From 3797a0a7b7aa8d0abd1b7ff7b95a40a9739d9278 Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Tue, 5 Jan 2021 13:08:28 +0000 Subject: [PATCH] maintenance: use Windows scheduled tasks Git's background maintenance uses cron by default, but this is not available on Windows. Instead, integrate with Task Scheduler. Tasks can be scheduled using the 'schtasks' command. There are several command-line options that can allow for some advanced scheduling, but unfortunately these seem to all require authenticating using a password. Instead, use the "/xml" option to pass an XML file that contains the configuration for the necessary schedule. These XML files are based on some that I exported after constructing a schedule in the Task Scheduler GUI. These options only run background maintenance when the user is logged in, and more fields are populated with the current username and SID at run-time by 'schtasks'. Since the GIT_TEST_MAINT_SCHEDULER environment variable allows us to specify 'schtasks' as the scheduler, we can test the Windows-specific logic on other platforms. Thus, add a check that the XML file written by Git is valid when xmllint exists on the system. Since we use a temporary file for the XML files sent to 'schtasks', we prefix the random characters with the frequency so it is easier to examine the proper file during tests. Instead of an exact match on the 'args' file, we 'grep' for the arguments other than the filename. There is a deficiency in the current design. Windows has two kinds of applications: GUI applications that start by "winmain()" and console applications that start by "main()". Console applications are attached to a new Console window if they are not already associated with a GUI application. This means that every hour the scheudled task launches a command window for the scheduled tasks. Not only is this visually obtrusive, but it also takes focus from whatever else the user is doing! A simple fix would be to insert a GUI application that acts as a shim between the scheduled task and Git. This is currently possible in Git for Windows by setting the tag equal to C:\Program Files\Git\git-bash.exe with options "--hide --no-needs-console --command=cmd\git.exe" followed by the arguments currently used. Since git-bash.exe is not included in Windows builds of core Git, I chose to leave out this feature. My plan is to submit a small patch to Git for Windows that converts the use of git.exe with this use of git-bash.exe in the short term. In the long term, we can consider creating this GUI shim application within core Git, perhaps in contrib/. Co-authored-by: Eric Sunshine Signed-off-by: Eric Sunshine Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano --- Documentation/git-maintenance.txt | 22 +++++ builtin/gc.c | 168 +++++++++++++++++++++++++++++++++++++- t/t7900-maintenance.sh | 37 +++++++++ 3 files changed, 226 insertions(+), 1 deletion(-) diff --git a/Documentation/git-maintenance.txt b/Documentation/git-maintenance.txt index 5f8f63f098..6970f2b898 100644 --- a/Documentation/git-maintenance.txt +++ b/Documentation/git-maintenance.txt @@ -313,6 +313,28 @@ To create more advanced customizations to your background tasks, see launchctl.plist(5) for more information. +BACKGROUND MAINTENANCE ON WINDOWS SYSTEMS +----------------------------------------- + +Windows does not support `cron` and instead has its own system for +scheduling background tasks. The `git maintenance start` command uses +the `schtasks` command to submit tasks to this system. You can inspect +all background tasks using the Task Scheduler application. The tasks +added by Git have names of the form `Git Maintenance ()`. +The Task Scheduler GUI has ways to inspect these tasks, but you can also +export the tasks to XML files and view the details there. + +Note that since Git is a console application, these background tasks +create a console window visible to the current user. This can be changed +manually by selecting the "Run whether user is logged in or not" option +in Task Scheduler. This change requires a password input, which is why +`git maintenance start` does not select it by default. + +If you want to customize the background tasks, please rename the tasks +so future calls to `git maintenance (start|stop)` do not overwrite your +custom tasks. + + GIT --- Part of the linkgit:git[1] suite diff --git a/builtin/gc.c b/builtin/gc.c index 782769f243..fdc95d9e99 100644 --- a/builtin/gc.c +++ b/builtin/gc.c @@ -1589,7 +1589,7 @@ static int launchctl_schedule_plist(const char *exec_path, enum schedule_priorit die(_("failed to create directories for '%s'"), filename); plist = xfopen(filename, "w"); - preamble = "\n" + preamble = "\n" "\n" "" "\n" @@ -1671,6 +1671,168 @@ static int launchctl_update_schedule(int run_maintenance, int fd, const char *cm return launchctl_remove_plists(cmd); } +static char *schtasks_task_name(const char *frequency) +{ + struct strbuf label = STRBUF_INIT; + strbuf_addf(&label, "Git Maintenance (%s)", frequency); + return strbuf_detach(&label, NULL); +} + +static int schtasks_remove_task(enum schedule_priority schedule, const char *cmd) +{ + int result; + struct strvec args = STRVEC_INIT; + const char *frequency = get_frequency(schedule); + char *name = schtasks_task_name(frequency); + + strvec_split(&args, cmd); + strvec_pushl(&args, "/delete", "/tn", name, "/f", NULL); + + result = run_command_v_opt(args.v, 0); + + strvec_clear(&args); + free(name); + return result; +} + +static int schtasks_remove_tasks(const char *cmd) +{ + return schtasks_remove_task(SCHEDULE_HOURLY, cmd) || + schtasks_remove_task(SCHEDULE_DAILY, cmd) || + schtasks_remove_task(SCHEDULE_WEEKLY, cmd); +} + +static int schtasks_schedule_task(const char *exec_path, enum schedule_priority schedule, const char *cmd) +{ + int result; + struct child_process child = CHILD_PROCESS_INIT; + const char *xml; + struct tempfile *tfile; + const char *frequency = get_frequency(schedule); + char *name = schtasks_task_name(frequency); + struct strbuf tfilename = STRBUF_INIT; + + strbuf_addf(&tfilename, "%s/schedule_%s_XXXXXX", + get_git_common_dir(), frequency); + tfile = xmks_tempfile(tfilename.buf); + strbuf_release(&tfilename); + + if (!fdopen_tempfile(tfile, "w")) + die(_("failed to create temp xml file")); + + xml = "\n" + "\n" + "\n" + "\n"; + fputs(xml, tfile->fp); + + switch (schedule) { + case SCHEDULE_HOURLY: + fprintf(tfile->fp, + "2020-01-01T01:00:00\n" + "true\n" + "\n" + "1\n" + "\n" + "\n" + "PT1H\n" + "PT23H\n" + "false\n" + "\n"); + break; + + case SCHEDULE_DAILY: + fprintf(tfile->fp, + "2020-01-01T00:00:00\n" + "true\n" + "\n" + "\n" + "\n" + "\n" + "\n" + "\n" + "\n" + "\n" + "\n" + "1\n" + "\n"); + break; + + case SCHEDULE_WEEKLY: + fprintf(tfile->fp, + "2020-01-01T00:00:00\n" + "true\n" + "\n" + "\n" + "\n" + "\n" + "1\n" + "\n"); + break; + + default: + break; + } + + xml = "\n" + "\n" + "\n" + "\n" + "InteractiveToken\n" + "LeastPrivilege\n" + "\n" + "\n" + "\n" + "IgnoreNew\n" + "true\n" + "true\n" + "true\n" + "false\n" + "PT72H\n" + "7\n" + "\n" + "\n" + "\n" + "\"%s\\git.exe\"\n" + "--exec-path=\"%s\" for-each-repo --config=maintenance.repo maintenance run --schedule=%s\n" + "\n" + "\n" + "\n"; + fprintf(tfile->fp, xml, exec_path, exec_path, frequency); + strvec_split(&child.args, cmd); + strvec_pushl(&child.args, "/create", "/tn", name, "/f", "/xml", + get_tempfile_path(tfile), NULL); + close_tempfile_gently(tfile); + + child.no_stdout = 1; + child.no_stderr = 1; + + if (start_command(&child)) + die(_("failed to start schtasks")); + result = finish_command(&child); + + delete_tempfile(&tfile); + free(name); + return result; +} + +static int schtasks_schedule_tasks(const char *cmd) +{ + const char *exec_path = git_exec_path(); + + return schtasks_schedule_task(exec_path, SCHEDULE_HOURLY, cmd) || + schtasks_schedule_task(exec_path, SCHEDULE_DAILY, cmd) || + schtasks_schedule_task(exec_path, SCHEDULE_WEEKLY, cmd); +} + +static int schtasks_update_schedule(int run_maintenance, int fd, const char *cmd) +{ + if (run_maintenance) + return schtasks_schedule_tasks(cmd); + else + return schtasks_remove_tasks(cmd); +} + #define BEGIN_LINE "# BEGIN GIT MAINTENANCE SCHEDULE" #define END_LINE "# END GIT MAINTENANCE SCHEDULE" @@ -1761,6 +1923,8 @@ done_editing: #if defined(__APPLE__) static const char platform_scheduler[] = "launchctl"; +#elif defined(GIT_WINDOWS_NATIVE) +static const char platform_scheduler[] = "schtasks"; #else static const char platform_scheduler[] = "crontab"; #endif @@ -1789,6 +1953,8 @@ static int update_background_schedule(int enable) if (!strcmp(scheduler, "launchctl")) result = launchctl_update_schedule(enable, lk.tempfile->fd, cmd); + else if (!strcmp(scheduler, "schtasks")) + result = schtasks_update_schedule(enable, lk.tempfile->fd, cmd); else if (!strcmp(scheduler, "crontab")) result = crontab_update_schedule(enable, lk.tempfile->fd, cmd); else diff --git a/t/t7900-maintenance.sh b/t/t7900-maintenance.sh index adf24dee72..135505f619 100755 --- a/t/t7900-maintenance.sh +++ b/t/t7900-maintenance.sh @@ -454,6 +454,43 @@ test_expect_success 'start and stop macOS maintenance' ' test_line_count = 0 actual ' +test_expect_success 'start and stop Windows maintenance' ' + write_script print-args <<-\EOF && + echo $* >>args + while test $# -gt 0 + do + case "$1" in + /xml) shift; xmlfile=$1; break ;; + *) shift ;; + esac + done + test -z "$xmlfile" || cp "$xmlfile" "$xmlfile.xml" + EOF + + rm -f args && + GIT_TEST_MAINT_SCHEDULER="schtasks:./print-args" git maintenance start && + + # start registers the repo + git config --get --global maintenance.repo "$(pwd)" && + + for frequency in hourly daily weekly + do + grep "/create /tn Git Maintenance ($frequency) /f /xml" args && + file=$(ls .git/schedule_${frequency}*.xml) && + test_xmllint "$file" || return 1 + done && + + rm -f args && + GIT_TEST_MAINT_SCHEDULER="schtasks:./print-args" git maintenance stop && + + # stop does not unregister the repo + git config --get --global maintenance.repo "$(pwd)" && + + printf "/delete /tn Git Maintenance (%s) /f\n" \ + hourly daily weekly >expect && + test_cmp expect args +' + test_expect_success 'register preserves existing strategy' ' git config maintenance.strategy none && git maintenance register && -- 2.11.4.GIT