Re: [PATCH] make config --add behave correctly for empty and NULL values

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4 messages, 3 authors, 2016-06-15 · open the first message on its own page

Re: [PATCH] make config --add behave correctly for empty and NULL values

From: Junio C Hamano <hidden>
Date: 2016-06-15 23:02:30

Jeff King [off-list ref] writes:

Here is the patch I wrote, for reference (I also think breaking the
"matches" function into a series of conditionals, as you showed, is way
more readable):

OK, while reviewing the today's issue of "What's cooking" and making
topics graduate to 'master', I got annoyed that the bottom of jch
branch still needed to be kept.  Let's do this.

-- >8 --
From: Jeff King <redacted>
Date: Tue, 19 Aug 2014 02:20:00 -0400
Subject: [PATCH] config: avoid a funny sentinel value "a^"

Introduce CONFIG_REGEX_NONE as a more explicit sentinel value to say
"we do not want to replace any existing entry" and use it in the
implementation of "git config --add".

Signed-off-by: Jeff King <redacted>
Signed-off-by: Junio C Hamano <redacted>
---
 builtin/config.c |  3 ++-
 cache.h          |  2 ++
 config.c         | 23 +++++++++++++++++------
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/builtin/config.c b/builtin/config.c
index 8224699..bf1aa6b 100644
--- a/builtin/config.c
+++ b/builtin/config.c

@@ -599,7 +599,8 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 		check_argc(argc, 2, 2);
 		value = normalize_value(argv[0], argv[1]);
 		return git_config_set_multivar_in_file(given_config_source.file,
-						       argv[0], value, "a^", 0);
+						       argv[0], value,
+						       CONFIG_REGEX_NONE, 0);
 	}
 	else if (actions == ACTION_REPLACE_ALL) {
 		check_write();

diff --git a/cache.h b/cache.h
index c708062..8356168 100644
--- a/cache.h
+++ b/cache.h

@@ -1233,6 +1233,8 @@ extern int update_server_info(int);
 #define CONFIG_INVALID_PATTERN 6
 #define CONFIG_GENERIC_ERROR 7
 
+#define CONFIG_REGEX_NONE ((void *)1)
+
 struct git_config_source {
 	unsigned int use_stdin:1;
 	const char *file;

diff --git a/config.c b/config.c
index ffe0104..2e709bf 100644
--- a/config.c
+++ b/config.c

@@ -1230,10 +1230,15 @@ static struct {
 
 static int matches(const char *key, const char *value)
 {
-	return !strcmp(key, store.key) &&
-		(store.value_regex == NULL ||
-		 (store.do_not_match ^
-		  (value && !regexec(store.value_regex, value, 0, NULL, 0))));
+	if (strcmp(key, store.key))
+		return 0; /* not ours */
+	if (!store.value_regex)
+		return 1; /* always matches */
+	if (store.value_regex == CONFIG_REGEX_NONE)
+		return 0; /* never matches */
+
+	return store.do_not_match ^
+		(value && !regexec(store.value_regex, value, 0, NULL, 0));
 }
 
 static int store_aux(const char *key, const char *value, void *cb)

@@ -1495,6 +1500,8 @@ out_free_ret_1:
 /*
  * If value==NULL, unset in (remove from) config,
  * if value_regex!=NULL, disregard key/value pairs where value does not match.
+ * if value_regex==CONFIG_REGEX_NONE, do not match any existing values
+ *     (only add a new one)
  * if multi_replace==0, nothing, or only one matching key/value is replaced,
  *     else all matching key/values (regardless how many) are removed,
  *     before the new pair is written.

@@ -1578,6 +1585,8 @@ int git_config_set_multivar_in_file(const char *config_filename,
 
 		if (value_regex == NULL)
 			store.value_regex = NULL;
+		else if (value_regex == CONFIG_REGEX_NONE)
+			store.value_regex = CONFIG_REGEX_NONE;
 		else {
 			if (value_regex[0] == '!') {
 				store.do_not_match = 1;

@@ -1609,7 +1618,8 @@ int git_config_set_multivar_in_file(const char *config_filename,
 		if (git_config_from_file(store_aux, config_filename, NULL)) {
 			error("invalid config file %s", config_filename);
 			free(store.key);
-			if (store.value_regex != NULL) {
+			if (store.value_regex != NULL &&
+			    store.value_regex != CONFIG_REGEX_NONE) {
 				regfree(store.value_regex);
 				free(store.value_regex);
 			}

@@ -1618,7 +1628,8 @@ int git_config_set_multivar_in_file(const char *config_filename,
 		}
 
 		free(store.key);
-		if (store.value_regex != NULL) {
+		if (store.value_regex != NULL &&
+		    store.value_regex != CONFIG_REGEX_NONE) {
 			regfree(store.value_regex);
 			free(store.value_regex);
 		}

-- 
2.1.0-466-g6597b3e

Re: [PATCH] make config --add behave correctly for empty and NULL values

From: Jeff King <hidden>
Date: 2016-06-15 23:02:30

On Thu, Sep 11, 2014 at 04:35:33PM -0700, Junio C Hamano wrote:

Jeff King [off-list ref] writes:

quoted

Here is the patch I wrote, for reference (I also think breaking the
"matches" function into a series of conditionals, as you showed, is way
more readable):

OK, while reviewing the today's issue of "What's cooking" and making
topics graduate to 'master', I got annoyed that the bottom of jch
branch still needed to be kept.  Let's do this.

-- >8 --
From: Jeff King <redacted>
Date: Tue, 19 Aug 2014 02:20:00 -0400
Subject: [PATCH] config: avoid a funny sentinel value "a^"

Introduce CONFIG_REGEX_NONE as a more explicit sentinel value to say
"we do not want to replace any existing entry" and use it in the
implementation of "git config --add".

Signed-off-by: Jeff King <redacted>
Signed-off-by: Junio C Hamano <redacted>

Looks good, and adding my signoff is fine. Thanks.

-Peff

[PATCH v2 1/2] document irregular config --add behaviour for empty and NULL values

From: Tanay Abhra <hidden>
Date: 2016-06-15 23:02:30

If we have a config file like,
[foo]
        baz
        bar =

and we try something like, "git config --add foo.baz roll", Git will
segfault. Moreover, for "git config --add foo.bar roll", it will
overwrite the original value instead of appending after the existing
empty value. Document these deficiencies in form of a test.

Helped-by: Junio C Hamano [off-list ref]
Signed-off-by: Tanay Abhra <redacted>
---

Sorry for this very late reply. I was stuck in a flood affected region
with no internet connectivity for the past week. I am safe now. :)

FWIW, here is the reroll with a set bit in the store struct and an exported
global. I could have done the reroll as you have done, but Jeff had mentioned
that he liked the version with a bit flag more. But you can choose the version
that seems better to you.

 t/t1303-wacky-config.sh | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/t/t1303-wacky-config.sh b/t/t1303-wacky-config.sh
index 3a2c819..e5c0f07 100755
--- a/t/t1303-wacky-config.sh
+++ b/t/t1303-wacky-config.sh

@@ -111,4 +111,24 @@ test_expect_success 'unset many entries' '
 	test_must_fail git config section.key
 '

+test_expect_failure '--add appends new value after existing empty value' '
+	cat >expect <<-\EOF &&
+
+
+	fool
+	roll
+	EOF
+	cp .git/config .git/config.old &&
+	test_when_finished "mv .git/config.old .git/config" &&
+	cat >.git/config <<-\EOF &&
+	[foo]
+		baz
+		baz =
+		baz = fool
+	EOF
+	git config --add foo.baz roll &&
+	git config --get-all foo.baz >output &&
+	test_cmp expect output
+'
+
 test_done

-- 
1.9.0.GIT

[PATCH v2 2/2] make config --add behave correctly for empty and NULL values

From: Tanay Abhra <hidden>
Date: 2016-06-15 23:02:30

The problem lies with the regexp used for simulating --add in
`git_config_set_multivar_in_file()`, "^$", which in ideal case should
not match with any string but is true for empty strings. Instead use a
sentinel value CONFIG_REGEX_NONE to say "we do not want to replace any
existing entry" and use it in the implementation of "git config --add".

For removing the segfault add a check for NULL values in `matches()` in
config.c.

Helped-by: Junio C Hamano [off-list ref]
Signed-off-by: Tanay Abhra <redacted>
---
 builtin/config.c        |  2 +-
 cache.h                 |  2 ++
 config.c                | 21 +++++++++++++++++----
 t/t1303-wacky-config.sh |  2 +-
 4 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/builtin/config.c b/builtin/config.c
index aba7135..195664b 100644
--- a/builtin/config.c
+++ b/builtin/config.c

@@ -611,7 +611,7 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 		check_argc(argc, 2, 2);
 		value = normalize_value(argv[0], argv[1]);
 		return git_config_set_multivar_in_file(given_config_source.file,
-						       argv[0], value, "^$", 0);
+						       argv[0], value, CONFIG_REGEX_NONE, 0);
 	}
 	else if (actions == ACTION_REPLACE_ALL) {
 		check_write();

diff --git a/cache.h b/cache.h
index dfa1a56..a09217d 100644
--- a/cache.h
+++ b/cache.h

@@ -1284,6 +1284,8 @@ extern int update_server_info(int);
 #define CONFIG_INVALID_PATTERN 6
 #define CONFIG_GENERIC_ERROR 7

+extern const char CONFIG_REGEX_NONE[];
+
 struct git_config_source {
 	unsigned int use_stdin:1;
 	const char *file;

diff --git a/config.c b/config.c
index 83c913a..20476e0 100644
--- a/config.c
+++ b/config.c

@@ -46,6 +46,8 @@ static int zlib_compression_seen;
  */
 static struct config_set the_config_set;

+const char CONFIG_REGEX_NONE[] = "a^";
+
 static int config_file_fgetc(struct config_source *conf)
 {
 	return fgetc(conf->u.file);

@@ -1607,14 +1609,20 @@ static struct {
 	unsigned int offset_alloc;
 	enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
 	int seen;
+	unsigned value_never_matches:1;
 } store;

 static int matches(const char *key, const char *value)
 {
-	return !strcmp(key, store.key) &&
-		(store.value_regex == NULL ||
-		 (store.do_not_match ^
-		  !regexec(store.value_regex, value, 0, NULL, 0)));
+	if (strcmp(key, store.key))
+		return 0; /* not ours */
+	if (!store.value_regex)
+		return 1; /* always matches */
+	if (store.value_never_matches)
+		return 0; /* never matches */
+
+	return store.do_not_match ^
+	(value && !regexec(store.value_regex, value, 0, NULL, 0));
 }

 static int store_aux(const char *key, const char *value, void *cb)

@@ -1876,6 +1884,8 @@ out_free_ret_1:
 /*
  * If value==NULL, unset in (remove from) config,
  * if value_regex!=NULL, disregard key/value pairs where value does not match.
+ * if value_regex==CONFIG_REGEX_NONE, do not match any existing values
+ * (only add a new one)
  * if multi_replace==0, nothing, or only one matching key/value is replaced,
  *     else all matching key/values (regardless how many) are removed,
  *     before the new pair is written.

@@ -1966,6 +1976,9 @@ int git_config_set_multivar_in_file(const char *config_filename,
 			} else
 				store.do_not_match = 0;

+			if (value_regex == CONFIG_REGEX_NONE)
+				store.value_never_matches = 1;
+
 			store.value_regex = (regex_t*)xmalloc(sizeof(regex_t));
 			if (regcomp(store.value_regex, value_regex,
 					REG_EXTENDED)) {

diff --git a/t/t1303-wacky-config.sh b/t/t1303-wacky-config.sh
index e5c0f07..3b92083 100755
--- a/t/t1303-wacky-config.sh
+++ b/t/t1303-wacky-config.sh

@@ -111,7 +111,7 @@ test_expect_success 'unset many entries' '
 	test_must_fail git config section.key
 '

-test_expect_failure '--add appends new value after existing empty value' '
+test_expect_success '--add appends new value after existing empty value' '
 	cat >expect <<-\EOF &&

-- 
1.9.0.GIT

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