[RFC PATCH 1/6] sha1-name: Add `GET_OID_GENTLY` flag

[Paul-Sebastian Ungureanu <ungureanupaulsebastian@gmail.com>]

The current API does not provide a method to call
`get_oid()` and avoid `exit()` to be called. This commit
intention is to introduce a flag in order to make `get_oid()`
able to get the sha1 safely, without exiting the program.

Since `get_oid()` calls a lot of functions, which call other
functions as well (and so on), there are a lot of cases in which
`exit()` could be called. To make this idea more clear, here
is one example, which could cause `get_oid()` to die.

  get_oid() -> get_oid_with_context() -> get_oid_with_context_1()
  -> get_oid_1() -> read_ref_at() -> exit()

Where `function1() -> function2()` means that `function1()` might
call `function2()` at some point.

Signed-off-by: Paul-Sebastian Ungureanu <ungureanupaulsebastian@gmail.com>
---
 cache.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/cache.h b/cache.h
index d49092d94..cb8803e2f 100644
--- a/cache.h
+++ b/cache.h
@@ -1314,6 +1314,7 @@ struct object_context {
 #define GET_OID_FOLLOW_SYMLINKS 0100
 #define GET_OID_RECORD_PATH     0200
 #define GET_OID_ONLY_TO_DIE    04000
+#define GET_OID_GENTLY	      010000
 
 #define GET_OID_DISAMBIGUATORS \
 	(GET_OID_COMMIT | GET_OID_COMMITTISH | \
-- 
2.18.0.rc2.184.ga79db55c2.dirty