--- /dev/null
+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@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
--- /dev/null
+#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]);
+}
projects / git.git / commitdiff