From 2dbc887eaa6fbd787edfc9472b86b0faeb54e2ae Mon Sep 17 00:00:00 2001 From: Greg Brockman Date: Wed, 28 Jul 2010 17:31:01 -0700 Subject: [PATCH] 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 Signed-off-by: Junio C Hamano --- shell.c | 44 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 42 insertions(+), 2 deletions(-) diff --git a/shell.c b/shell.c index e4864e04d..5b5e10501 100644 --- a/shell.c +++ b/shell.c @@ -3,6 +3,8 @@ #include "exec_cmd.h" #include "strbuf.h" +#define COMMAND_DIR "git-shell-commands" + static int do_generic_cmd(const char *me, char *arg) { const char *my_argv[4]; @@ -33,6 +35,29 @@ static int do_cvs_cmd(const char *me, char *arg) return execv_git_cmd(cvsserver_argv); } +static int is_valid_cmd_name(const char *cmd) +{ + /* Test command contains no . or / characters */ + return cmd[strcspn(cmd, "./")] == '\0'; +} + +static char *make_cmd(const char *prog) +{ + char *prefix = xmalloc((strlen(prog) + strlen(COMMAND_DIR) + 2)); + strcpy(prefix, COMMAND_DIR); + strcat(prefix, "/"); + strcat(prefix, prog); + return prefix; +} + +static void cd_to_homedir(void) +{ + const char *home = getenv("HOME"); + if (!home) + die("could not determine user's home directory; HOME is unset"); + if (chdir(home) == -1) + die("could not chdir to user's home directory"); +} static struct commands { const char *name; @@ -48,6 +73,7 @@ static struct commands { int main(int argc, char **argv) { char *prog; + const char **user_argv; struct commands *cmd; int devnull_fd; @@ -76,7 +102,7 @@ int main(int argc, char **argv) else if (argc != 3 || strcmp(argv[1], "-c")) die("What do you think I am? A shell?"); - prog = argv[2]; + prog = xstrdup(argv[2]); if (!strncmp(prog, "git", 3) && isspace(prog[3])) /* Accept "git foo" as if the caller said "git-foo". */ prog[3] = '-'; @@ -99,5 +125,19 @@ int main(int argc, char **argv) } exit(cmd->exec(cmd->name, arg)); } - die("unrecognized command '%s'", prog); + + cd_to_homedir(); + if (split_cmdline(prog, &user_argv) != -1) { + if (is_valid_cmd_name(user_argv[0])) { + prog = make_cmd(user_argv[0]); + user_argv[0] = prog; + execv(user_argv[0], (char *const *) user_argv); + } + free(prog); + free(user_argv); + die("unrecognized command '%s'", argv[2]); + } else { + free(prog); + die("invalid command format '%s'", argv[2]); + } } -- 2.26.2