Re: [PATCH 1/6] config: add helper function for parsing key names

13 messages, 4 authors, 2016-06-15 · open the first message on its own page

Re: [PATCH 1/6] config: add helper function for parsing key names

From: Junio C Hamano <hidden>
Date: 2016-06-15 22:55:48

Junio C Hamano [off-list ref] writes:

Jeff King [off-list ref] writes:

quoted

... did you have any comment on
the "struct config_key" alternative I sent as a follow-up?

I did read it but I cannot say I did so very carefully.  My gut
reaction was that the "take the variable name and section name,
return the subsection name pointer and length, if there is any, and
the key" made it readable enough.  The proposed interface to make
and lend a copy to the caller does make it more readble, but I do
not know if that is worth doing.  Neutral-to-slightly-in-favor, I
would say.

Now I re-read that "struct config_key" thing, I would have to say
that the idea of giving split and NUL-terminated strings to the
callers is good, but the "cheat" looks somewhat brittle for all the
reasons that come from using a static buffer (which you already
mentioned).  As I do not offhand think of a better alternative, I'd
say we leave it for another day.

[PATCHv2 0/8] config key-parsing cleanups

From: Jeff King <hidden>
Date: 2016-06-15 22:55:51

On Fri, Jan 18, 2013 at 12:53:32PM -0800, Junio C Hamano wrote:

quoted

... did you have any comment on
the "struct config_key" alternative I sent as a follow-up?

I did read it but I cannot say I did so very carefully.  My gut
reaction was that the "take the variable name and section name,
return the subsection name pointer and length, if there is any, and
the key" made it readable enough.  The proposed interface to make
and lend a copy to the caller does make it more readble, but I do
not know if that is worth doing.  Neutral-to-slightly-in-favor, I
would say.

Now I re-read that "struct config_key" thing, I would have to say
that the idea of giving split and NUL-terminated strings to the
callers is good, but the "cheat" looks somewhat brittle for all the
reasons that come from using a static buffer (which you already
mentioned).  As I do not offhand think of a better alternative, I'd
say we leave it for another day.

OK. I had the feeling if the config parser provided it to the caller
that more sites could take advantage of it (without adding too many
lines to call the parsing function). But looking again, there aren't
that many sites that would benefit. E.g., git_daemon_config in daemon.c
could use it to avoid using a constant offset. But the current code
there is not hard to read, and saving a few characters there is not
worth the complexity.

So I've re-rolled the original version, taking into account the comments
from you and Jonathan. I also clarified a few of the commit messages,
and modified two more sites to use the new function.

  [1/8]: config: add helper function for parsing key names

Same as before, but now called parse_config_key.

  [2/8]: archive-tar: use parse_config_key when parsing config

Same (rebased for new name, of course).

  [3/8]: convert some config callbacks to parse_config_key

Tweaked confusing "ep" variable name. Fixed missing "!name" check in
userdiff code (which gets removed in the next patch anyway).

  [4/8]: userdiff: drop parse_driver function
  [5/8]: submodule: use parse_config_key when parsing config
  [6/8]: submodule: simplify memory handling in config parsing

Same.

  [7/8]: help: use parse_config_key for man config
  [8/8]: reflog: use parse_config_key in config callback

Two new callsites. I split these out because unlike the ones in 3/8,
they do not benefit from a reduction in lines of code. However, I think
the results are still more readable. You can judge for yourself; drop
them if you disagree. Or feel free to squash them into 3/8 if that makes
more sense.

-Peff

[PATCHv2 1/8] config: add helper function for parsing key names

From: Jeff King <hidden>
Date: 2016-06-15 22:55:51

The config callback functions get keys of the general form:

  section.subsection.key

(where the subsection may be contain arbitrary data, or may
be missing). For matching keys without subsections, it is
simple enough to call "strcmp". Matching keys with
subsections is a little more complicated, and each callback
does it in an ad-hoc way, usually involving error-prone
pointer arithmetic.

Let's provide a helper that keeps the pointer arithmetic all
in one place.

Signed-off-by: Jeff King <redacted>
---
 cache.h  | 15 +++++++++++++++
 config.c | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/cache.h b/cache.h
index c257953..b19305b 100644
--- a/cache.h
+++ b/cache.h

@@ -1164,6 +1164,21 @@ extern int git_config_include(const char *name, const char *value, void *data);
 #define CONFIG_INCLUDE_INIT { 0 }
 extern int git_config_include(const char *name, const char *value, void *data);
 
+/*
+ * Match and parse a config key of the form:
+ *
+ *   section.(subsection.)?key
+ *
+ * (i.e., what gets handed to a config_fn_t). The caller provides the section;
+ * we return -1 if it does not match, 0 otherwise. The subsection and key
+ * out-parameters are filled by the function (and subsection is NULL if it is
+ * missing).
+ */
+extern int parse_config_key(const char *var,
+			    const char *section,
+			    const char **subsection, int *subsection_len,
+			    const char **key);
+
 extern int committer_ident_sufficiently_given(void);
 extern int author_ident_sufficiently_given(void);

diff --git a/config.c b/config.c
index 7b444b6..11bd4d8 100644
--- a/config.c
+++ b/config.c

@@ -1667,3 +1667,36 @@ int config_error_nonbool(const char *var)
 {
 	return error("Missing value for '%s'", var);
 }
+
+int parse_config_key(const char *var,
+		     const char *section,
+		     const char **subsection, int *subsection_len,
+		     const char **key)
+{
+	int section_len = strlen(section);
+	const char *dot;
+
+	/* Does it start with "section." ? */
+	if (prefixcmp(var, section) || var[section_len] != '.')
+		return -1;
+
+	/*
+	 * Find the key; we don't know yet if we have a subsection, but we must
+	 * parse backwards from the end, since the subsection may have dots in
+	 * it, too.
+	 */
+	dot = strrchr(var, '.');
+	*key = dot + 1;
+
+	/* Did we have a subsection at all? */
+	if (dot == var + section_len) {
+		*subsection = NULL;
+		*subsection_len = 0;
+	}
+	else {
+		*subsection = var + section_len + 1;
+		*subsection_len = dot - *subsection;
+	}
+
+	return 0;
+}

-- 
1.8.0.2.15.g815dc66

[PATCHv2 2/8] archive-tar: use parse_config_key when parsing config

From: Jeff King <hidden>
Date: 2016-06-15 22:55:51

This is fewer lines of code, but more importantly, fixes a
bogus pointer offset. We are looking for "tar." in the
section, but later assume that the dot we found is at offset
9, not 3. This is a holdover from an earlier iteration of
767cf45 which called the section "tarfilter".

As a result, we could erroneously reject some filters with
dots in their name, as well as read uninitialized memory.

Reported by (and test by) René Scharfe.

Signed-off-by: Jeff King <redacted>
---
 archive-tar.c       | 10 +---------
 t/t5000-tar-tree.sh |  3 ++-
 2 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/archive-tar.c b/archive-tar.c
index d1cce46..719b629 100644
--- a/archive-tar.c
+++ b/archive-tar.c

@@ -327,20 +327,12 @@ static int tar_filter_config(const char *var, const char *value, void *data)
 static int tar_filter_config(const char *var, const char *value, void *data)
 {
 	struct archiver *ar;
-	const char *dot;
 	const char *name;
 	const char *type;
 	int namelen;
 
-	if (prefixcmp(var, "tar."))
+	if (parse_config_key(var, "tar", &name, &namelen, &type) < 0 || !name)
 		return 0;
-	dot = strrchr(var, '.');
-	if (dot == var + 9)
-		return 0;
-
-	name = var + 4;
-	namelen = dot - name;
-	type = dot + 1;
 
 	ar = find_tar_filter(name, namelen);
 	if (!ar) {

diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh
index e7c240f..3fbd366 100755
--- a/t/t5000-tar-tree.sh
+++ b/t/t5000-tar-tree.sh

@@ -212,7 +212,8 @@ test_expect_success 'setup tar filters' '
 test_expect_success 'setup tar filters' '
 	git config tar.tar.foo.command "tr ab ba" &&
 	git config tar.bar.command "tr ab ba" &&
-	git config tar.bar.remote true
+	git config tar.bar.remote true &&
+	git config tar.invalid baz
 '
 
 test_expect_success 'archive --list mentions user filter' '

-- 
1.8.0.2.15.g815dc66

[PATCHv2 3/8] convert some config callbacks to parse_config_key

From: Jeff King <hidden>
Date: 2016-06-15 22:55:51

These callers can drop some inline pointer arithmetic and
magic offset constants, making them more readable and less
error-prone (those constants had to match the lengths of
strings, but there is no automatic verification of that
fact).

The "ep" pointer (presumably for "end pointer"), which
points to the final key segment of the config variable, is
given the more standard name "key" to describe its function
rather than its derivation.

Signed-off-by: Jeff King <redacted>
---
 convert.c  | 14 +++++---------
 ll-merge.c | 14 +++++---------
 userdiff.c | 13 +++----------
 3 files changed, 13 insertions(+), 28 deletions(-)

diff --git a/convert.c b/convert.c
index 6602155..3520252 100644
--- a/convert.c
+++ b/convert.c

@@ -457,7 +457,7 @@ static int read_convert_config(const char *var, const char *value, void *cb)
 
 static int read_convert_config(const char *var, const char *value, void *cb)
 {
-	const char *ep, *name;
+	const char *key, *name;
 	int namelen;
 	struct convert_driver *drv;

@@ -465,10 +465,8 @@ static int read_convert_config(const char *var, const char *value, void *cb)
 	 * External conversion drivers are configured using
 	 * "filter.<name>.variable".
 	 */
-	if (prefixcmp(var, "filter.") || (ep = strrchr(var, '.')) == var + 6)
+	if (parse_config_key(var, "filter", &name, &namelen, &key) < 0 || !name)
 		return 0;
-	name = var + 7;
-	namelen = ep - name;
 	for (drv = user_convert; drv; drv = drv->next)
 		if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
 			break;

@@ -479,8 +477,6 @@ static int read_convert_config(const char *var, const char *value, void *cb)
 		user_convert_tail = &(drv->next);
 	}
 
-	ep++;
-
 	/*
 	 * filter.<name>.smudge and filter.<name>.clean specifies
 	 * the command line:

@@ -490,13 +486,13 @@ static int read_convert_config(const char *var, const char *value, void *cb)
 	 * The command-line will not be interpolated in any way.
 	 */
 
-	if (!strcmp("smudge", ep))
+	if (!strcmp("smudge", key))
 		return git_config_string(&drv->smudge, var, value);
 
-	if (!strcmp("clean", ep))
+	if (!strcmp("clean", key))
 		return git_config_string(&drv->clean, var, value);
 
-	if (!strcmp("required", ep)) {
+	if (!strcmp("required", key)) {
 		drv->required = git_config_bool(var, value);
 		return 0;
 	}

diff --git a/ll-merge.c b/ll-merge.c
index acea33b..fb61ea6 100644
--- a/ll-merge.c
+++ b/ll-merge.c

@@ -222,7 +222,7 @@ static int read_merge_config(const char *var, const char *value, void *cb)
 static int read_merge_config(const char *var, const char *value, void *cb)
 {
 	struct ll_merge_driver *fn;
-	const char *ep, *name;
+	const char *key, *name;
 	int namelen;
 
 	if (!strcmp(var, "merge.default")) {

@@ -236,15 +236,13 @@ static int read_merge_config(const char *var, const char *value, void *cb)
 	 * especially, we do not want to look at variables such as
 	 * "merge.summary", "merge.tool", and "merge.verbosity".
 	 */
-	if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
+	if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 		return 0;
 
 	/*
 	 * Find existing one as we might be processing merge.<name>.var2
 	 * after seeing merge.<name>.var1.
 	 */
-	name = var + 6;
-	namelen = ep - name;
 	for (fn = ll_user_merge; fn; fn = fn->next)
 		if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 			break;

@@ -256,16 +254,14 @@ static int read_merge_config(const char *var, const char *value, void *cb)
 		ll_user_merge_tail = &(fn->next);
 	}
 
-	ep++;
-
-	if (!strcmp("name", ep)) {
+	if (!strcmp("name", key)) {
 		if (!value)
 			return error("%s: lacks value", var);
 		fn->description = xstrdup(value);
 		return 0;
 	}
 
-	if (!strcmp("driver", ep)) {
+	if (!strcmp("driver", key)) {
 		if (!value)
 			return error("%s: lacks value", var);
 		/*

@@ -289,7 +285,7 @@ static int read_merge_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
-	if (!strcmp("recursive", ep)) {
+	if (!strcmp("recursive", key)) {
 		if (!value)
 			return error("%s: lacks value", var);
 		fn->recursive = xstrdup(value);

diff --git a/userdiff.c b/userdiff.c
index ed958ef..a4ea1e9 100644
--- a/userdiff.c
+++ b/userdiff.c

@@ -188,20 +188,13 @@ static struct userdiff_driver *parse_driver(const char *var,
 		const char *value, const char *type)
 {
 	struct userdiff_driver *drv;
-	const char *dot;
-	const char *name;
+	const char *name, *key;
 	int namelen;
 
-	if (prefixcmp(var, "diff."))
-		return NULL;
-	dot = strrchr(var, '.');
-	if (dot == var + 4)
-		return NULL;
-	if (strcmp(type, dot+1))
+	if (parse_config_key(var, "diff", &name, &namelen, &key) < 0 ||
+	    !name || strcmp(type, key))
 		return NULL;
 
-	name = var + 5;
-	namelen = dot - name;
 	drv = userdiff_find_by_namelen(name, namelen);
 	if (!drv) {
 		ALLOC_GROW(drivers, ndrivers+1, drivers_alloc);

-- 
1.8.0.2.15.g815dc66

[PATCHv2 4/8] userdiff: drop parse_driver function

From: Jeff King <hidden>
Date: 2016-06-15 22:55:51

When we parse userdiff config, we generally assume that

  diff.name.key

will affect the "key" value of the "name" driver. However,
without confirming that the key is a valid userdiff key, we
may accidentally conflict with the ancient "diff.color.*"
namespace. The current code is careful not to even create a
driver struct if we do not see a key that is known by the
diff-driver code.

However, this carefulness is unnecessary; the default driver
with no keys set behaves exactly the same as having no
driver at all. We can simply set up the driver struct as
soon as we see we have a config key that looks like a
driver. This makes the code a bit more readable.

Signed-off-by: Jeff King <redacted>
---
 userdiff.c | 50 +++++++++++++++++++++-----------------------------
 1 file changed, 21 insertions(+), 29 deletions(-)

diff --git a/userdiff.c b/userdiff.c
index a4ea1e9..ea43a03 100644
--- a/userdiff.c
+++ b/userdiff.c

@@ -184,28 +184,6 @@ static struct userdiff_driver *userdiff_find_by_namelen(const char *k, int len)
 	return NULL;
 }
 
-static struct userdiff_driver *parse_driver(const char *var,
-		const char *value, const char *type)
-{
-	struct userdiff_driver *drv;
-	const char *name, *key;
-	int namelen;
-
-	if (parse_config_key(var, "diff", &name, &namelen, &key) < 0 ||
-	    !name || strcmp(type, key))
-		return NULL;
-
-	drv = userdiff_find_by_namelen(name, namelen);
-	if (!drv) {
-		ALLOC_GROW(drivers, ndrivers+1, drivers_alloc);
-		drv = &drivers[ndrivers++];
-		memset(drv, 0, sizeof(*drv));
-		drv->name = xmemdupz(name, namelen);
-		drv->binary = -1;
-	}
-	return drv;
-}
-
 static int parse_funcname(struct userdiff_funcname *f, const char *k,
 		const char *v, int cflags)
 {

@@ -233,20 +211,34 @@ int userdiff_config(const char *k, const char *v)
 int userdiff_config(const char *k, const char *v)
 {
 	struct userdiff_driver *drv;
+	const char *name, *type;
+	int namelen;
+
+	if (parse_config_key(k, "diff", &name, &namelen, &type) || !name)
+		return 0;
+
+	drv = userdiff_find_by_namelen(name, namelen);
+	if (!drv) {
+		ALLOC_GROW(drivers, ndrivers+1, drivers_alloc);
+		drv = &drivers[ndrivers++];
+		memset(drv, 0, sizeof(*drv));
+		drv->name = xmemdupz(name, namelen);
+		drv->binary = -1;
+	}
 
-	if ((drv = parse_driver(k, v, "funcname")))
+	if (!strcmp(type, "funcname"))
 		return parse_funcname(&drv->funcname, k, v, 0);
-	if ((drv = parse_driver(k, v, "xfuncname")))
+	if (!strcmp(type, "xfuncname"))
 		return parse_funcname(&drv->funcname, k, v, REG_EXTENDED);
-	if ((drv = parse_driver(k, v, "binary")))
+	if (!strcmp(type, "binary"))
 		return parse_tristate(&drv->binary, k, v);
-	if ((drv = parse_driver(k, v, "command")))
+	if (!strcmp(type, "command"))
 		return git_config_string(&drv->external, k, v);
-	if ((drv = parse_driver(k, v, "textconv")))
+	if (!strcmp(type, "textconv"))
 		return git_config_string(&drv->textconv, k, v);
-	if ((drv = parse_driver(k, v, "cachetextconv")))
+	if (!strcmp(type, "cachetextconv"))
 		return parse_bool(&drv->textconv_want_cache, k, v);
-	if ((drv = parse_driver(k, v, "wordregex")))
+	if (!strcmp(type, "wordregex"))
 		return git_config_string(&drv->word_regex, k, v);
 
 	return 0;

-- 
1.8.0.2.15.g815dc66

[PATCHv2 5/8] submodule: use parse_config_key when parsing config

From: Jeff King <hidden>
Date: 2016-06-15 22:55:51

This makes the code a lot simpler to read by dropping a
whole bunch of constant offsets.

As a bonus, it means we also feed the whole config variable
name to our error functions:

  [before]
  $ git -c submodule.foo.fetchrecursesubmodules=bogus checkout
  fatal: bad foo.fetchrecursesubmodules argument: bogus

  [after]
  $ git -c submodule.foo.fetchrecursesubmodules=bogus checkout
  fatal: bad submodule.foo.fetchrecursesubmodules argument: bogus

Signed-off-by: Jeff King <redacted>
---
 submodule.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/submodule.c b/submodule.c
index 2f55436..25413de 100644
--- a/submodule.c
+++ b/submodule.c

@@ -126,15 +126,16 @@ int parse_submodule_config_option(const char *var, const char *value)
 
 int parse_submodule_config_option(const char *var, const char *value)
 {
-	int len;
 	struct string_list_item *config;
 	struct strbuf submodname = STRBUF_INIT;
+	const char *name, *key;
+	int namelen;
 
-	var += 10;		/* Skip "submodule." */
+	if (parse_config_key(var, "submodule", &name, &namelen, &key) < 0 || !name)
+		return 0;
 
-	len = strlen(var);
-	if ((len > 5) && !strcmp(var + len - 5, ".path")) {
-		strbuf_add(&submodname, var, len - 5);
+	if (!strcmp(key, "path")) {
+		strbuf_add(&submodname, name, namelen);
 		config = unsorted_string_list_lookup(&config_name_for_path, value);
 		if (config)
 			free(config->util);

@@ -142,22 +143,22 @@ int parse_submodule_config_option(const char *var, const char *value)
 			config = string_list_append(&config_name_for_path, xstrdup(value));
 		config->util = strbuf_detach(&submodname, NULL);
 		strbuf_release(&submodname);
-	} else if ((len > 23) && !strcmp(var + len - 23, ".fetchrecursesubmodules")) {
-		strbuf_add(&submodname, var, len - 23);
+	} else if (!strcmp(key, "fetchrecursesubmodules")) {
+		strbuf_add(&submodname, name, namelen);
 		config = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, submodname.buf);
 		if (!config)
 			config = string_list_append(&config_fetch_recurse_submodules_for_name,
 						    strbuf_detach(&submodname, NULL));
 		config->util = (void *)(intptr_t)parse_fetch_recurse_submodules_arg(var, value);
 		strbuf_release(&submodname);
-	} else if ((len > 7) && !strcmp(var + len - 7, ".ignore")) {
+	} else if (!strcmp(key, "ignore")) {
 		if (strcmp(value, "untracked") && strcmp(value, "dirty") &&
 		    strcmp(value, "all") && strcmp(value, "none")) {
 			warning("Invalid parameter \"%s\" for config option \"submodule.%s.ignore\"", value, var);
 			return 0;
 		}
 
-		strbuf_add(&submodname, var, len - 7);
+		strbuf_add(&submodname, name, namelen);
 		config = unsorted_string_list_lookup(&config_ignore_for_name, submodname.buf);
 		if (config)
 			free(config->util);

-- 
1.8.0.2.15.g815dc66

[PATCHv2 6/8] submodule: simplify memory handling in config parsing

From: Jeff King <hidden>
Date: 2016-06-15 22:55:51

We keep a strbuf for the name of the submodule, even though
we only ever add one string to it. Let's just use xmemdupz
instead, which is slightly more efficient and makes it
easier to follow what is going on.

Unfortunately, we still end up having to deal with some
memory ownership issues in some code branches, as we have to
allocate the string in order to do a string list lookup, and
then only sometimes want to hand ownership of that string
over to the string_list. Still, making that explicit in the
code (as opposed to sometimes detaching the strbuf, and then
always releasing it) makes it a little more obvious what is
going on.

Signed-off-by: Jeff King <redacted>
---
 submodule.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/submodule.c b/submodule.c
index 25413de..9ba1496 100644
--- a/submodule.c
+++ b/submodule.c

@@ -127,7 +127,6 @@ int parse_submodule_config_option(const char *var, const char *value)
 int parse_submodule_config_option(const char *var, const char *value)
 {
 	struct string_list_item *config;
-	struct strbuf submodname = STRBUF_INIT;
 	const char *name, *key;
 	int namelen;

@@ -135,37 +134,36 @@ int parse_submodule_config_option(const char *var, const char *value)
 		return 0;
 
 	if (!strcmp(key, "path")) {
-		strbuf_add(&submodname, name, namelen);
 		config = unsorted_string_list_lookup(&config_name_for_path, value);
 		if (config)
 			free(config->util);
 		else
 			config = string_list_append(&config_name_for_path, xstrdup(value));
-		config->util = strbuf_detach(&submodname, NULL);
-		strbuf_release(&submodname);
+		config->util = xmemdupz(name, namelen);
 	} else if (!strcmp(key, "fetchrecursesubmodules")) {
-		strbuf_add(&submodname, name, namelen);
-		config = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, submodname.buf);
+		char *name_cstr = xmemdupz(name, namelen);
+		config = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, name_cstr);
 		if (!config)
-			config = string_list_append(&config_fetch_recurse_submodules_for_name,
-						    strbuf_detach(&submodname, NULL));
+			config = string_list_append(&config_fetch_recurse_submodules_for_name, name_cstr);
+		else
+			free(name_cstr);
 		config->util = (void *)(intptr_t)parse_fetch_recurse_submodules_arg(var, value);
-		strbuf_release(&submodname);
 	} else if (!strcmp(key, "ignore")) {
+		char *name_cstr;
+
 		if (strcmp(value, "untracked") && strcmp(value, "dirty") &&
 		    strcmp(value, "all") && strcmp(value, "none")) {
 			warning("Invalid parameter \"%s\" for config option \"submodule.%s.ignore\"", value, var);
 			return 0;
 		}
 
-		strbuf_add(&submodname, name, namelen);
-		config = unsorted_string_list_lookup(&config_ignore_for_name, submodname.buf);
-		if (config)
+		name_cstr = xmemdupz(name, namelen);
+		config = unsorted_string_list_lookup(&config_ignore_for_name, name_cstr);
+		if (config) {
 			free(config->util);
-		else
-			config = string_list_append(&config_ignore_for_name,
-						    strbuf_detach(&submodname, NULL));
-		strbuf_release(&submodname);
+			free(name_cstr);
+		} else
+			config = string_list_append(&config_ignore_for_name, name_cstr);
 		config->util = xstrdup(value);
 		return 0;
 	}

-- 
1.8.0.2.15.g815dc66

[PATCHv2 7/8] help: use parse_config_key for man config

From: Jeff King <hidden>
Date: 2016-06-15 22:55:51

The resulting code ends up about the same length, but it is
a little more self-explanatory. It now explicitly documents
and checks the pre-condition that the incoming var starts
with "man.", and drops the magic offset "4".

Signed-off-by: Jeff King <redacted>
---
 builtin/help.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/builtin/help.c b/builtin/help.c
index bd86253..04cb77d 100644
--- a/builtin/help.c
+++ b/builtin/help.c

@@ -237,21 +237,21 @@ static int add_man_viewer_info(const char *var, const char *value)
 
 static int add_man_viewer_info(const char *var, const char *value)
 {
-	const char *name = var + 4;
-	const char *subkey = strrchr(name, '.');
+	const char *name, *subkey;
+	int namelen;
 
-	if (!subkey)
+	if (parse_config_key(var, "man", &name, &namelen, &subkey) < 0 || !name)
 		return 0;
 
-	if (!strcmp(subkey, ".path")) {
+	if (!strcmp(subkey, "path")) {
 		if (!value)
 			return config_error_nonbool(var);
-		return add_man_viewer_path(name, subkey - name, value);
+		return add_man_viewer_path(name, namelen, value);
 	}
-	if (!strcmp(subkey, ".cmd")) {
+	if (!strcmp(subkey, "cmd")) {
 		if (!value)
 			return config_error_nonbool(var);
-		return add_man_viewer_cmd(name, subkey - name, value);
+		return add_man_viewer_cmd(name, namelen, value);
 	}
 
 	return 0;

-- 
1.8.0.2.15.g815dc66

[PATCHv2 8/8] reflog: use parse_config_key in config callback

From: Jeff King <hidden>
Date: 2016-06-15 22:55:51

This doesn't save any lines, but does keep us from doing
error-prone pointer arithmetic with constants.

Signed-off-by: Jeff King <redacted>
---
 builtin/reflog.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/builtin/reflog.c b/builtin/reflog.c
index b3c9e27..1fedf66 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c

@@ -510,26 +510,27 @@ static int reflog_expire_config(const char *var, const char *value, void *cb)
 
 static int reflog_expire_config(const char *var, const char *value, void *cb)
 {
-	const char *lastdot = strrchr(var, '.');
+	const char *pattern, *key;
+	int pattern_len;
 	unsigned long expire;
 	int slot;
 	struct reflog_expire_cfg *ent;
 
-	if (!lastdot || prefixcmp(var, "gc."))
+	if (parse_config_key(var, "gc", &pattern, &pattern_len, &key) < 0)
 		return git_default_config(var, value, cb);
 
-	if (!strcmp(lastdot, ".reflogexpire")) {
+	if (!strcmp(key, "reflogexpire")) {
 		slot = EXPIRE_TOTAL;
 		if (parse_expire_cfg_value(var, value, &expire))
 			return -1;
-	} else if (!strcmp(lastdot, ".reflogexpireunreachable")) {
+	} else if (!strcmp(key, "reflogexpireunreachable")) {
 		slot = EXPIRE_UNREACH;
 		if (parse_expire_cfg_value(var, value, &expire))
 			return -1;
 	} else
 		return git_default_config(var, value, cb);
 
-	if (lastdot == var + 2) {
+	if (!pattern) {
 		switch (slot) {
 		case EXPIRE_TOTAL:
 			default_reflog_expire = expire;

@@ -541,7 +542,7 @@ static int reflog_expire_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
-	ent = find_cfg_ent(var + 3, lastdot - (var+3));
+	ent = find_cfg_ent(pattern, pattern_len);
 	if (!ent)
 		return -1;
 	switch (slot) {

-- 
1.8.0.2.15.g815dc66

Re: [PATCHv2 0/8] config key-parsing cleanups

From: Jonathan Nieder <hidden>
Date: 2016-06-15 22:55:51

Jeff King wrote:

So I've re-rolled the original version

Lovely. :)
Reviewed-by: Jonathan Nieder <redacted>

Re: [PATCHv2 5/8] submodule: use parse_config_key when parsing config

From: Jens Lehmann <hidden>
Date: 2016-06-15 22:55:52

Am 23.01.2013 07:25, schrieb Jeff King:

This makes the code a lot simpler to read by dropping a
whole bunch of constant offsets.

As a bonus, it means we also feed the whole config variable
name to our error functions:

  [before]
  $ git -c submodule.foo.fetchrecursesubmodules=bogus checkout
  fatal: bad foo.fetchrecursesubmodules argument: bogus

  [after]
  $ git -c submodule.foo.fetchrecursesubmodules=bogus checkout
  fatal: bad submodule.foo.fetchrecursesubmodules argument: bogus

Thanks, that makes lots of sense!

Acked-by: Jens Lehmann <redacted>

quoted hunk

Signed-off-by: Jeff King <redacted>
---
 submodule.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/submodule.c b/submodule.c
index 2f55436..25413de 100644
--- a/submodule.c
+++ b/submodule.c

@@ -126,15 +126,16 @@ int parse_submodule_config_option(const char *var, const char *value)
 
 int parse_submodule_config_option(const char *var, const char *value)
 {
-	int len;
 	struct string_list_item *config;
 	struct strbuf submodname = STRBUF_INIT;
+	const char *name, *key;
+	int namelen;
 
-	var += 10;		/* Skip "submodule." */
+	if (parse_config_key(var, "submodule", &name, &namelen, &key) < 0 || !name)
+		return 0;
 
-	len = strlen(var);
-	if ((len > 5) && !strcmp(var + len - 5, ".path")) {
-		strbuf_add(&submodname, var, len - 5);
+	if (!strcmp(key, "path")) {
+		strbuf_add(&submodname, name, namelen);
 		config = unsorted_string_list_lookup(&config_name_for_path, value);
 		if (config)
 			free(config->util);

@@ -142,22 +143,22 @@ int parse_submodule_config_option(const char *var, const char *value)
 			config = string_list_append(&config_name_for_path, xstrdup(value));
 		config->util = strbuf_detach(&submodname, NULL);
 		strbuf_release(&submodname);
-	} else if ((len > 23) && !strcmp(var + len - 23, ".fetchrecursesubmodules")) {
-		strbuf_add(&submodname, var, len - 23);
+	} else if (!strcmp(key, "fetchrecursesubmodules")) {
+		strbuf_add(&submodname, name, namelen);
 		config = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, submodname.buf);
 		if (!config)
 			config = string_list_append(&config_fetch_recurse_submodules_for_name,
 						    strbuf_detach(&submodname, NULL));
 		config->util = (void *)(intptr_t)parse_fetch_recurse_submodules_arg(var, value);
 		strbuf_release(&submodname);
-	} else if ((len > 7) && !strcmp(var + len - 7, ".ignore")) {
+	} else if (!strcmp(key, "ignore")) {
 		if (strcmp(value, "untracked") && strcmp(value, "dirty") &&
 		    strcmp(value, "all") && strcmp(value, "none")) {
 			warning("Invalid parameter \"%s\" for config option \"submodule.%s.ignore\"", value, var);
 			return 0;
 		}
 
-		strbuf_add(&submodname, var, len - 7);
+		strbuf_add(&submodname, name, namelen);
 		config = unsorted_string_list_lookup(&config_ignore_for_name, submodname.buf);
 		if (config)
 			free(config->util);

Re: [PATCHv2 6/8] submodule: simplify memory handling in config parsing

From: Jens Lehmann <hidden>
Date: 2016-06-15 22:55:52

Am 23.01.2013 07:26, schrieb Jeff King:

We keep a strbuf for the name of the submodule, even though
we only ever add one string to it. Let's just use xmemdupz
instead, which is slightly more efficient and makes it
easier to follow what is going on.

Unfortunately, we still end up having to deal with some
memory ownership issues in some code branches, as we have to
allocate the string in order to do a string list lookup, and
then only sometimes want to hand ownership of that string
over to the string_list. Still, making that explicit in the
code (as opposed to sometimes detaching the strbuf, and then
always releasing it) makes it a little more obvious what is
going on.

Thanks, this helps until I some day find the time to refactor
that code into a more digestible shape ;-)

Acked-by: Jens Lehmann <redacted>

quoted hunk

Signed-off-by: Jeff King <redacted>
---
 submodule.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/submodule.c b/submodule.c
index 25413de..9ba1496 100644
--- a/submodule.c
+++ b/submodule.c

@@ -127,7 +127,6 @@ int parse_submodule_config_option(const char *var, const char *value)
 int parse_submodule_config_option(const char *var, const char *value)
 {
 	struct string_list_item *config;
-	struct strbuf submodname = STRBUF_INIT;
 	const char *name, *key;
 	int namelen;

@@ -135,37 +134,36 @@ int parse_submodule_config_option(const char *var, const char *value)
 		return 0;
 
 	if (!strcmp(key, "path")) {
-		strbuf_add(&submodname, name, namelen);
 		config = unsorted_string_list_lookup(&config_name_for_path, value);
 		if (config)
 			free(config->util);
 		else
 			config = string_list_append(&config_name_for_path, xstrdup(value));
-		config->util = strbuf_detach(&submodname, NULL);
-		strbuf_release(&submodname);
+		config->util = xmemdupz(name, namelen);
 	} else if (!strcmp(key, "fetchrecursesubmodules")) {
-		strbuf_add(&submodname, name, namelen);
-		config = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, submodname.buf);
+		char *name_cstr = xmemdupz(name, namelen);
+		config = unsorted_string_list_lookup(&config_fetch_recurse_submodules_for_name, name_cstr);
 		if (!config)
-			config = string_list_append(&config_fetch_recurse_submodules_for_name,
-						    strbuf_detach(&submodname, NULL));
+			config = string_list_append(&config_fetch_recurse_submodules_for_name, name_cstr);
+		else
+			free(name_cstr);
 		config->util = (void *)(intptr_t)parse_fetch_recurse_submodules_arg(var, value);
-		strbuf_release(&submodname);
 	} else if (!strcmp(key, "ignore")) {
+		char *name_cstr;
+
 		if (strcmp(value, "untracked") && strcmp(value, "dirty") &&
 		    strcmp(value, "all") && strcmp(value, "none")) {
 			warning("Invalid parameter \"%s\" for config option \"submodule.%s.ignore\"", value, var);
 			return 0;
 		}
 
-		strbuf_add(&submodname, name, namelen);
-		config = unsorted_string_list_lookup(&config_ignore_for_name, submodname.buf);
-		if (config)
+		name_cstr = xmemdupz(name, namelen);
+		config = unsorted_string_list_lookup(&config_ignore_for_name, name_cstr);
+		if (config) {
 			free(config->util);
-		else
-			config = string_list_append(&config_ignore_for_name,
-						    strbuf_detach(&submodname, NULL));
-		strbuf_release(&submodname);
+			free(name_cstr);
+		} else
+			config = string_list_append(&config_ignore_for_name, name_cstr);
 		config->util = xstrdup(value);
 		return 0;
 	}

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