From ebb4d2ffa34e8c37796cc1be14216af5b91869aa Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Mon, 29 Jun 2026 09:08:42 -0700 Subject: [PATCH] history: streamline message preparation and plug file stream leak An early part of fill_commit_message() function uses write_file_buf() to write out what was prepared in a strbuf, which is primarily meant for use by callers that have their own message prepared fully and called as the last thing to flush it to the destination file. However, the function then opens a file stream in append mode to further write into it. It may have been understandable if this was a later addition, but it seems it came from a single commit, d205234c (builtin/history: implement "reword" subcommand, 2026-01-13), which is somewhat puzzling, but anyway... Just open the file stream upfront for writing, write the message the function has in the strbuf, and then keep writing whatever it wants to write to the same open file stream. And do not forget to close the stream. We are about to pass the resulting file to an external editor, and on some systems, notably Windows, you are not supposed to keep a file open while expecting another program to access it. Diagnosed-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- builtin/history.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/builtin/history.c b/builtin/history.c index 8dcb9a6046..365e81379b 100644 --- a/builtin/history.c +++ b/builtin/history.c @@ -41,11 +41,6 @@ static int fill_commit_message(struct repository *repo, " empty message aborts the commit.\n"); struct wt_status s; - strbuf_addstr(out, default_message); - strbuf_addch(out, '\n'); - strbuf_commented_addf(out, comment_line_str, hint, action, comment_line_str); - write_file_buf(path, out->buf, out->len); - wt_status_prepare(repo, &s); FREE_AND_NULL(s.branch); s.ahead_behind_flags = AHEAD_BEHIND_QUICK; @@ -57,14 +52,22 @@ static int fill_commit_message(struct repository *repo, s.whence = FROM_COMMIT; s.committable = 1; - s.fp = fopen(git_path_commit_editmsg(), "a"); + s.fp = fopen(path, "w"); if (!s.fp) - return error_errno(_("could not open '%s'"), git_path_commit_editmsg()); + return error_errno(_("could not open '%s'"), path); + + strbuf_addstr(out, default_message); + strbuf_addch(out, '\n'); + strbuf_commented_addf(out, comment_line_str, hint, action, comment_line_str); + if (fwrite(out->buf, 1, out->len, s.fp) != out->len) + die_errno(_("could not write to '%s'"), path); wt_status_collect_changes_trees(&s, old_tree, new_tree); wt_status_print(&s); wt_status_collect_free_buffers(&s); string_list_clear_func(&s.change, change_data_free); + if (fclose(s.fp)) + die_errno(_("could not write to '%s'"), path); strbuf_reset(out); if (launch_editor(path, out, NULL)) {