Update documentation for git-format-patch

diff --git a/write-tree.c b/write-tree.c
index cef0c5bb422ae81b7d6be933b107244f8c9de789..7a4f691d8ab8f6f560685ec6fe71cf2d82e8a018 100644 (file)
--- a/write-tree.c
+++ b/write-tree.c
@@ -7,21 +7,20 @@
 #include "tree.h"
 #include "cache-tree.h"
 
-static unsigned char active_cache_sha1[20];
-static struct cache_tree *active_cache_tree;
-
 static int missing_ok = 0;
 
 static const char write_tree_usage[] = "git-write-tree [--missing-ok]";
 
+static struct cache_file cache_file;
+
 int main(int argc, char **argv)
 {
-       int entries;
+       int entries, was_valid, newfd;
 
        setup_git_directory();
 
-       entries = read_cache_1(active_cache_sha1);
-       active_cache_tree = read_cache_tree(active_cache_sha1);
+       newfd = hold_index_file_for_update(&cache_file, get_index_file());
+       entries = read_cache();
        if (argc == 2) {
                if (!strcmp(argv[1], "--missing-ok"))
                        missing_ok = 1;
@@ -35,11 +34,26 @@ int main(int argc, char **argv)
        if (entries < 0)
                die("git-write-tree: error reading cache");
 
-       if (cache_tree_update(active_cache_tree, active_cache, active_nr,
-                             missing_ok))
-               die("git-write-tree: error building trees");
-       write_cache_tree(active_cache_sha1, active_cache_tree);
-
+       if (!active_cache_tree)
+               active_cache_tree = cache_tree();
+
+       was_valid = cache_tree_fully_valid(active_cache_tree);
+       if (!was_valid) {
+               if (cache_tree_update(active_cache_tree,
+                                     active_cache, active_nr,
+                                     missing_ok, 0) < 0)
+                       die("git-write-tree: error building trees");
+               if (0 <= newfd) {
+                       if (!write_cache(newfd, active_cache, active_nr))
+                               commit_index_file(&cache_file);
+               }
+               /* Not being able to write is fine -- we are only interested
+                * in updating the cache-tree part, and if the next caller
+                * ends up using the old index with unupdated cache-tree part
+                * it misses the work we did here, but that is just a
+                * performance penalty and not a big deal.
+                */
+       }
        printf("%s\n", sha1_to_hex(active_cache_tree->sha1));
        return 0;
 }