oid: Export `git_oid_tostr_s` instead of `_allocfmt`vmg/tostr_s

The old `allocfmt` is of no use to callers, as they are not able to free
the returned buffer. Export a new API that returns a static string that
doesn't need to be freed.

3 files changed, 20 insertions, 0 deletions

diff --git a/src/global.h b/src/global.h
index 745df3e4a..106504628 100644
--- a/src/global.h
+++ b/src/global.h
@@ -13,6 +13,7 @@
 typedef struct {
 	git_error *last_error;
 	git_error error_t;
+	char oid_fmt[41];
 } git_global_st;
 
 #ifdef GIT_SSL
diff --git a/src/oid.c b/src/oid.c
index b640cadd1..969931d04 100644
--- a/src/oid.c
+++ b/src/oid.c
@@ -8,6 +8,7 @@
 #include "common.h"
 #include "git2/oid.h"
 #include "repository.h"
+#include "global.h"
 #include <string.h>
 #include <limits.h>
 
@@ -99,6 +100,13 @@ void git_oid_pathfmt(char *str, const git_oid *oid)
 		str = fmt_one(str, oid->id[i]);
 }
 
+char *git_oid_tostr_s(const git_oid *oid)
+{
+	char *str = GIT_GLOBAL->oid_fmt;
+	git_oid_nfmt(str, GIT_OID_HEXSZ + 1, oid);
+	return str;
+}
+
 char *git_oid_allocfmt(const git_oid *oid)
 {
 	char *str = git__malloc(GIT_OID_HEXSZ + 1);
diff --git a/src/oid.h b/src/oid.h
index cfe7ca1b2..aa1f0bfdc 100644
--- a/src/oid.h
+++ b/src/oid.h
@@ -9,6 +9,17 @@
 
 #include "git2/oid.h"
 
+/**
+ * Format a git_oid into a newly allocated c-string.
+ *
+ * The c-string is owned by the caller and needs to be manually freed.
+ *
+ * @param id the oid structure to format
+ * @return the c-string; NULL if memory is exhausted. Caller must
+ *			deallocate the string with git__free().
+ */
+char *git_oid_allocfmt(const git_oid *id);
+
 GIT_INLINE(int) git_oid__hashcmp(const unsigned char *sha1, const unsigned char *sha2)
 {
 	int i;