sed: fix temp file cleanup

Without this fix, the code would sometimes use FP after calling
fclose (FP), which has undefined behavior in C.
Problem found with --enable-gcc-warnings and GCC 12.
* sed/execute.c (open_next_file): Do not register here,
as it’s too late and this can cause the file to not
be cleaned up.
* sed/sed.c (G_file_to_unlink, register_cleanup_file, cancel_cleanup):
Move from here to utils.c.
(cleanup): Call remove_cleanup_file instead of doing it by hand.
* sed/utils.c (struct open_file): Remove member temp
(which was always false) and fclose_failed (which was
not enough to prevent calling fclose with a bad pointer).
All uses changed.
(register_open_file): Do not access p->fp after it’s fclosed,
as that has undefined behavior in C.
Use xmalloc instead of xcalloc, since we initialize all members.
(G_file_to_unlink, register_cleanup_file, cancel_cleanup):
Move from utils.c to here.
(remove_cleanup_file): New function.
(ck_mkstemp): Fix a screwup when mkostemp succeeded but
set_binary_mode or fdopen failed: we might misuse a null pointer,
or forget to clean up the newly-created temp file.
(ck_getdelim): Rename local to avoid confusion with global.
(mark_as_fclose_failed): Remove.  All uses removed.
(ck_fclose): Remove entry from open_files before attempting
to fclose it, so that panicking doesn’t try to fclose it again.
(do_ck_fclose): New arg NAME so that there’s no need to
call mark_as_fclose_failed, which inspected FP after fclosing
it, which is undefined behavior.
(ck_rename): Omit arg UNLINK_IF_FAIL.  All callers changed.
The cleanup handler removes this file now, as needed.

1 files changed, 4 insertions, 1 deletions

diff --git a/sed/utils.h b/sed/utils.h
index e3a8532..cac8a05 100644
--- a/sed/utils.h
+++ b/sed/utils.h
@@ -40,11 +40,14 @@ size_t ck_getdelim (char **text, size_t *buflen, char buffer_delimiter,
                     FILE *stream);
 FILE * ck_mkstemp (char **p_filename, const char *tmpdir, const char *base,
                    const char *mode) _GL_ARG_NONNULL ((1, 2, 3, 4));
-void ck_rename (const char *from, const char *to, const char *unlink_if_fail);
+void ck_rename (const char *from, const char *to);
 
 void *ck_malloc (size_t size);
 void *ck_realloc (void *ptr, size_t size);
 
+void cancel_cleanup (void);
+void remove_cleanup_file (void);
+
 struct buffer *init_buffer (void);
 char *get_buffer (struct buffer const *b) _GL_ATTRIBUTE_PURE;
 size_t size_buffer (struct buffer const *b) _GL_ATTRIBUTE_PURE;