Merge pull request #55 from fischerling/fix-t_dup

fix path resolution when creating files

mentos/inc/fs/namei.h

@@ -9,6 +9,7 @@
 
 #define REMOVE_TRAILING_SLASH 1 << 0
 #define FOLLOW_LINKS 1 << 1
+#define CREAT_LAST_COMPONENT 1 << 2
 
 /// @brief Resolve the path by following all symbolic links.
 /// @param path The path to resolve.

mentos/src/fs/namei.c

@@ -160,8 +160,19 @@ int resolve_path(const char *path, char *buffer, size_t buflen, int flags)
                 }
 
                 vfs_file_t *file;
-                file = vfs_open_abspath(abspath, O_RDONLY, 0);
-                if (!file) { return -errno; }
+                // No permissions are required for path resolution.
+                // Correct permissions of all path components must be
+                // checked by the filesystem implementation.
+                file = vfs_open_abspath(abspath, 0, 0);
+                if (!file) {
+                    // This is the last path component and we want to create
+                    // it anyway.
+                    if (!sep_after_cur && (flags & CREAT_LAST_COMPONENT)) {
+                        // Just copy the component into the buffer
+                        goto copy_path_component;
+                    }
+                    return -errno;
+                }
 
                 stat_t statbuf;
                 int ret = vfs_fstat(file, &statbuf);

mentos/src/fs/vfs.c

@@ -147,8 +147,13 @@ vfs_file_t *vfs_open(const char *path, int flags, mode_t mode)
 {
     // Allocate a variable for the path.
     char absolute_path[PATH_MAX];
-    // If the first character is not the '/' then get the absolute path.
-    int ret = resolve_path(path, absolute_path, sizeof(absolute_path), FOLLOW_LINKS);
+    // Resolve all symbolic links in the path before opening the file.
+    int resolve_flags = FOLLOW_LINKS;
+    // Allow the last component to be non existing when attempting to create it.
+    if (bitmask_check(flags, O_CREAT)) {
+        resolve_flags |= CREAT_LAST_COMPONENT;
+    }
+    int ret = resolve_path(path, absolute_path, sizeof(absolute_path), resolve_flags);
     if (ret < 0) {
         pr_err("vfs_open(%s): Cannot resolve path!\n", path);
         errno = -ret;