vfs: account for . and .. when resolving paths

Author: jewelcodes

fs/vfs/src/include/vfs/vfs.h

@@ -29,4 +29,4 @@ extern int mpCount;
 
 int findFSServer(const char *);
 void registerMountpoint(MountCommand *);
-char *resolve(char *, char *, char *, const char *);
+char *resolve(char *, char *, char *, char *);

fs/vfs/src/resolve.c

@@ -10,18 +10,69 @@
 #include <vfs.h>
 #include <string.h>
 
+/* clean(): helper function to clean up a path
+ * params: path - path to be cleaned, the string will be directly modified
+ * params: pointer to path
+ */
+
+static char *clean(char *path) {
+    if(strlen(path) == 1) return path;  // root will never need to be cleaned
+
+    // first try to get rid of excessive slashes
+    for(int i = 0; i < strlen(path); i++) {
+        if((path[i] == '/') && (i < strlen(path)-1) && (path[i+1] == '/')) {
+            memmove(&path[i], &path[i+1], strlen(&path[i])+1);
+            continue;
+        }
+    }
+
+    // if the last character is a slash, remove it except for the root dir
+    if(strlen(path) == 1) return path;
+    while(path[strlen(path)-1] == '/') path[strlen(path)-1] = 0;
+
+    // parse '../' to reflect the parent directory
+    for(int i = 0; i < strlen(path); i++) {
+        if((path[i] == '.') && (path[i+1] == '.') && ((path[i+2] == '/') || (!path[i+2]))) {
+            // find the parent
+            int parent = i-2;
+            for(; parent > 0; parent--) {
+                if(path[parent] == '/') break;
+            }
+
+            parent++;
+            memmove(&path[parent], &path[i+3], strlen(&path[i+3])+1);
+        }
+    }
+
+    // remove './' because it refers to the self directory
+    for(int i = 0; i < strlen(path); i++) {
+        if((path[i] == '.') && ((path[i+1] == '/') || (!path[i+1]))) {
+            memmove(&path[i], &path[i+2], strlen(&path[i+2])+1);
+            continue;
+        }
+    }
+
+    // and finally remove any trailing slashes left while processing the string
+    if(strlen(path) == 1) return path;
+    while(path[strlen(path)-1] == '/') path[strlen(path)-1] = 0;
+
+    return path;
+}
+
 /* resolve(): resolves a path relative to a mountpoint
  * params: buffer - destination to store the resolved path
  * params: type - buffer to store file system type
  * params: path - source absolute path
  * returns: pointer to resolved path on success, NULL on fail
  */
 
-char *resolve(char *buffer, char *type, char *source, const char *path) {
+char *resolve(char *buffer, char *type, char *source, char *path) {
     // iterate over the mountpoints to determine which device this path is
     // located on
     if(!mpCount) return NULL;
 
+    clean(path);
+
     for(int i = 0; i < mpCount; i++) {
         size_t mplen = strlen(mps[i].path);
         if(!memcmp(path, mps[i].path, mplen)) {