12 files changed, 578 insertions, 84 deletions

diff --git a/NEWS b/NEWS
index a564b2e..c9ab654 100644
--- a/NEWS
+++ b/NEWS
@@ -1,7 +1,7 @@
-GNU dbm NEWS -- history of user-visible changes. 2016-07-09
+GNU dbm NEWS -- history of user-visible changes. 2016-07-12
 Copyright (C) 1990-2016 Free Software Foundation, Inc.
 See the end of file for copying conditions.
 
 Please send gdbm bug reports to <bug-gdbm@gnu.org>.
 
 Version 1.12.90 (Git)
@@ -28,12 +28,17 @@ Instead it sets gdbm_errno to GDBM_MALLOC_ERROR and returns NULL datum.
 ** gdbm_last_errno
 
 ** gdbm_clear_error
 
 ** gdbm_needs_recovery
 
+* Line editing in gdbmtool
+
+The gdbmtool utility now offers the usual line-editing facilities (if
+the package has been compiled with GNU Readline.
+
 
 Version 1.12, 2016-05-16
 
 * New configuration variable COMPATINCLUDEDIR
 
 When used with --enable-libgdbm-compat, this variable points to the
diff --git a/README b/README
index 99e680a..369460a 100644
--- a/README
+++ b/README
@@ -56,12 +56,17 @@ a loader argument valid for the use with cc(1), e.g.: -lgdbm-1.8.
 Build gdbmexport with the gdbm library from the specified directory.
 
 ** --gdbm183-includedir=DIR
 
 Build gdbmexport with gdbm.h from the specified directory.
 
+** --without-readline
+
+Don't compile GNU Readline support.  By default, configure enables
+line-editing support if GNU Readline is available on the system.
+
 * Installation 
 
   make install
 
 * Bug reporting
 
diff --git a/configure.ac b/configure.ac
index 15270b9..336e05c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -121,12 +121,61 @@ AC_CHECK_MEMBERS([struct stat.st_blksize])
 AC_SUBST(GDBM183_LIBRARY)
 AC_SUBST(GDBM183_LIBDIR)
 AC_SUBST(GDBM183_INCLUDEDIR)
 AM_CONDITIONAL([COMPAT_OPT], [test "$want_compat" = yes])
 AM_CONDITIONAL([ENABLE_EXPORT], [test "$want_export" = yes])
 
+# Check for Curses libs.
+for lib in ncurses curses termcap
+do
+  AC_CHECK_LIB($lib, tputs, [CURSES_LIBS="-l$lib"; break])
+done
+
+AC_SUBST(CURSES_LIBS)
+# Readline
+AC_ARG_WITH([readline],
+            AC_HELP_STRING([--without-readline],
+                           [do not use readline]),
+            [
+case "${withval}" in
+  yes) status_readline=yes ;;
+  no)  status_readline=no ;;
+  *)   AC_MSG_ERROR(bad value ${withval} for --without-readline) ;;
+esac],[status_readline=probe])
+
+AC_SUBST(READLINE_LIBS)
+
+if test "$status_readline" != "no"; then
+  dnl FIXME This should only link in the curses libraries if it's
+  dnl really needed!
+  saved_LIBS=$LIBS
+  LIBS="$LIBS $CURSES_LIBS"
+  AC_CHECK_LIB(readline, readline,
+    [status_readline=yes],
+    [if test "$status_readline" = "yes"; then
+       AC_MSG_ERROR(readline requested but does not seem to be installed)
+     else
+       status_readline=no
+     fi])
+  LIBS=$saved_LIBS
+
+  if test "$status_readline" = "yes"; then
+    AC_CHECK_HEADERS(readline/readline.h,
+      AC_DEFINE(WITH_READLINE,1,[Enable use of readline]))
+      READLINE_LIBS="-lreadline $CURSES_LIBS"
+      saved_LIBS=$LIBS
+      LIBS="$LIBS $READLINE_LIBS"
+      AC_CHECK_FUNCS(rl_completion_matches)
+      LIBS=$saved_LIBS
+  fi
+else
+  status_readline=no
+fi
+
+AM_CONDITIONAL([GDBM_COND_READLINE], [test "$status_readline" = "yes"])
+
 # Initialize the test suite.
 AC_CONFIG_TESTDIR(tests)
 AC_CONFIG_FILES([tests/Makefile tests/atlocal po/Makefile.in])
 AM_MISSING_PROG([AUTOM4TE], [autom4te])
 
 AC_CONFIG_FILES([Makefile
diff --git a/doc/gdbm.texi b/doc/gdbm.texi
index 4c7c5c0..d172ad7 100644
--- a/doc/gdbm.texi
+++ b/doc/gdbm.texi
@@ -1825,12 +1825,18 @@ data? @kbd{3}
 
 However, such prompting is possible only in interactive mode.  In
 non-interactive mode (e.g.@: when running a script), all arguments must
 be supplied with each command, otherwise @command{gdbmtool} will report an
 error and exit immediately.
 
+@cindex readline
+@cindex GNU Readline
+If the package is compiled with GNU Readline, the input line can be
+edited (@pxref{Command Line Editing, ,
+Command Line Editing, readline, GNU Readline Library}).
+
 @menu
 * variables::      shell variables.
 * commands::       shell commands.
 * definitions::    how to define structured data.
 * startup files::
 @end menu
@@ -2110,12 +2116,28 @@ Import data from a flat dump file @var{file-name}
 (@pxref{Flat files}).  If the word @samp{replace} is given
 as an argument, any records with the same keys as the already
 existing ones will replace them.  The word @samp{nometa} turns off
 restoring meta-information from the dump file.
 @end deffn
 
+@deffn {command verb} history
+@deffnx {command verb} history @var{count}
+@deffnx {command verb} history @var{n} @var{count}
+Shows the command history list with line numbers.  When used without
+arguments, shows entire history.  When used with one argument,
+displays @var{count} last commands from the history.  With two
+arguments, displays @var{count} commands starting from @var{n}th
+command.  Command numbering starts with 1.
+
+This command is available only if GDBM was compiled with GNU Readline.
+The history is saved in file @file{.gdbmtool_history} in the user's
+home directory.  If this file exists upon startup, it is read to
+populate the history.  Thus, command history is preserved between
+@command{gdbmtool} invocations.
+@end deffn
+
 @deffn {command verb} list
 List the contents of the database.
 @end deffn
 
 @deffn {command verb} next [@var{key}]
 Sequential access: fetch and display the next record.  If the @var{key} is
diff --git a/doc/gdbmtool.1 b/doc/gdbmtool.1
index dae881c..c479822 100644
--- a/doc/gdbmtool.1
+++ b/doc/gdbmtool.1
@@ -10,13 +10,13 @@
 .\" but WITHOUT ANY WARRANTY; without even the implied warranty of
 .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 .\" GNU General Public License for more details.
 .\"
 .\" You should have received a copy of the GNU General Public License
 .\" along with GDBM. If not, see <http://www.gnu.org/licenses/>. */
-.TH GDBMTOOL 1 "May 18, 2016" "GDBM" "GDBM User Reference"
+.TH GDBMTOOL 1 "July 12, 2016" "GDBM" "GDBM User Reference"
 .SH NAME
 gdbmtool \- examine and modify a GDBM database
 .SH SYNOPSIS
 \fBgdbmtool\fR [\fB\-lmNnqrs\fR] [\fB\-b\fR \fISIZE\fR] [\fB\-c\fR \fISIZE\fR]\
  [\fB\-f\fR \fIFILE\fR] [\fB\-\-block\-size\fR=\fISIZE\fR]
          [\fB\-\-cache\-size\fR=\fISIZE\fR] [\fB\-\-file\fR \fIFILE\fR]\
@@ -155,13 +155,13 @@ Print the current bucket.
 \fBdelete\fR \fIKEY\fR
 Delete record with the given \fIKEY\fR.
 .TP
 .BR dir
 Print hash directory.
 .TP
-\fBexport\fR, \fBe\fR \fIFILE\-NAME\fR [\fBtruncate\fR] [\fBbinary\fR|\fBascii\fR]
+\fBexport\fR \fIFILE\-NAME\fR [\fBtruncate\fR] [\fBbinary\fR|\fBascii\fR]
 Export the database to the flat file \fIFILE\-NAME\fR.  This is equivalent to
 .BR gdbm_dump (1).
 
 This command will not overwrite an existing file, unless the 
 .B truncate
 parameter is also given.  Another optional parameter determines the type of
@@ -184,12 +184,23 @@ Print file header.
 .TP
 .BR help " or " ?
 Print a concise command summary, showing each command letter and
 verb with its parameters and a short description of what it does.
 Optional arguments are enclosed in square brackets.
 .TP
+.B history
+Shows the command history list with line numbers.  This command is
+available only if the program was compiled with GNU Readline.
+.TP
+\fBhistory\fR \fICOUNT\fR.
+Shows \fICOUNT\fR latest commands from the command history.
+.TP
+\fBhistory\fR \fIN\fR \fICOUNT\fR.
+Shows \fICOUNT\fR commands from the command history starting with \fIN\fRth
+command.
+.TP
 \fBimport\fR \fIFILE\-NAME\fR [\fBreplace\fR] [\fBnometa\fR]
 Import data from a flat dump file \fIFILE\-NAME\fR.
 If the
 .B replace
 argument is given, any records with the same keys as the already
 existing ones will replace them.  The
diff --git a/src/Makefile.am b/src/Makefile.am
index 6a05634..b55deb6 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -76,21 +76,31 @@ libgdbmapp_a_SOURCES =\
  parseopt.c\
  progname.c
 
 # Programs
 bin_PROGRAMS = gdbmtool gdbm_load gdbm_dump
 
-gdbmtool_LDADD  = ./libgdbmapp.a ./libgdbm.la
+gdbmtool_LDADD  = \
+ ./libgdbmapp.a\
+ ./libgdbm.la\
+ @READLINE_LIBS@
+
 gdbmtool_SOURCES = \
  datconv.c\
  gram.y\
  lex.l\
  gdbmtool.h\
  gdbmtool.c\
  var.c\
  util.c
 
+if GDBM_COND_READLINE
+  gdbmtool_SOURCES += input-rl.c
+else
+  gdbmtool_SOURCES += input-std.c
+endif
+
 AM_YFLAGS = -dtv
 #AM_LFLAGS = -d
 
 gdbm_load_LDADD  = ./libgdbmapp.a ./libgdbm.la 
 gdbm_dump_LDADD  = ./libgdbmapp.a ./libgdbm.la 
diff --git a/src/gdbmtool.c b/src/gdbmtool.c
index 65b6740..2d57cbc 100644
--- a/src/gdbmtool.c
+++ b/src/gdbmtool.c
@@ -320,26 +320,12 @@ get_screen_lines ()
   const char *lines = getenv ("LINES");
   if (lines)
     return strtol (lines, NULL, 10);
 #endif
   return -1;
 }
-
-
-#define ARG_UNUSED __attribute__ ((__unused__))
-
-#define NARGS 5
-
-struct handler_param
-{
-  int argc;
-  struct gdbmarg **argv;
-  FILE *fp;
-  void *data;
-};
-             
 
 /* Open database */
 void
 open_handler (struct handler_param *param)
 {
   if (opendb (param->argv[0]->v.string) == 0)
@@ -748,13 +734,13 @@ list_handler (struct handler_param *param)
 /* quit - quit the program */
 void
 quit_handler (struct handler_param *param ARG_UNUSED)
 {
   if (gdbm_file != NULL)
     gdbm_close (gdbm_file);
-
+  input_done ();
   exit (EXIT_OK);
 }
 
 /* export FILE [truncate] - export to a flat file format */
 void
 export_handler (struct handler_param *param)
@@ -888,24 +874,25 @@ struct argdef
 {
   char *name;
   int type;
   int ds;
 };
 
+#define NARGS 5
+
 struct command
 {
   char *name;           /* Command name */
   size_t len;           /* Name length */
   int tok;
   int  (*begin) (struct handler_param *param, size_t *);
   void (*handler) (struct handler_param *param);
   void (*end) (void *data);
   struct argdef args[NARGS];
   char *doc;
 };
-
 
 struct command command_tab[] = {
 #define S(s) #s, sizeof (#s) - 1
   { S(count), T_CMD,
     checkdb, count_handler, NULL,
     { { NULL } }, N_("count (number of entries)") },
@@ -1004,12 +991,19 @@ struct command command_tab[] = {
     NULL, close_handler, NULL,
     { { NULL } }, N_("close the database") },
   { S(open), T_CMD,
     NULL, open_handler, NULL,
     { { "FILE", GDBM_ARG_STRING }, { NULL } },
     N_("open new database") },
+#ifdef WITH_READLINE
+  { S(history), T_CMD,
+    input_history_begin, input_history_handler, NULL,
+    { { N_("[FROM]"), GDBM_ARG_STRING },
+      { N_("[COUNT]"), GDBM_ARG_STRING },
+      { NULL } }, N_("show input history") },
+#endif
 #undef S
   { 0 }
 };
 
 static int
 cmdcmp (const void *a, const void *b)
@@ -1023,12 +1017,45 @@ void
 sort_commands ()
 {
   qsort (command_tab, sizeof (command_tab) / sizeof (command_tab[0]) - 1,
          sizeof (command_tab[0]), cmdcmp);
 }
 
+/* Generator function for command completion.  STATE lets us know whether
+   to start from scratch; without any state (i.e. STATE == 0), then we
+   start at the top of the list. */
+char *
+command_generator (const char *text, int state)
+{
+  const char *name;
+  static int len;
+  static struct command *cmd;
+
+  /* If this is a new word to complete, initialize now.  This includes
+     saving the length of TEXT for efficiency, and initializing the index
+     variable to 0. */
+  if (!state)
+    {
+      cmd = command_tab;
+      len = strlen (text);
+    }
+
+  if (!cmd->name)
+    return NULL;
+
+  /* Return the next name which partially matches from the command list. */
+  while ((name = cmd->name))
+    {
+      cmd++;
+      if (strncmp (name, text, len) == 0)
+        return strdup (name);
+    }
+
+  /* If no names matched, then return NULL. */
+  return NULL;
+}
 
 /* ? - help handler */
 #define CMDCOLS 30
 
 int
 help_begin (struct handler_param *param ARG_UNUSED, size_t *exp_count)
@@ -1171,31 +1198,61 @@ gdbmarg_kvpair (struct kvpair *kvp, struct locus *loc)
     arg->loc = *loc;
   arg->v.kvpair = kvp;
   return arg;
 }
 
 struct slist *
-slist_new (char *s)
+slist_new_s (char *s)
 {
   struct slist *lp = emalloc (sizeof (*lp));
   lp->next = NULL;
   lp->str = s;
   return lp;
 }
 
+struct slist *
+slist_new (char const *s)
+{
+  return slist_new_s (estrdup (s));
+}
+
+struct slist *
+slist_new_l (char const *s, size_t l)
+{
+  char *copy = emalloc (l + 1);
+  memcpy (copy, s, l);
+  copy[l] = 0;
+  return slist_new_s (copy);
+}
+
 void
 slist_free (struct slist *lp)
 {
   while (lp)
     {
       struct slist *next = lp->next;
       free (lp->str);
       free (lp);
       lp = next;
     }
 }
+
+void
+slist_insert (struct slist **where, struct slist *what)
+{
+  if (*where)
+    {
+      while (what->next)
+        what = what->next;
+      what->next = (*where)->next;
+      (*where)->next = what;
+    }
+  else
+    what->next = NULL;
+  *where = what;
+}
 
 struct kvpair *
 kvpair_string (struct locus *loc, char *val)
 {
   struct kvpair *p = ecalloc (1, sizeof (*p));
   p->type = KV_STRING;
@@ -1213,13 +1270,12 @@ kvpair_list (struct locus *loc, struct slist *s)
   if (loc)
     p->loc = *loc;
   p->val.l = s;
   return p;
 }  
 
-
 static void
 kvlist_free (struct kvpair *kvp)
 {
   while (kvp)
     {
       struct kvpair *next = kvp->next;
@@ -1531,32 +1587,36 @@ int
 main (int argc, char *argv[])
 {
   int intr;  
   int opt;
   int bv;
   int norc = 0;
+  int res;
   char *source = "-";
   
   set_progname (argv[0]);
 
 #ifdef HAVE_SETLOCALE
   setlocale (LC_ALL, "");
 #endif
   bindtextdomain (PACKAGE, LOCALEDIR);
   textdomain (PACKAGE);
 
   sort_commands ();
-
+  
   /* Initialize variables. */
   intr = isatty (0);
+  interactive = intr; /* Used early by input_init */
   dsdef[DS_KEY] = dsegm_new_field (datadef_lookup ("string"), NULL, 1);
   dsdef[DS_CONTENT] = dsegm_new_field (datadef_lookup ("string"), NULL, 1);
 
   variable_set ("open", VART_STRING, "wrcreat");
   variable_set ("pager", VART_STRING, getenv ("PAGER"));
   
+  input_init ();
+  
   for (opt = parseopt_first (argc, argv, optab);
        opt != EOF;
        opt = parseopt_next ())
     switch (opt)
       {
       case 'f':
@@ -1637,8 +1697,10 @@ main (int argc, char *argv[])
   /* Welcome message. */
   if (intr && !variable_is_true ("quiet"))
     printf (_("\nWelcome to the gdbm tool.  Type ? for help.\n\n"));
 
   if (setsource (source, intr))
     exit (EXIT_FATAL);
-  return yyparse ();
+  res = yyparse ();
+  input_done ();
+  return res;
 }
diff --git a/src/gdbmtool.h b/src/gdbmtool.h
index 84f1409..d0e9aa0 100644
--- a/src/gdbmtool.h
+++ b/src/gdbmtool.h
@@ -21,12 +21,14 @@
 #include "gdbmapp.h"
 #include <stdlib.h>
 #include <stdio.h>
 #include <stdarg.h>
 #include <ctype.h>
 
+#define ARG_UNUSED __attribute__ ((__unused__))
+
 /* Position in input file */
 struct point
 {
   char *file;             /* file name */
   unsigned line;          /* line number */  
   unsigned col;           /* column number */ 
@@ -91,32 +93,46 @@ typedef struct locus gdbm_yyltype_t;
 
 void vlerror (struct locus *loc, const char *fmt, va_list ap);
 void lerror (struct locus *loc, const char *fmt, ...);
 
 void terror (const char *fmt, ...);
 
-void print_prompt (void);
+char *make_prompt (void);
 
 int setsource (const char *filename, int intr);
 
 extern char *file_name;
 extern int interactive;
 extern int open_mode;
 
 #define GDBMTOOLRC ".gdbmtoolrc"
 #define GDBMTOOL_DEFFILE "junk.gdbm"
+
+ssize_t input_read (FILE *fp, char *buf, size_t size);
+void input_init (void);
+void input_done (void);
+
+struct handler_param;
+void input_history_handler (struct handler_param *param);
+int input_history_begin (struct handler_param *param, size_t *exp_count);
+
+void print_prompt_at_bol (void);
+char *command_generator (const char *text, int state);
 
 
 struct slist
 {
   struct slist *next;
   char *str;
 };
 
-struct slist *slist_new (char *s);
+struct slist *slist_new (char const *s);
+struct slist *slist_new_s (char *s);
+struct slist *slist_new_l (char const *s, size_t l);
 void slist_free (struct slist *);
+void slist_insert (struct slist **where, struct slist *what);
 
 #define KV_STRING 0
 #define KV_LIST   1
 
 struct kvpair
 {
@@ -158,12 +174,20 @@ struct gdbmarg
 /* List of arguments */
 struct gdbmarglist
 {
   struct gdbmarg *head, *tail;
 };
 
+struct handler_param
+{
+  int argc;
+  struct gdbmarg **argv;
+  FILE *fp;
+  void *data;
+};
+
 void gdbmarglist_init (struct gdbmarglist *, struct gdbmarg *);
 void gdbmarglist_add (struct gdbmarglist *, struct gdbmarg *);
 void gdbmarglist_free (struct gdbmarglist *lst);
 
 struct gdbmarg *gdbmarg_string (char *, struct locus *);
 struct gdbmarg *gdbmarg_datum (datum *, struct locus *);
@@ -259,6 +283,9 @@ int datum_scan (datum *dat, struct dsegm *ds, struct kvpair *kv);
 void dsprint (FILE *fp, int what, struct dsegm *ds);
 
 char *mkfilename (const char *dir, const char *file, const char *suf);
 char *tildexpand (char *s);
 int vgetyn (const char *prompt, va_list ap);
 int getyn (const char *prompt, ...);
+
+int getnum (int *pnum, char *arg, char **endp);
+int get_screen_lines (void);
diff --git a/src/gram.y b/src/gram.y
index 9a6e3c2..2f6d7c0 100644
--- a/src/gram.y
+++ b/src/gram.y
@@ -165,19 +165,18 @@ value     : string
               $$ = kvpair_list (&@1, $2.head);
             }
           ;
 
 slist     : string
             {
-              $$.head = $$.tail = slist_new ($1);
+              $$.head = $$.tail = slist_new_s ($1);
             }
           | slist ',' string
             {
-              struct slist *s = slist_new ($3);
-              $1.tail->next = s;
-              $1.tail = s;
+              struct slist *s = slist_new_s ($3);
+              slist_insert (&$1.tail, s);
               $$ = $1;
             }
           ;
 
 string    : T_IDENT
           | T_WORD
diff --git a/src/input-rl.c b/src/input-rl.c
new file mode 100644
index 0000000..f435ed4
--- a/dev/null
+++ b/src/input-rl.c
@@ -0,0 +1,235 @@
+/* This file is part of GDBM, the GNU data base manager.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+
+   GDBM is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   GDBM is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with GDBM. If not, see <http://www.gnu.org/licenses/>.    */
+
+#include "gdbmtool.h"
+#include <readline/readline.h>
+#include <readline/history.h>
+
+static char *pre_input_line;
+
+static int
+pre_input (void)
+{
+  if (pre_input_line)
+    {
+      rl_insert_text (pre_input_line);
+      free (pre_input_line);
+      pre_input_line = NULL;
+      rl_redisplay ();
+    }
+  return 0;
+}
+
+static int
+retrieve_history (char *str)
+{
+  char *out;
+  int rc;
+
+  rc = history_expand (str, &out);
+  switch (rc)
+    {
+    case -1:
+      yyerror (out);
+      free (out);
+      return 1;
+
+    case 0:
+      break;
+
+    case 1:
+      pre_input_line = out;
+      return 1;
+
+    case 2:
+      printf ("%s\n", out);
+      free (out);
+      return 1;
+    }
+  return 0;
+}
+
+ssize_t
+input_read (FILE *fp, char *buf, size_t size)
+{
+  static char *input_line;
+  static size_t input_length;
+  static size_t input_off;
+#define input_ptr() (input_line + input_off)
+#define input_size() (input_length - input_off)
+  
+  if (interactive)
+    {
+      size_t len = input_size ();
+      if (!len)
+        {
+          if (input_line)
+            {
+            newline:
+              free (input_line);
+              input_line = NULL;
+              buf[0] = '\n';
+              return 1;
+            }
+          else
+            {
+              char *prompt;
+            again:
+              prompt = make_prompt ();
+              input_line = readline (prompt);
+              free (prompt);
+              if (!input_line)
+                return 0;
+              input_length = strlen (input_line);
+              input_off = 0;
+              if (input_length)
+                {
+                  if (retrieve_history (input_line))
+                    {
+                      free (input_line);
+                      goto again;
+                    }
+                }
+              else
+                goto newline;
+              len = input_size ();
+              add_history (input_line);
+            }
+        }
+
+      if (len > size)
+        len = size;
+      memcpy (buf, input_ptr (), len);
+      input_off += len;
+
+      return len;
+    }
+  return fread (buf, 1, size, fp);
+} 
+
+struct history_param
+{
+  int from;
+  int count;
+};
+  
+int
+input_history_begin (struct handler_param *param, size_t *exp_count)
+{
+  struct history_param *p;
+  int from = 0, count = history_length;
+
+  switch (param->argc)
+    {
+    case 1:
+      if (getnum (&count, param->argv[0]->v.string, NULL))
+        return 1;
+      if (count > history_length)
+        count = history_length;
+      else
+        from = history_length - count;
+      break;
+
+    case 2:
+      if (getnum (&from, param->argv[0]->v.string, NULL))
+        return 1;
+      if (from)
+        --from;
+      if (getnum (&count, param->argv[1]->v.string, NULL))
+        return 1;
+
+      if (count > history_length)
+        count = history_length;
+    }
+  p = emalloc (sizeof *p);
+  p->from = from;
+  p->count = count;
+  param->data = p;
+  if (exp_count)
+    *exp_count = count;
+  return 0;
+}
+
+void
+input_history_handler (struct handler_param *param)
+{
+  struct history_param *p = param->data;
+  int i;
+  HIST_ENTRY **hlist;
+  FILE *fp = param->fp;
+  
+  hlist = history_list ();
+  for (i = 0; i < p->count; i++)
+    fprintf (fp, "%4d) %s\n", p->from + i + 1, hlist[p->from + i]->line);
+}
+
+#define HISTFILE_PREFIX "~/."
+#define HISTFILE_SUFFIX "_history"
+
+static char *
+get_history_file_name ()
+{
+  static char *filename = NULL;
+
+  if (!filename)
+    {
+      char *hname;
+
+      hname = emalloc (sizeof HISTFILE_PREFIX + strlen (rl_readline_name) +
+                       sizeof HISTFILE_SUFFIX - 1);
+      strcpy (hname, HISTFILE_PREFIX);
+      strcat (hname, rl_readline_name);
+      strcat (hname, HISTFILE_SUFFIX);
+      filename = tildexpand (hname);
+      free (hname);
+    }
+  return filename;
+}
+ 
+static char **
+shell_completion (const char *text, int start, int end)
+{
+  char **matches;
+
+  matches = (char **) NULL;
+
+  /* If this word is at the start of the line, then it is a command
+     to complete.  Otherwise it is the name of a file in the current
+     directory. */
+  if (start == 0)
+    matches = rl_completion_matches (text, command_generator);
+
+  return (matches);
+}
+
+void
+input_init (void)
+{
+  /* Allow conditional parsing of the ~/.inputrc file. */
+  rl_readline_name = (char *) progname;
+  rl_attempted_completion_function = shell_completion;
+  rl_pre_input_hook = pre_input;
+  if (interactive)
+    read_history (get_history_file_name ());
+}
+
+void
+input_done (void)
+{
+  if (interactive)
+    write_history (get_history_file_name ());
+}
+
diff --git a/src/input-std.c b/src/input-std.c
new file mode 100644
index 0000000..4508368
--- a/dev/null
+++ b/src/input-std.c
@@ -0,0 +1,43 @@
+/* This file is part of GDBM, the GNU data base manager.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+
+   GDBM is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   GDBM is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with GDBM. If not, see <http://www.gnu.org/licenses/>.    */
+
+#include "gdbmtool.h"
+
+ssize_t
+input_read (FILE *fp, char *buf, size_t size)
+{
+  if (interactive)
+    {
+      print_prompt_at_bol ();
+      if (fgets (buf, size, fp) == NULL)
+        return 0;
+      return strlen (buf);
+    }
+  return fread (buf, 1, size, fp);
+}
+
+void
+input_init (void)
+{
+  /* nothing */
+}
+
+void
+input_done (void)
+{
+  /* nothing */
+}
+
diff --git a/src/lex.l b/src/lex.l
index 9c2c5f8..236474d 100644
--- a/src/lex.l
+++ b/src/lex.l
@@ -43,24 +43,22 @@ advance_line ()
   while (0);
 
 #undef YY_INPUT
 #define YY_INPUT(buf,result,max_size)                                   \
           do                                                            \
             {                                                           \
-              result = read_input (buf, max_size);                      \
+              result = input_read (yyin, buf, max_size);                \
             }                                                           \
   while (0);
  
 void string_begin (void);
 void string_add (const char *s, int l);
 void string_addc (int c);
 char *string_end (void);
 int unescape (int c);
 
-static ssize_t read_input (char *buf, size_t size);
-
 struct context                /* Input context */
 {
   struct context *parent;     /* Pointer to the parent context */
   struct locus locus;         /* Locus */
   struct point point;
   int interactive;
@@ -312,24 +310,22 @@ begin_def (void)
 void
 end_def (void)
 {
   BEGIN (INITIAL);
 } 
 
-static ssize_t
-read_input (char *buf, size_t size)
+void
+print_prompt_at_bol (void)
 {
-  if (interactive)
+  if (YY_AT_BOL ())
     {
-      if (YY_AT_BOL ())
-        print_prompt ();
-      if (fgets (buf, size, yyin) == NULL)
-        return 0;
-      return strlen (buf);
+      char *s = make_prompt ();
+      fputs (s, stdout);
+      fflush (stdout);
+      free (s);
     }
-  return fread (buf, 1, size, yyin);
 }
   
 
 struct strseg
 {
   struct strseg *next;
@@ -450,121 +446,151 @@ lerror (struct locus *loc, const char *fmt, ...)
   va_start (ap, fmt);
   vlerror (loc, fmt, ap);
   va_end (ap);
 }
 
 
-struct prompt_exp;
-
-void
-pe_file_name (struct prompt_exp *p)
+static struct slist *
+pe_file_name (void)
 {
-  if (file_name)
-    fwrite (file_name, strlen (file_name), 1, stdout);
+  return file_name ? slist_new (file_name) : NULL;
 }
 
-void
-pe_program_name (struct prompt_exp *p)
+static struct slist *
+pe_program_name (void)
 {
-  fwrite (progname, strlen (progname), 1, stdout);
+  return slist_new (progname);
 }
 
-void
-pe_package_name (struct prompt_exp *p)
+static struct slist *
+pe_package_name (void)
 {
-  fwrite (PACKAGE_NAME, sizeof (PACKAGE_NAME) - 1, 1, stdout);
+  return slist_new (PACKAGE_NAME);
 }
 
-void
-pe_program_version (struct prompt_exp *p)
+static struct slist *
+pe_program_version (void)
 {
-  fwrite (PACKAGE_VERSION, sizeof (PACKAGE_VERSION) - 1, 1, stdout);
+  return slist_new (PACKAGE_VERSION);
 }
 
-void
-pe_space (struct prompt_exp *p)
+static struct slist *
+pe_space (void)
 {
-  fwrite (" ", 1, 1, stdout);
+  return slist_new (" ");
 }
 
 struct prompt_exp
 {
   int ch;
-  void (*fun) (struct prompt_exp *);
-  char *cache;
+  struct slist *(*fun) (void);
 };
 
 struct prompt_exp prompt_exp[] = {
   { 'f', pe_file_name },
   { 'p', pe_program_name },
   { 'P', pe_package_name },
   { 'v', pe_program_version },
   { '_', pe_space },
   { 0 }
 };
 
-static void
-expand_char (int c)
+static int
+expand_char (int c, struct slist **tailp)
 {
   struct prompt_exp *p;
 
   if (c && c != '%')
     {
       for (p = prompt_exp; p->ch; p++)
         {
           if (c == p->ch)
             {
-              if (p->cache)
-                free (p->cache);
-              p->fun (p);
-              return;
+              struct slist *s = p->fun ();
+              if (s)
+                slist_insert (tailp, s);
+              return 0;
             }
         }
     }
-  putchar ('%');
-  putchar (c);
+  return 1;
 }
 
 char const *
-psname ()
+psname (void)
 {
   if (YYSTATE == DEF || YYSTATE == MLSTR)
     return "ps2";
   return "ps1";
 }
 
-void
-print_prompt ()
+char *
+make_prompt (void)
 {
   const char *s;
   const char *prompt;
-
+  struct slist *head = NULL, *tail = NULL, *p;
+  char *ret, *end;
+  size_t len;
+  
   switch (variable_get (psname (), VART_STRING, (void *) &prompt))
     {
     case VAR_OK:
       break;
 
     case VAR_ERR_NOTSET:
-      return;
+      return NULL;
       
     default:
       abort ();
     }
-  
-  for (s = prompt; *s; s++)
+
+  for (s = prompt; *s; )
     {
-      if (*s == '%')
+      if (*s == '%' && s[1])
         {
-          if (!*++s)
+          if (s > prompt)
+            {
+              slist_insert (&tail, slist_new_l (prompt, s - prompt));
+              if (!head)
+                head = tail;
+            }
+          if (expand_char (s[1], &tail) == 0)
             {
-              putchar ('%');
-              break;
+              if (!head)
+                head = tail;
+              prompt = s + 2;
             }
-          expand_char (*s);
+          else
+            prompt = s;
+          s += 2;
         }
       else
-        putchar (*s);
+        ++s;
+    }
+
+  if (s > prompt)
+    {
+      slist_insert (&tail, slist_new_l (prompt, s - prompt));
+      if (!head)
+        head = tail;
     }
 
-  fflush (stdout);
+  len = 0;
+  for (p = head; p; p = p->next)
+    len += strlen (p->str);
+
+  ret = emalloc (len + 1);
+  end = ret;
+  for (p = head; p; p = p->next)
+    {
+      s = p->str;
+      while (*s)
+        *end++ = *s++;
+    }
+  *end = 0;
+
+  slist_free (head);
+  
+  return ret;
 }