Introduce the config variable pack.packSizeLimit

"git pack-objects" has the option --max-pack-size to limit the file
size of the packs to a certain amount of bytes.  On platforms where
the pack file size is limited by filesystem constraints, it is easy
to forget this option, and this option does not exist for "git gc"
to begin with.

So introduce a config variable to set the default maximum, but make
this overrideable by the command line.

Suggested by Tor Arvid Lund.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -766,6 +766,12 @@ pack.indexVersion::
 	whenever the corresponding pack is larger than 2 GB.  Otherwise
 	the default is 1.
 
+pack.packSizeLimit:
+	The default maximum size of a pack.  This setting only affects
+	packing to a file, i.e. the git:// protocol is unaffected.  It
+	can be overridden by the `\--max-pack-size` option of
+	linkgit:git-repack[1].
+
 pull.octopus::
 	The default merge strategy to use when pulling multiple branches
 	at once.

Documentation/git-pack-objects.txt

@@ -99,7 +99,8 @@ base-name::
 --max-pack-size=<n>::
 	Maximum size of each output packfile, expressed in MiB.
 	If specified,  multiple packfiles may be created.
-	The default is unlimited.
+	The default is unlimited, unless the config variable
+	`pack.packSizeLimit` is set.
 
 --incremental::
 	This flag causes an object already in a pack ignored

builtin-pack-objects.c

@@ -68,7 +68,7 @@ static int allow_ofs_delta;
 static const char *base_name;
 static int progress = 1;
 static int window = 10;
-static uint32_t pack_size_limit;
+static uint32_t pack_size_limit, pack_size_limit_cfg;
 static int depth = 50;
 static int delta_search_threads = 1;
 static int pack_to_stdout;
@@ -1867,6 +1867,10 @@ static int git_pack_config(const char *k, const char *v)
 			die("bad pack.indexversion=%d", pack_idx_default_version);
 		return 0;
 	}
+	if (!strcmp(k, "pack.packsizelimit")) {
+		pack_size_limit_cfg = git_config_ulong(k, v);
+		return 0;
+	}
 	return git_default_config(k, v);
 }
 
@@ -2096,6 +2100,7 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 		}
 		if (!prefixcmp(arg, "--max-pack-size=")) {
 			char *end;
+			pack_size_limit_cfg = 0;
 			pack_size_limit = strtoul(arg+16, &end, 0) * 1024 * 1024;
 			if (!arg[16] || *end)
 				usage(pack_usage);
@@ -2220,6 +2225,9 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 	if (pack_to_stdout != !base_name)
 		usage(pack_usage);
 
+	if (!pack_to_stdout && !pack_size_limit)
+		pack_size_limit = pack_size_limit_cfg;
+
 	if (pack_to_stdout && pack_size_limit)
 		die("--max-pack-size cannot be used to build a pack for transfer.");
 

t/t5300-pack-object.sh

@@ -268,4 +268,10 @@ test_expect_success \
     'make sure index-pack detects the SHA1 collision' \
     '! git-index-pack -o bad.idx test-3.pack'
 
+test_expect_success \
+    'honor pack.packSizeLimit' \
+    'git config pack.packSizeLimit 200 &&
+     packname_4=$(git pack-objects test-4 <obj-list) &&
+     test 3 = $(ls test-4-*.pack | wc -l)'
+
 test_done