Allow creation of arbitrary git-shell commands
This provides a mechanism for the server to expose custom functionality to clients. My particular use case is that I would like a way of discovering all repositories available for cloning. A client that clones via git clone user@example.com can invoke a command by ssh user@example.com $command Signed-off-by: Greg Brockman <gdb@mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Greg Brockman committed
Jul 28, 2010 at 17:31 UTC
2dbc887eaa6fbd787edfc9472b86b0faeb54e2ae
1 file changed
+42
-2
shell.c
+42
-2
@@ -3,6 +3,8 @@
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#include "exec_cmd.h"
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#include "strbuf.h"
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+#define COMMAND_DIR "git-shell-commands"
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+
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static int do_generic_cmd(const char *me, char *arg)
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{
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const char *my_argv[4];
@@ -33,6 +35,29 @@ static int do_cvs_cmd(const char *me, char *arg)
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return execv_git_cmd(cvsserver_argv);
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}
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+static int is_valid_cmd_name(const char *cmd)
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+{
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+ /* Test command contains no . or / characters */
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+ return cmd[strcspn(cmd, "./")] == '\0';
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+}
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+
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+static char *make_cmd(const char *prog)
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+{
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+ char *prefix = xmalloc((strlen(prog) + strlen(COMMAND_DIR) + 2));
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+ strcpy(prefix, COMMAND_DIR);
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+ strcat(prefix, "/");
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+ strcat(prefix, prog);
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+ return prefix;
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+}
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+
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+static void cd_to_homedir(void)
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+{
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+ const char *home = getenv("HOME");
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+ if (!home)
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+ die("could not determine user's home directory; HOME is unset");
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+ if (chdir(home) == -1)
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+ die("could not chdir to user's home directory");
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+}
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static struct commands {
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const char *name;
@@ -48,6 +73,7 @@ static struct commands {
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int main(int argc, char **argv)
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{
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char *prog;
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+ const char **user_argv;
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struct commands *cmd;
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int devnull_fd;
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@@ -76,7 +102,7 @@ int main(int argc, char **argv)
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else if (argc != 3 || strcmp(argv[1], "-c"))
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die("What do you think I am? A shell?");
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- prog = argv[2];
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+ prog = xstrdup(argv[2]);
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if (!strncmp(prog, "git", 3) && isspace(prog[3]))
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/* Accept "git foo" as if the caller said "git-foo". */
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prog[3] = '-';
@@ -99,5 +125,19 @@ int main(int argc, char **argv)
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}
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exit(cmd->exec(cmd->name, arg));
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}
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- die("unrecognized command '%s'", prog);
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+
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+ cd_to_homedir();
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+ if (split_cmdline(prog, &user_argv) != -1) {
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+ if (is_valid_cmd_name(user_argv[0])) {
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+ prog = make_cmd(user_argv[0]);
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+ user_argv[0] = prog;
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+ execv(user_argv[0], (char *const *) user_argv);
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+ }
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+ free(prog);
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+ free(user_argv);
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+ die("unrecognized command '%s'", argv[2]);
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+ } else {
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+ free(prog);
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+ die("invalid command format '%s'", argv[2]);
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+ }
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}