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authorMasaya Suzuki <masayasuzuki@google.com>2018-12-29 21:19:15 (GMT)
committerJunio C Hamano <gitster@pobox.com>2019-01-02 21:05:30 (GMT)
commit2d103c31c2cfcf03ff1408d639043469b0c93f70 (patch)
tree17a4e7a35fb5401fad2b8713e17360af0573682e
parent01f9ec64c8a82a05ba7e5a17b292ede037a469ea (diff)
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pack-protocol.txt: accept error packets in any context
In the Git pack protocol definition, an error packet may appear only in a certain context. However, servers can face a runtime error (e.g. I/O error) at an arbitrary timing. This patch changes the protocol to allow an error packet to be sent instead of any packet. Without this protocol spec change, when a server cannot process a request, there's no way to tell that to a client. Since the server cannot produce a valid response, it would be forced to cut a connection without telling why. With this protocol spec change, the server can be more gentle in this situation. An old client may see these error packets as an unexpected packet, but this is not worse than having an unexpected EOF. Following this protocol spec change, the error packet handling code is moved to pkt-line.c. Implementation wise, this implementation uses pkt-line to communicate with a subprocess. Since this is not a part of Git protocol, it's possible that a packet that is not supposed to be an error packet is mistakenly parsed as an error packet. This error packet handling is enabled only for the Git pack protocol parsing code considering this. Signed-off-by: Masaya Suzuki <masayasuzuki@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r--Documentation/technical/pack-protocol.txt20
-rw-r--r--builtin/archive.c6
-rw-r--r--builtin/fetch-pack.c3
-rw-r--r--builtin/receive-pack.c4
-rw-r--r--builtin/send-pack.c3
-rw-r--r--connect.c3
-rw-r--r--fetch-pack.c8
-rw-r--r--pkt-line.c4
-rw-r--r--pkt-line.h8
-rw-r--r--remote-curl.c9
-rw-r--r--send-pack.c4
-rw-r--r--serve.c5
-rwxr-xr-xt/t5703-upload-pack-ref-in-want.sh4
-rw-r--r--transport.c3
-rw-r--r--upload-pack.c4
15 files changed, 54 insertions, 34 deletions
diff --git a/Documentation/technical/pack-protocol.txt b/Documentation/technical/pack-protocol.txt
index 6ac774d..7a2375a 100644
--- a/Documentation/technical/pack-protocol.txt
+++ b/Documentation/technical/pack-protocol.txt
@@ -22,6 +22,16 @@ protocol-common.txt. When the grammar indicate `PKT-LINE(...)`, unless
otherwise noted the usual pkt-line LF rules apply: the sender SHOULD
include a LF, but the receiver MUST NOT complain if it is not present.
+An error packet is a special pkt-line that contains an error string.
+
+----
+ error-line = PKT-LINE("ERR" SP explanation-text)
+----
+
+Throughout the protocol, where `PKT-LINE(...)` is expected, an error packet MAY
+be sent. Once this packet is sent by a client or a server, the data transfer
+process defined in this protocol is terminated.
+
Transports
----------
There are three transports over which the packfile protocol is
@@ -89,13 +99,6 @@ process on the server side over the Git protocol is this:
"0039git-upload-pack /schacon/gitbook.git\0host=example.com\0" |
nc -v example.com 9418
-If the server refuses the request for some reasons, it could abort
-gracefully with an error message.
-
-----
- error-line = PKT-LINE("ERR" SP explanation-text)
-----
-
SSH Transport
-------------
@@ -398,12 +401,11 @@ from the client).
Then the server will start sending its packfile data.
----
- server-response = *ack_multi ack / nak / error-line
+ server-response = *ack_multi ack / nak
ack_multi = PKT-LINE("ACK" SP obj-id ack_status)
ack_status = "continue" / "common" / "ready"
ack = PKT-LINE("ACK" SP obj-id)
nak = PKT-LINE("NAK")
- error-line = PKT-LINE("ERR" SP explanation-text)
----
A simple clone may look like this (with no 'have' lines):
diff --git a/builtin/archive.c b/builtin/archive.c
index 2fe1f05..45d1166 100644
--- a/builtin/archive.c
+++ b/builtin/archive.c
@@ -53,15 +53,15 @@ static int run_remote_archiver(int argc, const char **argv,
packet_write_fmt(fd[1], "argument %s\n", argv[i]);
packet_flush(fd[1]);
- packet_reader_init(&reader, fd[0], NULL, 0, PACKET_READ_CHOMP_NEWLINE);
+ packet_reader_init(&reader, fd[0], NULL, 0,
+ PACKET_READ_CHOMP_NEWLINE |
+ PACKET_READ_DIE_ON_ERR_PACKET);
if (packet_reader_read(&reader) != PACKET_READ_NORMAL)
die(_("git archive: expected ACK/NAK, got a flush packet"));
if (strcmp(reader.line, "ACK")) {
if (starts_with(reader.line, "NACK "))
die(_("git archive: NACK %s"), reader.line + 5);
- if (starts_with(reader.line, "ERR "))
- die(_("remote error: %s"), reader.line + 4);
die(_("git archive: protocol error"));
}
diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 63e69a5..85dbc2a 100644
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -217,7 +217,8 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
packet_reader_init(&reader, fd[0], NULL, 0,
PACKET_READ_CHOMP_NEWLINE |
- PACKET_READ_GENTLE_ON_EOF);
+ PACKET_READ_GENTLE_ON_EOF |
+ PACKET_READ_DIE_ON_ERR_PACKET);
switch (discover_version(&reader)) {
case protocol_v2:
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 81cc073..d58b775 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -1986,7 +1986,9 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
if (advertise_refs)
return 0;
- packet_reader_init(&reader, 0, NULL, 0, PACKET_READ_CHOMP_NEWLINE);
+ packet_reader_init(&reader, 0, NULL, 0,
+ PACKET_READ_CHOMP_NEWLINE |
+ PACKET_READ_DIE_ON_ERR_PACKET);
if ((commands = read_head_info(&reader, &shallow)) != NULL) {
const char *unpack_status = NULL;
diff --git a/builtin/send-pack.c b/builtin/send-pack.c
index 8e3c749..098ebf2 100644
--- a/builtin/send-pack.c
+++ b/builtin/send-pack.c
@@ -250,7 +250,8 @@ int cmd_send_pack(int argc, const char **argv, const char *prefix)
packet_reader_init(&reader, fd[0], NULL, 0,
PACKET_READ_CHOMP_NEWLINE |
- PACKET_READ_GENTLE_ON_EOF);
+ PACKET_READ_GENTLE_ON_EOF |
+ PACKET_READ_DIE_ON_ERR_PACKET);
switch (discover_version(&reader)) {
case protocol_v2:
diff --git a/connect.c b/connect.c
index 24281b6..4813f00 100644
--- a/connect.c
+++ b/connect.c
@@ -296,7 +296,6 @@ struct ref **get_remote_heads(struct packet_reader *reader,
struct ref **orig_list = list;
int len = 0;
enum get_remote_heads_state state = EXPECTING_FIRST_REF;
- const char *arg;
*list = NULL;
@@ -306,8 +305,6 @@ struct ref **get_remote_heads(struct packet_reader *reader,
die_initial_contact(1);
case PACKET_READ_NORMAL:
len = reader->pktlen;
- if (len > 4 && skip_prefix(reader->line, "ERR ", &arg))
- die(_("remote error: %s"), arg);
break;
case PACKET_READ_FLUSH:
state = EXPECTING_DONE;
diff --git a/fetch-pack.c b/fetch-pack.c
index 86790b9..3f9626d 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -182,8 +182,6 @@ static enum ack_type get_ack(struct packet_reader *reader,
return ACK;
}
}
- if (skip_prefix(reader->line, "ERR ", &arg))
- die(_("remote error: %s"), arg);
die(_("git fetch-pack: expected ACK/NAK, got '%s'"), reader->line);
}
@@ -258,7 +256,8 @@ static int find_common(struct fetch_negotiator *negotiator,
die(_("--stateless-rpc requires multi_ack_detailed"));
packet_reader_init(&reader, fd[0], NULL, 0,
- PACKET_READ_CHOMP_NEWLINE);
+ PACKET_READ_CHOMP_NEWLINE |
+ PACKET_READ_DIE_ON_ERR_PACKET);
if (!args->no_dependents) {
mark_tips(negotiator, args->negotiation_tips);
@@ -1358,7 +1357,8 @@ static struct ref *do_fetch_pack_v2(struct fetch_pack_args *args,
struct fetch_negotiator negotiator;
fetch_negotiator_init(&negotiator, negotiation_algorithm);
packet_reader_init(&reader, fd[0], NULL, 0,
- PACKET_READ_CHOMP_NEWLINE);
+ PACKET_READ_CHOMP_NEWLINE |
+ PACKET_READ_DIE_ON_ERR_PACKET);
while (state != FETCH_DONE) {
switch (state) {
diff --git a/pkt-line.c b/pkt-line.c
index 04d10bb..e70ea6d 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -346,6 +346,10 @@ enum packet_read_status packet_read_with_status(int fd, char **src_buffer,
return PACKET_READ_EOF;
}
+ if ((options & PACKET_READ_DIE_ON_ERR_PACKET) &&
+ starts_with(buffer, "ERR "))
+ die(_("remote error: %s"), buffer + 4);
+
if ((options & PACKET_READ_CHOMP_NEWLINE) &&
len && buffer[len-1] == '\n')
len--;
diff --git a/pkt-line.h b/pkt-line.h
index 5b28d43..d7e1dbc 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -62,9 +62,13 @@ int write_packetized_from_buf(const char *src_in, size_t len, int fd_out);
*
* If options contains PACKET_READ_CHOMP_NEWLINE, a trailing newline (if
* present) is removed from the buffer before returning.
+ *
+ * If options contains PACKET_READ_DIE_ON_ERR_PACKET, it dies when it sees an
+ * ERR packet.
*/
-#define PACKET_READ_GENTLE_ON_EOF (1u<<0)
-#define PACKET_READ_CHOMP_NEWLINE (1u<<1)
+#define PACKET_READ_GENTLE_ON_EOF (1u<<0)
+#define PACKET_READ_CHOMP_NEWLINE (1u<<1)
+#define PACKET_READ_DIE_ON_ERR_PACKET (1u<<2)
int packet_read(int fd, char **src_buffer, size_t *src_len, char
*buffer, unsigned size, int options);
diff --git a/remote-curl.c b/remote-curl.c
index bbd9ba0..10b5086 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -204,7 +204,8 @@ static struct ref *parse_git_refs(struct discovery *heads, int for_push)
packet_reader_init(&reader, -1, heads->buf, heads->len,
PACKET_READ_CHOMP_NEWLINE |
- PACKET_READ_GENTLE_ON_EOF);
+ PACKET_READ_GENTLE_ON_EOF |
+ PACKET_READ_DIE_ON_ERR_PACKET);
heads->version = discover_version(&reader);
switch (heads->version) {
@@ -411,7 +412,8 @@ static struct discovery *discover_refs(const char *service, int for_push)
!strbuf_cmp(&exp, &type)) {
struct packet_reader reader;
packet_reader_init(&reader, -1, last->buf, last->len,
- PACKET_READ_CHOMP_NEWLINE);
+ PACKET_READ_CHOMP_NEWLINE |
+ PACKET_READ_DIE_ON_ERR_PACKET);
/*
* smart HTTP response; validate that the service
@@ -1182,7 +1184,8 @@ static void proxy_state_init(struct proxy_state *p, const char *service_name,
p->headers = curl_slist_append(p->headers, buf.buf);
packet_reader_init(&p->reader, p->in, NULL, 0,
- PACKET_READ_GENTLE_ON_EOF);
+ PACKET_READ_GENTLE_ON_EOF |
+ PACKET_READ_DIE_ON_ERR_PACKET);
strbuf_release(&buf);
}
diff --git a/send-pack.c b/send-pack.c
index 9136450..7b9829f 100644
--- a/send-pack.c
+++ b/send-pack.c
@@ -558,7 +558,9 @@ int send_pack(struct send_pack_args *args,
in = demux.out;
}
- packet_reader_init(&reader, in, NULL, 0, PACKET_READ_CHOMP_NEWLINE);
+ packet_reader_init(&reader, in, NULL, 0,
+ PACKET_READ_CHOMP_NEWLINE |
+ PACKET_READ_DIE_ON_ERR_PACKET);
if (need_pack_data && cmds_sent) {
if (pack_objects(out, remote_refs, extra_have, args) < 0) {
diff --git a/serve.c b/serve.c
index bda085f..317256c 100644
--- a/serve.c
+++ b/serve.c
@@ -167,7 +167,8 @@ static int process_request(void)
packet_reader_init(&reader, 0, NULL, 0,
PACKET_READ_CHOMP_NEWLINE |
- PACKET_READ_GENTLE_ON_EOF);
+ PACKET_READ_GENTLE_ON_EOF |
+ PACKET_READ_DIE_ON_ERR_PACKET);
/*
* Check to see if the client closed their end before sending another
@@ -175,7 +176,7 @@ static int process_request(void)
*/
if (packet_reader_peek(&reader) == PACKET_READ_EOF)
return 1;
- reader.options = PACKET_READ_CHOMP_NEWLINE;
+ reader.options &= ~PACKET_READ_GENTLE_ON_EOF;
while (state != PROCESS_REQUEST_DONE) {
switch (packet_reader_peek(&reader)) {
diff --git a/t/t5703-upload-pack-ref-in-want.sh b/t/t5703-upload-pack-ref-in-want.sh
index 3f58f05..d2a9d0c 100755
--- a/t/t5703-upload-pack-ref-in-want.sh
+++ b/t/t5703-upload-pack-ref-in-want.sh
@@ -208,7 +208,7 @@ test_expect_success 'server is initially ahead - no ref in want' '
cp -r "$LOCAL_PRISTINE" local &&
inconsistency master 1234567890123456789012345678901234567890 &&
test_must_fail git -C local fetch 2>err &&
- grep "ERR upload-pack: not our ref" err
+ grep "fatal: remote error: upload-pack: not our ref" err
'
test_expect_success 'server is initially ahead - ref in want' '
@@ -254,7 +254,7 @@ test_expect_success 'server loses a ref - ref in want' '
echo "s/master/raster/" >"$HTTPD_ROOT_PATH/one-time-sed" &&
test_must_fail git -C local fetch 2>err &&
- grep "ERR unknown ref refs/heads/raster" err
+ grep "fatal: remote error: unknown ref refs/heads/raster" err
'
stop_httpd
diff --git a/transport.c b/transport.c
index 5a74b60..12db425 100644
--- a/transport.c
+++ b/transport.c
@@ -273,7 +273,8 @@ static struct ref *handshake(struct transport *transport, int for_push,
packet_reader_init(&reader, data->fd[0], NULL, 0,
PACKET_READ_CHOMP_NEWLINE |
- PACKET_READ_GENTLE_ON_EOF);
+ PACKET_READ_GENTLE_ON_EOF |
+ PACKET_READ_DIE_ON_ERR_PACKET);
data->version = discover_version(&reader);
switch (data->version) {
diff --git a/upload-pack.c b/upload-pack.c
index 1638825..08b547c 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -1078,7 +1078,9 @@ void upload_pack(struct upload_pack_options *options)
if (options->advertise_refs)
return;
- packet_reader_init(&reader, 0, NULL, 0, PACKET_READ_CHOMP_NEWLINE);
+ packet_reader_init(&reader, 0, NULL, 0,
+ PACKET_READ_CHOMP_NEWLINE |
+ PACKET_READ_DIE_ON_ERR_PACKET);
receive_needs(&reader, &want_obj);
if (want_obj.nr) {