[RFC PATCH 03/18] midx: create core.midx config setting

[Derrick Stolee <stolee@gmail.com>]

As the multi-pack-index feature is being developed, we use a config
setting 'core.midx' to enable all use of MIDX files.

Since MIDX files are designed as a way to augment the existing data
stores in Git, turning this setting off will revert to previous
behavior without needing to downgrade. This can also be a repo-
specific setting if the MIDX is misbehaving in only one repo.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 Documentation/config.txt | 3 +++
 cache.h                  | 1 +
 config.c                 | 5 +++++
 environment.c            | 2 ++
 4 files changed, 11 insertions(+)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 64c1dbba94..dc7cb4b900 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -896,6 +896,9 @@ core.notesRef::
 This setting defaults to "refs/notes/commits", and it can be overridden by
 the `GIT_NOTES_REF` environment variable.  See linkgit:git-notes[1].
 
+core.midx::
+	Enable "multi-pack-index" feature. Set to true to read and write MIDX files.
+
 core.sparseCheckout::
 	Enable "sparse checkout" feature. See section "Sparse checkout" in
 	linkgit:git-read-tree[1] for more information.
diff --git a/cache.h b/cache.h
index a2ec8c0b55..f4943d3136 100644
--- a/cache.h
+++ b/cache.h
@@ -820,6 +820,7 @@ extern int precomposed_unicode;
 extern int protect_hfs;
 extern int protect_ntfs;
 extern const char *core_fsmonitor;
+extern int core_midx;
 
 /*
  * Include broken refs in all ref iterations, which will
diff --git a/config.c b/config.c
index e617c2018d..17f560ddc4 100644
--- a/config.c
+++ b/config.c
@@ -1223,6 +1223,11 @@ static int git_default_core_config(const char *var, const char *value)
 		return 0;
 	}
 
+	if (!strcmp(var, "core.midx")) {
+		core_midx = git_config_bool(var, value);
+		return 0;
+	}
+
 	if (!strcmp(var, "core.sparsecheckout")) {
 		core_apply_sparse_checkout = git_config_bool(var, value);
 		return 0;
diff --git a/environment.c b/environment.c
index 63ac38a46f..57a3943849 100644
--- a/environment.c
+++ b/environment.c
@@ -78,6 +78,8 @@ int protect_hfs = PROTECT_HFS_DEFAULT;
 int protect_ntfs = PROTECT_NTFS_DEFAULT;
 const char *core_fsmonitor;
 
+int core_midx;
+
 /*
  * The character that begins a commented line in user-editable file
  * that is subject to stripspace.
-- 
2.15.0