builtin/remote-ext.c

   1 #include "builtin.h"
   2 #include "transport.h"
   3 #include "run-command.h"
   4
   5 /*
   6  * URL syntax:
   7  *      'command [arg1 [arg2 [...]]]'   Invoke command with given arguments.
   8  *      Special characters:
   9  *      '% ': Literal space in argument.
  10  *      '%%': Literal percent sign.
  11  *      '%S': Name of service (git-upload-pack/git-upload-archive/
  12  *              git-receive-pack.
  13  *      '%s': Same as \s, but with possible git- prefix stripped.
  14  *      '%G': Only allowed as first 'character' of argument. Do not pass this
  15  *              Argument to command, instead send this as name of repository
  16  *              in in-line git://-style request (also activates sending this
  17  *              style of request).
  18  *      '%V': Only allowed as first 'character' of argument. Used in
  19  *              conjunction with '%G': Do not pass this argument to command,
  20  *              instead send this as vhost in git://-style request (note: does
  21  *              not activate sending git:// style request).
  22  */
  23
  24 static char *git_req;
  25 static char *git_req_vhost;
  26
  27 static char *strip_escapes(const char *str, const char *service,
  28         const char **next)
  29 {
  30         size_t rpos = 0;
  31         int escape = 0;
  32         char special = 0;
  33         size_t psoff = 0;
  34         struct strbuf ret = STRBUF_INIT;
  35
  36         /* Calculate prefix length for \s and lengths for \s and \S */
  37         if (!strncmp(service, "git-", 4))
  38                 psoff = 4;
  39
  40         /* Pass the service to command. */
  41         setenv("GIT_EXT_SERVICE", service, 1);
  42         setenv("GIT_EXT_SERVICE_NOPREFIX", service + psoff, 1);
  43
  44         /* Scan the length of argument. */
  45         while (str[rpos] && (escape || str[rpos] != ' ')) {
  46                 if (escape) {
  47                         switch (str[rpos]) {
  48                         case ' ':
  49                         case '%':
  50                         case 's':
  51                         case 'S':
  52                                 break;
  53                         case 'G':
  54                         case 'V':
  55                                 special = str[rpos];
  56                                 if (rpos == 1)
  57                                         break;
  58                                 /* Fall-through to error. */
  59                         default:
  60                                 die("Bad remote-ext placeholder '%%%c'.",
  61                                         str[rpos]);
  62                         }
  63                         escape = 0;
  64                 } else
  65                         escape = (str[rpos] == '%');
  66                 rpos++;
  67         }
  68         if (escape && !str[rpos])
  69                 die("remote-ext command has incomplete placeholder");
  70         *next = str + rpos;
  71         if (**next == ' ')
  72                 ++*next;        /* Skip over space */
  73
  74         /*
  75          * Do the actual placeholder substitution. The string will be short
  76          * enough not to overflow integers.
  77          */
  78         rpos = special ? 2 : 0;         /* Skip first 2 bytes in specials. */
  79         escape = 0;
  80         while (str[rpos] && (escape || str[rpos] != ' ')) {
  81                 if (escape) {
  82                         switch (str[rpos]) {
  83                         case ' ':
  84                         case '%':
  85                                 strbuf_addch(&ret, str[rpos]);
  86                                 break;
  87                         case 's':
  88                                 strbuf_addstr(&ret, service + psoff);
  89                                 break;
  90                         case 'S':
  91                                 strbuf_addstr(&ret, service);
  92                                 break;
  93                         }
  94                         escape = 0;
  95                 } else
  96                         switch (str[rpos]) {
  97                         case '%':
  98                                 escape = 1;
  99                                 break;
 100                         default:
 101                                 strbuf_addch(&ret, str[rpos]);
 102                                 break;
 103                         }
 104                 rpos++;
 105         }
 106         switch (special) {
 107         case 'G':
 108                 git_req = strbuf_detach(&ret, NULL);
 109                 return NULL;
 110         case 'V':
 111                 git_req_vhost = strbuf_detach(&ret, NULL);
 112                 return NULL;
 113         default:
 114                 return strbuf_detach(&ret, NULL);
 115         }
 116 }
 117
 118 /* Should be enough... */
 119 #define MAXARGUMENTS 256
 120
 121 static const char **parse_argv(const char *arg, const char *service)
 122 {
 123         int arguments = 0;
 124         int i;
 125         const char **ret;
 126         char *temparray[MAXARGUMENTS + 1];
 127
 128         while (*arg) {
 129                 char *expanded;
 130                 if (arguments == MAXARGUMENTS)
 131                         die("remote-ext command has too many arguments");
 132                 expanded = strip_escapes(arg, service, &arg);
 133                 if (expanded)
 134                         temparray[arguments++] = expanded;
 135         }
 136
 137         ret = xmalloc((arguments + 1) * sizeof(char *));
 138         for (i = 0; i < arguments; i++)
 139                 ret[i] = temparray[i];
 140         ret[arguments] = NULL;
 141         return ret;
 142 }
 143
 144 static void send_git_request(int stdin_fd, const char *serv, const char *repo,
 145         const char *vhost)
 146 {
 147         size_t bufferspace;
 148         size_t wpos = 0;
 149         char *buffer;
 150
 151         /*
 152          * Request needs 12 bytes extra if there is vhost (xxxx \0host=\0) and
 153          * 6 bytes extra (xxxx \0) if there is no vhost.
 154          */
 155         if (vhost)
 156                 bufferspace = strlen(serv) + strlen(repo) + strlen(vhost) + 12;
 157         else
 158                 bufferspace = strlen(serv) + strlen(repo) + 6;
 159
 160         if (bufferspace > 0xFFFF)
 161                 die("Request too large to send");
 162         buffer = xmalloc(bufferspace);
 163
 164         /* Make the packet. */
 165         wpos = sprintf(buffer, "%04x%s %s%c", (unsigned)bufferspace,
 166                 serv, repo, 0);
 167
 168         /* Add vhost if any. */
 169         if (vhost)
 170                 sprintf(buffer + wpos, "host=%s%c", vhost, 0);
 171
 172         /* Send the request */
 173         if (write_in_full(stdin_fd, buffer, bufferspace) < 0)
 174                 die_errno("Failed to send request");
 175
 176         free(buffer);
 177 }
 178
 179 static int run_child(const char *arg, const char *service)
 180 {
 181         int r;
 182         struct child_process child = CHILD_PROCESS_INIT;
 183
 184         child.in = -1;
 185         child.out = -1;
 186         child.err = 0;
 187         child.argv = parse_argv(arg, service);
 188
 189         if (start_command(&child) < 0)
 190                 die("Can't run specified command");
 191
 192         if (git_req)
 193                 send_git_request(child.in, service, git_req, git_req_vhost);
 194
 195         r = bidirectional_transfer_loop(child.out, child.in);
 196         if (!r)
 197                 r = finish_command(&child);
 198         else
 199                 finish_command(&child);
 200         return r;
 201 }
 202
 203 #define MAXCOMMAND 4096
 204
 205 static int command_loop(const char *child)
 206 {
 207         char buffer[MAXCOMMAND];
 208
 209         while (1) {
 210                 size_t i;
 211                 if (!fgets(buffer, MAXCOMMAND - 1, stdin)) {
 212                         if (ferror(stdin))
 213                                 die("Comammand input error");
 214                         exit(0);
 215                 }
 216                 /* Strip end of line characters. */
 217                 i = strlen(buffer);
 218                 while (i > 0 && isspace(buffer[i - 1]))
 219                         buffer[--i] = 0;
 220
 221                 if (!strcmp(buffer, "capabilities")) {
 222                         printf("*connect\n\n");
 223                         fflush(stdout);
 224                 } else if (!strncmp(buffer, "connect ", 8)) {
 225                         printf("\n");
 226                         fflush(stdout);
 227                         return run_child(child, buffer + 8);
 228                 } else {
 229                         fprintf(stderr, "Bad command");
 230                         return 1;
 231                 }
 232         }
 233 }
 234
 235 int cmd_remote_ext(int argc, const char **argv, const char *prefix)
 236 {
 237         if (argc != 3)
 238                 die("Expected two arguments");
 239
 240         return command_loop(argv[2]);
 241 }