Merge branch 'ab/free-and-null'

A common pattern to free a piece of memory and assign NULL to the
pointer that used to point at it has been replaced with a new
FREE_AND_NULL() macro.

* ab/free-and-null:
  *.[ch] refactoring: make use of the FREE_AND_NULL() macro
  coccinelle: make use of the "expression" FREE_AND_NULL() rule
  coccinelle: add a rule to make "expression" code use FREE_AND_NULL()
  coccinelle: make use of the "type" FREE_AND_NULL() rule
  coccinelle: add a rule to make "type" code use FREE_AND_NULL()
  git-compat-util: add a FREE_AND_NULL() wrapper around free(ptr); ptr = NULL

alias.c

@@ -62,8 +62,7 @@ int split_cmdline(char *cmdline, const char ***argv)
 				src++;
 				c = cmdline[src];
 				if (!c) {
-					free(*argv);
-					*argv = NULL;
+					FREE_AND_NULL(*argv);
 					return -SPLIT_CMDLINE_BAD_ENDING;
 				}
 			}
@@ -75,8 +74,7 @@ int split_cmdline(char *cmdline, const char ***argv)
 	cmdline[dst] = 0;
 
 	if (quoted) {
-		free(*argv);
-		*argv = NULL;
+		FREE_AND_NULL(*argv);
 		return -SPLIT_CMDLINE_UNCLOSED_QUOTE;
 	}
 

apply.c

@@ -3695,8 +3695,7 @@ static int check_preimage(struct apply_state *state,
  is_new:
 	patch->is_new = 1;
 	patch->is_delete = 0;
-	free(patch->old_name);
-	patch->old_name = NULL;
+	FREE_AND_NULL(patch->old_name);
 	return 0;
 }
 

attr.c

@@ -639,13 +639,11 @@ void attr_check_reset(struct attr_check *check)
 
 void attr_check_clear(struct attr_check *check)
 {
-	free(check->items);
-	check->items = NULL;
+	FREE_AND_NULL(check->items);
 	check->alloc = 0;
 	check->nr = 0;
 
-	free(check->all_attrs);
-	check->all_attrs = NULL;
+	FREE_AND_NULL(check->all_attrs);
 	check->all_attrs_nr = 0;
 
 	drop_attr_stack(&check->stack);

blame.c

@@ -314,8 +314,7 @@ static void fill_origin_blob(struct diff_options *opt,
 static void drop_origin_blob(struct blame_origin *o)
 {
 	if (o->file.ptr) {
-		free(o->file.ptr);
-		o->file.ptr = NULL;
+		FREE_AND_NULL(o->file.ptr);
 	}
 }
 

branch.c

@@ -25,8 +25,7 @@ static int find_tracked_branch(struct remote *remote, void *priv)
 		} else {
 			free(tracking->spec.src);
 			if (tracking->src) {
-				free(tracking->src);
-				tracking->src = NULL;
+				FREE_AND_NULL(tracking->src);
 			}
 		}
 		tracking->spec.src = NULL;

builtin/am.c

@@ -484,8 +484,7 @@ static int run_applypatch_msg_hook(struct am_state *state)
 	ret = run_hook_le(NULL, "applypatch-msg", am_path(state, "final-commit"), NULL);
 
 	if (!ret) {
-		free(state->msg);
-		state->msg = NULL;
+		FREE_AND_NULL(state->msg);
 		if (read_commit_msg(state) < 0)
 			die(_("'%s' was deleted by the applypatch-msg hook"),
 				am_path(state, "final-commit"));
@@ -1074,17 +1073,10 @@ static void am_next(struct am_state *state)
 {
 	struct object_id head;
 
-	free(state->author_name);
-	state->author_name = NULL;
-
-	free(state->author_email);
-	state->author_email = NULL;
-
-	free(state->author_date);
-	state->author_date = NULL;
-
-	free(state->msg);
-	state->msg = NULL;
+	FREE_AND_NULL(state->author_name);
+	FREE_AND_NULL(state->author_email);
+	FREE_AND_NULL(state->author_date);
+	FREE_AND_NULL(state->msg);
 	state->msg_len = 0;
 
 	unlink(am_path(state, "author-script"));

builtin/clean.c

@@ -838,8 +838,7 @@ static void interactive_main_loop(void)
 			int ret;
 			ret = menus[*chosen].fn();
 			if (ret != MENU_RETURN_NO_LOOP) {
-				free(chosen);
-				chosen = NULL;
+				FREE_AND_NULL(chosen);
 				if (!del_list.nr) {
 					clean_print_color(CLEAN_COLOR_ERROR);
 					printf_ln(_("No more files to clean, exiting."));
@@ -852,8 +851,7 @@ static void interactive_main_loop(void)
 			quit_cmd();
 		}
 
-		free(chosen);
-		chosen = NULL;
+		FREE_AND_NULL(chosen);
 		break;
 	}
 }

builtin/config.c

@@ -215,8 +215,7 @@ static int get_value(const char *key_, const char *regex_)
 		key_regexp = (regex_t*)xmalloc(sizeof(regex_t));
 		if (regcomp(key_regexp, key, REG_EXTENDED)) {
 			error("invalid key pattern: %s", key_);
-			free(key_regexp);
-			key_regexp = NULL;
+			FREE_AND_NULL(key_regexp);
 			ret = CONFIG_INVALID_PATTERN;
 			goto free_strings;
 		}
@@ -236,8 +235,7 @@ static int get_value(const char *key_, const char *regex_)
 		regexp = (regex_t*)xmalloc(sizeof(regex_t));
 		if (regcomp(regexp, regex_, REG_EXTENDED)) {
 			error("invalid pattern: %s", regex_);
-			free(regexp);
-			regexp = NULL;
+			FREE_AND_NULL(regexp);
 			ret = CONFIG_INVALID_PATTERN;
 			goto free_strings;
 		}

builtin/index-pack.c

@@ -389,8 +389,7 @@ static struct base_data *alloc_base_data(void)
 static void free_base_data(struct base_data *c)
 {
 	if (c->data) {
-		free(c->data);
-		c->data = NULL;
+		FREE_AND_NULL(c->data);
 		get_thread_data()->base_cache_used -= c->size;
 	}
 }
@@ -606,8 +605,7 @@ static void *unpack_data(struct object_entry *obj,
 	git_inflate_end(&stream);
 	free(inbuf);
 	if (consume) {
-		free(data);
-		data = NULL;
+		FREE_AND_NULL(data);
 	}
 	return data;
 }

builtin/pack-objects.c

@@ -265,8 +265,7 @@ static unsigned long write_no_reuse_object(struct sha1file *f, struct object_ent
 		 * make sure no cached delta data remains from a
 		 * previous attempt before a pack split occurred.
 		 */
-		free(entry->delta_data);
-		entry->delta_data = NULL;
+		FREE_AND_NULL(entry->delta_data);
 		entry->z_delta_size = 0;
 	} else if (entry->delta_data) {
 		size = entry->delta_size;
@@ -1376,12 +1375,10 @@ static void cleanup_preferred_base(void)
 		if (!pbase_tree_cache[i])
 			continue;
 		free(pbase_tree_cache[i]->tree_data);
-		free(pbase_tree_cache[i]);
-		pbase_tree_cache[i] = NULL;
+		FREE_AND_NULL(pbase_tree_cache[i]);
 	}
 
-	free(done_pbase_paths);
-	done_pbase_paths = NULL;
+	FREE_AND_NULL(done_pbase_paths);
 	done_pbase_paths_num = done_pbase_paths_alloc = 0;
 }
 
@@ -1971,8 +1968,7 @@ static unsigned long free_unpacked(struct unpacked *n)
 	n->index = NULL;
 	if (n->data) {
 		freed_mem += n->entry->size;
-		free(n->data);
-		n->data = NULL;
+		FREE_AND_NULL(n->data);
 	}
 	n->entry = NULL;
 	n->depth = 0;

builtin/unpack-objects.c

@@ -113,8 +113,7 @@ static void *get_data(unsigned long size)
 			break;
 		if (ret != Z_OK) {
 			error("inflate returned %d", ret);
-			free(buf);
-			buf = NULL;
+			FREE_AND_NULL(buf);
 			if (!recover)
 				exit(1);
 			has_errors = 1;

builtin/worktree.c

@@ -300,10 +300,8 @@ static int add_worktree(const char *path, const char *refname,
 	}
 
 	is_junk = 0;
-	free(junk_work_tree);
-	free(junk_git_dir);
-	junk_work_tree = NULL;
-	junk_git_dir = NULL;
+	FREE_AND_NULL(junk_work_tree);
+	FREE_AND_NULL(junk_git_dir);
 
 done:
 	if (ret || !opts->keep_locked) {

commit-slab.h

@@ -82,8 +82,7 @@ static MAYBE_UNUSED void clear_ ##slabname(struct slabname *s)		\
 	for (i = 0; i < s->slab_count; i++)				\
 		free(s->slab[i]);					\
 	s->slab_count = 0;						\
-	free(s->slab);							\
-	s->slab = NULL;							\
+	FREE_AND_NULL(s->slab);						\
 }									\
 									\
 static MAYBE_UNUSED elemtype *slabname## _at_peek(struct slabname *s,	\

commit.c

@@ -287,8 +287,7 @@ void free_commit_buffer(struct commit *commit)
 {
 	struct commit_buffer *v = buffer_slab_peek(&buffer_slab, commit);
 	if (v) {
-		free(v->buffer);
-		v->buffer = NULL;
+		FREE_AND_NULL(v->buffer);
 		v->size = 0;
 	}
 }

config.c

@@ -394,8 +394,7 @@ static int git_config_parse_key_1(const char *key, char **store_key, int *basele
 
 out_free_ret_1:
 	if (store_key) {
-		free(*store_key);
-		*store_key = NULL;
+		FREE_AND_NULL(*store_key);
 	}
 	return -CONFIG_INVALID_KEY;
 }

contrib/coccinelle/free.cocci

@@ -9,3 +9,18 @@ expression E;
 @@
 - if (!E)
   free(E);
+
+@@
+type T;
+T *ptr;
+@@
+- free(ptr);
+- ptr = NULL;
++ FREE_AND_NULL(ptr);
+
+@@
+expression E;
+@@
+- free(E);
+- E = NULL;
++ FREE_AND_NULL(E);

credential.c

@@ -94,8 +94,7 @@ static void credential_apply_config(struct credential *c)
 	c->configured = 1;
 
 	if (!c->use_http_path && proto_is_http(c->protocol)) {
-		free(c->path);
-		c->path = NULL;
+		FREE_AND_NULL(c->path);
 	}
 }
 
@@ -315,10 +314,8 @@ void credential_reject(struct credential *c)
 	for (i = 0; i < c->helpers.nr; i++)
 		credential_do(c, c->helpers.items[i].string, "erase");
 
-	free(c->username);
-	c->username = NULL;
-	free(c->password);
-	c->password = NULL;
+	FREE_AND_NULL(c->username);
+	FREE_AND_NULL(c->password);
 	c->approved = 0;
 }
 

diff-lib.c

@@ -179,8 +179,7 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 				free(dpath);
 				continue;
 			}
-			free(dpath);
-			dpath = NULL;
+			FREE_AND_NULL(dpath);
 
 			/*
 			 * Show the diff for the 'ce' if we found the one

diff.c

@@ -1219,8 +1219,7 @@ static void free_diff_words_data(struct emit_callback *ecbdata)
 			regfree(ecbdata->diff_words->word_regex);
 			free(ecbdata->diff_words->word_regex);
 		}
-		free(ecbdata->diff_words);
-		ecbdata->diff_words = NULL;
+		FREE_AND_NULL(ecbdata->diff_words);
 	}
 }
 
@@ -2952,8 +2951,7 @@ void diff_free_filespec_blob(struct diff_filespec *s)
 void diff_free_filespec_data(struct diff_filespec *s)
 {
 	diff_free_filespec_blob(s);
-	free(s->cnt_data);
-	s->cnt_data = NULL;
+	FREE_AND_NULL(s->cnt_data);
 }
 
 static void prep_temp_blob(const char *path, struct diff_tempfile *temp,

diffcore-rename.c

@@ -667,11 +667,9 @@ void diffcore_rename(struct diff_options *options)
 	for (i = 0; i < rename_dst_nr; i++)
 		free_filespec(rename_dst[i].two);
 
-	free(rename_dst);
-	rename_dst = NULL;
+	FREE_AND_NULL(rename_dst);
 	rename_dst_nr = rename_dst_alloc = 0;
-	free(rename_src);
-	rename_src = NULL;
+	FREE_AND_NULL(rename_src);
 	rename_src_nr = rename_src_alloc = 0;
 	return;
 }

dir.c

@@ -2127,8 +2127,7 @@ int read_directory(struct dir_struct *dir, struct index_state *istate,
 		for (i = j = 0; j < dir->nr; j++) {
 			if (i &&
 			    check_dir_entry_contains(dir->entries[i - 1], dir->entries[j])) {
-				free(dir->entries[j]);
-				dir->entries[j] = NULL;
+				FREE_AND_NULL(dir->entries[j]);
 			} else {
 				dir->entries[i++] = dir->entries[j];
 			}
@@ -2154,8 +2153,7 @@ int read_directory(struct dir_struct *dir, struct index_state *istate,
 		     dir->untracked->dir_invalidated))
 			istate->cache_changed |= UNTRACKED_CHANGED;
 		if (dir->untracked != istate->untracked) {
-			free(dir->untracked);
-			dir->untracked = NULL;
+			FREE_AND_NULL(dir->untracked);
 		}
 	}
 	return dir->nr;
@@ -2498,8 +2496,7 @@ void write_untracked_extension(struct strbuf *out, struct untracked_cache *untra
 	strbuf_addbuf(out, &untracked->ident);
 
 	strbuf_add(out, ouc, ouc_size(len));
-	free(ouc);
-	ouc = NULL;
+	FREE_AND_NULL(ouc);
 
 	if (!untracked->root) {
 		varint_len = encode_varint(0, varbuf);

fast-import.c

@@ -1064,8 +1064,7 @@ static void end_packfile(void)
 		close(pack_data->pack_fd);
 		unlink_or_warn(pack_data->pack_name);
 	}
-	free(pack_data);
-	pack_data = NULL;
+	FREE_AND_NULL(pack_data);
 	running = 0;
 
 	/* We can't carry a delta across packfiles. */
@@ -1150,8 +1149,7 @@ static int store_object(
 
 		/* We cannot carry a delta into the new pack. */
 		if (delta) {
-			free(delta);
-			delta = NULL;
+			FREE_AND_NULL(delta);
 
 			git_deflate_init(&s, pack_compression_level);
 			s.next_in = (void *)dat->buf;

git-compat-util.h

@@ -808,6 +808,12 @@ extern char *xgetcwd(void);
 extern FILE *fopen_for_writing(const char *path);
 extern FILE *fopen_or_warn(const char *path, const char *mode);
 
+/*
+ * FREE_AND_NULL(ptr) is like free(ptr) followed by ptr = NULL. Note
+ * that ptr is used twice, so don't pass e.g. ptr++.
+ */
+#define FREE_AND_NULL(p) do { free(p); (p) = NULL; } while (0)
+
 #define ALLOC_ARRAY(x, alloc) (x) = xmalloc(st_mult(sizeof(*(x)), (alloc)))
 #define REALLOC_ARRAY(x, alloc) (x) = xrealloc((x), st_mult(sizeof(*(x)), (alloc)))