Add configuration file support.

README.md

@@ -30,7 +30,14 @@ Then run:
 
 Usage
 -----
-    $ xcape [-d] [-f] [-t <timeout ms>] [-e <map-expression>]
+    $ xcape [file ...] [-d] [-f] [-t <timeout ms>] [-e <map-expression>]
+
+### `file ...`
+
+Configuration files containing expressions. Each line is an expression 
+following the form `'ModKey=Key[|OtherKey]`. Comments may be introduced
+via the `#` character, which will ignore the proceeding line. To read
+from standard input, you may use the `-` character.
 
 ### `-d`
 
@@ -68,6 +75,18 @@ key name is found.
 
         xcape -e 'Shift_L=Escape;Control_L=Control_L|O'
 
++   This configuration file produces the same behavior as above.
+
+        # map.xcape
+        # Map left shift to Escape
+        Shift_L=Escape
+        # Map Left control to Ctrl-O 
+        Control_L=Control_L|O
+
+    which can then be read via xcape using the following command
+
+        xcape map.xcape
+
 +   In conjunction with xmodmap it is possible to make an ordinary key act
     as an extra modifier. First map the key to the modifier with xmodmap
     and then the modifier back to the key with xcape. However, this has

xcape.1

@@ -5,6 +5,7 @@ xcape \- use a modifier key as another key
 
 .SH SYNOPSIS
 .B xcape
+[file ...]
 [\fB-d\fR]
 [\fB-f\fR]
 [\fB-t\fR \fItimeout\fR]
@@ -17,6 +18,13 @@ key in place of \fIControl_L\fR (Left Control).
 
 .SH OPTIONS
 .TP
+.BR file\ ...
+Configuration files containing expressions. Each line is an expression 
+following the form \'\fBModKey\fR=\fBKey\fR[|\fBOtherKey\fR]\'.
+Comments may be introduced via the '#' character, which will
+ignore the proceeding line. To read from standard input, you may use
+the '\-' character.
+.TP
 .BR \-d
 Debug mode.  Will run as a foreground process and print debug information.
 .TP

xcape.c

@@ -20,6 +20,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <ctype.h>
 #include <string.h>
 #include <sys/time.h>
 #include <signal.h>
@@ -76,6 +77,8 @@ void *sig_handler (void *user_data);
 
 void intercept (XPointer user_data, XRecordInterceptData *data);
 
+KeyMap_t *parse_confs (Display *ctrl_conn, char **files, size_t n_confs, Bool debug);
+
 KeyMap_t *parse_mapping (Display *ctrl_conn, char *mapping, Bool debug);
 
 void delete_mapping (KeyMap_t *map);
@@ -96,7 +99,9 @@ int main (int argc, char **argv)
     int dummy, ch;
 
     static char default_mapping[] = "Control_L=Escape";
-    char *mapping = default_mapping;
+    char *mapping = NULL;
+    char **conf_files = NULL;
+    size_t n_conf = 0;
 
     XRecordRange *rec_range = XRecordAllocRange();
     XRecordClientSpec client_spec = XRecordAllClients;
@@ -147,9 +152,8 @@ int main (int argc, char **argv)
 
     if (optind < argc)
     {
-        fprintf (stderr, "Not a command line option: '%s'\n", argv[optind]);
-        print_usage (argv[0]);
-        return EXIT_SUCCESS;
+        conf_files = argv + optind;
+        n_conf = argc - optind;
     }
 
     if (!XInitThreads ())
@@ -184,12 +188,56 @@ int main (int argc, char **argv)
         exit (EXIT_FAILURE);
     }
 
-    self->map = parse_mapping (self->ctrl_conn, mapping, self->debug);
+    /* This reduces error-prone logic when rearranging the parsing order,
+     * as we don't need to check for self->map existence */
+
+    KeyMap_t **current_map = &self->map;
+
+    /* parse mappings given by -e first */
 
-    if (self->map == NULL)
+    if (mapping)
     {
-        fprintf (stderr, "Failed to parse_mapping\n");
-        exit (EXIT_FAILURE);
+        KeyMap_t *emapping = parse_mapping (self->ctrl_conn, mapping, self->debug);
+
+        if (emapping == NULL)
+        {
+            fprintf (stderr, "Failed to parse_mapping\n");
+            exit (EXIT_FAILURE);
+        }
+
+        *current_map = emapping;
+        current_map = &(*current_map)->next;
+    }
+
+    /* parse config files */
+
+    if (conf_files)
+    {
+        KeyMap_t *conf_mapping = parse_confs (self->ctrl_conn, conf_files, n_conf, self->debug);
+
+        if (conf_mapping == NULL)
+        {
+            fprintf (stderr, "Failed to parse_confs\n");
+            exit (EXIT_FAILURE);
+        }
+
+        *current_map = conf_mapping;
+        current_map = &(*current_map)->next;
+    }
+
+    /* if there were no config files or mappings supplied, try the default mapping */
+
+    if (!conf_files && !mapping)
+    {
+        KeyMap_t *def_mapping = parse_mapping (self->ctrl_conn, default_mapping, self->debug);
+
+        if (def_mapping == NULL)
+        {
+            fprintf (stderr, "Failed to parse_mapping default\n");
+            exit (EXIT_FAILURE);
+        }
+
+        *current_map = def_mapping;
     }
 
     if (self->foreground != True)
@@ -438,7 +486,7 @@ KeyMap_t *parse_token (Display *dpy, char *token, Bool debug)
             errno = 0;
             parsed_code = strtoul (from, NULL, 0); /* dec, oct, hex automatically */
             if (errno == 0
-                   && parsed_code <=255
+                   && parsed_code <= 255
                    && XkbKeycodeToKeysym (dpy, (KeyCode) parsed_code, 0, 0) != NoSymbol)
             {
                 km->UseKeyCode = True;
@@ -538,6 +586,105 @@ KeyMap_t *parse_token (Display *dpy, char *token, Bool debug)
     return km;
 }
 
+char *read_line (FILE *file)
+{
+    size_t cap = 1024;
+    size_t nlen = 0;
+    char *line = realloc (NULL, cap*sizeof(char));
+
+    int c = EOF;
+    int reading = 1;
+    while (reading)
+    {
+        c = fgetc(file);
+        if (nlen == cap)
+        {
+            cap *= 2;
+            line = realloc (line, cap*sizeof(char));
+        }
+        switch (c)
+        {
+        case '\r':
+            /* check for \r\n */
+            {
+                int c = fgetc(file);
+                if(c != '\n'){
+                    ungetc(c, file);
+                }
+            }
+            break;
+        case '\n': /* FALLTHROUGH */
+        case '\0':
+            line[nlen++] = '\0';
+            reading = 0;
+            break;
+        case EOF:
+            reading = 0;
+            break;
+        default:
+            line[nlen++] = c;
+            break;
+        }
+    }
+    if(nlen == 0)
+    {
+        free (line);
+        return NULL;
+    }
+    /* shrink down to size */
+    line = realloc (line, nlen);
+    return line;
+}
+
+KeyMap_t *parse_confs (Display *ctrl_conn, char **files, size_t n_confs, Bool debug)
+{
+    KeyMap_t *rval = NULL;
+    KeyMap_t **current = &rval;
+    for (size_t i = 0; i < n_confs; ++i)
+    {
+        char *filename = files[i];
+        FILE *file = NULL;
+
+        /* determine if reading from stdin or file */
+        if (!strcmp (filename, "-"))
+        {
+            file = stdin;
+        }
+        else
+        {
+            file = fopen (filename, "r");
+            if (file == NULL)
+            {
+                fprintf (stderr, "unable to open file %s: %s\n", filename, strerror(errno));
+                break;
+            }
+        }
+
+        /* Read file line by line, treating each line as an expression */
+        char *line = NULL;
+        while ((line = read_line (file)) != NULL)
+        {
+            /* trim leading whitespace */
+            char *trimmed = line;
+            while(isspace(*trimmed)) ++trimmed;
+            /* check for comments or empty lines */
+            if(*trimmed && *trimmed != '#'){
+                *current = parse_token (ctrl_conn, trimmed, debug);
+                if (*current == NULL)
+                {
+                    break;
+                }
+                current = &(*current)->next;
+            }
+            free (line);
+        }
+
+        if (file != stdin)
+            fclose (file);
+    }
+    return rval;
+}
+
 KeyMap_t *parse_mapping (Display *ctrl_conn, char *mapping, Bool debug)
 {
     char     *token;
@@ -589,6 +736,6 @@ void delete_keys (Key_t *keys)
 
 void print_usage (const char *program_name)
 {
-    fprintf (stdout, "Usage: %s [-d] [-f] [-t timeout_ms] [-e <mapping>]\n", program_name);
+    fprintf (stdout, "Usage: %s [file ...] [-d] [-f] [-t timeout_ms] [-e <mapping>]\n", program_name);
     fprintf (stdout, "Runs as a daemon unless -d or -f flag is set\n");
 }