Add patatt install-hook subcommandv0.4.7

Make it easy to enable a repo for signing. Instead of reading the
manpage and finding the commands to add to the sendemail-validate hook,
add a subcommand that will do it for you.

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>

4 files changed, 55 insertions, 9 deletions

diff --git a/README.rst b/README.rst
index de299d1..7135b9f 100644
--- a/README.rst
+++ b/README.rst
@@ -182,7 +182,12 @@ You can now validate your own message::
 Automatic signing via the sendemail-validate hook
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 If everything is working well, you can start automatically signing all
-outgoing patches sent via git-send-email::
+outgoing patches sent via git-send-email. Inside the repo you want enabled
+for signing, run::
+
+    $ patatt install-hook
+
+Or you can do it manually::
 
     $ echo 'patatt sign --hook "${1}"' > "$(git rev-parse --git-dir)/hooks/sendemail-validate"
     $ chmod a+x "$(git rev-parse --git-dir)/hooks/sendemail-validate"
diff --git a/man/patatt.5 b/man/patatt.5
index 1e46a8a..841f670 100644
--- a/man/patatt.5
+++ b/man/patatt.5
@@ -1,6 +1,6 @@
 .\" Man page generated from reStructuredText.
 .
-.TH PATATT 5 "2021-05-21" "0.4.0" ""
+.TH PATATT 5 "2021-09-10" "0.4.7" ""
 .SH NAME
 PATATT \- DKIM-like cryptographic patch attestation
 .
@@ -32,7 +32,7 @@ level margin: \\n[rst2man-indent\\n[rst2man-indent-level]]
 ..
 .SH SYNOPSIS
 .sp
-patatt {sign,validate,genkey} [options]
+patatt {sign,validate,genkey,install\-hook} [options]
 .SH DESCRIPTION
 .sp
 This tools allows cryptographically signing patches sent via email
@@ -75,7 +75,20 @@ end.
 .SH USING AS A GIT HOOK
 .sp
 If you use \fBgit\-send\-email\fP for sending patches, then you can get
-them automatically signed via the \fBsendemail\-validate\fP hook:
+them automatically signed via the \fBsendemail\-validate\fP hook. To install,
+run the following command in the repository you want enabled for signing:
+.INDENT 0.0
+.INDENT 3.5
+.sp
+.nf
+.ft C
+$ patatt install\-hook
+.ft P
+.fi
+.UNINDENT
+.UNINDENT
+.sp
+Or you can install it manually:
 .INDENT 0.0
 .INDENT 3.5
 .sp
@@ -95,6 +108,8 @@ $ chmod a+x .git/hooks/sendemail\-validate
 \fIpatatt validate\fP: basic validation for signed messages
 .IP \(bu 2
 \fIpatatt genkey\fP: generate a new ed25519 keypair
+.IP \(bu 2
+\fIpatatt install\-hook\fP: install sendemail\-validate hook in the current repository
 .UNINDENT
 .sp
 You can run \fBpatatt [subcommand] \-\-help\fP to see a summary of flags for
diff --git a/man/patatt.5.rst b/man/patatt.5.rst
index 845595b..12bb0bd 100644
--- a/man/patatt.5.rst
+++ b/man/patatt.5.rst
@@ -5,15 +5,15 @@ DKIM-like cryptographic patch attestation
 -----------------------------------------
 
 :Author:    mricon@kernel.org
-:Date:      2021-05-21
+:Date:      2021-09-10
 :Copyright: The Linux Foundation and contributors
 :License:   MIT-0
-:Version:   0.4.0
+:Version:   0.4.7
 :Manual section: 5
 
 SYNOPSIS
 --------
-patatt {sign,validate,genkey} [options]
+patatt {sign,validate,genkey,install-hook} [options]
 
 DESCRIPTION
 -----------
@@ -42,7 +42,12 @@ end.
 USING AS A GIT HOOK
 -------------------
 If you use ``git-send-email`` for sending patches, then you can get
-them automatically signed via the ``sendemail-validate`` hook::
+them automatically signed via the ``sendemail-validate`` hook. To install,
+run the following command in the repository you want enabled for signing::
+
+    $ patatt install-hook
+
+Or you can install it manually::
 
     $ echo 'patatt sign --hook "${1}"' >> .git/hooks/sendemail-validate
     $ chmod a+x .git/hooks/sendemail-validate
@@ -52,6 +57,7 @@ SUBCOMMANDS
 * *patatt sign*: sign stdin or RFC2822 files passed as arguments
 * *patatt validate*: basic validation for signed messages
 * *patatt genkey*: generate a new ed25519 keypair
+* *patatt install-hook*: install sendemail-validate hook in the current repository
 
 You can run ``patatt [subcommand] --help`` to see a summary of flags for
 each subcommand.
diff --git a/patatt/__init__.py b/patatt/__init__.py
index 8f183d6..4262a4a 100644
--- a/patatt/__init__.py
+++ b/patatt/__init__.py
@@ -47,7 +47,7 @@ OPT_HDRS = [b'message-id']
 KEYCACHE = dict()
 
 # My version
-__VERSION__ = '0.4.6'
+__VERSION__ = '0.4.7'
 MAX_SUPPORTED_FORMAT_VERSION = 1
 
 
@@ -1115,6 +1115,23 @@ def cmd_genkey(cmdargs, config: dict) -> None:
     logger.critical(pkey)
 
 
+def cmd_install_hook(cmdargs, config: dict):  # noqa
+    gitrepo = get_git_toplevel()
+    if not gitrepo:
+        logger.critical('Not in a git tree, cannot install hook')
+        sys.exit(1)
+    hookfile = os.path.join(gitrepo, '.git', 'hooks', 'sendemail-validate')
+    if os.path.exists(hookfile):
+        logger.critical('Hook already exists: %s', hookfile)
+        sys.exit(1)
+    with open(hookfile, 'w') as fh:
+        fh.write('#!/bin/sh\n')
+        fh.write('# installed by patatt install-hook\n')
+        fh.write('patatt sign --hook "${1}"\n')
+        os.chmod(hookfile, 0o755)
+    logger.critical('Hook installed as %s', hookfile)
+
+
 def command() -> None:
     import argparse
     # noinspection PyTypeChecker
@@ -1150,6 +1167,9 @@ def command() -> None:
                         help='Overwrite any existing keys, if found')
     sp_gen.set_defaults(func=cmd_genkey)
 
+    sp_install = subparsers.add_parser('install-hook', help='Install sendmail-validate hook into the current repo')
+    sp_install.set_defaults(func=cmd_install_hook)
+
     _args = parser.parse_args()
 
     logger.setLevel(logging.DEBUG)