1 files changed, 76 insertions, 0 deletions
diff --git a/src/cmd/shell/parser.c b/src/cmd/shell/parser.c
new file mode 100644
index 0000000..ad09348
--- /dev/null
+++ b/src/cmd/shell/parser.c
@@ -0,0 +1,76 @@
+#include "shell.h"
+#include <ctype.h>
+#include <stdbool.h>
+#include <string.h>
+
+static char skipspace(char **sp) {
+	char *s = *sp;
+	while (*s && isspace(*s)) s++;
+	*sp = s;
+	return *s;
+}
+
+static bool isspecial(char c) {
+	return c == '>' || c == '#';
+}
+
+static char *parg(char **sp) {
+	char *s = *sp;
+	char *res = NULL;
+
+	if (skipspace(&s)) {
+		// TODO incorrectly handles strings like a"b"
+		switch (*s) {
+			case '"':
+				s++;
+				res = s;
+				while (*s && *s != '"')
+					s++;
+				break;
+			default:
+				res = s;
+				while (*s && !isspace(*s) && !isspecial(*s))
+					s++;
+				if (*s == '#') {
+					*s = '\0'; /* end parsing early */
+					if (res == s) /* don't output an empty arg */
+						res = NULL;
+				}
+				break;
+		}
+		if (*s) *s++ = '\0';
+	}
+
+	*sp = s;
+	return res;
+}
+
+int parse(char *s, char **argv, size_t argvlen, struct redir *redir) {
+	if (argvlen == 0) return -1;
+	size_t argc = 0;
+	char *arg;
+
+	*argv = NULL;
+	redir->stdout = NULL;
+	redir->append = false;
+
+	while (skipspace(&s)) {
+		switch (*s) {
+			case '>':
+				s++;
+				if (*s == '>') {
+					s++;
+					redir->append = true;
+				}
+				redir->stdout = parg(&s);
+				break;
+			default:
+				arg = parg(&s);
+				argv[argc++] = arg;
+				if (argc >= argvlen)
+					return -1;
+		}
+	}
+	argv[argc] = NULL;
+	return argc;
+}