Use git_buf for path storage instead of stack-based buffers

This converts virtually all of the places that allocate GIT_PATH_MAX
buffers on the stack for manipulating paths to use git_buf objects
instead.  The patch is pretty careful not to touch the public API
for libgit2, so there are a few places that still use GIT_PATH_MAX.

This extends and changes some details of the git_buf implementation
to add a couple of extra functions and to make error handling easier.

This includes serious alterations to all the path.c functions, and
several of the fileops.c ones, too.  Also, there are a number of new
functions that parallel existing ones except that use a git_buf
instead of a stack-based buffer (such as git_config_find_global_r
that exists alongsize git_config_find_global).

This also modifies the win32 version of p_realpath to allocate whatever
buffer size is needed to accommodate the realpath instead of hardcoding
a GIT_PATH_MAX limit, but that change needs to be tested still.

1 files changed, 94 insertions, 73 deletions

diff --git a/src/status.c b/src/status.c
index 26dd11ea8..05e07be0a 100644
--- a/src/status.c
+++ b/src/status.c
@@ -28,12 +28,10 @@ struct status_entry {
 
 static struct status_entry *status_entry_new(git_vector *entries, const char *path)
 {
-	struct status_entry *e = git__malloc(sizeof(*e) + strlen(path) + 1);
+	struct status_entry *e = git__calloc(sizeof(*e) + strlen(path) + 1, 1);
 	if (e == NULL)
 		return NULL;
 
-	memset(e, 0x0, sizeof(*e));
-
 	if (entries != NULL)
 		git_vector_insert(entries, e);
 
@@ -73,7 +71,7 @@ static void status_entry_update_from_index(struct status_entry *e, git_index *in
 	status_entry_update_from_index_entry(e, index_entry);
 }
 
-static int status_entry_update_from_workdir(struct status_entry *e, char* full_path)
+static int status_entry_update_from_workdir(struct status_entry *e, const char* full_path)
 {
 	struct stat filest;
 
@@ -125,7 +123,7 @@ struct status_st {
 	git_tree *tree;
 
 	int workdir_path_len;
-	char* head_tree_relative_path;
+	git_buf head_tree_relative_path;
 	int head_tree_relative_path_len;
 	unsigned int tree_position;
 	unsigned int index_position;
@@ -155,6 +153,7 @@ static int retrieve_head_tree(git_tree **tree_out, git_repository *repo)
 		return git__rethrow(error, "The tip of HEAD can't be retrieved");
 
 	git_reference_free(resolved_head_ref);
+
 	if ((error = git_commit_tree(&tree, head_commit)) < GIT_SUCCESS) {
 		error = git__rethrow(error, "The tree of HEAD can't be retrieved");
 		goto exit;
@@ -174,12 +173,15 @@ enum path_type {
 	GIT_STATUS_PATH_FOLDER,
 };
 
-static int dirent_cb(void *state, char *full_path);
+static int dirent_cb(void *state, git_buf *full_path);
 static int alphasorted_futils_direach(
-	char *path, size_t path_sz,
-	int (*fn)(void *, char *), void *arg);
+	git_buf *path, int (*fn)(void *, git_buf *), void *arg);
 
-static int process_folder(struct status_st *st, const git_tree_entry *tree_entry, char *full_path, enum path_type path_type)
+static int process_folder(
+	struct status_st *st,
+	const git_tree_entry *tree_entry,
+	git_buf *full_path,
+	enum path_type path_type)
 {
 	git_object *subtree = NULL;
 	git_tree *pushed_tree = NULL;
@@ -209,10 +211,9 @@ static int process_folder(struct status_st *st, const git_tree_entry *tree_entry
 	}
 
 	if (full_path != NULL && path_type == GIT_STATUS_PATH_FOLDER)
-		error = alphasorted_futils_direach(full_path, GIT_PATH_MAX, dirent_cb, st);
-	else {
+		error = alphasorted_futils_direach(full_path, dirent_cb, st);
+	else
 		error = dirent_cb(st, NULL);
-	}
 
 	if (tree_entry_type == GIT_OBJ_TREE) {
 		git_object_free(subtree);
@@ -229,7 +230,7 @@ static int store_if_changed(struct status_st *st, struct status_entry *e)
 {
 	int error;
 	if ((error = status_entry_update_flags(e)) < GIT_SUCCESS)
-			return git__throw(error, "Failed to process the file '%s'. It doesn't exist in the workdir, in the HEAD nor in the index", e->path);
+		return git__throw(error, "Failed to process the file '%s'. It doesn't exist in the workdir, in the HEAD nor in the index", e->path);
 
 	if (e->status_flags == GIT_STATUS_CURRENT) {
 		git__free(e);
@@ -243,7 +244,7 @@ static int determine_status(struct status_st *st,
 	int in_head, int in_index, int in_workdir,
 	const git_tree_entry *tree_entry,
 	const git_index_entry *index_entry,
-	char *full_path,
+	git_buf *full_path,
 	const char *status_path,
 	enum path_type path_type)
 {
@@ -273,7 +274,8 @@ static int determine_status(struct status_st *st,
 		}
 
 		if (in_workdir)
-			if ((error = status_entry_update_from_workdir(e, full_path)) < GIT_SUCCESS)
+			if ((error = status_entry_update_from_workdir(e, full_path->ptr
+)) < GIT_SUCCESS)
 				return error;	/* The callee has already set the error message */
 
 		return store_if_changed(st, e);
@@ -284,7 +286,7 @@ static int determine_status(struct status_st *st,
 	return process_folder(st, tree_entry, full_path, path_type);
 }
 
-static int path_type_from(char *full_path, int is_dir)
+static int path_type_from(git_buf *full_path, int is_dir)
 {
 	if (full_path == NULL)
 		return GIT_STATUS_PATH_NULL;
@@ -292,7 +294,7 @@ static int path_type_from(char *full_path, int is_dir)
 	if (!is_dir)
 		return GIT_STATUS_PATH_FILE;
 
-	if (!git__suffixcmp(full_path, "/" DOT_GIT "/"))
+	if (!git__suffixcmp(full_path->ptr, "/" DOT_GIT "/"))
 		return GIT_STATUS_PATH_IGNORE;
 
 	return GIT_STATUS_PATH_FOLDER;
@@ -330,7 +332,7 @@ static int compare(const char *left, const char *right)
 /* Greatly inspired from JGit IndexTreeWalker */
 /* https://github.com/spearce/jgit/blob/ed47e29c777accfa78c6f50685a5df2b8f5b8ff5/org.spearce.jgit/src/org/spearce/jgit/lib/IndexTreeWalker.java#L88 */
 
-static int dirent_cb(void *state, char *a)
+static int dirent_cb(void *state, git_buf *a)
 {
 	const git_tree_entry *m;
 	const git_index_entry *entry;
@@ -346,7 +348,7 @@ static int dirent_cb(void *state, char *a)
 	if (path_type == GIT_STATUS_PATH_IGNORE)
 		return GIT_SUCCESS;	/* Let's skip the ".git" directory */
 
-	a_name = (path_type != GIT_STATUS_PATH_NULL) ? a + st->workdir_path_len : NULL;
+	a_name = (path_type != GIT_STATUS_PATH_NULL) ? a->ptr + st->workdir_path_len : NULL;
 
 	while (1) {
 		if (st->tree == NULL)
@@ -360,15 +362,18 @@ static int dirent_cb(void *state, char *a)
 			return GIT_SUCCESS;
 
 		if (m != NULL) {
-			st->head_tree_relative_path[st->head_tree_relative_path_len] = '\0';
-
+			git_buf_truncate(&st->head_tree_relative_path,
+							 st->head_tree_relative_path_len);
+			git_buf_joinpath(&st->head_tree_relative_path,
+							 st->head_tree_relative_path.ptr, m->filename);
 			/* When the tree entry is a folder, append a forward slash to its name */
 			if (git_tree_entry_type(m) == GIT_OBJ_TREE)
-				git_path_join_n(st->head_tree_relative_path, 3, st->head_tree_relative_path, m->filename, "");
-			else
-				git_path_join(st->head_tree_relative_path, st->head_tree_relative_path, m->filename);
-		
-			m_name = st->head_tree_relative_path;
+				git_path_to_dir(&st->head_tree_relative_path);
+
+			if (error < GIT_SUCCESS)
+				return git__rethrow(error, "An error occured while determining the status of '%s'", a->ptr);
+
+			m_name = st->head_tree_relative_path.ptr;
 		} else
 			m_name = NULL;
 
@@ -383,7 +388,7 @@ static int dirent_cb(void *state, char *a)
 		pi = ((cmpmi >= 0) && (cmpai >= 0)) ? i_name : NULL;
 
 		if((error = determine_status(st, pm != NULL, pi != NULL, pa != NULL, m, entry, a, status_path(pm, pi, pa), path_type)) < GIT_SUCCESS)
-			return git__rethrow(error, "An error occured while determining the status of '%s'", a);
+			return git__rethrow(error, "An error occured while determining the status of '%s'", a->ptr);
 
 		if ((pa != NULL) || (path_type == GIT_STATUS_PATH_FOLDER))
 			return GIT_SUCCESS;
@@ -404,9 +409,8 @@ int git_status_foreach(git_repository *repo, int (*callback)(const char *, unsig
 {
 	git_vector entries;
 	git_index *index = NULL;
-	char temp_path[GIT_PATH_MAX];
-	char tree_path[GIT_PATH_MAX] = "";
-	struct status_st dirent_st;
+	git_buf temp_path = GIT_BUF_INIT;
+	struct status_st dirent_st = {0};
 	int error = GIT_SUCCESS;
 	unsigned int i;
 	git_tree *tree;
@@ -435,23 +439,21 @@ int git_status_foreach(git_repository *repo, int (*callback)(const char *, unsig
 	dirent_st.tree = tree;
 	dirent_st.index = index;
 	dirent_st.vector = &entries;
-	dirent_st.head_tree_relative_path = tree_path;
+	git_buf_init(&dirent_st.head_tree_relative_path, 0);
 	dirent_st.head_tree_relative_path_len = 0;
 	dirent_st.is_dir = 1;
 
-	strcpy(temp_path, workdir);
-
-	if (git_futils_isdir(temp_path)) {
+	if (git_futils_isdir(workdir)) {
 		error = git__throw(GIT_EINVALIDPATH,
 			"Failed to determine status of file '%s'. "
-			"The given path doesn't lead to a folder", temp_path);
+			"The given path doesn't lead to a folder", workdir);
 		goto exit;
 	}
 
+	git_buf_sets(&temp_path, workdir);
+
 	error = alphasorted_futils_direach(
-		temp_path, sizeof(temp_path),
-		dirent_cb, &dirent_st
-	);
+		&temp_path, dirent_cb, &dirent_st);
 
 	if (error < GIT_SUCCESS)
 		error = git__rethrow(error,
@@ -477,6 +479,8 @@ int git_status_foreach(git_repository *repo, int (*callback)(const char *, unsig
 	}
 
 exit:
+	git_buf_free(&dirent_st.head_tree_relative_path);
+	git_buf_free(&temp_path);
 	git_vector_free(&entries);
 	git_tree_free(tree);
 	return error;
@@ -521,7 +525,7 @@ int git_status_file(unsigned int *status_flags, git_repository *repo, const char
 {
 	struct status_entry *e;
 	git_index *index = NULL;
-	char temp_path[GIT_PATH_MAX];
+	git_buf temp_path = GIT_BUF_INIT;
 	int error = GIT_SUCCESS;
 	git_tree *tree = NULL;
 	const char *workdir;
@@ -532,60 +536,72 @@ int git_status_file(unsigned int *status_flags, git_repository *repo, const char
 		return git__throw(GIT_ERROR,
 			"Cannot retrieve status on a bare repository");
 
-	git_path_join(temp_path, workdir, path);
-	if (git_futils_isdir(temp_path) == GIT_SUCCESS)
+	if ((error = git_buf_joinpath(&temp_path, workdir, path)) < GIT_SUCCESS)
+		return git__rethrow(error,
+			"Failed to determine status of file '%s'", path);
+
+	if (git_futils_isdir(temp_path.ptr) == GIT_SUCCESS) {
+		git_buf_free(&temp_path);
 		return git__throw(GIT_EINVALIDPATH,
 			"Failed to determine status of file '%s'. "
 			"Given path leads to a folder, not a file", path);
+	}
 
 	e = status_entry_new(NULL, path);
-	if (e == NULL)
+	if (e == NULL) {
+		git_buf_free(&temp_path);
 		return GIT_ENOMEM;
+	}
 
 	/* Find file in Workdir */
-	if (git_futils_exists(temp_path) == GIT_SUCCESS) {
-		if ((error = status_entry_update_from_workdir(e, temp_path)) < GIT_SUCCESS)
-			goto exit;	/* The callee has already set the error message */
+	if (git_futils_exists(temp_path.ptr) == GIT_SUCCESS) {
+		if ((error = status_entry_update_from_workdir(e, temp_path.ptr)) < GIT_SUCCESS)
+			goto cleanup;	/* The callee has already set the error message */
 	}
 
 	/* Find file in Index */
 	if ((error = git_repository_index__weakptr(&index, repo)) < GIT_SUCCESS) {
-		error = git__rethrow(error,
+		git__rethrow(error,
 			"Failed to determine status of file '%s'."
 			"Index can't be opened", path);
-		goto exit;
+		goto cleanup;
 	}
 
 	status_entry_update_from_index(e, index);
 
 	if ((error = retrieve_head_tree(&tree, repo)) < GIT_SUCCESS) {
-		error = git__rethrow(error,
+		git__rethrow(error,
 			"Failed to determine status of file '%s'", path);
-		goto exit;
+		goto cleanup;
 	}
 
 	/* If the repository is not empty, try and locate the file in HEAD */
 	if (tree != NULL) {
-		strcpy(temp_path, path);
+		if ((error = git_buf_sets(&temp_path, path)) < GIT_SUCCESS) {
+			git__rethrow(error,
+				"Failed to determine status of file '%s'", path);
+			goto cleanup;
+		}
 
-		error = recurse_tree_entry(tree, e, temp_path);
+		error = recurse_tree_entry(tree, e, temp_path.ptr);
 		if (error < GIT_SUCCESS) {
-			error = git__rethrow(error,
+			git__rethrow(error,
 				"Failed to determine status of file '%s'. "
 				"An error occured while processing the tree", path);
-			goto exit;
+			goto cleanup;
 		}
 	}
 
 	/* Determine status */
 	if ((error = status_entry_update_flags(e)) < GIT_SUCCESS) {
-		error = git__throw(error, "Nonexistent file");
-		goto exit;
+		git__throw(error, "Nonexistent file");
+		goto cleanup;
 	}
 
 	*status_flags = e->status_flags;
 
-exit:
+cleanup:
+	git_buf_free(&temp_path);
 	git_tree_free(tree);
 	git__free(e);
 	return error;
@@ -600,37 +616,34 @@ exit:
 
 struct alphasorted_dirent_info {
 	int is_dir;
-
 	char path[GIT_FLEX_ARRAY]; /* more */
 };
 
-static struct alphasorted_dirent_info *alphasorted_dirent_info_new(const char *path)
+static struct alphasorted_dirent_info *alphasorted_dirent_info_new(const git_buf *path)
 {
 	int is_dir, size;
 	struct alphasorted_dirent_info *di;
 
-	is_dir = git_futils_isdir(path) == GIT_SUCCESS ? 1 : 0;
-	size = sizeof(*di) + (is_dir ? GIT_PATH_MAX : strlen(path)) + 2;
+	is_dir = git_futils_isdir(path->ptr) == GIT_SUCCESS ? 1 : 0;
+	size   = sizeof(*di) + path->size + is_dir + 1;
 
-	di = git__malloc(size);
+	di = git__calloc(size, 1);
 	if (di == NULL)
 		return NULL;
 
-	memset(di, 0x0, size);
-
-	strcpy(di->path, path);
+	git_buf_copy_cstr(di->path, path->size + 1, path);
 
 	if (is_dir) {
 		di->is_dir = 1;
 
-		/* 
-		 * Append a forward slash to the name to force folders 
+		/*
+		 * Append a forward slash to the name to force folders
 		 * to be ordered in a similar way than in a tree
 		 *
 		 * The file "subdir" should appear before the file "subdir.txt"
 		 * The folder "subdir" should appear after the file "subdir.txt"
 		 */
-		di->path[strlen(path)] = '/';
+		di->path[path->size] = '/';
 	}
 
 	return di;
@@ -644,7 +657,7 @@ static int alphasorted_dirent_info_cmp(const void *a, const void *b)
 	return strcmp(stra->path, strb->path);
 }
 
-static int alphasorted_dirent_cb(void *state, char *full_path)
+static int alphasorted_dirent_cb(void *state, git_buf *full_path)
 {
 	struct alphasorted_dirent_info *entry;
 	git_vector *entry_names;
@@ -664,34 +677,42 @@ static int alphasorted_dirent_cb(void *state, char *full_path)
 }
 
 static int alphasorted_futils_direach(
-	char *path,
-	size_t path_sz,
-	int (*fn)(void *, char *),
+	git_buf *path,
+	int (*fn)(void *, git_buf *),
 	void *arg)
 {
 	struct alphasorted_dirent_info *entry;
 	git_vector entry_names;
 	unsigned int idx;
 	int error = GIT_SUCCESS;
+	git_buf entry_path = GIT_BUF_INIT;
 
 	if (git_vector_init(&entry_names, 16, alphasorted_dirent_info_cmp) < GIT_SUCCESS)
 		return GIT_ENOMEM;
 
-	error = git_futils_direach(path, path_sz, alphasorted_dirent_cb, &entry_names);
+	error = git_futils_direach(path, alphasorted_dirent_cb, &entry_names);
 
 	git_vector_sort(&entry_names);
 
 	for (idx = 0; idx < entry_names.length; ++idx) {
 		entry = (struct alphasorted_dirent_info *)git_vector_get(&entry_names, idx);
 
+		/* We have to walk the entire vector even if there was an error,
+		 * in order to free up memory, but we stop making callbacks after
+		 * an error.
+		 */
+		if (error == GIT_SUCCESS)
+			error = git_buf_sets(&entry_path, entry->path);
+
 		if (error == GIT_SUCCESS) {
 			((struct status_st *)arg)->is_dir = entry->is_dir;
-			error = fn(arg, entry->path);
+			error = fn(arg, &entry_path);
 		}
 
 		git__free(entry);
 	}
 
+	git_buf_free(&entry_path);
 	git_vector_free(&entry_names);
 	return error;
 }