rsh.c

   1 #include "rsh.h"
   2
   3 #include <string.h>
   4 #include <sys/types.h>
   5 #include <sys/socket.h>
   6
   7 #include "cache.h"
   8
   9 #define COMMAND_SIZE 4096
  10
  11 /*
  12  * Write a shell-quoted version of a string into a buffer, and
  13  * return bytes that ought to be output excluding final null.
  14  */
  15 static int shell_quote(char *buf, int nmax, const char *str)
  16 {
  17         char ch;
  18         int nq;
  19         int oc = 0;
  20
  21         while ( (ch = *str++) ) {
  22                 nq = 0;
  23                 if ( strchr(" !\"#$%&\'()*;<=>?[\\]^`{|}", ch) )
  24                         nq = 1;
  25
  26                 if ( nq ) {
  27                         if ( nmax > 1 ) {
  28                                 *buf++ = '\\';
  29                                 nmax--;
  30                         }
  31                         oc++;
  32                 }
  33
  34                 if ( nmax > 1 ) {
  35                         *buf++ = ch;
  36                         nmax--;
  37                 }
  38                 oc++;
  39         }
  40
  41         if ( nmax )
  42                 *buf = '\0';
  43
  44         return oc;
  45 }
  46
  47 /*
  48  * Append a string to a string buffer, with or without quoting.  Return true
  49  * if the buffer overflowed.
  50  */
  51 static int add_to_string(char **ptrp, int *sizep, const char *str, int quote)
  52 {
  53         char *p = *ptrp;
  54         int size = *sizep;
  55         int oc;
  56         int err = 0;
  57
  58         if ( quote ) {
  59                 oc = shell_quote(p, size, str);
  60         } else {
  61                 oc = strlen(str);
  62                 memcpy(p, str, (oc >= size) ? size-1 : oc);
  63         }
  64
  65         if ( oc >= size ) {
  66                 err = 1;
  67                 oc = size-1;
  68         }
  69
  70         *ptrp  += oc;
  71         **ptrp  = '\0';
  72         *sizep -= oc;
  73         return err;
  74 }
  75
  76 int setup_connection(int *fd_in, int *fd_out, const char *remote_prog,
  77                      char *url, int rmt_argc, char **rmt_argv)
  78 {
  79         char *host;
  80         char *path;
  81         int sv[2];
  82         char command[COMMAND_SIZE];
  83         char *posn;
  84         int sizen;
  85         int of;
  86         int i;
  87
  88         if (!strcmp(url, "-")) {
  89                 *fd_in = 0;
  90                 *fd_out = 1;
  91                 return 0;
  92         }
  93
  94         host = strstr(url, "//");
  95         if (host) {
  96                 host += 2;
  97                 path = strchr(host, '/');
  98         } else {
  99                 host = url;
 100                 path = strchr(host, ':');
 101                 if (path)
 102                         *(path++) = '\0';
 103         }
 104         if (!path) {
 105                 return error("Bad URL: %s", url);
 106         }
 107         /* $GIT_RSH <host> "env GIT_DIR=<path> <remote_prog> <args...>" */
 108         sizen = COMMAND_SIZE;
 109         posn = command;
 110         of = 0;
 111         of |= add_to_string(&posn, &sizen, "env ", 0);
 112         of |= add_to_string(&posn, &sizen, GIT_DIR_ENVIRONMENT, 0);
 113         of |= add_to_string(&posn, &sizen, "=", 0);
 114         of |= add_to_string(&posn, &sizen, path, 1);
 115         of |= add_to_string(&posn, &sizen, " ", 0);
 116         of |= add_to_string(&posn, &sizen, remote_prog, 1);
 117
 118         for ( i = 0 ; i < rmt_argc ; i++ ) {
 119                 of |= add_to_string(&posn, &sizen, " ", 0);
 120                 of |= add_to_string(&posn, &sizen, rmt_argv[i], 1);
 121         }
 122
 123         of |= add_to_string(&posn, &sizen, " -", 0);
 124
 125         if ( of )
 126                 return error("Command line too long");
 127
 128         if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv))
 129                 return error("Couldn't create socket");
 130
 131         if (!fork()) {
 132                 const char *ssh, *ssh_basename;
 133                 ssh = getenv("GIT_SSH");
 134                 if (!ssh) ssh = "ssh";
 135                 ssh_basename = strrchr(ssh, '/');
 136                 if (!ssh_basename)
 137                         ssh_basename = ssh;
 138                 else
 139                         ssh_basename++;
 140                 close(sv[1]);
 141                 dup2(sv[0], 0);
 142                 dup2(sv[0], 1);
 143                 execlp(ssh, ssh_basename, host, command, NULL);
 144         }
 145         close(sv[0]);
 146         *fd_in = sv[1];
 147         *fd_out = sv[1];
 148         return 0;
 149 }