1 files changed, 53 insertions, 0 deletions
diff --git a/src/libk/path.c b/src/libk/path.c
new file mode 100644
index 0000000..4e3077b
--- /dev/null
+++ b/src/libk/path.c
@@ -0,0 +1,53 @@
+#include <assert.h>
+#include <camellia/path.h>
+#include <shared/mem.h>
+#include <stdbool.h>
+
+size_t path_simplify(const char *in, char *out, size_t len) {
+	if (len == 0)     return 0; /* empty paths are invalid */
+	if (in[0] != '/') return 0; /* so are relative paths */
+
+	int seg_len;
+	int out_pos = 0;
+	bool directory = false;
+
+	for (size_t i = 0; i < len; i += seg_len + 1) {
+		assert(in[i] == '/');
+
+		seg_len = 0;
+		directory = false;
+		for (size_t j = i + 1; j < len; j++) {
+			if (in[j] == '/') {
+				directory = true;
+				break;
+			}
+			seg_len++;
+		}
+
+		/*      |i=5 |next i = i + seg_len + 1 = 10
+		 *      v    v
+		 * /some/path/asdf
+		 *       |--|
+		 *       seg_len = 4, segment starts at i+1 */
+
+		if (seg_len == 0 || (seg_len == 1 && in[i + 1] == '.')) {
+			/*  // or /./  */
+			directory = true;
+		} else if (seg_len == 2 && in[i + 1] == '.' && in[i + 2] == '.') {
+			/*  /../  */
+			directory = true;
+			/* try to backtrack to the last slash */
+			while (--out_pos >= 0 && out[out_pos] != '/');
+			if (out_pos < 0) return 0;
+		} else {
+			/* a normal segment, e.g. /asdf/ */
+			out[out_pos] = '/';
+			memcpy(&out[out_pos + 1], &in[i + 1], seg_len);
+			out_pos += seg_len + 1;
+		}
+	}
+
+	if (directory) out[out_pos++] = '/';
+	assert(0 < out_pos && (size_t)out_pos <= len);
+	return out_pos;
+}