mirror of
https://github.com/git/git.git
synced 2026-01-17 22:26:32 +00:00
2afe7e3567
The existing mechanism for scheduling background maintenance is done through cron. The 'crontab -e' command allows updating the schedule while cron itself runs those commands. While this is technically supported by macOS, it has some significant deficiencies: 1. Every run of 'crontab -e' must request elevated privileges through the user interface. When running 'git maintenance start' from the Terminal app, it presents a dialog box saying "Terminal.app would like to administer your computer. Administration can include modifying passwords, networking, and system settings." This is more alarming than what we are hoping to achieve. If this alert had some information about how "git" is trying to run "crontab" then we would have some reason to believe that this dialog might be fine. However, it also doesn't help that some scenarios just leave Git waiting for a response without presenting anything to the user. I experienced this when executing the command from a Bash terminal view inside Visual Studio Code. 2. While cron initializes a user environment enough for "git config --global --show-origin" to show the correct config file information, it does not set up the environment enough for Git Credential Manager Core to load credentials during a 'prefetch' task. My prefetches against private repositories required re-authenticating through UI pop-ups in a way that should not be required. The solution is to switch from cron to the Apple-recommended [1] 'launchd' tool. [1] https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/ScheduledJobs.html The basics of this tool is that we need to create XML-formatted "plist" files inside "~/Library/LaunchAgents/" and then use the 'launchctl' tool to make launchd aware of them. The plist files include all of the scheduling information, along with the command-line arguments split across an array of <string> tags. For example, here is my plist file for the weekly scheduled tasks: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"><dict> <key>Label</key><string>org.git-scm.git.weekly</string> <key>ProgramArguments</key> <array> <string>/usr/local/libexec/git-core/git</string> <string>--exec-path=/usr/local/libexec/git-core</string> <string>for-each-repo</string> <string>--config=maintenance.repo</string> <string>maintenance</string> <string>run</string> <string>--schedule=weekly</string> </array> <key>StartCalendarInterval</key> <array> <dict> <key>Day</key><integer>0</integer> <key>Hour</key><integer>0</integer> <key>Minute</key><integer>0</integer> </dict> </array> </dict> </plist> The schedules for the daily and hourly tasks are more complicated since we need to use an array for the StartCalendarInterval with an entry for each of the six days other than the 0th day (to avoid colliding with the weekly task), and each of the 23 hours other than the 0th hour (to avoid colliding with the daily task). The "Label" value is currently filled with "org.git-scm.git.X" where X is the frequency. We need a different plist file for each frequency. The launchctl command needs to be aligned with a user id in order to initialize the command environment. This must be done using the 'launchctl bootstrap' subcommand. This subcommand is new as of macOS 10.11, which was released in September 2015. Before that release the 'launchctl load' subcommand was recommended. The best source of information on this transition I have seen is available at [2]. The current design does not preclude a future version that detects the available fatures of 'launchctl' to use the older commands. However, it is best to rely on the newest version since Apple might completely remove the deprecated version on short notice. [2] https://babodee.wordpress.com/2016/04/09/launchctl-2-0-syntax/ To remove a schedule, we must run 'launchctl bootout' with a valid plist file. We also need to 'bootout' a task before the 'bootstrap' subcommand will succeed, if such a task already exists. The need for a user id requires us to run 'id -u' which works on POSIX systems but not Windows. Further, the need for fully-qualitifed path names including $HOME behaves differently in the Git internals and the external test suite. The $HOME variable starts with "C:\..." instead of the "/c/..." that is provided by Git in these subcommands. The test therefore has a prerequisite that we are not on Windows. The cross- platform logic still allows us to test the macOS logic on a Linux machine. We can verify the commands that were run by 'git maintenance start' and 'git maintenance stop' by injecting a script that writes the command-line arguments into GIT_TEST_MAINT_SCHEDULER. An earlier version of this patch accidentally had an opening "<dict>" tag when it should have had a closing "</dict>" tag. This was caught during manual testing with actual 'launchctl' commands, but we do not want to update developers' tasks when running tests. It appears that macOS includes the "xmllint" tool which can verify the XML format. This is useful for any system that might contain the tool, so use it whenever it is available. We strive to make these tests work on all platforms, but Windows caused some headaches. In particular, the value of getuid() called by the C code is not guaranteed to be the same as `$(id -u)` invoked by a test. This is because `git.exe` is a native Windows program, whereas the utility programs run by the test script mostly utilize the MSYS2 runtime, which emulates a POSIX-like environment. Since the purpose of the test is to check that the input to the hook is well-formed, the actual user ID is immaterial, thus we can work around the problem by making the the test UID-agnostic. Another subtle issue is the $HOME environment variable being a Windows-style path instead of a Unix-style path. We can be more flexible here instead of expecting exact path matches. Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Co-authored-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-<commandname>.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission). To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://lore.kernel.org/git/, http://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks