If stdin and stdout are TTYs, use readline() where possible.

configure

@@ -2477,6 +2477,8 @@ as_fn_append ac_header_c_list " sys/stat.h sys_stat_h HAVE_SYS_STAT_H"
 as_fn_append ac_header_c_list " sys/types.h sys_types_h HAVE_SYS_TYPES_H"
 as_fn_append ac_header_c_list " unistd.h unistd_h HAVE_UNISTD_H"
 as_fn_append ac_header_c_list " sys/time.h sys_time_h HAVE_SYS_TIME_H"
+as_fn_append ac_header_c_list " readline/readline.h readline_readline_h HAVE_READLINE_READLINE_H"
+as_fn_append ac_header_c_list " readline/history.h readline_history_h HAVE_READLINE_HISTORY_H"
 
 # Auxiliary files required by this configure script.
 ac_aux_files="install-sh"
@@ -3941,6 +3943,57 @@ then :
 
 fi
 
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for readline in -lreadline" >&5
+printf %s "checking for readline in -lreadline... " >&6; }
+if test ${ac_cv_lib_readline_readline+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) ac_check_lib_save_LIBS=$LIBS
+LIBS="-lreadline  $LIBS"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.
+   The 'extern "C"' is for builds by C++ compilers;
+   although this is not generally supported in C code supporting it here
+   has little cost and some practical benefit (sr 110532).  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char readline (void);
+int
+main (void)
+{
+return readline ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"
+then :
+  ac_cv_lib_readline_readline=yes
+else case e in #(
+  e) ac_cv_lib_readline_readline=no ;;
+esac
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_readline_readline" >&5
+printf "%s\n" "$ac_cv_lib_readline_readline" >&6; }
+if test "x$ac_cv_lib_readline_readline" = xyes
+then :
+  printf "%s\n" "#define HAVE_LIBREADLINE 1" >>confdefs.h
+
+  LIBS="-lreadline $LIBS"
+
+fi
+
 ac_header= ac_cache=
 for ac_item in $ac_header_c_list
 do
@@ -3973,6 +4026,8 @@ fi
 
 
 
+
+
 # The cast to long int works around a bug in the HP C Compiler
 # version HP92453-01 B.11.11.23709.GP, which incorrectly rejects
 # declarations like 'int a3[[(sizeof (unsigned char)) >= 0]];'.
@@ -4270,6 +4325,12 @@ then :
   printf "%s\n" "#define HAVE_INOTIFY_INIT1 1" >>confdefs.h
 
 fi
+ac_fn_c_check_func "$LINENO" "readline" "ac_cv_func_readline"
+if test "x$ac_cv_func_readline" = xyes
+then :
+  printf "%s\n" "#define HAVE_READLINE 1" >>confdefs.h
+
+fi
 
 
 VERSION=$PACKAGE_VERSION

configure.ac

@@ -30,7 +30,8 @@ AC_PATH_PROG([PERL], [perl])
 
 dnl Checks for libraries.
 AC_CHECK_LIB(m, sqrt)
-AC_CHECK_HEADERS_ONCE([sys/time.h stdint.h])
+AC_CHECK_LIB(readline, readline)
+AC_CHECK_HEADERS_ONCE([sys/time.h stdint.h readline/readline.h readline/history.h])
 
 dnl Integer sizes
 AC_CHECK_SIZEOF(unsigned int)
@@ -84,7 +85,7 @@ if test "$?" != 0 ; then
     echo "*** COULD NOT DETERMINE RELEASE DATE: docs/WHATSNEW is incorrect!"
     exit 1
 fi
-AC_CHECK_FUNCS(strdup strcasecmp strncasecmp setenv unsetenv glob mbstowcs setlocale initgroups inotify_init1)
+AC_CHECK_FUNCS(strdup strcasecmp strncasecmp setenv unsetenv glob mbstowcs setlocale initgroups inotify_init1 readline)
 
 VERSION=$PACKAGE_VERSION
 CONFIG_CMD="$0$ac_configure_args_raw"

src/config.h.in

@@ -45,6 +45,9 @@
 /* Define to 1 if you have the <stdlib.h> header file. */
 #undef HAVE_STDLIB_H
 
+/* Define to 1 if you have the `readline' function. */
+#undef HAVE_READLINE
+
 /* Define to 1 if you have the `strcasecmp' function. */
 #undef HAVE_STRCASECMP
 
@@ -81,6 +84,12 @@
 /* Define to 1 if you have the <wctype.h> header file. */
 #undef HAVE_WCTYPE_H
 
+/* Define to 1 if you have the <readline/history.h> header file. */
+#undef HAVE_READLINE_HISTORY_H
+
+/* Define to 1 if you have the <readline/readline.h> header file. */
+#undef HAVE_READLINE_READLINE_H
+
 /* Define to the address where bug reports for this package should be sent. */
 #undef PACKAGE_BUGREPORT
 

src/custom.h

@@ -159,3 +159,15 @@
 #else
 #undef REM_USE_WCHAR
 #endif
+
+#if defined(HAVE_READLINE) && defined(HAVE_READLINE_READLINE_H)
+#define USE_READLINE 1
+#else
+#undef USE_READLINE 1
+#endif
+
+#if defined(HAVE_READLINE) && defined(HAVE_READLINE_READLINE_H) && defined(HAVE_READLINE_HISTORY_H)
+#define USE_READLINE_HISTORY 1
+#else
+#undef USE_READLINE_HISTORY 1
+#endif

src/custom.h.in

@@ -22,8 +22,8 @@
 /* The default values are initially set to the city hall in Ottawa,    */
 /* Ontario, Canada.                                                    */
 /*---------------------------------------------------------------------*/
-#define DEFAULT_LATITUDE 45.420556
-#define DEFAULT_LONGITUDE -75.689722
+#define DEFAULT_LATITUDE 45.42055555555555
+#define DEFAULT_LONGITUDE -75.68944444444445
 #define LOCATION "Ottawa"
 
 /*---------------------------------------------------------------------*/
@@ -159,3 +159,15 @@
 #else
 #undef REM_USE_WCHAR
 #endif
+
+#if defined(HAVE_READLINE) && defined(HAVE_READLINE_READLINE_H)
+#define USE_READLINE 1
+#else
+#undef USE_READLINE 1
+#endif
+
+#if defined(HAVE_READLINE) && defined(HAVE_READLINE_READLINE_H) && defined(HAVE_READLINE_HISTORY_H)
+#define USE_READLINE_HISTORY 1
+#else
+#undef USE_READLINE_HISTORY 1
+#endif

src/files.c

@@ -41,6 +41,13 @@
 #include "globals.h"
 #include "err.h"
 
+#ifdef USE_READLINE
+#include <readline/readline.h>
+#endif
+#ifdef USE_READLINE_HISTORY
+#include <readline/history.h>
+#endif
+
 
 /* Convenient macros for closing files */
 #define FCLOSE(fp) ((((fp)!=stdin)) ? (fclose(fp),(fp)=NULL) : ((fp)=NULL))
@@ -134,6 +141,9 @@ void InitFiles(void)
         fprintf(ErrFp, "Unable to initialize filename hash table: Out of memory.  Exiting.\n");
         exit(1);
     }
+#ifdef USE_READLINE_HISTORY
+    using_history();
+#endif
 }
 
 void SetCurrentFilename(char const *fname)
@@ -280,7 +290,9 @@ static int ReadLineFromFile(int use_pclose)
     int l;
     char copy_buffer[4096];
     size_t n;
+    int force_eof = 0;
 
+    int read_some = 0;
     DynamicBuffer buf;
 
     DBufInit(&buf);
@@ -288,17 +300,48 @@ static int ReadLineFromFile(int use_pclose)
 
     LineNoStart = LineNo+1;
     while(fp) {
+#ifdef USE_READLINE
+        if (fileno(fp) == STDIN_FILENO && isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
+            char *l;
+            if (read_some) {
+                l = readline("Rem...> ");
+            } else {
+                l = readline("Remind> ");
+                read_some = 1;
+            }
+            if (l) {
+#ifdef USE_READLINE_HISTORY
+                if (*l) {
+                    add_history(l);
+                }
+#endif
+                DBufFree(&buf);
+                if (DBufPuts(&buf, l) != OK) {
+                    free(l);
+                    DBufFree(&buf);
+                    return E_NO_MEM;
+                }
+                free(l);
+                force_eof = 0;
+            } else {
+                force_eof = 1;
+            }
+        } else {
+#endif
         if (DBufGets(&buf, fp) != OK) {
             DBufFree(&LineBuffer);
             return E_NO_MEM;
         }
+#ifdef USE_READLINE
+        }
+#endif
         LineNo++;
         if (ferror(fp)) {
             DBufFree(&buf);
             DBufFree(&LineBuffer);
             return E_IO_ERR;
         }
-        if (feof(fp)) {
+        if (feof(fp) || force_eof) {
             if (use_pclose) {
                 PCLOSE(fp);
             } else {