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[PATCH 12/28] attr: convert git_all_attrs() to use "struct git_attr_check"

From
Stefan Beller <sbeller@google.com>
Date
Oct 11, 2016, 00:20 UTC
Message-ID
<20161011002115.23312-13-sbeller@google.com>
In-Reply-To
<20161011002115.23312-1-sbeller@google.com>
From: Junio C Hamano <gitster@pobox.com>

This updates the other two ways the attribute check is done via an array of "struct git_attr_check_elem" elements. These two niches appear only in "git check-attr".

 * The caller does not know offhand what attributes it wants to ask
   about and cannot use git_attr_check_initl() to prepare the
   git_attr_check structure.
 * The caller may not know what attributes it wants to ask at all,
   and instead wants to learn everything that the given path has.

Such a caller can call git_attr_check_alloc() to allocate an empty git_attr_check, and then call git_attr_check_append() to add attribute names one by one. A new attribute can be appended until git_attr_check structure is "finalized", which happens when it is used to ask for attributes for any path by calling git_check_attr() or git_all_attrs(). A git_attr_check structure that is initialized by git_attr_check_initl() is already finalized when it is returned.

I am not at all happy with the way git_all_attrs() API turned out to be, but it is only to support one niche caller ("check-attr --all"), so I'll stop here for now.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
---
 attr.c               | 75 ++++++++++++++++++++++++++++++++++++++--------------
 attr.h               | 16 ++++++-----
 builtin/check-attr.c | 51 ++++++++++++++++++-----------------
 3 files changed, 90 insertions(+), 52 deletions(-)
diff --git a/attr.c b/attr.c
index 861e1a2..76f0d6b 100644
--- a/attr.c
+++ b/attr.c
@@ -724,6 +724,11 @@ static int macroexpand_one(int nr, int rem)
 	return rem;
 }
 
+static int attr_check_is_dynamic(const struct git_attr_check *check)
+{
+	return (void *)(check->check) != (void *)(check + 1);
+}
+
 /*
  * Collect attributes for path into the array pointed to by
  * check_all_attr. If num is non-zero, only attributes in check[] are
@@ -789,32 +794,21 @@ int git_check_attrs(const char *path, int num, struct git_attr_check_elem *check
 	return 0;
 }
 
-int git_all_attrs(const char *path, int *num, struct git_attr_check_elem **check)
+void git_all_attrs(const char *path, struct git_attr_check *check)
 {
-	int i, count, j;
+	int i;
 
+	git_attr_check_clear(check);
 	collect_some_attrs(path, 0, NULL);
 
-	/* Count the number of attributes that are set. */
-	count = 0;
-	for (i = 0; i < attr_nr; i++) {
-		const char *value = check_all_attr[i].value;
-		if (value != ATTR__UNSET && value != ATTR__UNKNOWN)
-			++count;
-	}
-	*num = count;
-	ALLOC_ARRAY(*check, count);
-	j = 0;
 	for (i = 0; i < attr_nr; i++) {
+		const char *name = check_all_attr[i].attr->name;
 		const char *value = check_all_attr[i].value;
-		if (value != ATTR__UNSET && value != ATTR__UNKNOWN) {
-			(*check)[j].attr = check_all_attr[i].attr;
-			(*check)[j].value = value;
-			++j;
-		}
+		if (value == ATTR__UNSET || value == ATTR__UNKNOWN)
+			continue;
+		git_attr_check_append(check, git_attr(name));
+		check->check[check->check_nr - 1].value = value;
 	}
-
-	return 0;
 }
 
 void git_attr_set_direction(enum git_attr_direction new, struct index_state *istate)
@@ -832,6 +826,7 @@ void git_attr_set_direction(enum git_attr_direction new, struct index_state *ist
 
 int git_check_attr(const char *path, struct git_attr_check *check)
 {
+	check->finalized = 1;
 	return git_check_attrs(path, check->check_nr, check->check);
 }
 
@@ -849,17 +844,57 @@ struct git_attr_check *git_attr_check_initl(const char *one, ...)
 	check = xcalloc(1,
 			sizeof(*check) + cnt * sizeof(*(check->check)));
 	check->check_nr = cnt;
+	check->finalized = 1;
 	check->check = (struct git_attr_check_elem *)(check + 1);
 
 	check->check[0].attr = git_attr(one);
 	va_start(params, one);
 	for (cnt = 1; cnt < check->check_nr; cnt++) {
+		struct git_attr *attr;
 		param = va_arg(params, const char *);
 		if (!param)
 			die("BUG: counted %d != ended at %d",
 			    check->check_nr, cnt);
-		check->check[cnt].attr = git_attr(param);
+		attr = git_attr(param);
+		if (!attr)
+			die("BUG: %s: not a valid attribute name", param);
+		check->check[cnt].attr = attr;
 	}
 	va_end(params);
 	return check;
 }
+
+struct git_attr_check *git_attr_check_alloc(void)
+{
+	return xcalloc(1, sizeof(struct git_attr_check));
+}
+
+struct git_attr_check_elem *git_attr_check_append(struct git_attr_check *check,
+						  const struct git_attr *attr)
+{
+	struct git_attr_check_elem *elem;
+	if (check->finalized)
+		die("BUG: append after git_attr_check structure is finalized");
+	if (!attr_check_is_dynamic(check))
+		die("BUG: appending to a statically initialized git_attr_check");
+	ALLOC_GROW(check->check, check->check_nr + 1, check->check_alloc);
+	elem = &check->check[check->check_nr++];
+	elem->attr = attr;
+	return elem;
+}
+
+void git_attr_check_clear(struct git_attr_check *check)
+{
+	if (!attr_check_is_dynamic(check))
+		die("BUG: clearing a statically initialized git_attr_check");
+	free(check->check);
+	check->check_nr = 0;
+	check->check_alloc = 0;
+	check->finalized = 0;
+}
+
+void git_attr_check_free(struct git_attr_check *check)
+{
+	git_attr_check_clear(check);
+	free(check);
+}
diff --git a/attr.h b/attr.h
index 3fd8690..0d94077 100644
--- a/attr.h
+++ b/attr.h
@@ -30,6 +30,7 @@ struct git_attr_check_elem {
 };
 
 struct git_attr_check {
+	int finalized;
 	int check_nr;
 	int check_alloc;
 	struct git_attr_check_elem *check;
@@ -38,6 +39,12 @@ struct git_attr_check {
 extern struct git_attr_check *git_attr_check_initl(const char *, ...);
 extern int git_check_attr(const char *path, struct git_attr_check *);
 
+extern struct git_attr_check *git_attr_check_alloc(void);
+extern struct git_attr_check_elem *git_attr_check_append(struct git_attr_check *, const struct git_attr *);
+
+extern void git_attr_check_clear(struct git_attr_check *);
+extern void git_attr_check_free(struct git_attr_check *);
+
 /*
  * Return the name of the attribute represented by the argument.  The
  * return value is a pointer to a null-delimited string that is part
@@ -48,13 +55,10 @@ extern const char *git_attr_name(const struct git_attr *);
 int git_check_attrs(const char *path, int, struct git_attr_check_elem *);
 
 /*
- * Retrieve all attributes that apply to the specified path.  *num
- * will be set to the number of attributes on the path; **check will
- * be set to point at a newly-allocated array of git_attr_check
- * objects describing the attributes and their values.  *check must be
- * free()ed by the caller.
+ * Retrieve all attributes that apply to the specified path.
+ * check holds the attributes and their values.
  */
-int git_all_attrs(const char *path, int *num, struct git_attr_check_elem **check);
+void git_all_attrs(const char *path, struct git_attr_check *check);
 
 enum git_attr_direction {
 	GIT_ATTR_CHECKIN,
diff --git a/builtin/check-attr.c b/builtin/check-attr.c
index 97e3837..ec61476 100644
--- a/builtin/check-attr.c
+++ b/builtin/check-attr.c
@@ -24,12 +24,13 @@ static const struct option check_attr_options[] = {
 	OPT_END()
 };
 
-static void output_attr(int cnt, struct git_attr_check_elem *check,
-			const char *file)
+static void output_attr(struct git_attr_check *check, const char *file)
 {
 	int j;
+	int cnt = check->check_nr;
+
 	for (j = 0; j < cnt; j++) {
-		const char *value = check[j].value;
+		const char *value = check->check[j].value;
 
 		if (ATTR_TRUE(value))
 			value = "set";
@@ -42,36 +43,37 @@ static void output_attr(int cnt, struct git_attr_check_elem *check,
 			printf("%s%c" /* path */
 			       "%s%c" /* attrname */
 			       "%s%c" /* attrvalue */,
-			       file, 0, git_attr_name(check[j].attr), 0, value, 0);
+			       file, 0,
+			       git_attr_name(check->check[j].attr), 0, value, 0);
 		} else {
 			quote_c_style(file, NULL, stdout, 0);
-			printf(": %s: %s\n", git_attr_name(check[j].attr), value);
+			printf(": %s: %s\n",
+			       git_attr_name(check->check[j].attr), value);
 		}
-
 	}
 }
 
 static void check_attr(const char *prefix,
-		       int cnt, struct git_attr_check_elem *check,
+		       struct git_attr_check *check,
 		       const char *file)
 {
 	char *full_path =
 		prefix_path(prefix, prefix ? strlen(prefix) : 0, file);
 	if (check != NULL) {
-		if (git_check_attrs(full_path, cnt, check))
-			die("git_check_attrs died");
-		output_attr(cnt, check, file);
+		if (git_check_attr(full_path, check))
+			die("git_check_attr died");
+		output_attr(check, file);
 	} else {
-		if (git_all_attrs(full_path, &cnt, &check))
-			die("git_all_attrs died");
-		output_attr(cnt, check, file);
-		free(check);
+		check = git_attr_check_alloc();
+		git_all_attrs(full_path, check);
+		output_attr(check, file);
+		git_attr_check_free(check);
 	}
 	free(full_path);
 }
 
 static void check_attr_stdin_paths(const char *prefix,
-				   int cnt, struct git_attr_check_elem *check)
+				   struct git_attr_check *check)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct strbuf unquoted = STRBUF_INIT;
@@ -85,7 +87,7 @@ static void check_attr_stdin_paths(const char *prefix,
 				die("line is badly quoted");
 			strbuf_swap(&buf, &unquoted);
 		}
-		check_attr(prefix, cnt, check, buf.buf);
+		check_attr(prefix, check, buf.buf);
 		maybe_flush_or_die(stdout, "attribute to stdout");
 	}
 	strbuf_release(&buf);
@@ -100,7 +102,7 @@ static NORETURN void error_with_usage(const char *msg)
 
 int cmd_check_attr(int argc, const char **argv, const char *prefix)
 {
-	struct git_attr_check_elem *check;
+	struct git_attr_check *check;
 	int cnt, i, doubledash, filei;
 
 	if (!is_bare_repository())
@@ -163,24 +165,21 @@ int cmd_check_attr(int argc, const char **argv, const char *prefix)
 	if (all_attrs) {
 		check = NULL;
 	} else {
-		check = xcalloc(cnt, sizeof(*check));
+		check = git_attr_check_alloc();
 		for (i = 0; i < cnt; i++) {
-			const char *name;
-			struct git_attr *a;
-			name = argv[i];
-			a = git_attr(name);
+			struct git_attr *a = git_attr(argv[i]);
 			if (!a)
 				return error("%s: not a valid attribute name",
-					name);
-			check[i].attr = a;
+					     argv[i]);
+			git_attr_check_append(check, a);
 		}
 	}
 
 	if (stdin_paths)
-		check_attr_stdin_paths(prefix, cnt, check);
+		check_attr_stdin_paths(prefix, check);
 	else {
 		for (i = filei; i < argc; i++)
-			check_attr(prefix, cnt, check, argv[i]);
+			check_attr(prefix, check, argv[i]);
 		maybe_flush_or_die(stdout, "attribute to stdout");
 	}
 	return 0;

-- 
2.10.1.382.ga23ca1b.dirty
Previous: Junio C Hamano
Message 44 of 44 in “Revamping the attr subsystem!”
  1. 00/28 Revamping the attr subsystem!Stefan Beller, Oct 11, 2016
  2. 01/28 commit.c: use strchrnul() to scan for one lineStefan Beller, Oct 11, 2016
  3. 02/28 attr.c: use strchrnul() to scan for one lineStefan Beller, Oct 11, 2016
  4. 03/28 attr.c: update a stale comment on "struct match_attr"Stefan Beller, Oct 11, 2016
  5. 07/28 attr.c: simplify macroexpand_one()Stefan Beller, Oct 11, 2016
  6. 05/28 attr.c: complete a sentence in a commentStefan Beller, Oct 11, 2016
  7. 04/28 attr.c: explain the lack of attr-name syntax check in parse_attr()Stefan Beller, Oct 11, 2016
  8. 06/28 attr.c: mark where #if DEBUG ends more clearlyStefan Beller, Oct 11, 2016
  9. 09/28 attr.c: plug small leak in parse_attr_line()Stefan Beller, Oct 11, 2016
  10. 08/28 attr.c: tighten constness around "git_attr" structureStefan Beller, Oct 11, 2016
  11. 10/28 attr: rename function and struct related to checking attributesStefan Beller, Oct 11, 2016
  12. 14/28 attr: retire git_check_attrs() APIStefan Beller, Oct 11, 2016
  13. 13/28 attr: convert git_check_attrs() callers to use the new APIStefan Beller, Oct 11, 2016
  14. 16/28 attr: add counted string version of git_attr()Stefan Beller, Oct 11, 2016
  15. 17/28 attr: expose validity check for attribute namesStefan Beller, Oct 11, 2016
  16. Brandon WilliamsOct 11, 2016
  17. Stefan BellerOct 11, 2016
  18. Brandon WilliamsOct 11, 2016
  19. Stefan BellerOct 11, 2016
  20. Brandon WilliamsOct 11, 2016
  21. 15/28 attr: add counted string version of git_check_attr()Stefan Beller, Oct 11, 2016
  22. 19/28 attr.c: add push_stack() helperStefan Beller, Oct 11, 2016
  23. 18/28 attr: support quoting pathname patterns in C styleStefan Beller, Oct 11, 2016
  24. 21/28 attr.c: rename a local variable checkStefan Beller, Oct 11, 2016
  25. 25/28 attr.c: outline the future plans by heavily commentingStefan Beller, Oct 11, 2016
  26. 20/28 attr.c: pass struct git_attr_check down the callchainStefan Beller, Oct 11, 2016
  27. 26/28 attr: make git_attr_counted staticStefan Beller, Oct 11, 2016
  28. Brandon WilliamsOct 11, 2016
  29. Stefan BellerOct 11, 2016
  30. 27/28 attr: make git_check_attr_counted staticStefan Beller, Oct 11, 2016
  31. 23/28 attr.c: introduce empty_attr_check_elems()Stefan Beller, Oct 11, 2016
  32. 28/28 attr: convert to new threadsafe APIStefan Beller, Oct 11, 2016
  33. Brandon WilliamsOct 11, 2016
  34. Junio C HamanoOct 11, 2016
  35. Stefan BellerOct 11, 2016
  36. Junio C HamanoOct 11, 2016
  37. Stefan BellerOct 11, 2016
  38. Junio C HamanoOct 11, 2016
  39. 24/28 attr.c: always pass check[] to collect_some_attrs()Stefan Beller, Oct 11, 2016
  40. 22/28 attr.c: correct ugly hack for git_all_attrs()Stefan Beller, Oct 11, 2016
  41. 11/28 attr: (re)introduce git_check_attr() and struct git_attr_checkStefan Beller, Oct 11, 2016
  42. Brandon WilliamsOct 11, 2016
  43. Junio C HamanoOct 11, 2016
  44. 12/28 attr: convert git_all_attrs() to use "struct git_attr_check"Stefan Beller, Oct 11, 2016

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