Add preliminary support for options

opts/opts.c

@@ -0,0 +1,74 @@
+#include "opts.h"
+#include "hw/v4l2.h"
+
+#include <stddef.h>
+#include <stdio.h>
+
+static void print_help(option_t *options)
+{
+  for (int i = 0; options[i].name; i++) {
+    printf("%20s ", options[i].name);
+
+    if (options[i].ptr) {
+      printf(options[i].format, options[i].ptr);
+    } else {
+      printf(options[i].format, *options[i].value);
+    }
+    printf("\n");
+  }
+}
+
+static int parse_opt(option_t *options, const char *key, const char *value)
+{
+  option_t *option = NULL;
+
+  for (int i = 0; options[i].name; i++) {
+    if (!strcmp(key, options[i].name)) {
+      option = &options[i];
+      break;
+    }
+  }
+
+  if (!option) {
+    return -EINVAL;
+  }
+
+  int ret = 0;
+  if (option->ptr) {
+    ret = sscanf(value, option->format, option->ptr);
+  } else {
+    ret = sscanf(value, option->format, option->value);
+  }
+  return ret;
+}
+
+int parse_opts(option_t *options, int argc, char *argv[])
+{
+  int arg;
+
+  for (arg = 1; arg < argc; arg += 2) {
+    const char *key = argv[arg];
+    if (!strcmp(key, "-help")) {
+      print_help(options);
+      return -1;
+    }
+
+    if (arg+1 == argc) {
+      E_LOG_ERROR(NULL, "The %s is missing argument.", key);
+    }
+
+    if (key[0] != '-') {
+      E_LOG_ERROR(NULL, "The '%s' is not option (should start with -).", key);
+    }
+
+    int ret = parse_opt(options, key+1, argv[arg+1]);
+    if (ret <= 0) {
+      E_LOG_ERROR(NULL, "Parsing '%s %s' returned '%d'.", key, argv[arg+1], ret);
+    }
+  }
+
+  return 0;
+
+error:
+  return -1;
+}