user/libc: port skeeto's getopt

1 files changed, 75 insertions, 0 deletions

diff --git a/src/user/lib/vendor/getopt/getopt.c b/src/user/lib/vendor/getopt/getopt.c
new file mode 100644
index 0000000..63c9b51
--- /dev/null
+++ b/src/user/lib/vendor/getopt/getopt.c
@@ -0,0 +1,75 @@
+/* Adapted from https://github.com/skeeto/getopt by Chris Wellons */
+
+/* A minimal POSIX getopt() implementation in ANSI C
+ *
+ * This is free and unencumbered software released into the public domain.
+ *
+ * This implementation supports the convention of resetting the option
+ * parser by assigning optind to 0. This resets the internal state
+ * appropriately.
+ *
+ * Ref: http://pubs.opengroup.org/onlinepubs/9699919799/functions/getopt.html
+ */
+#include <ctype.h>
+#include <stdio.h>
+#include <string.h>
+#include "getopt.h"
+
+int optind;
+int opterr = 1;
+int optopt;
+char *optarg;
+
+int
+getopt(int argc, char * const argv[], const char *optstring)
+{
+	static int optpos = 1;
+	const char *arg;
+
+	/* Reset? */
+	if (optind == 0) {
+		optind = !!argc;
+		optpos = 1;
+	}
+
+	arg = argv[optind];
+	if (arg && strcmp(arg, "--") == 0) {
+		optind++;
+		return -1;
+	} else if (!arg || arg[0] != '-' || !isalnum(arg[1])) {
+		return -1;
+	} else {
+		const char *opt = strchr(optstring, arg[optpos]);
+		optopt = arg[optpos];
+		if (!opt) {
+			if (opterr && *optstring != ':')
+				fprintf(stderr, "%s: illegal option: %c\n", argv[0], optopt);
+			return '?';
+		} else if (opt[1] == ':') {
+			if (arg[optpos + 1]) {
+				optarg = (char *)arg + optpos + 1;
+				optind++;
+				optpos = 1;
+				return optopt;
+			} else if (argv[optind + 1]) {
+				optarg = (char *)argv[optind + 1];
+				optind += 2;
+				optpos = 1;
+				return optopt;
+			} else {
+				if (opterr && *optstring != ':')
+					fprintf(stderr,
+					        "%s: option requires an argument: %c\n",
+					        argv[0], optopt);
+				return *optstring == ':' ? ':' : '?';
+			}
+		} else {
+			if (!arg[++optpos]) {
+				optind++;
+				optpos = 1;
+			}
+			return optopt;
+		}
+	}
+}
+