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, 40 insertions, 36 deletions

diff --git a/src/email.c b/src/email.c
index df63b6ec3..3459c0540 100644
--- a/src/email.c
+++ b/src/email.c
@@ -7,9 +7,11 @@
 
 #include "email.h"
 
-#include "buffer.h"
 #include "common.h"
+#include "buf.h"
 #include "diff_generate.h"
+#include "diff_stats.h"
+#include "patch.h"
 
 #include "git2/email.h"
 #include "git2/patch.h"
@@ -32,7 +34,7 @@ GIT_INLINE(int) include_prefix(
 }
 
 static int append_prefix(
-	git_buf *out,
+	git_str *out,
 	size_t patch_idx,
 	size_t patch_count,
 	git_email_create_options *opts)
@@ -40,16 +42,16 @@ static int append_prefix(
 	const char *subject_prefix = opts->subject_prefix ?
 		opts->subject_prefix : "PATCH";
 
-	git_buf_putc(out, '[');
+	git_str_putc(out, '[');
 
 	if (*subject_prefix)
-		git_buf_puts(out, subject_prefix);
+		git_str_puts(out, subject_prefix);
 
 	if (opts->reroll_number) {
 		if (*subject_prefix)
-			git_buf_putc(out, ' ');
+			git_str_putc(out, ' ');
 
-		git_buf_printf(out, "v%" PRIuZ, opts->reroll_number);
+		git_str_printf(out, "v%" PRIuZ, opts->reroll_number);
 	}
 
 	if ((opts->flags & GIT_EMAIL_CREATE_ALWAYS_NUMBER) != 0 ||
@@ -58,20 +60,20 @@ static int append_prefix(
 			opts->start_number : 1;
 
 		if (*subject_prefix || opts->reroll_number)
-			git_buf_putc(out, ' ');
+			git_str_putc(out, ' ');
 
-		git_buf_printf(out, "%" PRIuZ "/%" PRIuZ,
+		git_str_printf(out, "%" PRIuZ "/%" PRIuZ,
 		               patch_idx + (start_number - 1),
 		               patch_count + (start_number - 1));
 	}
 
-	git_buf_puts(out, "]");
+	git_str_puts(out, "]");
 
-	return git_buf_oom(out) ? -1 : 0;
+	return git_str_oom(out) ? -1 : 0;
 }
 
 static int append_subject(
-	git_buf *out,
+	git_str *out,
 	size_t patch_idx,
 	size_t patch_count,
 	const char *summary,
@@ -88,25 +90,25 @@ static int append_subject(
 			summary_len = (nl - summary);
 	}
 
-	if ((error = git_buf_puts(out, "Subject: ")) < 0)
+	if ((error = git_str_puts(out, "Subject: ")) < 0)
 		return error;
 
 	if (prefix &&
 	    (error = append_prefix(out, patch_idx, patch_count, opts)) < 0)
 		return error;
 
-	if (prefix && summary_len && (error = git_buf_putc(out, ' ')) < 0)
+	if (prefix && summary_len && (error = git_str_putc(out, ' ')) < 0)
 		return error;
 
 	if (summary_len &&
-	    (error = git_buf_put(out, summary, summary_len)) < 0)
+	    (error = git_str_put(out, summary, summary_len)) < 0)
 		return error;
 
-	return git_buf_putc(out, '\n');
+	return git_str_putc(out, '\n');
 }
 
 static int append_header(
-	git_buf *out,
+	git_str *out,
 	size_t patch_idx,
 	size_t patch_count,
 	const git_oid *commit_id,
@@ -119,20 +121,20 @@ static int append_header(
 	int error;
 
 	if ((error = git_oid_fmt(id, commit_id)) < 0 ||
-	    (error = git_buf_printf(out, "From %.*s %s\n", GIT_OID_HEXSZ, id, EMAIL_TIMESTAMP)) < 0 ||
-	    (error = git_buf_printf(out, "From: %s <%s>\n", author->name, author->email)) < 0 ||
+	    (error = git_str_printf(out, "From %.*s %s\n", GIT_OID_HEXSZ, id, EMAIL_TIMESTAMP)) < 0 ||
+	    (error = git_str_printf(out, "From: %s <%s>\n", author->name, author->email)) < 0 ||
 	    (error = git__date_rfc2822_fmt(date, sizeof(date), &author->when)) < 0 ||
-	    (error = git_buf_printf(out, "Date: %s\n", date)) < 0 ||
+	    (error = git_str_printf(out, "Date: %s\n", date)) < 0 ||
 	    (error = append_subject(out, patch_idx, patch_count, summary, opts)) < 0)
 		return error;
 
-	if ((error = git_buf_putc(out, '\n')) < 0)
+	if ((error = git_str_putc(out, '\n')) < 0)
 		return error;
 
 	return 0;
 }
 
-static int append_body(git_buf *out, const char *body)
+static int append_body(git_str *out, const char *body)
 {
 	size_t body_len;
 	int error;
@@ -142,16 +144,16 @@ static int append_body(git_buf *out, const char *body)
 
 	body_len = strlen(body);
 
-	if ((error = git_buf_puts(out, body)) < 0)
+	if ((error = git_str_puts(out, body)) < 0)
 		return error;
 
 	if (body_len && body[body_len - 1] != '\n')
-		error = git_buf_putc(out, '\n');
+		error = git_str_putc(out, '\n');
 
 	return error;
 }
 
-static int append_diffstat(git_buf *out, git_diff *diff)
+static int append_diffstat(git_str *out, git_diff *diff)
 {
 	git_diff_stats *stats = NULL;
 	unsigned int format_flags;
@@ -160,14 +162,14 @@ static int append_diffstat(git_buf *out, git_diff *diff)
 	format_flags = GIT_DIFF_STATS_FULL | GIT_DIFF_STATS_INCLUDE_SUMMARY;
 
 	if ((error = git_diff_get_stats(&stats, diff)) == 0 &&
-	    (error = git_diff_stats_to_buf(out, stats, format_flags, 0)) == 0)
-		error = git_buf_putc(out, '\n');
+	    (error = git_diff__stats_to_buf(out, stats, format_flags, 0)) == 0)
+		error = git_str_putc(out, '\n');
 
 	git_diff_stats_free(stats);
 	return error;
 }
 
-static int append_patches(git_buf *out, git_diff *diff)
+static int append_patches(git_str *out, git_diff *diff)
 {
 	size_t i, deltas;
 	int error = 0;
@@ -178,7 +180,7 @@ static int append_patches(git_buf *out, git_diff *diff)
 		git_patch *patch = NULL;
 
 		if ((error = git_patch_from_diff(&patch, diff, i)) >= 0)
-			error = git_patch_to_buf(out, patch);
+			error = git_patch__to_buf(out, patch);
 
 		git_patch_free(patch);
 
@@ -190,7 +192,7 @@ static int append_patches(git_buf *out, git_diff *diff)
 }
 
 int git_email__append_from_diff(
-	git_buf *out,
+	git_str *out,
 	git_diff *diff,
 	size_t patch_idx,
 	size_t patch_count,
@@ -216,14 +218,12 @@ int git_email__append_from_diff(
 	if (given_opts)
 		memcpy(&opts, given_opts, sizeof(git_email_create_options));
 
-	git_buf_sanitize(out);
-
 	if ((error = append_header(out, patch_idx, patch_count, commit_id, summary, author, &opts)) == 0 &&
 	    (error = append_body(out, body)) == 0 &&
-	    (error = git_buf_puts(out, "---\n")) == 0 &&
+	    (error = git_str_puts(out, "---\n")) == 0 &&
 	    (error = append_diffstat(out, diff)) == 0 &&
 	    (error = append_patches(out, diff)) == 0)
-		error = git_buf_puts(out, "--\nlibgit2 " LIBGIT2_VERSION "\n\n");
+		error = git_str_puts(out, "--\nlibgit2 " LIBGIT2_VERSION "\n\n");
 
 	return error;
 }
@@ -239,15 +239,19 @@ int git_email_create_from_diff(
 	const git_signature *author,
 	const git_email_create_options *given_opts)
 {
+	git_str email = GIT_STR_INIT;
 	int error;
 
-	git_buf_sanitize(out);
-	git_buf_clear(out);
+	git_buf_tostr(&email, out);
 
-	error = git_email__append_from_diff(out, diff, patch_idx,
+	error = git_email__append_from_diff(&email, diff, patch_idx,
 		patch_count, commit_id, summary, body, author,
 		given_opts);
 
+	if (error == 0)
+		error = git_buf_fromstr(out, &email);
+
+	git_str_dispose(&email);
 	return error;
 }