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[PATCHv3 6/9] receive-pack: Prepare for addition of the new 'limit-*' family of capabilities

From
Johan Herland <johan@herland.net>
Date
May 15, 2011, 21:37 UTC
Message-ID
<1305495440-30836-7-git-send-email-johan@herland.net>
In-Reply-To
<1305495440-30836-1-git-send-email-johan@herland.net>

This adds some technical documentation on the 'limit-*' family of capabilities that will be added in the following commits.

Also refactor the generation of the capabilities declaration in receive-pack. This will also be further expanded in the following commits.

Finally, change the return type of server_supports() to allow the caller to more closely examine the found capability, e.g. by calling server_supports("limit-foo="), and then use the return value to parse the value following the '='.

Signed-off-by: Johan Herland <johan@herland.net>
---
 Documentation/technical/pack-protocol.txt         |    6 ++--
 Documentation/technical/protocol-capabilities.txt |   22 +++++++++++++++++++++
 builtin/receive-pack.c                            |   16 +++++++++++---
 cache.h                                           |    2 +-
 connect.c                                         |    7 +++--
 5 files changed, 42 insertions(+), 11 deletions(-)
diff --git a/Documentation/technical/pack-protocol.txt b/Documentation/technical/pack-protocol.txt
index 4a68f0f..ddc0d0e 100644
--- a/Documentation/technical/pack-protocol.txt
+++ b/Documentation/technical/pack-protocol.txt
@@ -167,7 +167,7 @@ MUST peel the ref if it's an annotated tag.
   other-peeled     =  obj-id SP refname "^{}" LF
 
   capability-list  =  capability *(SP capability)
-  capability       =  1*(LC_ALPHA / DIGIT / "-" / "_")
+  capability       =  1*(LC_ALPHA / DIGIT / "-" / "_" / "=")
   LC_ALPHA         =  %x61-7A
 ----
 
@@ -391,8 +391,8 @@ The reference discovery phase is done nearly the same way as it is in the
 fetching protocol. Each reference obj-id and name on the server is sent
 in packet-line format to the client, followed by a flush-pkt.  The only
 real difference is that the capability listing is different - the only
-possible values are 'report-status', 'delete-refs', 'side-band-64k' and
-'ofs-delta'.
+possible values are 'report-status', 'delete-refs', 'side-band-64k',
+'ofs-delta' and 'limit-*'.
 
 Reference Update Request and Packfile Transfer
 ----------------------------------------------
diff --git a/Documentation/technical/protocol-capabilities.txt b/Documentation/technical/protocol-capabilities.txt
index b732e80..11849a3 100644
--- a/Documentation/technical/protocol-capabilities.txt
+++ b/Documentation/technical/protocol-capabilities.txt
@@ -21,6 +21,9 @@ NOT advertise capabilities it does not understand.
 The 'report-status' and 'delete-refs' capabilities are sent and
 recognized by the receive-pack (push to server) process.
 
+Any 'limit-*' capabilities may only be sent by the receive-pack
+process. It is never requested by client.
+
 The 'side-band-64k' and 'ofs-delta' capabilities are sent and
 recognized by both upload-pack and receive-pack protocols.
 
@@ -185,3 +188,22 @@ it is capable of accepting a zero-id value as the target
 value of a reference update.  It is not sent back by the client, it
 simply informs the client that it can be sent zero-id values
 to delete references.
+
+limit-*
+-------
+
+If the server sends one or more capabilities that start with "limit-",
+it means that there are certain limits to what kind of pack the server
+will receive. More specifically, these capabilities must be of the form
+"limit-<what>=<num>" where "<what>" (a sequence of lower-case letters,
+digits and "-") describes which property of the pack is limited, and
+"<num>" (a sequence of decimal digits) specifies the limit value.
+Capabilities of this type are not sent back by the client; instead the
+client must verify that the created packfile does not exceed the given
+limits. This check should happen prior to transferring the packfile to
+the server. If the check fails, the client must abort the upload, and
+report the reason for the aborted push back to the user.
+The following "limit-*" capabilites are recognized:
+
+More "limit-*" capabilities may be added in the future. The client
+is free to ignore any "limit-*" capabilities it does not understand.
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index e1ba4dc..c55989d 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -106,15 +106,23 @@ static int receive_pack_config(const char *var, const char *value, void *cb)
 	return git_default_config(var, value, cb);
 }
 
+static const char *capabilities()
+{
+	static char buf[1024];
+	int ret = snprintf(buf, sizeof(buf),
+			   " report-status delete-refs side-band-64k%s",
+			   prefer_ofs_delta ? " ofs-delta" : "");
+	assert(ret < sizeof(buf));
+	return buf;
+}
+
 static int show_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 {
 	if (sent_capabilities)
 		packet_write(1, "%s %s\n", sha1_to_hex(sha1), path);
 	else
-		packet_write(1, "%s %s%c%s%s\n",
-			     sha1_to_hex(sha1), path, 0,
-			     " report-status delete-refs side-band-64k",
-			     prefer_ofs_delta ? " ofs-delta" : "");
+		packet_write(1, "%s %s%c%s\n",
+			     sha1_to_hex(sha1), path, 0, capabilities());
 	sent_capabilities = 1;
 	return 0;
 }
diff --git a/cache.h b/cache.h
index 2b34116..db97097 100644
--- a/cache.h
+++ b/cache.h
@@ -981,7 +981,7 @@ struct extra_have_objects {
 	unsigned char (*array)[20];
 };
 extern struct ref **get_remote_heads(int in, struct ref **list, int nr_match, char **match, unsigned int flags, struct extra_have_objects *);
-extern int server_supports(const char *feature);
+extern const char *server_supports(const char *feature);
 
 extern struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path);
 
diff --git a/connect.c b/connect.c
index 57dc20c..015c570 100644
--- a/connect.c
+++ b/connect.c
@@ -102,10 +102,11 @@ struct ref **get_remote_heads(int in, struct ref **list,
 	return list;
 }
 
-int server_supports(const char *feature)
+const char *server_supports(const char *feature)
 {
-	return server_capabilities &&
-		strstr(server_capabilities, feature) != NULL;
+	if (server_capabilities)
+		return strstr(server_capabilities, feature);
+	return NULL;
 }
 
 int path_match(const char *path, int nr, char **match)

-- 
1.7.5.rc1.3.g4d7b
Previous: Johan HerlandNext: Junio C Hamano
Message 38 of 53 in “receive-pack: Add receive.denyObjectLimit to refuse push with too many objects”
  1. 2/2 receive-pack: Add receive.denyObjectLimit to refuse push with too many objectsJohan Herland, May 13, 2011
  2. Junio C HamanoMay 13, 2011
  3. Johan HerlandMay 14, 2011
  4. 2/2 receive-pack: Add receive.objectCountLimit to refuse push with too many objectsJohan Herland, May 14, 2011
  5. Shawn PearceMay 14, 2011
  6. Johan HerlandMay 14, 2011
  7. Shawn PearceMay 14, 2011
  8. Johan HerlandMay 15, 2011
  9. 0/9 Push limitsJohan Herland, May 15, 2011
  10. 1/9 Update technical docs to reflect side-band-64k capability in receive-packJohan Herland, May 15, 2011
  11. 2/9 send-pack: Attempt to retrieve remote status even if pack-objects failsJohan Herland, May 15, 2011
  12. Jeff KingMay 16, 2011
  13. Jeff KingMay 16, 2011
  14. Jeff KingMay 16, 2011
  15. 1/3 connect: treat generic proxy processes like ssh processesJeff King, May 16, 2011
  16. Johannes SixtMay 16, 2011
  17. Junio C HamanoMay 16, 2011
  18. Jeff KingMay 17, 2011
  19. Johannes SixtMay 17, 2011
  20. Jeff KingMay 18, 2011
  21. 2/3 connect: let callers know if connection is a socketJeff King, May 16, 2011
  22. 3/3 send-pack: avoid deadlock on git:// push with failed pack-objectsJeff King, May 16, 2011
  23. Johannes SixtMay 16, 2011
  24. Jeff KingMay 17, 2011
  25. Windows: add a wrapper for the shutdown() system callJohannes Sixt, May 18, 2011
  26. 3/9 pack-objects: Allow --max-pack-size to be used together with --stdoutJohan Herland, May 15, 2011
  27. Shawn PearceMay 15, 2011
  28. Johan HerlandMay 16, 2011
  29. Junio C HamanoMay 16, 2011
  30. Johan HerlandMay 16, 2011
  31. 4/9 pack-objects: Teach new option --max-object-count, similar to --max-pack-sizeJohan Herland, May 15, 2011
  32. Shawn PearceMay 15, 2011
  33. Johan HerlandMay 15, 2011
  34. Shawn PearceMay 15, 2011
  35. Junio C HamanoMay 16, 2011
  36. Johan HerlandMay 16, 2011
  37. 5/9 pack-objects: Teach new option --max-commit-count, limiting #commits in packJohan Herland, May 15, 2011
  38. 6/9 receive-pack: Prepare for addition of the new 'limit-*' family of capabilitiesJohan Herland, May 15, 2011
  39. Junio C HamanoMay 16, 2011
  40. Johan HerlandMay 16, 2011
  41. Sverre RabbelierMay 16, 2011
  42. Junio C HamanoMay 16, 2011
  43. Sverre RabbelierMay 16, 2011
  44. Junio C HamanoMay 16, 2011
  45. Sverre RabbelierMay 16, 2011
  46. 7/9 send-pack/receive-pack: Allow server to refuse pushes with too many objectsJohan Herland, May 15, 2011
  47. 8/9 send-pack/receive-pack: Allow server to refuse pushing too large packsJohan Herland, May 15, 2011
  48. 9/9 send-pack/receive-pack: Allow server to refuse pushes with too many commitsJohan Herland, May 15, 2011
  49. Ævar Arnfjörð BjarmasonMay 15, 2011
  50. Junio C HamanoMay 14, 2011
  51. Shawn PearceMay 14, 2011
  52. Johannes SixtMay 13, 2011
  53. Johan HerlandMay 14, 2011

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