From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 19 Mar 2013 19:15:14 +0000 (-0700)
Subject: Merge branch 'nd/doc-index-format'
X-Git-Tag: v1.8.3-rc0~223
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/865e99b5fde9a9128b34b6f3805f726c7a3b1b13?hp=f944ec9aa53d22fb1d2f4e0b2974eb90c0cf3a15

Merge branch 'nd/doc-index-format'

Update the index format documentation to mention the v4 format.

* nd/doc-index-format:
update-index: list supported idx versions and their features
read-cache.c: use INDEX_FORMAT_{LB,UB} in verify_hdr()
index-format.txt: mention of v4 is missing in some places
---

diff --git a/Documentation/git-update-index.txt b/Documentation/git-update-index.txt
index 77a912d4ea..c92775829b 100644
--- a/Documentation/git-update-index.txt
+++ b/Documentation/git-update-index.txt
@@ -145,7 +145,15 @@ you will need to handle the situation manually.
 
 --index-version <n>::
 	Write the resulting index out in the named on-disk format version.
-	The current default version is 2.
+	Supported versions are 2, 3 and 4. The current default version is 2
+	or 3, depending on whether extra features are used, such as
+	`git add -N`.
++
+Version 4 performs a simple pathname compression that reduces index
+size by 30%-50% on large repositories, which results in faster load
+time. Version 4 is relatively young (first released in in 1.8.0 in
+October 2012). Other Git implementations such as JGit and libgit2
+may not support it yet.
 
 -z::
 	Only meaningful with `--stdin` or `--index-info`; paths are
diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt
index 27c716b15f..0810251f5a 100644
--- a/Documentation/technical/index-format.txt
+++ b/Documentation/technical/index-format.txt
@@ -12,7 +12,7 @@ Git index format
        The signature is { 'D', 'I', 'R', 'C' } (stands for "dircache")
 
      4-byte version number:
-       The current supported versions are 2 and 3.
+       The current supported versions are 2, 3 and 4.
 
      32-bit number of index entries.
 
@@ -93,8 +93,8 @@ Git index format
     12-bit name length if the length is less than 0xFFF; otherwise 0xFFF
     is stored in this field.
 
-  (Version 3) A 16-bit field, only applicable if the "extended flag"
-  above is 1, split into (high to low bits).
+  (Version 3 or later) A 16-bit field, only applicable if the
+  "extended flag" above is 1, split into (high to low bits).
 
     1-bit reserved for future
 
diff --git a/read-cache.c b/read-cache.c
index 827ae55c50..670a06bc79 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1260,7 +1260,7 @@ static int verify_hdr(struct cache_header *hdr, unsigned long size)
 	if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
 		return error("bad signature");
 	hdr_version = ntohl(hdr->hdr_version);
-	if (hdr_version < 2 || 4 < hdr_version)
+	if (hdr_version < INDEX_FORMAT_LB || INDEX_FORMAT_UB < hdr_version)
 		return error("bad index version %d", hdr_version);
 	git_SHA1_Init(&c);
 	git_SHA1_Update(&c, hdr, size - 20);