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                 char *split_args;
  77                 const char **argv;
  78                 int code;
  79                 int count;
  80
  81                 fprintf(stderr, "git> ");
  82                 if (strbuf_getline(&line, stdin, '\n') == EOF) {
  83                         fprintf(stderr, "\n");
  84                         strbuf_release(&line);
  85                         break;
  86                 }
  87                 strbuf_trim(&line);
  88                 rawargs = strbuf_detach(&line, NULL);
  89                 split_args = xstrdup(rawargs);
  90                 count = split_cmdline(split_args, &argv);
  91                 if (count < 0) {
  92                         fprintf(stderr, "invalid command format '%s': %s\n", rawargs,
  93                                 split_cmdline_strerror(count));
  94                         free(split_args);
  95                         free(rawargs);
  96                         continue;
  97                 }
  98
  99                 prog = argv[0];
 100                 if (!strcmp(prog, "")) {
 101                 } else if (!strcmp(prog, "quit") || !strcmp(prog, "logout") ||
 102                            !strcmp(prog, "exit") || !strcmp(prog, "bye")) {
 103                         done = 1;
 104                 } else if (is_valid_cmd_name(prog)) {
 105                         full_cmd = make_cmd(prog);
 106                         argv[0] = full_cmd;
 107                         code = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE);
 108                         if (code == -1 && errno == ENOENT) {
 109                                 fprintf(stderr, "unrecognized command '%s'\n", prog);
 110                         }
 111                         free(full_cmd);
 112                 } else {
 113                         fprintf(stderr, "invalid command format '%s'\n", prog);
 114                 }
 115
 116                 free(argv);
 117                 free(rawargs);
 118         } while (!done);
 119 }
 120
 121 static struct commands {
 122         const char *name;
 123         int (*exec)(const char *me, char *arg);
 124 } cmd_list[] = {
 125         { "git-receive-pack", do_generic_cmd },
 126         { "git-upload-pack", do_generic_cmd },
 127         { "git-upload-archive", do_generic_cmd },
 128         { "cvs", do_cvs_cmd },
 129         { NULL },
 130 };
 131
 132 int main(int argc, char **argv)
 133 {
 134         char *prog;
 135         const char **user_argv;
 136         struct commands *cmd;
 137         int devnull_fd;
 138         int count;
 139
 140         /*
 141          * Always open file descriptors 0/1/2 to avoid clobbering files
 142          * in die().  It also avoids not messing up when the pipes are
 143          * dup'ed onto stdin/stdout/stderr in the child processes we spawn.
 144          */
 145         devnull_fd = open("/dev/null", O_RDWR);
 146         while (devnull_fd >= 0 && devnull_fd <= 2)
 147                 devnull_fd = dup(devnull_fd);
 148         if (devnull_fd == -1)
 149                 die_errno("opening /dev/null failed");
 150         close (devnull_fd);
 151
 152         /*
 153          * Special hack to pretend to be a CVS server
 154          */
 155         if (argc == 2 && !strcmp(argv[1], "cvs server")) {
 156                 argv--;
 157         } else if (argc == 1) {
 158                 /* Allow the user to run an interactive shell */
 159                 cd_to_homedir();
 160                 if (access(COMMAND_DIR, R_OK | X_OK) == -1) {
 161                         die("Interactive git shell is not enabled.\n"
 162                             "hint: ~/" COMMAND_DIR " should exist "
 163                             "and have read and execute access.");
 164                 }
 165                 run_shell();
 166                 exit(0);
 167         } else if (argc != 3 || strcmp(argv[1], "-c")) {
 168                 /*
 169                  * We do not accept any other modes except "-c" followed by
 170                  * "cmd arg", where "cmd" is a very limited subset of git
 171                  * commands or a command in the COMMAND_DIR
 172                  */
 173                 die("Run with no arguments or with -c cmd");
 174         }
 175
 176         prog = xstrdup(argv[2]);
 177         if (!strncmp(prog, "git", 3) && isspace(prog[3]))
 178                 /* Accept "git foo" as if the caller said "git-foo". */
 179                 prog[3] = '-';
 180
 181         for (cmd = cmd_list ; cmd->name ; cmd++) {
 182                 int len = strlen(cmd->name);
 183                 char *arg;
 184                 if (strncmp(cmd->name, prog, len))
 185                         continue;
 186                 arg = NULL;
 187                 switch (prog[len]) {
 188                 case '\0':
 189                         arg = NULL;
 190                         break;
 191                 case ' ':
 192                         arg = prog + len + 1;
 193                         break;
 194                 default:
 195                         continue;
 196                 }
 197                 exit(cmd->exec(cmd->name, arg));
 198         }
 199
 200         cd_to_homedir();
 201         count = split_cmdline(prog, &user_argv);
 202         if (count >= 0) {
 203                 if (is_valid_cmd_name(user_argv[0])) {
 204                         prog = make_cmd(user_argv[0]);
 205                         user_argv[0] = prog;
 206                         execv(user_argv[0], (char *const *) user_argv);
 207                 }
 208                 free(prog);
 209                 free(user_argv);
 210                 die("unrecognized command '%s'", argv[2]);
 211         } else {
 212                 free(prog);
 213                 die("invalid command format '%s': %s", argv[2],
 214                     split_cmdline_strerror(count));
 215         }
 216 }