select screen

src/args.c

@@ -6,21 +6,29 @@
 #include <string.h>
 
 void print_help(int status_code) {
-  puts(PACKAGE " " VERSION "\n\n"
-               "usage: " PACKAGE " "
-               "[--help] "
-               "[-v] "
-               "\n\n"
-               "Fusion Of Real-time Generative Effects.\n\n"
-               "options:\n"
-               "  --help             show this help message and exit\n"
-               "  -v, --version      print version\n");
+  puts(PACKAGE
+       " " VERSION "\n\n"
+       "usage: " PACKAGE " "
+       "[--help] "
+       "[-v] "
+       "[-s=SCREEN] "
+       "\n\n"
+       "Fusion Of Real-time Generative Effects.\n\n"
+       "options:\n"
+       "  --help             show this help message and exit\n"
+       "  -v, --version      print version\n"
+       "  -s, --screen       output screen number (default: primary)\n");
   exit(status_code);
 }
 
 void invalid_arg(char *arg) {
   fprintf(stderr, "invalid argument: '%s'\n\n", arg);
-  print_help(EXIT_FAILURE);
+  print_help(1);
+}
+
+void invalid_value(char *arg, char *value) {
+  fprintf(stderr, "invalid value for argument '%s': '%s'\n\n", arg, value);
+  print_help(1);
 }
 
 bool is_arg(char *arg, char *ref) { return strcoll(arg, ref) == 0; }
@@ -30,8 +38,37 @@ char *split_arg_value(char *arg) {
   return strtok(NULL, "=");
 }
 
-parameters parse_args(int argc, char **argv) {
-  parameters params;
+bool is_digit(char c) { return c >= '0' && c <= '9'; }
+
+bool is_number(char *value) {
+  if (value == NULL) {
+    return false;
+  }
+  unsigned long value_len = strlen(value);
+  unsigned int i;
+  for (i = 0; i < value_len; i++) {
+    if (!is_digit(value[i])) {
+      return false;
+    }
+  }
+  return true;
+}
+
+unsigned char parse_uchar(char *arg, char *value) {
+  if (!is_number(value)) {
+    invalid_value(arg, value);
+  }
+  unsigned long long tmp_value = (unsigned long long)atoll(value);
+  if (tmp_value >= 256) {
+    invalid_value(arg, value);
+  }
+  return (unsigned char)tmp_value;
+}
+
+Parameters parse_args(int argc, char **argv) {
+  Parameters params;
+
+  params.screen = 0;
 
   int i;
   char *arg;
@@ -44,6 +81,8 @@ parameters parse_args(int argc, char **argv) {
     } else if (is_arg(arg, "-v") || is_arg(arg, "--version")) {
       puts(PACKAGE " " VERSION);
       exit(EXIT_SUCCESS);
+    } else if (is_arg(arg, "-s") || is_arg(arg, "--screen")) {
+      params.screen = parse_uchar(arg, value);
     } else {
       invalid_arg(arg);
     }