str: introduce `git_str` for internal, `git_buf` is externalethomson/gitstr

libgit2 has two distinct requirements that were previously solved by
`git_buf`.  We require:

1. A general purpose string class that provides a number of utility APIs
   for manipulating data (eg, concatenating, truncating, etc).
2. A structure that we can use to return strings to callers that they
   can take ownership of.

By using a single class (`git_buf`) for both of these purposes, we have
confused the API to the point that refactorings are difficult and
reasoning about correctness is also difficult.

Move the utility class `git_buf` to be called `git_str`: this represents
its general purpose, as an internal string buffer class.  The name also
is an homage to Junio Hamano ("gitstr").

The public API remains `git_buf`, and has a much smaller footprint.  It
is generally only used as an "out" param with strict requirements that
follow the documentation.  (Exceptions exist for some legacy APIs to
avoid breaking callers unnecessarily.)

Utility functions exist to convert a user-specified `git_buf` to a
`git_str` so that we can call internal functions, then converting it
back again.

1 files changed, 36 insertions, 37 deletions

diff --git a/src/stash.c b/src/stash.c
index 49ea26fdd..5fc01ac36 100644
--- a/src/stash.c
+++ b/src/stash.c
@@ -9,7 +9,6 @@
 
 #include "repository.h"
 #include "commit.h"
-#include "message.h"
 #include "tree.h"
 #include "reflog.h"
 #include "blob.h"
@@ -43,20 +42,20 @@ static int retrieve_head(git_reference **out, git_repository *repo)
 	return error;
 }
 
-static int append_abbreviated_oid(git_buf *out, const git_oid *b_commit)
+static int append_abbreviated_oid(git_str *out, const git_oid *b_commit)
 {
 	char *formatted_oid;
 
 	formatted_oid = git_oid_allocfmt(b_commit);
 	GIT_ERROR_CHECK_ALLOC(formatted_oid);
 
-	git_buf_put(out, formatted_oid, 7);
+	git_str_put(out, formatted_oid, 7);
 	git__free(formatted_oid);
 
-	return git_buf_oom(out) ? -1 : 0;
+	return git_str_oom(out) ? -1 : 0;
 }
 
-static int append_commit_description(git_buf *out, git_commit *commit)
+static int append_commit_description(git_str *out, git_commit *commit)
 {
 	const char *summary = git_commit_summary(commit);
 	GIT_ERROR_CHECK_ALLOC(summary);
@@ -64,16 +63,16 @@ static int append_commit_description(git_buf *out, git_commit *commit)
 	if (append_abbreviated_oid(out, git_commit_id(commit)) < 0)
 		return -1;
 
-	git_buf_putc(out, ' ');
-	git_buf_puts(out, summary);
-	git_buf_putc(out, '\n');
+	git_str_putc(out, ' ');
+	git_str_puts(out, summary);
+	git_str_putc(out, '\n');
 
-	return git_buf_oom(out) ? -1 : 0;
+	return git_str_oom(out) ? -1 : 0;
 }
 
 static int retrieve_base_commit_and_message(
 	git_commit **b_commit,
-	git_buf *stash_message,
+	git_str *stash_message,
 	git_repository *repo)
 {
 	git_reference *head = NULL;
@@ -83,9 +82,9 @@ static int retrieve_base_commit_and_message(
 		return error;
 
 	if (strcmp("HEAD", git_reference_name(head)) == 0)
-		error = git_buf_puts(stash_message, "(no branch): ");
+		error = git_str_puts(stash_message, "(no branch): ");
 	else
-		error = git_buf_printf(
+		error = git_str_printf(
 			stash_message,
 			"%s: ",
 			git_reference_name(head) + strlen(GIT_REFS_HEADS_DIR));
@@ -128,13 +127,13 @@ static int commit_index(
 {
 	git_tree *i_tree = NULL;
 	git_oid i_commit_oid;
-	git_buf msg = GIT_BUF_INIT;
+	git_str msg = GIT_STR_INIT;
 	int error;
 
 	if ((error = build_tree_from_index(&i_tree, repo, index)) < 0)
 		goto cleanup;
 
-	if ((error = git_buf_printf(&msg, "index on %s\n", message)) < 0)
+	if ((error = git_str_printf(&msg, "index on %s\n", message)) < 0)
 		goto cleanup;
 
 	if ((error = git_commit_create(
@@ -144,7 +143,7 @@ static int commit_index(
 		stasher,
 		stasher,
 		NULL,
-		git_buf_cstr(&msg),
+		git_str_cstr(&msg),
 		i_tree,
 		1,
 		&parent)) < 0)
@@ -154,7 +153,7 @@ static int commit_index(
 
 cleanup:
 	git_tree_free(i_tree);
-	git_buf_dispose(&msg);
+	git_str_dispose(&msg);
 	return error;
 }
 
@@ -303,13 +302,13 @@ static int commit_untracked(
 {
 	git_tree *u_tree = NULL;
 	git_oid u_commit_oid;
-	git_buf msg = GIT_BUF_INIT;
+	git_str msg = GIT_STR_INIT;
 	int error;
 
 	if ((error = build_untracked_tree(&u_tree, repo, i_commit, flags)) < 0)
 		goto cleanup;
 
-	if ((error = git_buf_printf(&msg, "untracked files on %s\n", message)) < 0)
+	if ((error = git_str_printf(&msg, "untracked files on %s\n", message)) < 0)
 		goto cleanup;
 
 	if ((error = git_commit_create(
@@ -319,7 +318,7 @@ static int commit_untracked(
 		stasher,
 		stasher,
 		NULL,
-		git_buf_cstr(&msg),
+		git_str_cstr(&msg),
 		u_tree,
 		0,
 		NULL)) < 0)
@@ -329,7 +328,7 @@ static int commit_untracked(
 
 cleanup:
 	git_tree_free(u_tree);
-	git_buf_dispose(&msg);
+	git_str_dispose(&msg);
 	return error;
 }
 
@@ -437,33 +436,33 @@ cleanup:
 	return error;
 }
 
-static int prepare_worktree_commit_message(git_buf *out, const char *user_message)
+static int prepare_worktree_commit_message(git_str *out, const char *user_message)
 {
-	git_buf buf = GIT_BUF_INIT;
+	git_str buf = GIT_STR_INIT;
 	int error = 0;
 
 	if (!user_message) {
-		git_buf_printf(&buf, "WIP on %s", git_buf_cstr(out));
+		git_str_printf(&buf, "WIP on %s", git_str_cstr(out));
 	} else {
 		const char *colon;
 
-		if ((colon = strchr(git_buf_cstr(out), ':')) == NULL)
+		if ((colon = strchr(git_str_cstr(out), ':')) == NULL)
 			goto cleanup;
 
-		git_buf_puts(&buf, "On ");
-		git_buf_put(&buf, git_buf_cstr(out), colon - out->ptr);
-		git_buf_printf(&buf, ": %s\n", user_message);
+		git_str_puts(&buf, "On ");
+		git_str_put(&buf, git_str_cstr(out), colon - out->ptr);
+		git_str_printf(&buf, ": %s\n", user_message);
 	}
 
-	if (git_buf_oom(&buf)) {
+	if (git_str_oom(&buf)) {
 		error = -1;
 		goto cleanup;
 	}
 
-	git_buf_swap(out, &buf);
+	git_str_swap(out, &buf);
 
 cleanup:
-	git_buf_dispose(&buf);
+	git_str_dispose(&buf);
 	return error;
 }
 
@@ -543,7 +542,7 @@ int git_stash_save(
 {
 	git_index *index = NULL;
 	git_commit *b_commit = NULL, *i_commit = NULL, *u_commit = NULL;
-	git_buf msg = GIT_BUF_INIT;
+	git_str msg = GIT_STR_INIT;
 	int error;
 
 	GIT_ASSERT_ARG(out);
@@ -563,24 +562,24 @@ int git_stash_save(
 		goto cleanup;
 
 	if ((error = commit_index(&i_commit, repo, index, stasher,
-				  git_buf_cstr(&msg), b_commit)) < 0)
+				  git_str_cstr(&msg), b_commit)) < 0)
 		goto cleanup;
 
 	if ((flags & (GIT_STASH_INCLUDE_UNTRACKED | GIT_STASH_INCLUDE_IGNORED)) &&
 	    (error = commit_untracked(&u_commit, repo, stasher,
-				      git_buf_cstr(&msg), i_commit, flags)) < 0)
+				      git_str_cstr(&msg), i_commit, flags)) < 0)
 		goto cleanup;
 
 	if ((error = prepare_worktree_commit_message(&msg, message)) < 0)
 		goto cleanup;
 
-	if ((error = commit_worktree(out, repo, stasher, git_buf_cstr(&msg),
+	if ((error = commit_worktree(out, repo, stasher, git_str_cstr(&msg),
 				     i_commit, b_commit, u_commit)) < 0)
 		goto cleanup;
 
-	git_buf_rtrim(&msg);
+	git_str_rtrim(&msg);
 
-	if ((error = update_reflog(out, repo, git_buf_cstr(&msg))) < 0)
+	if ((error = update_reflog(out, repo, git_str_cstr(&msg))) < 0)
 		goto cleanup;
 
 	if ((error = reset_index_and_workdir(repo, (flags & GIT_STASH_KEEP_INDEX) ? i_commit : b_commit,
@@ -589,7 +588,7 @@ int git_stash_save(
 
 cleanup:
 
-	git_buf_dispose(&msg);
+	git_str_dispose(&msg);
 	git_commit_free(i_commit);
 	git_commit_free(b_commit);
 	git_commit_free(u_commit);