make alias lookup a public, procedural function

This converts git_config_alias to the public alias_lookup
function. Because of the nature of our config parser, we
still have to rely on setting static data. However, that
interface is wrapped so that you can just say

  value = alias_lookup(key);

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

4 files changed, 29 insertions, 15 deletions

diff --git a/Makefile b/Makefile
index d33a556ff..b460bb216 100644
--- a/Makefile
+++ b/Makefile
@@ -327,7 +327,8 @@ LIB_OBJS = \
 	alloc.o merge-file.o path-list.o help.o unpack-trees.o $(DIFF_OBJS) \
 	color.o wt-status.o archive-zip.o archive-tar.o shallow.o utf8.o \
 	convert.o attr.o decorate.o progress.o mailmap.o symlinks.o remote.o \
-	transport.o bundle.o walker.o parse-options.o ws.o archive.o
+	transport.o bundle.o walker.o parse-options.o ws.o archive.o \
+	alias.o
 
 BUILTIN_OBJS = \
 	builtin-add.o \
diff --git a/alias.c b/alias.c
new file mode 100644
index 000000000..116cac87c
--- /dev/null
+++ b/alias.c
@@ -0,0 +1,22 @@
+#include "cache.h"
+
+static const char *alias_key;
+static char *alias_val;
+static int alias_lookup_cb(const char *k, const char *v)
+{
+	if (!prefixcmp(k, "alias.") && !strcmp(k+6, alias_key)) {
+		if (!v)
+			return config_error_nonbool(k);
+		alias_val = xstrdup(v);
+		return 0;
+	}
+	return 0;
+}
+
+char *alias_lookup(const char *alias)
+{
+	alias_key = alias;
+	alias_val = NULL;
+	git_config(alias_lookup_cb);
+	return alias_val;
+}
diff --git a/cache.h b/cache.h
index fa5a9e523..1e9c93729 100644
--- a/cache.h
+++ b/cache.h
@@ -765,4 +765,6 @@ int pathspec_match(const char **spec, char *matched, const char *filename, int s
 int report_path_error(const char *ps_matched, const char **pathspec, int prefix_offset);
 void overlay_tree_on_cache(const char *tree_name, const char *prefix);
 
+char *alias_lookup(const char *alias);
+
 #endif /* CACHE_H */
diff --git a/git.c b/git.c
index 0cb86884d..8f08b1229 100644
--- a/git.c
+++ b/git.c
@@ -87,19 +87,6 @@ static int handle_options(const char*** argv, int* argc, int* envchanged)
 	return handled;
 }
 
-static const char *alias_command;
-static char *alias_string;
-
-static int git_alias_config(const char *var, const char *value)
-{
-	if (!prefixcmp(var, "alias.") && !strcmp(var + 6, alias_command)) {
-		if (!value)
-			return config_error_nonbool(var);
-		alias_string = xstrdup(value);
-	}
-	return 0;
-}
-
 static int split_cmdline(char *cmdline, const char ***argv)
 {
 	int src, dst, count = 0, size = 16;
@@ -159,11 +146,13 @@ static int handle_alias(int *argcp, const char ***argv)
 	const char *subdir;
 	int count, option_count;
 	const char** new_argv;
+	const char *alias_command;
+	char *alias_string;
 
 	subdir = setup_git_directory_gently(&nongit);
 
 	alias_command = (*argv)[0];
-	git_config(git_alias_config);
+	alias_string = alias_lookup(alias_command);
 	if (alias_string) {
 		if (alias_string[0] == '!') {
 			if (*argcp > 1) {