Commit 2dbc887e authored by Greg Brockman's avatar Greg Brockman Committed by Junio C Hamano

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: default avatarGreg Brockman <gdb@mit.edu>
Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
parent 64fdc08d
......@@ -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]);
}
}
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