( s ) ;
     }
     (void) strncpy ( s, my_fgets_line, n-1 ) ;
     (void) strcat ( s, "\n" ) ;
     if ( *my_fgets_line ) add_history ( my_fgets_line ) ;
-    free ( my_fgets_line ) ;
+    rl_free ( my_fgets_line ) ;
     return ( s ) ;
   } else {
     static fgets_t _fgets ;
diff -ubr readline-5.2-orig/examples/rlfe/rlfe.c 
readline-5.2/examples/rlfe/rlfe.c
--- readline-5.2-orig/examples/rlfe/rlfe.c      2004-11-04 23:32:14.000000000 
+0100
+++ readline-5.2/examples/rlfe/rlfe.c   2006-11-01 11:39:56.750000000 +0100
@@ -338,7 +338,7 @@
           if (*line)
             add_history (line);
         }
-      free (line);
+      rl_free (line);
     }
   rl_callback_handler_remove ();
   buf_count = 0;
diff -ubr readline-5.2-orig/examples/rltest.c readline-5.2/examples/rltest.c
--- readline-5.2-orig/examples/rltest.c 2005-08-02 23:25:10.000000000 +0200
+++ readline-5.2/examples/rltest.c      2006-11-01 11:45:13.296875000 +0100
@@ -87,7 +87,7 @@
                fprintf (stderr, "%d: %s\r\n", i, list[i]->line);
            }
        }
-      free (temp);
+      rl_free (temp);
     }
   exit (0);
 }
diff -ubr readline-5.2-orig/readline.c readline-5.2/readline.c
--- readline-5.2-orig/readline.c        2006-08-16 22:00:36.000000000 +0200
+++ readline-5.2/readline.c     2006-11-01 11:50:30.234375000 +0100
@@ -1212,3 +1212,16 @@
 
   return (0);
 }
+
+/* Free the buffer returned by readline(), the buffer passed as the
+   parameter to lhandler function installed by rl_callback_handler_install()
+   and buffers allocated by readline library functions.
+   Use this funtion instead of free().
+   This function MUST be used instead free() if readline is linked as
+   DLL on WIN32 */
+void
+rl_free (buff)
+     void *buff;
+{
+  free(buff);
+}
diff -ubr readline-5.2-orig/readline.h readline-5.2/readline.h
--- readline-5.2-orig/readline.h        2006-08-16 22:17:00.000000000 +0200
+++ readline-5.2/readline.h     2006-11-01 11:50:27.578125000 +0100
@@ -279,6 +279,13 @@
 /* Readline functions. */
 /* Read a line of input.  Prompt with PROMPT.  A NULL PROMPT means none. */
 extern char *readline PARAMS((const char *));
+/* Free the buffer returned by readline(), the buffer passed as the
+   parameter to lhandler function installed by rl_callback_handler_install()
+   and buffers allocated by readline library functions.
+   Use this funtion instead of free().
+   This function MUST be used instead free() if readline is linked as
+   DLL on WIN32 */
+extern void rl_free PARAMS((void *));
 
 extern int rl_set_prompt PARAMS((const char *));
 extern int rl_expand_prompt PARAMS((char *));