[PATCHv4 0/3] Updated patch series for providing mechanism to list available repositories

[PATCHv4 0/3] Updated patch series for providing mechanism to list available repositories

[Greg Brockman]

This revised patch series should address all comments given thus far.
The specific changes made between v3 and v4 are documented in the
patch emails.

Thanks,

Greg

[PATCHv4 1/3] Allow creation of arbitrary git-shell commands

[Greg Brockman]

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>
---
 shell.c |   43 +++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 41 insertions(+), 2 deletions(-)

This patch differs from its v3 version by the addition of a 'cd_to_homedir' method
and a call to it prior to running any commands in git-shell-commands.  This ensures
that all commands are run out of $HOME/git-shell-commands.

diff --git a/shell.c b/shell.c
index e4864e0..88b29aa 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 +35,28 @@ 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) {
+	struct passwd *pw = getpwuid(geteuid());
+	if (pw == NULL)
+		die("could not retrieve user's passwd entry");
+	if (chdir(pw->pw_dir) == -1)
+		die("could not chdir to user's home directory");
+}
 
 static struct commands {
 	const char *name;
@@ -48,6 +72,7 @@ static struct commands {
 int main(int argc, char **argv)
 {
 	char *prog;
+	const char **user_argv;
 	struct commands *cmd;
 	int devnull_fd;
 
@@ -76,7 +101,7 @@ 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 +124,19 @@ 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]);
+	}
 }
-- 
1.7.0.4

Re: [PATCHv4 1/3] Allow creation of arbitrary git-shell commands

[Greg Brockman]

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>
---
 shell.c |   44 ++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 42 insertions(+), 2 deletions(-)

As discussed on-list, it should be fine to trust the value of HOME.
This patch differs from the previous only in the implementation of
cd_to_homedir.

diff --git a/shell.c b/shell.c
index e4864e0..1e6077d 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)
+{
+	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]);
+	}
 }
-- 
1.7.0.4

Re: [PATCHv4 1/3] Allow creation of arbitrary git-shell commands

[Greg Brockman]

Err, actually it would probably be a good idea to
s/char *home = getenv("HOME");/const char *home = getenv("HOME");/

Greg



On Wed, Jul 28, 2010 at 5:31 PM, Greg Brockman <gdb@mit.edu> wrote:
> 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>
> ---
>  shell.c |   44 ++++++++++++++++++++++++++++++++++++++++++--
>  1 files changed, 42 insertions(+), 2 deletions(-)
>
> As discussed on-list, it should be fine to trust the value of HOME.
> This patch differs from the previous only in the implementation of
> cd_to_homedir.
>
> diff --git a/shell.c b/shell.c
> index e4864e0..1e6077d 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)
> +{
> +       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]);
> +       }
>  }
> --
> 1.7.0.4
>

[PATCHv4 2/3] Add interactive mode to git-shell for user-friendliness

[Greg Brockman]

Signed-off-by: Greg Brockman <gdb@mit.edu>
---
 shell.c |   76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 70 insertions(+), 6 deletions(-)

This patch differs from v3 by the addition of a 'cd_to_homedir' call prior to
spawning the shell.

diff --git a/shell.c b/shell.c
index 88b29aa..a40b839 100644
--- a/shell.c
+++ b/shell.c
@@ -2,8 +2,10 @@
 #include "quote.h"
 #include "exec_cmd.h"
 #include "strbuf.h"
+#include "run-command.h"
 
 #define COMMAND_DIR "git-shell-commands"
+#define HELP_COMMAND COMMAND_DIR "/help"
 
 static int do_generic_cmd(const char *me, char *arg)
 {
@@ -58,6 +60,56 @@ static void cd_to_homedir(void) {
 		die("could not chdir to user's home directory");
 }
 
+static void run_shell(void)
+{
+	int done = 0;
+	static const char *help_argv[] = { HELP_COMMAND, NULL };
+	/* Print help if enabled */
+	run_command_v_opt(help_argv, RUN_SILENT_EXEC_FAILURE);
+
+	do {
+		struct strbuf line = STRBUF_INIT;
+		const char *prog;
+		char *full_cmd;
+		char *rawargs;
+		const char **argv;
+		int code;
+
+		fprintf(stderr, "git> ");
+		if (strbuf_getline(&line, stdin, '\n') == EOF) {
+			fprintf(stderr, "\n");
+			strbuf_release(&line);
+			break;
+		}
+		strbuf_trim(&line);
+		rawargs = strbuf_detach(&line, NULL);
+		if (split_cmdline(rawargs, &argv) == -1) {
+			free(rawargs);
+			continue;
+		}
+
+		prog = argv[0];
+		if (!strcmp(prog, "")) {
+		} else if (!strcmp(prog, "quit") || !strcmp(prog, "logout") ||
+			   !strcmp(prog, "exit") || !strcmp(prog, "bye")) {
+			done = 1;
+		} else if (is_valid_cmd_name(prog)) {
+			full_cmd = make_cmd(prog);
+			argv[0] = full_cmd;
+			code = run_command_v_opt(argv, RUN_SILENT_EXEC_FAILURE);
+			if (code == -1 && errno == ENOENT) {
+				fprintf(stderr, "unrecognized command '%s'\n", prog);
+			}
+			free(full_cmd);
+		} else {
+			fprintf(stderr, "invalid command format '%s'\n", prog);
+		}
+
+		free(argv);
+		free(rawargs);
+	} while (!done);
+}
+
 static struct commands {
 	const char *name;
 	int (*exec)(const char *me, char *arg);
@@ -91,15 +143,27 @@ int main(int argc, char **argv)
 	/*
 	 * Special hack to pretend to be a CVS server
 	 */
-	if (argc == 2 && !strcmp(argv[1], "cvs server"))
+	if (argc == 2 && !strcmp(argv[1], "cvs server")) {
 		argv--;
-
+	}
 	/*
-	 * We do not accept anything but "-c" followed by "cmd arg",
-	 * where "cmd" is a very limited subset of git commands.
+	 * Allow the user to run an interactive shell
 	 */
-	else if (argc != 3 || strcmp(argv[1], "-c"))
-		die("What do you think I am? A shell?");
+	else if (argc == 1) {
+		cd_to_homedir();
+		if (access(COMMAND_DIR, R_OK | X_OK) == -1)
+			die("Sorry, the interactive git-shell is not enabled");
+		run_shell();
+		exit(0);
+	}
+	/*
+	 * We do not accept any other modes except "-c" followed by
+	 * "cmd arg", where "cmd" is a very limited subset of git
+	 * commands or a command in the COMMAND_DIR
+	 */
+	else if (argc != 3 || strcmp(argv[1], "-c")) {
+		die("Run with no arguments or with -c cmd");
+	}
 
 	prog = xstrdup(argv[2]);
 	if (!strncmp(prog, "git", 3) && isspace(prog[3]))
-- 
1.7.0.4

[PATCHv4 3/3] Add sample commands for git-shell

[Greg Brockman]

Provide a 'list' command to view available bare repositories ending in
.git and a 'help command to display usage.  Also add documentation in
a README

Signed-off-by: Greg Brockman <gdb@mit.edu>
---
 contrib/git-shell-commands/README |   18 ++++++++++++++++++
 contrib/git-shell-commands/help   |   16 ++++++++++++++++
 contrib/git-shell-commands/list   |   10 ++++++++++
 3 files changed, 44 insertions(+), 0 deletions(-)
 create mode 100644 contrib/git-shell-commands/README
 create mode 100755 contrib/git-shell-commands/help
 create mode 100755 contrib/git-shell-commands/list

This differs from v3 in that:

* the 'find' command in 'list' discards its stderr.  This is useful for
  avoiding noise from inaccessible directories or non-git repositories with
  name matching '*.git'.
* the README does not mention that commands will be run from $(pwd)/git-shell-commands,
  because they will now be run from $HOME/git-shell-commands.

diff --git a/contrib/git-shell-commands/README b/contrib/git-shell-commands/README
new file mode 100644
index 0000000..438463b
--- /dev/null
+++ b/contrib/git-shell-commands/README
@@ -0,0 +1,18 @@
+Sample programs callable through git-shell.  Place a directory named
+'git-shell-commands' in the home directory of a user whose shell is
+git-shell.  Then anyone logging in as that user will be able to run
+executables in the 'git-shell-commands' directory.
+
+Provided commands:
+
+help: Prints out the names of available commands.  When run
+interactively, git-shell will automatically run 'help' on startup,
+provided it exists.
+
+list: Displays any bare repository whose name ends with ".git" under
+user's home directory.  No other git repositories are visible,
+although they might be clonable through git-shell.  'list' is designed
+to minimize the number of calls to git that must be made in finding
+available repositories; if your setup has additional repositories that
+should be user-discoverable, you may wish to modify 'list'
+accordingly.
diff --git a/contrib/git-shell-commands/help b/contrib/git-shell-commands/help
new file mode 100755
index 0000000..a43fcd6
--- /dev/null
+++ b/contrib/git-shell-commands/help
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+if tty -s; then
+    echo "Run 'help' for help, or 'exit' to leave.  Available commands:"
+else
+    echo "Run 'help' for help.  Available commands:"
+fi
+
+cd "$(dirname "$0")"
+
+for cmd in *; do
+    case "$cmd" in
+	help) ;;
+	*) [ -f "$cmd" ] && [ -x "$cmd" ] && echo "$cmd" ;;
+    esac
+done
diff --git a/contrib/git-shell-commands/list b/contrib/git-shell-commands/list
new file mode 100755
index 0000000..ffc5ac4
--- /dev/null
+++ b/contrib/git-shell-commands/list
@@ -0,0 +1,10 @@
+#!/bin/sh
+
+print_if_bare_repo='
+       if "$(git --git-dir="$1" rev-parse --is-bare-repository)" = true
+       then
+               printf "%s\n" "${1#./}"
+       fi
+'
+
+find -type d -name "*.git" -exec sh -c "$print_if_bare_repo" -- \{} \; -prune 2>/dev/null
-- 
1.7.0.4

Re: [PATCHv4 0/3] Updated patch series for providing mechanism to list available repositories

[Junio C Hamano]

Greg Brockman <gdb@MIT.EDU> writes:

> This revised patch series should address all comments given thus far.
> The specific changes made between v3 and v4 are documented in the
> patch emails.

Thanks, all; will queue.