Added git_prettify_dir_path().

Clean up a provided absolute or relative directory path.

This prettification relies on basic operations such as coalescing multiple forward slashes into a single slash, removing '.' and './' current directory segments, and removing parent directory whenever '..' is encountered. If not empty, the returned path ends with a forward slash.

For instance, this will turn "d1/s1///s2/..//../s3" into "d1/s3/".

This only performs a string based analysis of the path. No checks are done to make sure the path actually makes sense from the file system perspective.

2 files changed, 101 insertions, 0 deletions

diff --git a/src/fileops.c b/src/fileops.c
index 68f45c25a..37affe00f 100644
--- a/src/fileops.c
+++ b/src/fileops.c
@@ -364,5 +364,82 @@ int gitfo_mkdir_recurs(const char *path, int mode)
 
 	free(path_copy);
 	return error;
+}
+
+static int retrieve_previous_path_component_start(const char *path)
+{
+	int error = GIT_SUCCESS;
+	int offset, len, start = 0;
+	
+	len = strlen(path);
+	offset = len - 1;
 
+	/* Skip leading slash */
+	if (path[start] == '/')
+		start++;
+
+	/* Skip trailing slash */
+	if (path[offset] == '/')
+		offset--;
+
+	if (offset < 0)
+		return GIT_ERROR;
+
+	while (offset > start && path[offset-1] != '/') {
+		offset--;
+	}
+
+	return offset;
 }
+
+int git_prettify_dir_path(char *buffer_out, const char *path)
+{
+	int len = 0;
+	char *current;
+	const char *buffer_out_start, *buffer_end;
+
+	buffer_out_start = buffer_out;
+	current = (char *)path;
+	buffer_end = path + strlen(path);
+
+	while (current < buffer_end) {
+		/* Prevent multiple slashes from being added to the output */
+		if (*current == '/' && len > 0 && buffer_out_start[len - 1] == '/') {
+			current++;
+			continue;
+		}
+		
+		/* Skip current directory */
+		if (*current == '.') {
+			current++;
+
+			/* Handle the double-dot upward directory navigation */
+			if (*current == '.') {
+				current++;
+
+				*buffer_out ='\0';
+				len = retrieve_previous_path_component_start(buffer_out_start);
+				if (len < GIT_SUCCESS)
+					return GIT_ERROR;
+
+				buffer_out = (char *)buffer_out_start + len;
+			}
+
+			if (*current == '/')
+				current++;
+
+			continue;
+		}
+
+		*buffer_out++ = *current++;
+		len++;
+	}
+
+	/* Add a trailing slash if required */
+	if (len > 0 && buffer_out_start[len-1] != '/')
+		*buffer_out++ = '/';
+
+	*buffer_out = '\0';
+
+	return GIT_SUCCESS;
+}
\ No newline at end of file
diff --git a/src/fileops.h b/src/fileops.h
index 6656cdf43..30dc0b849 100644
--- a/src/fileops.h
+++ b/src/fileops.h
@@ -131,4 +131,28 @@ extern int gitfo_write_cached(gitfo_cache *ioc, void *buf, size_t len);
 extern int gitfo_flush_cached(gitfo_cache *ioc);
 extern int gitfo_close_cached(gitfo_cache *ioc);
 
+/**
+ * Clean up a provided absolute or relative directory path.
+ * 
+ * This prettification relies on basic operations such as coalescing 
+ * multiple forward slashes into a single slash, removing '.' and 
+ * './' current directory segments, and removing parent directory 
+ * whenever '..' is encountered.
+ *
+ * If not empty, the returned path ends with a forward slash.
+ *
+ * For instance, this will turn "d1/s1///s2/..//../s3" into "d1/s3/".
+ *
+ * This only performs a string based analysis of the path.
+ * No checks are done to make sure the path actually makes sense from 
+ * the file system perspective.
+ *
+ * @param buffer_out buffer to populate with the normalized path.
+ * @param path directory path to clean up.
+ * @return
+ * - GIT_SUCCESS on success;
+ * - GIT_ERROR when the input path is invalid or escapes the current directory.
+ */
+GIT_EXTERN(int) git_prettify_dir_path(char *buffer_out, const char *path);
+
 #endif /* INCLUDE_fileops_h__ */