4 files changed, 34 insertions, 24 deletions

diff --git a/src/kernel/mem/virt.h b/src/kernel/mem/virt.h
index 3a42e9e..b858bdd 100644
--- a/src/kernel/mem/virt.h
+++ b/src/kernel/mem/virt.h
@@ -1,5 +1,6 @@
 /* contains utilities for interacting with virtual memory */
 #pragma once
+#include <kernel/mem/alloc.h>
 #include <shared/types.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -38,3 +39,15 @@ static inline bool virt_cpy_from(struct pagedir *src_pages, // virtual -> physic
 		void *dest, const void __user *src, size_t length) {
 	return virt_cpy(NULL, (userptr_t)dest, src_pages, src, length);
 }
+
+/** Copies a chunk of virtual memory to a newly kmalloc'd buffer. */
+static inline void *virt_cpy2kmalloc(struct pagedir *src_pages,
+		const void __user *src, size_t length) {
+	void *buf = kmalloc(length);
+	if (virt_cpy_from(src_pages, buf, src, length)) {
+		return buf;
+	} else {
+		kfree(buf);
+		return NULL;
+	}
+}
diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index 5cee090..9a9b5d6 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -49,10 +49,8 @@ handle_t _syscall_open(const char __user *path, int len) {
 	if (process_find_handle(process_current) < 0)
 		return -1;
 
-	// copy the path to the kernel, simplify it
-	path_buf = kmalloc(len); // gets freed in vfs_request_finish
-	if (!virt_cpy_from(process_current->pages, path_buf, path, len))
-		goto fail;
+	path_buf = virt_cpy2kmalloc(process_current->pages, path, len);
+	if (!path_buf) goto fail;
 
 	len = path_simplify(path_buf, path_buf, len);
 	if (len < 0) goto fail;
@@ -90,9 +88,9 @@ int _syscall_mount(handle_t handle, const char __user *path, int len) {
 	if (PATH_MAX < len) return -1;
 
 	// copy the path to the kernel to simplify it
-	path_buf = kmalloc(len);
-	if (!virt_cpy_from(process_current->pages, path_buf, path, len))
-		goto fail;
+	path_buf = virt_cpy2kmalloc(process_current->pages, path, len);
+	if (!path_buf) goto fail;
+
 	len = path_simplify(path_buf, path_buf, len);
 	if (len < 0) goto fail;
 
diff --git a/src/kernel/tests/vfs.c b/src/kernel/tests/vfs.c
index 8b450e5..339c6bd 100644
--- a/src/kernel/tests/vfs.c
+++ b/src/kernel/tests/vfs.c
@@ -38,6 +38,12 @@ TEST(path_simplify) {
 	TEST_WRAPPER("/asdf/.",   "/asdf/");
 	TEST_WRAPPER("/asdf//.",  "/asdf/");
 
+	TEST_WRAPPER("/foo/bar/..", "/foo/");
+	TEST_WRAPPER("/foo/bar/../bar",  "/foo/bar");
+	TEST_WRAPPER("/foo/bar/../bar/", "/foo/bar/");
+	TEST_WRAPPER("/foo/bar/xyz/..",  "/foo/bar/");
+	TEST_WRAPPER("/foo/bar/xyz/../", "/foo/bar/");
+
 	// going under the root or close to it
 	TEST_WRAPPER("/..",        NULL);
 	TEST_WRAPPER("/../asdf",   NULL);
diff --git a/src/kernel/vfs/path.c b/src/kernel/vfs/path.c
index 00af95c..096d3fe 100644
--- a/src/kernel/vfs/path.c
+++ b/src/kernel/vfs/path.c
@@ -5,7 +5,6 @@ int path_simplify(const char *in, char *out, size_t len) {
 	if (len == 0)     return -1; // empty paths are invalid
 	if (in[0] != '/') return -1; // so are relative paths
 
-	int depth = 0; // shouldn't be needed!
 	int seg_len; // the length of the current path segment
 	int out_pos = 0;
 	bool directory = 0;
@@ -33,32 +32,26 @@ int path_simplify(const char *in, char *out, size_t len) {
 		 *           (segment starts at i+1) */
 
 		if (seg_len == 0 || (seg_len == 1 && in[i + 1] == '.')) {
-			// the segment is // or /./
+			/*  // or /./  */
 			directory = true;
 		} else if (seg_len == 2 && in[i + 1] == '.' && in[i + 2] == '.') {
-			// the segment is /../
-			if (--depth < 0)
-				return -1;
-			// backtrack to last slash
-			while (out[--out_pos] != '/');
+			/*  /../  */
+			directory = true;
+
+			/* try to backtrack to the last slash */
+			while (--out_pos >= 0 && out[out_pos] != '/');
+			if (out_pos < 0) return -1;
 		} else {
-			// normal segment
+			/* a normal segment, e.g. /asdf/ */
 			out[out_pos] = '/';
 			memcpy(&out[out_pos + 1], &in[i + 1], seg_len);
 			out_pos += seg_len + 1;
-			depth++;
 		}
 
 	}
 
-	/* if we were backtracking, out_pos can become 0. i don't like this,
-	 * it feels sloppy. this algorithm should be implemented differently. TODO? */
-	if (out_pos == 0)
-		out[out_pos++] = '/';
-
-	if (directory) // if the path refers to a directory, append a trailing slash
-		if (out[out_pos-1] != '/') // unless it's already there
-			out[out_pos++] = '/';
+	/* paths to directories should have a trailing slash */
+	if (directory) out[out_pos++] = '/';
 
 	return out_pos;
 }