Add config read fns with controlled error behavior

This adds `git_config__lookup_entry` which will look up a key in
a config and return either the entry or NULL if the key was not
present.  Optionally, it can either suppress all errors or can
return them (although not finding the key is not an error for this
function).  Unlike other accessors, this does not normalize the
config key string, so it must only be used when the key is known
to be in normalized form (i.e. all lower-case before the first dot
and after the last dot, with no invalid characters).

This also adds three high-level helper functions to look up config
values with no errors and a fallback value.  The three functions
are for string, bool, and int values, and will resort to the
fallback value for any error that arises.  They are:

* `git_config__get_string_force`
* `git_config__get_bool_force`
* `git_config__get_int_force`

None of them normalize the config `key` either, so they can only
be used for internal cases where the key is known to be in normal
format.

1 files changed, 19 insertions, 20 deletions

diff --git a/src/diff_driver.c b/src/diff_driver.c
index bd5a8fbd9..167c0cc5a 100644
--- a/src/diff_driver.c
+++ b/src/diff_driver.c
@@ -14,6 +14,7 @@
 #include "strmap.h"
 #include "map.h"
 #include "buf_text.h"
+#include "config.h"
 #include "repository.h"
 
 GIT__USE_STRMAP;
@@ -130,14 +131,14 @@ static git_diff_driver_registry *git_repository_driver_registry(
 static int git_diff_driver_load(
 	git_diff_driver **out, git_repository *repo, const char *driver_name)
 {
-	int error = 0, bval;
+	int error = 0;
 	git_diff_driver_registry *reg;
 	git_diff_driver *drv;
 	size_t namelen = strlen(driver_name);
 	khiter_t pos;
 	git_config *cfg;
 	git_buf name = GIT_BUF_INIT;
-	const char *val;
+	const git_config_entry *ce;
 	bool found_driver = false;
 
 	reg = git_repository_driver_registry(repo);
@@ -164,23 +165,21 @@ static int git_diff_driver_load(
 
 	if ((error = git_buf_printf(&name, "diff.%s.binary", driver_name)) < 0)
 		goto done;
-	if ((error = git_config_get_string(&val, cfg, name.ptr)) < 0) {
-		if (error != GIT_ENOTFOUND)
-			goto done;
-		/* diff.<driver>.binary unspecified, so just continue */
-		giterr_clear();
-	} else if (git_config_parse_bool(&bval, val) < 0) {
-		/* TODO: warn that diff.<driver>.binary has invalid value */
-		giterr_clear();
-	} else if (bval) {
+
+	switch (git_config__get_bool_force(cfg, name.ptr, -1)) {
+	case true:
 		/* if diff.<driver>.binary is true, just return the binary driver */
 		*out = &global_drivers[DIFF_DRIVER_BINARY];
 		goto done;
-	} else {
+	case false:
 		/* if diff.<driver>.binary is false, force binary checks off */
 		/* but still may have custom function context patterns, etc. */
 		drv->binary_flags = GIT_DIFF_FORCE_TEXT;
 		found_driver = true;
+		break;
+	default:
+		/* diff.<driver>.binary unspecified, so just continue */
+		break;
 	}
 
 	/* TODO: warn if diff.<name>.command or diff.<name>.textconv are set */
@@ -211,16 +210,16 @@ static int git_diff_driver_load(
 
 	git_buf_truncate(&name, namelen + strlen("diff.."));
 	git_buf_put(&name, "wordregex", strlen("wordregex"));
-	if ((error = git_config_get_string(&val, cfg, name.ptr)) < 0) {
-		if (error != GIT_ENOTFOUND)
-			goto done;
-		giterr_clear(); /* no diff.<driver>.wordregex, so just continue */
-	} else if ((error = regcomp(&drv->word_pattern, val, REG_EXTENDED)) != 0) {
-		/* TODO: warning about bad regex instead of failure */
-		error = giterr_set_regex(&drv->word_pattern, error);
+	if ((error = git_config__lookup_entry(&ce, cfg, name.ptr, false)) < 0)
 		goto done;
-	} else {
+	if (!ce || !ce->value)
+		/* no diff.<driver>.wordregex, so just continue */;
+	else if (!(error = regcomp(&drv->word_pattern, ce->value, REG_EXTENDED)))
 		found_driver = true;
+	else {
+		/* TODO: warn about bad regex instead of failure */
+		error = giterr_set_regex(&drv->word_pattern, error);
+		goto done;
 	}
 
 	/* TODO: look up diff.<driver>.algorithm to turn on minimal / patience