shell.c

   1 #include "cache.h"
   2 #include "quote.h"
   3 #include "exec_cmd.h"
   4 #include "strbuf.h"
   5 #include "run-command.h"
   6
   7 #define COMMAND_DIR "git-shell-commands"
   8 #define HELP_COMMAND COMMAND_DIR "/help"
   9
  10 static int do_generic_cmd(const char *me, char *arg)
  11 {
  12         const char *my_argv[4];
  13
  14         setup_path();
  15         if (!arg || !(arg = sq_dequote(arg)))
  16                 die("bad argument");
  17         if (prefixcmp(me, "git-"))
  18                 die("bad command");
  19
  20         my_argv[0] = me + 4;
  21         my_argv[1] = arg;
  22         my_argv[2] = NULL;
  23
  24         return execv_git_cmd(my_argv);
  25 }
  26
  27 static int do_cvs_cmd(const char *me, char *arg)
  28 {
  29         const char *cvsserver_argv[3] = {
  30                 "cvsserver", "server", NULL
  31         };
  32
  33         if (!arg || strcmp(arg, "server"))
  34                 die("git-cvsserver only handles server: %s", arg);
  35
  36         setup_path();
  37         return execv_git_cmd(cvsserver_argv);
  38 }
  39
  40 static int is_valid_cmd_name(const char *cmd)
  41 {
  42         /* Test command contains no . or / characters */
  43         return cmd[strcspn(cmd, "./")] == '\0';
  44 }
  45
  46 static char *make_cmd(const char *prog)
  47 {
  48         char *prefix = xmalloc((strlen(prog) + strlen(COMMAND_DIR) + 2));
  49         strcpy(prefix, COMMAND_DIR);
  50         strcat(prefix, "/");
  51         strcat(prefix, prog);
  52         return prefix;
  53 }
  54
  55 static void cd_to_homedir(void)
  56 {
  57         const char *home = getenv("HOME");
  58         if (!home)
  59                 die("could not determine user's home directory; HOME is unset");
  60         if (chdir(home) == -1)
  61                 die("could not chdir to user's home directory");
  62 }
  63
  64 static void run_shell(void)
  65 {
  66         int done = 0;
  67         static const char *help_argv[] = { HELP_COMMAND, NULL };
  68         /* Print help if enabled */
  69         run_command_v_opt(help_argv, RUN_SILENT_EXEC_FAILURE);
  70
  71         do {
  72                 struct strbuf line = STRBUF_INIT;
  73                 const char *prog;
  74                 char *full_cmd;
  75                 char *rawargs;
  76                 const char **argv;
  77                 int code;
  78
  79                 fprintf(stderr, "git> ");
  80                 if (strbuf_getline(&line, stdin, '\n') == EOF) {
  81                         fprintf(stderr, "\n");
  82                         strbuf_release(&line);
  83                         break;
  84                 }
  85                 strbuf_trim(&line);
  86                 rawargs = strbuf_detach(&line, NULL);
  87                 if (split_cmdline(rawargs, &argv) == -1) {
  88                         free(rawargs);
  89                         continue;
  90                 }
  91
  92                 prog = argv[0];
  93                 if (!strcmp(prog, "")) {
  94                 } else if (!strcmp(prog, "quit") || !strcmp(prog, "logout") ||
  95                            !strcmp(prog, "exit") || !strcmp(prog, "bye")) {
  96                         done = 1;
  97                 } else if (is_valid_cmd_name(prog)) {
  98                         full_cmd = make_cmd(prog);
  99                         argv[0] = full_cmd;
 100                         code = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE);
 101                         if (code == -1 && errno == ENOENT) {
 102                                 fprintf(stderr, "unrecognized command '%s'\n", prog);
 103                         }
 104                         free(full_cmd);
 105                 } else {
 106                         fprintf(stderr, "invalid command format '%s'\n", prog);
 107                 }
 108
 109                 free(argv);
 110                 free(rawargs);
 111         } while (!done);
 112 }
 113
 114 static struct commands {
 115         const char *name;
 116         int (*exec)(const char *me, char *arg);
 117 } cmd_list[] = {
 118         { "git-receive-pack", do_generic_cmd },
 119         { "git-upload-pack", do_generic_cmd },
 120         { "git-upload-archive", do_generic_cmd },
 121         { "cvs", do_cvs_cmd },
 122         { NULL },
 123 };
 124
 125 int main(int argc, char **argv)
 126 {
 127         char *prog;
 128         const char **user_argv;
 129         struct commands *cmd;
 130         int devnull_fd;
 131
 132         /*
 133          * Always open file descriptors 0/1/2 to avoid clobbering files
 134          * in die().  It also avoids not messing up when the pipes are
 135          * dup'ed onto stdin/stdout/stderr in the child processes we spawn.
 136          */
 137         devnull_fd = open("/dev/null", O_RDWR);
 138         while (devnull_fd >= 0 && devnull_fd <= 2)
 139                 devnull_fd = dup(devnull_fd);
 140         if (devnull_fd == -1)
 141                 die_errno("opening /dev/null failed");
 142         close (devnull_fd);
 143
 144         /*
 145          * Special hack to pretend to be a CVS server
 146          */
 147         if (argc == 2 && !strcmp(argv[1], "cvs server")) {
 148                 argv--;
 149         } else if (argc == 1) {
 150                 /* Allow the user to run an interactive shell */
 151                 cd_to_homedir();
 152                 if (access(COMMAND_DIR, R_OK | X_OK) == -1) {
 153                         die("Interactive git shell is not enabled.\n"
 154                             "hint: ~/" COMMAND_DIR " should exist "
 155                             "and have read and execute access.");
 156                 }
 157                 run_shell();
 158                 exit(0);
 159         } else if (argc != 3 || strcmp(argv[1], "-c")) {
 160                 /*
 161                  * We do not accept any other modes except "-c" followed by
 162                  * "cmd arg", where "cmd" is a very limited subset of git
 163                  * commands or a command in the COMMAND_DIR
 164                  */
 165                 die("Run with no arguments or with -c cmd");
 166         }
 167
 168         prog = xstrdup(argv[2]);
 169         if (!strncmp(prog, "git", 3) && isspace(prog[3]))
 170                 /* Accept "git foo" as if the caller said "git-foo". */
 171                 prog[3] = '-';
 172
 173         for (cmd = cmd_list ; cmd->name ; cmd++) {
 174                 int len = strlen(cmd->name);
 175                 char *arg;
 176                 if (strncmp(cmd->name, prog, len))
 177                         continue;
 178                 arg = NULL;
 179                 switch (prog[len]) {
 180                 case '\0':
 181                         arg = NULL;
 182                         break;
 183                 case ' ':
 184                         arg = prog + len + 1;
 185                         break;
 186                 default:
 187                         continue;
 188                 }
 189                 exit(cmd->exec(cmd->name, arg));
 190         }
 191
 192         cd_to_homedir();
 193         if (split_cmdline(prog, &user_argv) != -1) {
 194                 if (is_valid_cmd_name(user_argv[0])) {
 195                         prog = make_cmd(user_argv[0]);
 196                         user_argv[0] = prog;
 197                         execv(user_argv[0], (char *const *) user_argv);
 198                 }
 199                 free(prog);
 200                 free(user_argv);
 201                 die("unrecognized command '%s'", argv[2]);
 202         } else {
 203                 free(prog);
 204                 die("invalid command format '%s'", argv[2]);
 205         }
 206 }