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
committed by
Junio C Hamano
Junio C Hamano
parent
3a9ed4bdee
commit
7f3ecebfcd
248
builtin/remote-ext.c
Normal file
248
builtin/remote-ext.c
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#include "git-compat-util.h"
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#include "transport.h"
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#include "run-command.h"
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/*
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* URL syntax:
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* 'command [arg1 [arg2 [...]]]' Invoke command with given arguments.
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* Special characters:
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* '% ': Literal space in argument.
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* '%%': Literal percent sign.
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* '%S': Name of service (git-upload-pack/git-upload-archive/
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* git-receive-pack.
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* '%s': Same as \s, but with possible git- prefix stripped.
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* '%G': Only allowed as first 'character' of argument. Do not pass this
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* Argument to command, instead send this as name of repository
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* in in-line git://-style request (also activates sending this
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* style of request).
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* '%V': Only allowed as first 'character' of argument. Used in
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* conjunction with '%G': Do not pass this argument to command,
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* instead send this as vhost in git://-style request (note: does
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* not activate sending git:// style request).
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*/
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static char *git_req;
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static char *git_req_vhost;
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static char *strip_escapes(const char *str, const char *service,
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const char **next)
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{
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size_t rpos = 0;
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int escape = 0;
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char special = 0;
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size_t pslen = 0;
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size_t pSlen = 0;
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size_t psoff = 0;
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struct strbuf ret = STRBUF_INIT;
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/* Calculate prefix length for \s and lengths for \s and \S */
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if (!strncmp(service, "git-", 4))
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psoff = 4;
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pSlen = strlen(service);
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pslen = pSlen - psoff;
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/* Pass the service to command. */
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setenv("GIT_EXT_SERVICE", service, 1);
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setenv("GIT_EXT_SERVICE_NOPREFIX", service + psoff, 1);
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/* Scan the length of argument. */
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while (str[rpos] && (escape || str[rpos] != ' ')) {
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if (escape) {
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switch (str[rpos]) {
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case ' ':
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case '%':
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case 's':
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case 'S':
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break;
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case 'G':
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case 'V':
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special = str[rpos];
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if (rpos == 1)
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break;
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/* Fall-through to error. */
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default:
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die("Bad remote-ext placeholder '%%%c'.",
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str[rpos]);
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}
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escape = 0;
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} else
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escape = (str[rpos] == '%');
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rpos++;
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}
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if (escape && !str[rpos])
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die("remote-ext command has incomplete placeholder");
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*next = str + rpos;
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if (**next == ' ')
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++*next; /* Skip over space */
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/*
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* Do the actual placeholder substitution. The string will be short
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* enough not to overflow integers.
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*/
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rpos = special ? 2 : 0; /* Skip first 2 bytes in specials. */
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escape = 0;
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while (str[rpos] && (escape || str[rpos] != ' ')) {
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if (escape) {
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switch (str[rpos]) {
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case ' ':
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case '%':
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strbuf_addch(&ret, str[rpos]);
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break;
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case 's':
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strbuf_addstr(&ret, service + psoff);
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break;
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case 'S':
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strbuf_addstr(&ret, service);
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break;
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}
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escape = 0;
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} else
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switch (str[rpos]) {
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case '%':
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escape = 1;
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break;
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default:
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strbuf_addch(&ret, str[rpos]);
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break;
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}
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rpos++;
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}
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switch (special) {
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case 'G':
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git_req = strbuf_detach(&ret, NULL);
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return NULL;
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case 'V':
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git_req_vhost = strbuf_detach(&ret, NULL);
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return NULL;
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default:
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return strbuf_detach(&ret, NULL);
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}
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}
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/* Should be enough... */
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#define MAXARGUMENTS 256
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static const char **parse_argv(const char *arg, const char *service)
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{
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int arguments = 0;
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int i;
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const char **ret;
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char *temparray[MAXARGUMENTS + 1];
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while (*arg) {
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char *expanded;
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if (arguments == MAXARGUMENTS)
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die("remote-ext command has too many arguments");
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expanded = strip_escapes(arg, service, &arg);
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if (expanded)
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temparray[arguments++] = expanded;
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}
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ret = xmalloc((arguments + 1) * sizeof(char *));
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for (i = 0; i < arguments; i++)
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ret[i] = temparray[i];
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ret[arguments] = NULL;
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return (const char **)ret;
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}
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static void send_git_request(int stdin_fd, const char *serv, const char *repo,
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const char *vhost)
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{
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size_t bufferspace;
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size_t wpos = 0;
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char *buffer;
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/*
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* Request needs 12 bytes extra if there is vhost (xxxx \0host=\0) and
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* 6 bytes extra (xxxx \0) if there is no vhost.
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*/
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if (vhost)
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bufferspace = strlen(serv) + strlen(repo) + strlen(vhost) + 12;
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else
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bufferspace = strlen(serv) + strlen(repo) + 6;
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if (bufferspace > 0xFFFF)
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die("Request too large to send");
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buffer = xmalloc(bufferspace);
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/* Make the packet. */
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wpos = sprintf(buffer, "%04x%s %s%c", (unsigned)bufferspace,
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serv, repo, 0);
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/* Add vhost if any. */
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if (vhost)
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sprintf(buffer + wpos, "host=%s%c", vhost, 0);
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/* Send the request */
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if (write_in_full(stdin_fd, buffer, bufferspace) < 0)
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die_errno("Failed to send request");
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free(buffer);
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}
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static int run_child(const char *arg, const char *service)
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{
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int r;
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struct child_process child;
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memset(&child, 0, sizeof(child));
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child.in = -1;
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child.out = -1;
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child.err = 0;
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child.argv = parse_argv(arg, service);
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if (start_command(&child) < 0)
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die("Can't run specified command");
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if (git_req)
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send_git_request(child.in, service, git_req, git_req_vhost);
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r = bidirectional_transfer_loop(child.out, child.in);
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if (!r)
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r = finish_command(&child);
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else
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finish_command(&child);
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return r;
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}
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#define MAXCOMMAND 4096
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static int command_loop(const char *child)
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{
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char buffer[MAXCOMMAND];
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while (1) {
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size_t length;
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if (!fgets(buffer, MAXCOMMAND - 1, stdin)) {
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if (ferror(stdin))
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die("Comammand input error");
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exit(0);
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}
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/* Strip end of line characters. */
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length = strlen(buffer);
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while (isspace((unsigned char)buffer[length - 1]))
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buffer[--length] = 0;
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if (!strcmp(buffer, "capabilities")) {
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printf("*connect\n\n");
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fflush(stdout);
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} else if (!strncmp(buffer, "connect ", 8)) {
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printf("\n");
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fflush(stdout);
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return run_child(child, buffer + 8);
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} else {
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fprintf(stderr, "Bad command");
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return 1;
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}
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}
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}
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int cmd_remote_ext(int argc, const char **argv, const char *prefix)
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{
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if (argc < 3) {
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fprintf(stderr, "Error: URL missing");
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exit(1);
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}
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return command_loop(argv[2]);
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}
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