Teach fetch-pack and upload-pack to support excluding large blobs
through a blob-max-bytes parameter.

Signed-off-by: Jonathan Tan <jonathanta...@google.com>
---
 Documentation/technical/pack-protocol.txt         |  9 ++++++++
 Documentation/technical/protocol-capabilities.txt |  7 ++++++
 builtin/fetch-pack.c                              | 11 +++++++++
 fetch-pack.c                                      | 11 +++++++++
 fetch-pack.h                                      |  1 +
 t/t5500-fetch-pack.sh                             | 27 +++++++++++++++++++++++
 upload-pack.c                                     | 16 +++++++++++++-
 7 files changed, 81 insertions(+), 1 deletion(-)

diff --git a/Documentation/technical/pack-protocol.txt 
b/Documentation/technical/pack-protocol.txt
index ed1eae8b8..db0e1150b 100644
--- a/Documentation/technical/pack-protocol.txt
+++ b/Documentation/technical/pack-protocol.txt
@@ -212,6 +212,7 @@ out of what the server said it could do with the first 
'want' line.
   upload-request    =  want-list
                       *shallow-line
                       *1depth-request
+                      *1blob-max-bytes
                       flush-pkt
 
   want-list         =  first-want
@@ -223,10 +224,14 @@ out of what the server said it could do with the first 
'want' line.
                       PKT-LINE("deepen-since" SP timestamp) /
                       PKT-LINE("deepen-not" SP ref)
 
+  blob-max-bytes    =  PKT-LINE("blob-max-bytes" SP magnitude)
+
   first-want        =  PKT-LINE("want" SP obj-id SP capability-list)
   additional-want   =  PKT-LINE("want" SP obj-id)
 
   depth             =  1*DIGIT
+
+  magnitude         =  1*DIGIT
 ----
 
 Clients MUST send all the obj-ids it wants from the reference
@@ -249,6 +254,10 @@ complete those commits. Commits whose parents are not 
received as a
 result are defined as shallow and marked as such in the server. This
 information is sent back to the client in the next step.
 
+The client can optionally request a partial packfile that omits blobs
+above a certain size threshold using "blob-max-bytes". Files whose names
+start with ".git" are always included in the packfile, however.
+
 Once all the 'want's and 'shallow's (and optional 'deepen') are
 transferred, clients MUST send a flush-pkt, to tell the server side
 that it is done sending the list.
diff --git a/Documentation/technical/protocol-capabilities.txt 
b/Documentation/technical/protocol-capabilities.txt
index 26dcc6f50..7e878fce5 100644
--- a/Documentation/technical/protocol-capabilities.txt
+++ b/Documentation/technical/protocol-capabilities.txt
@@ -309,3 +309,10 @@ to accept a signed push certificate, and asks the <nonce> 
to be
 included in the push certificate.  A send-pack client MUST NOT
 send a push-cert packet unless the receive-pack server advertises
 this capability.
+
+blob-max-bytes
+--------------
+
+If the upload-pack server advertises this capability, fetch-pack
+may send "blob-max-bytes" to request the server to omit blobs above a
+certain size from the packfile.
diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 9a7ebf6e9..116be9bf5 100644
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -4,6 +4,7 @@
 #include "remote.h"
 #include "connect.h"
 #include "sha1-array.h"
+#include "config.h"
 
 static const char fetch_pack_usage[] =
 "git fetch-pack [--all] [--stdin] [--quiet | -q] [--keep | -k] [--thin] "
@@ -153,6 +154,16 @@ int cmd_fetch_pack(int argc, const char **argv, const char 
*prefix)
                        args.no_haves = 1;
                        continue;
                }
+               if (skip_prefix(arg, "--blob-max-bytes=", &arg)) {
+                       unsigned long *ptr = xmalloc(sizeof(*ptr));
+                       if (!git_parse_ulong(arg, ptr)) {
+                               error("Invalid --blob-max-bytes value: %s",
+                                     arg);
+                               usage(fetch_pack_usage);
+                       }
+                       args.blob_max_bytes = ptr;
+                       continue;
+               }
                usage(fetch_pack_usage);
        }
        if (deepen_not.nr)
diff --git a/fetch-pack.c b/fetch-pack.c
index d376c4ef1..19b8e9322 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -26,6 +26,7 @@ static int prefer_ofs_delta = 1;
 static int no_done;
 static int deepen_since_ok;
 static int deepen_not_ok;
+static int blob_max_bytes_ok;
 static int fetch_fsck_objects = -1;
 static int transfer_fsck_objects = -1;
 static int agent_supported;
@@ -407,6 +408,13 @@ static int find_common(struct fetch_pack_args *args,
                        packet_buf_write(&req_buf, "deepen-not %s", s->string);
                }
        }
+       if (args->blob_max_bytes) {
+               if (blob_max_bytes_ok)
+                       packet_buf_write(&req_buf, "blob-max-bytes %ld",
+                                        *args->blob_max_bytes);
+               else
+                       warning("blob-max-bytes not recognized by server, 
ignoring");
+       }
        packet_buf_flush(&req_buf);
        state_len = req_buf.len;
 
@@ -983,6 +991,8 @@ static struct ref *do_fetch_pack(struct fetch_pack_args 
*args,
                die(_("Server does not support --shallow-exclude"));
        if (!server_supports("deepen-relative") && args->deepen_relative)
                die(_("Server does not support --deepen"));
+       if (server_supports("blob-max-bytes"))
+               blob_max_bytes_ok = 1;
 
        if (everything_local(args, &ref, sought, nr_sought)) {
                packet_flush(fd[1]);
@@ -1169,6 +1179,7 @@ struct ref *fetch_pack(struct fetch_pack_args *args,
                packet_flush(fd[1]);
                die(_("no matching remote head"));
        }
+
        prepare_shallow_info(&si, shallow);
        ref_cpy = do_fetch_pack(args, fd, ref, sought, nr_sought,
                                &si, pack_lockfile);
diff --git a/fetch-pack.h b/fetch-pack.h
index 84904c348..3743a0ab2 100644
--- a/fetch-pack.h
+++ b/fetch-pack.h
@@ -12,6 +12,7 @@ struct fetch_pack_args {
        int depth;
        const char *deepen_since;
        const struct string_list *deepen_not;
+       unsigned long *blob_max_bytes;
        unsigned deepen_relative:1;
        unsigned quiet:1;
        unsigned keep_pack:1;
diff --git a/t/t5500-fetch-pack.sh b/t/t5500-fetch-pack.sh
index 80a1a3239..62e384230 100755
--- a/t/t5500-fetch-pack.sh
+++ b/t/t5500-fetch-pack.sh
@@ -755,4 +755,31 @@ test_expect_success 'fetching deepen' '
        )
 '
 
+test_expect_success '--blob-max-bytes' '
+       rm -rf server client &&
+       test_create_repo server &&
+       test_commit -C server one &&
+       test_config -C server uploadpack.advertiseblobmaxbytes 1 &&
+
+       test_create_repo client &&
+       git -C client fetch-pack --blob-max-bytes=0 ../server HEAD &&
+
+       # Ensure that object is not inadvertently fetched
+       test_must_fail git -C client cat-file -e $(git hash-object server/one.t)
+'
+
+test_expect_success '--blob-max-bytes has no effect if support for it is not 
advertised' '
+       rm -rf server client &&
+       test_create_repo server &&
+       test_commit -C server one &&
+
+       test_create_repo client &&
+       git -C client fetch-pack --blob-max-bytes=0 ../server HEAD 2> err &&
+
+       # Ensure that object is fetched
+       git -C client cat-file -e $(git hash-object server/one.t) &&
+
+       test_i18ngrep "blob-max-bytes not recognized by server" err
+'
+
 test_done
diff --git a/upload-pack.c b/upload-pack.c
index 7efff2fbf..484704eb6 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -63,6 +63,8 @@ static int use_sideband;
 static int advertise_refs;
 static int stateless_rpc;
 static const char *pack_objects_hook;
+static int advertise_blob_max_bytes;
+static char *blob_max_bytes;
 
 static void reset_timeout(void)
 {
@@ -131,6 +133,8 @@ static void create_pack_file(void)
                argv_array_push(&pack_objects.args, "--delta-base-offset");
        if (use_include_tag)
                argv_array_push(&pack_objects.args, "--include-tag");
+       if (blob_max_bytes)
+               argv_array_push(&pack_objects.args, blob_max_bytes);
 
        pack_objects.in = -1;
        pack_objects.out = -1;
@@ -794,6 +798,13 @@ static void receive_needs(void)
                        deepen_rev_list = 1;
                        continue;
                }
+               if (skip_prefix(line, "blob-max-bytes ", &arg)) {
+                       unsigned long s;
+                       if (!git_parse_ulong(arg, &s))
+                               die("git upload-pack: invalid blob-max-bytes 
value: %s", line);
+                       blob_max_bytes = xstrfmt("--blob-max-bytes=%lu", s);
+                       continue;
+               }
                if (!skip_prefix(line, "want ", &arg) ||
                    get_oid_hex(arg, &oid_buf))
                        die("git upload-pack: protocol error, "
@@ -940,7 +951,7 @@ static int send_ref(const char *refname, const struct 
object_id *oid,
                struct strbuf symref_info = STRBUF_INIT;
 
                format_symref_info(&symref_info, cb_data);
-               packet_write_fmt(1, "%s %s%c%s%s%s%s%s agent=%s\n",
+               packet_write_fmt(1, "%s %s%c%s%s%s%s%s%s agent=%s\n",
                             oid_to_hex(oid), refname_nons,
                             0, capabilities,
                             (allow_unadvertised_object_request & 
ALLOW_TIP_SHA1) ?
@@ -949,6 +960,7 @@ static int send_ref(const char *refname, const struct 
object_id *oid,
                                     " allow-reachable-sha1-in-want" : "",
                             stateless_rpc ? " no-done" : "",
                             symref_info.buf,
+                            advertise_blob_max_bytes ? " blob-max-bytes" : "",
                             git_user_agent_sanitized());
                strbuf_release(&symref_info);
        } else {
@@ -1028,6 +1040,8 @@ static int upload_pack_config(const char *var, const char 
*value, void *unused)
        } else if (current_config_scope() != CONFIG_SCOPE_REPO) {
                if (!strcmp("uploadpack.packobjectshook", var))
                        return git_config_string(&pack_objects_hook, var, 
value);
+       } else if (!strcmp("uploadpack.advertiseblobmaxbytes", var)) {
+               advertise_blob_max_bytes = git_config_bool(var, value);
        }
        return parse_hide_refs_config(var, value, "uploadpack");
 }
-- 
2.14.2.822.g60be5d43e6-goog

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