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git-remote-ext

This remote helper invokes external command and passes raw smart transport
stream through it. This is useful for instance for invoking ssh with
one-off odd options, connecting to git services in unix domain
sockets, in abstract namespace, using TLS or other secure protocols,
etc...

Signed-off-by: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Ilari Liusvaara 2010-10-12 19:39:43 +03:00 committed by Junio C Hamano
parent 3a9ed4bdee
commit 7f3ecebfcd
6 changed files with 377 additions and 0 deletions

1
.gitignore vendored
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@ -113,6 +113,7 @@
/git-remote-ftp
/git-remote-ftps
/git-remote-fd
/git-remote-ext
/git-remote-testgit
/git-repack
/git-replace

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@ -0,0 +1,125 @@
git-remote-ext(1)
=================
NAME
----
git-remote-ext - Bridge smart transport to external command.
SYNOPSIS
--------
git remote add nick "ext::<command>[ <arguments>...]"
DESCRIPTION
-----------
This remote helper uses the specified 'program' to connect
to a remote git server.
Data written to stdin of this specified 'program' is assumed
to be sent to git:// server, git-upload-pack, git-receive-pack
or git-upload-archive (depending on situation), and data read
from stdout of this program is assumed to be received from
the same service.
Command and arguments are separated by unescaped space.
The following sequences have a special meaning:
'% '::
Literal space in command or argument.
'%%'::
Literal percent sign.
'%s'::
Replaced with name (receive-pack, upload-pack, or
upload-archive) of the service git wants to invoke.
'%S'::
Replaced with long name (git-receive-pack,
git-upload-pack, or git-upload-archive) of the service
git wants to invoke.
'%G<repository>' (as argument)::
This argument will not be passed to 'program'. Instead, it
will cause helper to start by sending git:// service request to
remote side with service field set to approiate value and
repository field set to <repository>. Default is not to send
such request.
+
This is useful if remote side is git:// server accessed over
some tunnel.
'%V<host>' (as argument)::
This argument will not be passed to 'program'. Instead it sets
the vhost field in git:// service request. Default is not to
send vhost in such request (if sent).
ENVIRONMENT VARIABLES:
----------------------
GIT_TRANSLOOP_DEBUG::
If set, prints debugging information about various reads/writes.
ENVIRONMENT VARIABLES PASSED TO COMMAND:
----------------------------------------
GIT_EXT_SERVICE::
Set to long name (git-upload-pack, etc...) of service helper needs
to invoke.
GIT_EXT_SERVICE_NOPREFIX::
Set to long name (upload-pack, etc...) of service helper needs
to invoke.
EXAMPLES:
---------
This remote helper is transparently used by git when
you use commands such as "git fetch <URL>", "git clone <URL>",
, "git push <URL>" or "git remote add nick <URL>", where <URL>
begins with `ext::`. Examples:
"ext::ssh -i /home/foo/.ssh/somekey user&#64;host.example %S 'foo/repo'"::
Like host.example:foo/repo, but use /home/foo/.ssh/somekey as
keypair and user as user on remote side. This avoids needing to
edit .ssh/config.
"ext::socat -t3600 - ABSTRACT-CONNECT:/git-server %G/somerepo"::
Represents repository with path /somerepo accessable over
git protocol at abstract namespace address /git-server.
"ext::git-server-alias foo %G/repo"::
Represents a repository with path /repo accessed using the
helper program "git-server-alias foo". The path to the
repository and type of request are not passed on the command
line but as part of the protocol stream, as usual with git://
protocol.
"ext::git-server-alias foo %G/repo %Vfoo"::
Represents a repository with path /repo accessed using the
helper program "git-server-alias foo". The hostname for the
remote server passed in the protocol stream will be "foo"
(this allows multiple virtual git servers to share a
link-level address).
"ext::git-server-alias foo %G/repo% with% spaces %Vfoo"::
Represents a repository with path '/repo with spaces' accessed
using the helper program "git-server-alias foo". The hostname for
the remote server passed in the protocol stream will be "foo"
(this allows multiple virtual git servers to share a
link-level address).
"ext::git-ssl foo.example /bar"::
Represents a repository accessed using the helper program
"git-ssl foo.example /bar". The type of request can be
determined by the helper using environment variables (see
above).
Documentation
--------------
Documentation by Ilari Liusvaara, Jonathan Nieder and the git list
<git@vger.kernel.org>
GIT
---
Part of the linkgit:git[1] suite

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@ -723,6 +723,7 @@ BUILTIN_OBJS += builtin/read-tree.o
BUILTIN_OBJS += builtin/receive-pack.o
BUILTIN_OBJS += builtin/reflog.o
BUILTIN_OBJS += builtin/remote.o
BUILTIN_OBJS += builtin/remote-ext.o
BUILTIN_OBJS += builtin/remote-fd.o
BUILTIN_OBJS += builtin/replace.o
BUILTIN_OBJS += builtin/rerere.o

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@ -107,6 +107,7 @@ extern int cmd_read_tree(int argc, const char **argv, const char *prefix);
extern int cmd_receive_pack(int argc, const char **argv, const char *prefix);
extern int cmd_reflog(int argc, const char **argv, const char *prefix);
extern int cmd_remote(int argc, const char **argv, const char *prefix);
extern int cmd_remote_ext(int argc, const char **argv, const char *prefix);
extern int cmd_remote_fd(int argc, const char **argv, const char *prefix);
extern int cmd_config(int argc, const char **argv, const char *prefix);
extern int cmd_rerere(int argc, const char **argv, const char *prefix);

248
builtin/remote-ext.c Normal file
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@ -0,0 +1,248 @@
#include "git-compat-util.h"
#include "transport.h"
#include "run-command.h"
/*
* URL syntax:
* 'command [arg1 [arg2 [...]]]' Invoke command with given arguments.
* Special characters:
* '% ': Literal space in argument.
* '%%': Literal percent sign.
* '%S': Name of service (git-upload-pack/git-upload-archive/
* git-receive-pack.
* '%s': Same as \s, but with possible git- prefix stripped.
* '%G': Only allowed as first 'character' of argument. Do not pass this
* Argument to command, instead send this as name of repository
* in in-line git://-style request (also activates sending this
* style of request).
* '%V': Only allowed as first 'character' of argument. Used in
* conjunction with '%G': Do not pass this argument to command,
* instead send this as vhost in git://-style request (note: does
* not activate sending git:// style request).
*/
static char *git_req;
static char *git_req_vhost;
static char *strip_escapes(const char *str, const char *service,
const char **next)
{
size_t rpos = 0;
int escape = 0;
char special = 0;
size_t pslen = 0;
size_t pSlen = 0;
size_t psoff = 0;
struct strbuf ret = STRBUF_INIT;
/* Calculate prefix length for \s and lengths for \s and \S */
if (!strncmp(service, "git-", 4))
psoff = 4;
pSlen = strlen(service);
pslen = pSlen - psoff;
/* Pass the service to command. */
setenv("GIT_EXT_SERVICE", service, 1);
setenv("GIT_EXT_SERVICE_NOPREFIX", service + psoff, 1);
/* Scan the length of argument. */
while (str[rpos] && (escape || str[rpos] != ' ')) {
if (escape) {
switch (str[rpos]) {
case ' ':
case '%':
case 's':
case 'S':
break;
case 'G':
case 'V':
special = str[rpos];
if (rpos == 1)
break;
/* Fall-through to error. */
default:
die("Bad remote-ext placeholder '%%%c'.",
str[rpos]);
}
escape = 0;
} else
escape = (str[rpos] == '%');
rpos++;
}
if (escape && !str[rpos])
die("remote-ext command has incomplete placeholder");
*next = str + rpos;
if (**next == ' ')
++*next; /* Skip over space */
/*
* Do the actual placeholder substitution. The string will be short
* enough not to overflow integers.
*/
rpos = special ? 2 : 0; /* Skip first 2 bytes in specials. */
escape = 0;
while (str[rpos] && (escape || str[rpos] != ' ')) {
if (escape) {
switch (str[rpos]) {
case ' ':
case '%':
strbuf_addch(&ret, str[rpos]);
break;
case 's':
strbuf_addstr(&ret, service + psoff);
break;
case 'S':
strbuf_addstr(&ret, service);
break;
}
escape = 0;
} else
switch (str[rpos]) {
case '%':
escape = 1;
break;
default:
strbuf_addch(&ret, str[rpos]);
break;
}
rpos++;
}
switch (special) {
case 'G':
git_req = strbuf_detach(&ret, NULL);
return NULL;
case 'V':
git_req_vhost = strbuf_detach(&ret, NULL);
return NULL;
default:
return strbuf_detach(&ret, NULL);
}
}
/* Should be enough... */
#define MAXARGUMENTS 256
static const char **parse_argv(const char *arg, const char *service)
{
int arguments = 0;
int i;
const char **ret;
char *temparray[MAXARGUMENTS + 1];
while (*arg) {
char *expanded;
if (arguments == MAXARGUMENTS)
die("remote-ext command has too many arguments");
expanded = strip_escapes(arg, service, &arg);
if (expanded)
temparray[arguments++] = expanded;
}
ret = xmalloc((arguments + 1) * sizeof(char *));
for (i = 0; i < arguments; i++)
ret[i] = temparray[i];
ret[arguments] = NULL;
return (const char **)ret;
}
static void send_git_request(int stdin_fd, const char *serv, const char *repo,
const char *vhost)
{
size_t bufferspace;
size_t wpos = 0;
char *buffer;
/*
* Request needs 12 bytes extra if there is vhost (xxxx \0host=\0) and
* 6 bytes extra (xxxx \0) if there is no vhost.
*/
if (vhost)
bufferspace = strlen(serv) + strlen(repo) + strlen(vhost) + 12;
else
bufferspace = strlen(serv) + strlen(repo) + 6;
if (bufferspace > 0xFFFF)
die("Request too large to send");
buffer = xmalloc(bufferspace);
/* Make the packet. */
wpos = sprintf(buffer, "%04x%s %s%c", (unsigned)bufferspace,
serv, repo, 0);
/* Add vhost if any. */
if (vhost)
sprintf(buffer + wpos, "host=%s%c", vhost, 0);
/* Send the request */
if (write_in_full(stdin_fd, buffer, bufferspace) < 0)
die_errno("Failed to send request");
free(buffer);
}
static int run_child(const char *arg, const char *service)
{
int r;
struct child_process child;
memset(&child, 0, sizeof(child));
child.in = -1;
child.out = -1;
child.err = 0;
child.argv = parse_argv(arg, service);
if (start_command(&child) < 0)
die("Can't run specified command");
if (git_req)
send_git_request(child.in, service, git_req, git_req_vhost);
r = bidirectional_transfer_loop(child.out, child.in);
if (!r)
r = finish_command(&child);
else
finish_command(&child);
return r;
}
#define MAXCOMMAND 4096
static int command_loop(const char *child)
{
char buffer[MAXCOMMAND];
while (1) {
size_t length;
if (!fgets(buffer, MAXCOMMAND - 1, stdin)) {
if (ferror(stdin))
die("Comammand input error");
exit(0);
}
/* Strip end of line characters. */
length = strlen(buffer);
while (isspace((unsigned char)buffer[length - 1]))
buffer[--length] = 0;
if (!strcmp(buffer, "capabilities")) {
printf("*connect\n\n");
fflush(stdout);
} else if (!strncmp(buffer, "connect ", 8)) {
printf("\n");
fflush(stdout);
return run_child(child, buffer + 8);
} else {
fprintf(stderr, "Bad command");
return 1;
}
}
}
int cmd_remote_ext(int argc, const char **argv, const char *prefix)
{
if (argc < 3) {
fprintf(stderr, "Error: URL missing");
exit(1);
}
return command_loop(argv[2]);
}

1
git.c
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@ -374,6 +374,7 @@ static void handle_internal_command(int argc, const char **argv)
{ "receive-pack", cmd_receive_pack },
{ "reflog", cmd_reflog, RUN_SETUP },
{ "remote", cmd_remote, RUN_SETUP },
{ "remote-ext", cmd_remote_ext },
{ "remote-fd", cmd_remote_fd },
{ "replace", cmd_replace, RUN_SETUP },
{ "repo-config", cmd_config, RUN_SETUP_GENTLY },