rsh.c

   1 #include <string.h>
   2 #include <sys/types.h>
   3 #include <sys/socket.h>
   4
   5 #include "rsh.h"
   6 #include "quote.h"
   7 #include "cache.h"
   8
   9 #define COMMAND_SIZE 4096
  10
  11 /*
  12  * Append a string to a string buffer, with or without shell quoting.
  13  * Return true if the buffer overflowed.
  14  */
  15 static int add_to_string(char **ptrp, int *sizep, const char *str, int quote)
  16 {
  17         char *p = *ptrp;
  18         int size = *sizep;
  19         int oc;
  20         int err = 0;
  21
  22         if ( quote ) {
  23                 oc = sq_quote_buf(p, size, str);
  24         } else {
  25                 oc = strlen(str);
  26                 memcpy(p, str, (oc >= size) ? size-1 : oc);
  27         }
  28
  29         if ( oc >= size ) {
  30                 err = 1;
  31                 oc = size-1;
  32         }
  33
  34         *ptrp  += oc;
  35         **ptrp  = '\0';
  36         *sizep -= oc;
  37         return err;
  38 }
  39
  40 int setup_connection(int *fd_in, int *fd_out, const char *remote_prog,
  41                      char *url, int rmt_argc, char **rmt_argv)
  42 {
  43         char *host;
  44         char *path;
  45         int sv[2];
  46         char command[COMMAND_SIZE];
  47         char *posn;
  48         int sizen;
  49         int of;
  50         int i;
  51         pid_t pid;
  52
  53         if (!strcmp(url, "-")) {
  54                 *fd_in = 0;
  55                 *fd_out = 1;
  56                 return 0;
  57         }
  58
  59         host = strstr(url, "//");
  60         if (host) {
  61                 host += 2;
  62                 path = strchr(host, '/');
  63         } else {
  64                 host = url;
  65                 path = strchr(host, ':');
  66                 if (path)
  67                         *(path++) = '\0';
  68         }
  69         if (!path) {
  70                 return error("Bad URL: %s", url);
  71         }
  72         /* $GIT_RSH <host> "env GIT_DIR=<path> <remote_prog> <args...>" */
  73         sizen = COMMAND_SIZE;
  74         posn = command;
  75         of = 0;
  76         of |= add_to_string(&posn, &sizen, "env ", 0);
  77         of |= add_to_string(&posn, &sizen, GIT_DIR_ENVIRONMENT "=", 0);
  78         of |= add_to_string(&posn, &sizen, path, 1);
  79         of |= add_to_string(&posn, &sizen, " ", 0);
  80         of |= add_to_string(&posn, &sizen, remote_prog, 1);
  81
  82         for ( i = 0 ; i < rmt_argc ; i++ ) {
  83                 of |= add_to_string(&posn, &sizen, " ", 0);
  84                 of |= add_to_string(&posn, &sizen, rmt_argv[i], 1);
  85         }
  86
  87         of |= add_to_string(&posn, &sizen, " -", 0);
  88
  89         if ( of )
  90                 return error("Command line too long");
  91
  92         if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv))
  93                 return error("Couldn't create socket");
  94
  95         pid = fork();
  96         if (pid < 0)
  97                 return error("Couldn't fork");
  98         if (!pid) {
  99                 const char *ssh, *ssh_basename;
 100                 ssh = getenv("GIT_SSH");
 101                 if (!ssh) ssh = "ssh";
 102                 ssh_basename = strrchr(ssh, '/');
 103                 if (!ssh_basename)
 104                         ssh_basename = ssh;
 105                 else
 106                         ssh_basename++;
 107                 close(sv[1]);
 108                 dup2(sv[0], 0);
 109                 dup2(sv[0], 1);
 110                 execlp(ssh, ssh_basename, host, command, NULL);
 111         }
 112         close(sv[0]);
 113         *fd_in = sv[1];
 114         *fd_out = sv[1];
 115         return 0;
 116 }