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