From patchwork Thu Oct 21 14:24:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Hostetler X-Patchwork-Id: 12575217 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DCD5DC433FE for ; Thu, 21 Oct 2021 14:25:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C53FD6120F for ; Thu, 21 Oct 2021 14:25:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231739AbhJUO2D (ORCPT ); Thu, 21 Oct 2021 10:28:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231282AbhJUO1l (ORCPT ); Thu, 21 Oct 2021 10:27:41 -0400 Received: from mail-wm1-x336.google.com (mail-wm1-x336.google.com [IPv6:2a00:1450:4864:20::336]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD6FDC0613B9 for ; Thu, 21 Oct 2021 07:25:21 -0700 (PDT) Received: by mail-wm1-x336.google.com with SMTP id g39so884580wmp.3 for ; Thu, 21 Oct 2021 07:25:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=oerTFL3ZpA9bnr7l1TxJfDSKtRrWUGz63Bx3wNffIeA=; b=mXgx825aHy9Vh//WJKC4Cj3nEIjhoTiAcZDNVw5WsWF5UrCoby5B7FPrgOLJUf5CwG q0HG7yxi/V1W+gteIS3KuW5VhDFICSlpwfDJ30tJ3FfmN+h72piFNw3JBVwT3nSEx8ox XdAbYiEjuxnED7/oV9iDE+b64C6c4Oo3DCV/z8YkX504LNbAZVT4oCRSOsKJfS+n4MBI bW0useHRMQYWugYUc+zCN0YI+u8/Ntfld+uvqBkDTt/1RSbpPTK8yuMQdmGHpb9pPpLB UyYLHAvTjAZUHewkX8T+Hop/mqfhKwaLyT2Vpbw0xVjeJPnO6wjMhqLPKxSLpa9LjHVg vs4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=oerTFL3ZpA9bnr7l1TxJfDSKtRrWUGz63Bx3wNffIeA=; b=YfliWm86HMZVXzY8KTDzggIyyz+bTKBmVe/i3Wdp7KjQpWFgsHUnXZn0ebER1BX8/P HoWfks+LeOQtKnNSA0k8apoqhkN6zrb8g3ns8AWHwojXCyzzYNZ6pz+cJ+lSS/312eb8 d7GxIm5xrw3M//zH2kjZqacVS6rrn7eK9XJCKjJ8SMYr3qN15sGb6yWk+eiSowdPVJu9 XG9XrBhlDnW//xSizoWOFnKc8ppnAgNwAOuURf50irtJs8MYZvl9tXWxSmHbdoZxR/XY rCX6dLD+MYyl/dMEAZKJk0JZP6RURd7JFclrRaaTo5KkpS15ovZlS1Esxt9MKibxVUUL YmDw== X-Gm-Message-State: AOAM530RI4CTSTESa6KSkKsbZSjmsCBSLuFH9nG45Uh+UX+2dMM6XX0/ 9UElM/UPXU9QMPszxSc7QRzjc16rFbI= X-Google-Smtp-Source: ABdhPJx76M+aHplAJUSW5a9mXX/omaKen8PRQiwOqjPMJp/6Fz3bQZ/t9EVO8S076y8Dhw48rJQxDQ== X-Received: by 2002:a7b:ce1a:: with SMTP id m26mr4485562wmc.187.1634826320271; Thu, 21 Oct 2021 07:25:20 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id u10sm6185921wrs.5.2021.10.21.07.25.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Oct 2021 07:25:20 -0700 (PDT) Message-Id: In-Reply-To: References: Date: Thu, 21 Oct 2021 14:24:55 +0000 Subject: [PATCH v4 15/29] compat/fsmonitor/fsm-listen-win32: implement FSMonitor backend on Windows Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Jeff Hostetler , Jeff Hostetler , Jeff Hostetler Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Jeff Hostetler From: Jeff Hostetler Teach the win32 backend to register a watch on the working tree root directory (recursively). Also watch the if it is not inside the working tree. And to collect path change notifications into batches and publish. Signed-off-by: Jeff Hostetler --- compat/fsmonitor/fsm-listen-win32.c | 565 ++++++++++++++++++++++++++++ 1 file changed, 565 insertions(+) diff --git a/compat/fsmonitor/fsm-listen-win32.c b/compat/fsmonitor/fsm-listen-win32.c index 916cbea254f..c2d11acbc1e 100644 --- a/compat/fsmonitor/fsm-listen-win32.c +++ b/compat/fsmonitor/fsm-listen-win32.c @@ -2,20 +2,585 @@ #include "config.h" #include "fsmonitor.h" #include "fsm-listen.h" +#include "fsmonitor--daemon.h" + +/* + * The documentation of ReadDirectoryChangesW() states that the maximum + * buffer size is 64K when the monitored directory is remote. + * + * Larger buffers may be used when the monitored directory is local and + * will help us receive events faster from the kernel and avoid dropped + * events. + * + * So we try to use a very large buffer and silently fallback to 64K if + * we get an error. + */ +#define MAX_RDCW_BUF_FALLBACK (65536) +#define MAX_RDCW_BUF (65536 * 8) + +struct one_watch +{ + char buffer[MAX_RDCW_BUF]; + DWORD buf_len; + DWORD count; + + struct strbuf path; + HANDLE hDir; + HANDLE hEvent; + OVERLAPPED overlapped; + + /* + * Is there an active ReadDirectoryChangesW() call pending. If so, we + * need to later call GetOverlappedResult() and possibly CancelIoEx(). + */ + BOOL is_active; +}; + +struct fsmonitor_daemon_backend_data +{ + struct one_watch *watch_worktree; + struct one_watch *watch_gitdir; + + HANDLE hEventShutdown; + + HANDLE hListener[3]; /* we don't own these handles */ +#define LISTENER_SHUTDOWN 0 +#define LISTENER_HAVE_DATA_WORKTREE 1 +#define LISTENER_HAVE_DATA_GITDIR 2 + int nr_listener_handles; +}; + +/* + * Convert the WCHAR path from the notification into UTF8 and + * then normalize it. + */ +static int normalize_path_in_utf8(FILE_NOTIFY_INFORMATION *info, + struct strbuf *normalized_path) +{ + int reserve; + int len = 0; + + strbuf_reset(normalized_path); + if (!info->FileNameLength) + goto normalize; + + /* + * Pre-reserve enough space in the UTF8 buffer for + * each Unicode WCHAR character to be mapped into a + * sequence of 2 UTF8 characters. That should let us + * avoid ERROR_INSUFFICIENT_BUFFER 99.9+% of the time. + */ + reserve = info->FileNameLength + 1; + strbuf_grow(normalized_path, reserve); + + for (;;) { + len = WideCharToMultiByte(CP_UTF8, 0, info->FileName, + info->FileNameLength / sizeof(WCHAR), + normalized_path->buf, + strbuf_avail(normalized_path) - 1, + NULL, NULL); + if (len > 0) + goto normalize; + if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) { + error("[GLE %ld] could not convert path to UTF-8: '%.*ls'", + GetLastError(), + (int)(info->FileNameLength / sizeof(WCHAR)), + info->FileName); + return -1; + } + + strbuf_grow(normalized_path, + strbuf_avail(normalized_path) + reserve); + } + +normalize: + strbuf_setlen(normalized_path, len); + return strbuf_normalize_path(normalized_path); +} void fsm_listen__stop_async(struct fsmonitor_daemon_state *state) { + SetEvent(state->backend_data->hListener[LISTENER_SHUTDOWN]); +} + +static struct one_watch *create_watch(struct fsmonitor_daemon_state *state, + const char *path) +{ + struct one_watch *watch = NULL; + DWORD desired_access = FILE_LIST_DIRECTORY; + DWORD share_mode = + FILE_SHARE_WRITE | FILE_SHARE_READ | FILE_SHARE_DELETE; + HANDLE hDir; + wchar_t wpath[MAX_PATH]; + + if (xutftowcs_path(wpath, path) < 0) { + error(_("could not convert to wide characters: '%s'"), path); + return NULL; + } + + hDir = CreateFileW(wpath, + desired_access, share_mode, NULL, OPEN_EXISTING, + FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED, + NULL); + if (hDir == INVALID_HANDLE_VALUE) { + error(_("[GLE %ld] could not watch '%s'"), + GetLastError(), path); + return NULL; + } + + CALLOC_ARRAY(watch, 1); + + watch->buf_len = sizeof(watch->buffer); /* assume full MAX_RDCW_BUF */ + + strbuf_init(&watch->path, 0); + strbuf_addstr(&watch->path, path); + + watch->hDir = hDir; + watch->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL); + + return watch; +} + +static void destroy_watch(struct one_watch *watch) +{ + if (!watch) + return; + + strbuf_release(&watch->path); + if (watch->hDir != INVALID_HANDLE_VALUE) + CloseHandle(watch->hDir); + if (watch->hEvent != INVALID_HANDLE_VALUE) + CloseHandle(watch->hEvent); + + free(watch); +} + +static int start_rdcw_watch(struct fsmonitor_daemon_backend_data *data, + struct one_watch *watch) +{ + DWORD dwNotifyFilter = + FILE_NOTIFY_CHANGE_FILE_NAME | + FILE_NOTIFY_CHANGE_DIR_NAME | + FILE_NOTIFY_CHANGE_ATTRIBUTES | + FILE_NOTIFY_CHANGE_SIZE | + FILE_NOTIFY_CHANGE_LAST_WRITE | + FILE_NOTIFY_CHANGE_CREATION; + + ResetEvent(watch->hEvent); + + memset(&watch->overlapped, 0, sizeof(watch->overlapped)); + watch->overlapped.hEvent = watch->hEvent; + + /* + * Queue an async call using Overlapped IO. This returns immediately. + * Our event handle will be signalled when the real result is available. + * + * The return value here just means that we successfully queued it. + * We won't know if the Read...() actually produces data until later. + */ + watch->is_active = ReadDirectoryChangesW( + watch->hDir, watch->buffer, watch->buf_len, TRUE, + dwNotifyFilter, &watch->count, &watch->overlapped, NULL); + + if (watch->is_active) + return 0; + + error("ReadDirectoryChangedW failed on '%s' [GLE %ld]", + watch->path.buf, GetLastError()); + return -1; +} + +static int recv_rdcw_watch(struct one_watch *watch) +{ + DWORD gle; + + watch->is_active = FALSE; + + /* + * The overlapped result is ready. If the Read...() was successful + * we finally receive the actual result into our buffer. + */ + if (GetOverlappedResult(watch->hDir, &watch->overlapped, &watch->count, + TRUE)) + return 0; + + gle = GetLastError(); + if (gle == ERROR_INVALID_PARAMETER && + /* + * The kernel throws an invalid parameter error when our + * buffer is too big and we are pointed at a remote + * directory (and possibly for other reasons). Quietly + * set it down and try again. + * + * See note about MAX_RDCW_BUF at the top. + */ + watch->buf_len > MAX_RDCW_BUF_FALLBACK) { + watch->buf_len = MAX_RDCW_BUF_FALLBACK; + return -2; + } + + /* + * NEEDSWORK: If an external is deleted, the above + * returns an error. I'm not sure that there's anything that + * we can do here other than failing -- the /.git + * link file would be broken anyway. We might try to check + * for that and return a better error message, but I'm not + * sure it is worth it. + */ + + error("GetOverlappedResult failed on '%s' [GLE %ld]", + watch->path.buf, gle); + return -1; +} + +static void cancel_rdcw_watch(struct one_watch *watch) +{ + DWORD count; + + if (!watch || !watch->is_active) + return; + + /* + * The calls to ReadDirectoryChangesW() and GetOverlappedResult() + * form a "pair" (my term) where we queue an IO and promise to + * hang around and wait for the kernel to give us the result. + * + * If for some reason after we queue the IO, we have to quit + * or otherwise not stick around for the second half, we must + * tell the kernel to abort the IO. This prevents the kernel + * from writing to our buffer and/or signalling our event + * after we free them. + * + * (Ask me how much fun it was to track that one down). + */ + CancelIoEx(watch->hDir, &watch->overlapped); + GetOverlappedResult(watch->hDir, &watch->overlapped, &count, TRUE); + watch->is_active = FALSE; +} + +/* + * Process filesystem events that happen anywhere (recursively) under the + * root directory. For a normal working directory, this includes + * both version controlled files and the contents of the .git/ directory. + * + * If /.git is a file, then we only see events for the file + * itself. + */ +static int process_worktree_events(struct fsmonitor_daemon_state *state) +{ + struct fsmonitor_daemon_backend_data *data = state->backend_data; + struct one_watch *watch = data->watch_worktree; + struct strbuf path = STRBUF_INIT; + struct string_list cookie_list = STRING_LIST_INIT_DUP; + struct fsmonitor_batch *batch = NULL; + const char *p = watch->buffer; + + /* + * If the kernel gets more events than will fit in the kernel + * buffer associated with our RDCW handle, it drops them and + * returns a count of zero. + * + * Yes, the call returns WITHOUT error and with length zero. + * This is the documented behavior. (My testing has confirmed + * that it also sets the last error to ERROR_NOTIFY_ENUM_DIR, + * but we do not rely on that since the function did not + * return an error and it is not documented.) + * + * (The "overflow" case is not ambiguous with the "no data" case + * because we did an INFINITE wait.) + * + * This means we have a gap in coverage. Tell the daemon layer + * to resync. + */ + if (!watch->count) { + trace2_data_string("fsmonitor", NULL, "fsm-listen/kernel", + "overflow"); + fsmonitor_force_resync(state); + return LISTENER_HAVE_DATA_WORKTREE; + } + + /* + * On Windows, `info` contains an "array" of paths that are + * relative to the root of whichever directory handle received + * the event. + */ + for (;;) { + FILE_NOTIFY_INFORMATION *info = (void *)p; + const char *slash; + enum fsmonitor_path_type t; + + strbuf_reset(&path); + if (normalize_path_in_utf8(info, &path) == -1) + goto skip_this_path; + + t = fsmonitor_classify_path_workdir_relative(path.buf); + + switch (t) { + case IS_INSIDE_DOT_GIT_WITH_COOKIE_PREFIX: + /* special case cookie files within .git */ + + /* Use just the filename of the cookie file. */ + slash = find_last_dir_sep(path.buf); + string_list_append(&cookie_list, + slash ? slash + 1 : path.buf); + break; + + case IS_INSIDE_DOT_GIT: + /* ignore everything inside of "/.git/" */ + break; + + case IS_DOT_GIT: + /* "/.git" was deleted (or renamed away) */ + if ((info->Action == FILE_ACTION_REMOVED) || + (info->Action == FILE_ACTION_RENAMED_OLD_NAME)) { + trace2_data_string("fsmonitor", NULL, + "fsm-listen/dotgit", + "removed"); + goto force_shutdown; + } + break; + + case IS_WORKDIR_PATH: + /* queue normal pathname */ + if (!batch) + batch = fsmonitor_batch__new(); + fsmonitor_batch__add_path(batch, path.buf); + break; + + case IS_GITDIR: + case IS_INSIDE_GITDIR: + case IS_INSIDE_GITDIR_WITH_COOKIE_PREFIX: + default: + BUG("unexpected path classification '%d' for '%s'", + t, path.buf); + } + +skip_this_path: + if (!info->NextEntryOffset) + break; + p += info->NextEntryOffset; + } + + fsmonitor_publish(state, batch, &cookie_list); + batch = NULL; + string_list_clear(&cookie_list, 0); + strbuf_release(&path); + return LISTENER_HAVE_DATA_WORKTREE; + +force_shutdown: + fsmonitor_batch__free_list(batch); + string_list_clear(&cookie_list, 0); + strbuf_release(&path); + return LISTENER_SHUTDOWN; +} + +/* + * Process filesystem events that happened anywhere (recursively) under the + * external (such as non-primary worktrees or submodules). + * We only care about cookie files that our client threads created here. + * + * Note that we DO NOT get filesystem events on the external + * itself (it is not inside something that we are watching). In particular, + * we do not get an event if the external is deleted. + */ +static int process_gitdir_events(struct fsmonitor_daemon_state *state) +{ + struct fsmonitor_daemon_backend_data *data = state->backend_data; + struct one_watch *watch = data->watch_gitdir; + struct strbuf path = STRBUF_INIT; + struct string_list cookie_list = STRING_LIST_INIT_DUP; + const char *p = watch->buffer; + + if (!watch->count) { + trace2_data_string("fsmonitor", NULL, "fsm-listen/kernel", + "overflow"); + fsmonitor_force_resync(state); + return LISTENER_HAVE_DATA_GITDIR; + } + + for (;;) { + FILE_NOTIFY_INFORMATION *info = (void *)p; + const char *slash; + enum fsmonitor_path_type t; + + strbuf_reset(&path); + if (normalize_path_in_utf8(info, &path) == -1) + goto skip_this_path; + + t = fsmonitor_classify_path_gitdir_relative(path.buf); + + switch (t) { + case IS_INSIDE_GITDIR_WITH_COOKIE_PREFIX: + /* special case cookie files within gitdir */ + + /* Use just the filename of the cookie file. */ + slash = find_last_dir_sep(path.buf); + string_list_append(&cookie_list, + slash ? slash + 1 : path.buf); + break; + + case IS_INSIDE_GITDIR: + goto skip_this_path; + + default: + BUG("unexpected path classification '%d' for '%s'", + t, path.buf); + } + +skip_this_path: + if (!info->NextEntryOffset) + break; + p += info->NextEntryOffset; + } + + fsmonitor_publish(state, NULL, &cookie_list); + string_list_clear(&cookie_list, 0); + strbuf_release(&path); + return LISTENER_HAVE_DATA_GITDIR; } void fsm_listen__loop(struct fsmonitor_daemon_state *state) { + struct fsmonitor_daemon_backend_data *data = state->backend_data; + DWORD dwWait; + int result; + + state->error_code = 0; + + if (start_rdcw_watch(data, data->watch_worktree) == -1) + goto force_error_stop; + + if (data->watch_gitdir && + start_rdcw_watch(data, data->watch_gitdir) == -1) + goto force_error_stop; + + for (;;) { + dwWait = WaitForMultipleObjects(data->nr_listener_handles, + data->hListener, + FALSE, INFINITE); + + if (dwWait == WAIT_OBJECT_0 + LISTENER_HAVE_DATA_WORKTREE) { + result = recv_rdcw_watch(data->watch_worktree); + if (result == -1) { + /* hard error */ + goto force_error_stop; + } + if (result == -2) { + /* retryable error */ + if (start_rdcw_watch(data, data->watch_worktree) == -1) + goto force_error_stop; + continue; + } + + /* have data */ + if (process_worktree_events(state) == LISTENER_SHUTDOWN) + goto force_shutdown; + if (start_rdcw_watch(data, data->watch_worktree) == -1) + goto force_error_stop; + continue; + } + + if (dwWait == WAIT_OBJECT_0 + LISTENER_HAVE_DATA_GITDIR) { + result = recv_rdcw_watch(data->watch_gitdir); + if (result == -1) { + /* hard error */ + goto force_error_stop; + } + if (result == -2) { + /* retryable error */ + if (start_rdcw_watch(data, data->watch_gitdir) == -1) + goto force_error_stop; + continue; + } + + /* have data */ + if (process_gitdir_events(state) == LISTENER_SHUTDOWN) + goto force_shutdown; + if (start_rdcw_watch(data, data->watch_gitdir) == -1) + goto force_error_stop; + continue; + } + + if (dwWait == WAIT_OBJECT_0 + LISTENER_SHUTDOWN) + goto clean_shutdown; + + error(_("could not read directory changes [GLE %ld]"), + GetLastError()); + goto force_error_stop; + } + +force_error_stop: + state->error_code = -1; + +force_shutdown: + /* + * Tell the IPC thead pool to stop (which completes the await + * in the main thread (which will also signal this thread (if + * we are still alive))). + */ + ipc_server_stop_async(state->ipc_server_data); + +clean_shutdown: + cancel_rdcw_watch(data->watch_worktree); + cancel_rdcw_watch(data->watch_gitdir); } int fsm_listen__ctor(struct fsmonitor_daemon_state *state) { + struct fsmonitor_daemon_backend_data *data; + + CALLOC_ARRAY(data, 1); + + data->hEventShutdown = CreateEvent(NULL, TRUE, FALSE, NULL); + + data->watch_worktree = create_watch(state, + state->path_worktree_watch.buf); + if (!data->watch_worktree) + goto failed; + + if (state->nr_paths_watching > 1) { + data->watch_gitdir = create_watch(state, + state->path_gitdir_watch.buf); + if (!data->watch_gitdir) + goto failed; + } + + data->hListener[LISTENER_SHUTDOWN] = data->hEventShutdown; + data->nr_listener_handles++; + + data->hListener[LISTENER_HAVE_DATA_WORKTREE] = + data->watch_worktree->hEvent; + data->nr_listener_handles++; + + if (data->watch_gitdir) { + data->hListener[LISTENER_HAVE_DATA_GITDIR] = + data->watch_gitdir->hEvent; + data->nr_listener_handles++; + } + + state->backend_data = data; + return 0; + +failed: + CloseHandle(data->hEventShutdown); + destroy_watch(data->watch_worktree); + destroy_watch(data->watch_gitdir); + return -1; } void fsm_listen__dtor(struct fsmonitor_daemon_state *state) { + struct fsmonitor_daemon_backend_data *data; + + if (!state || !state->backend_data) + return; + + data = state->backend_data; + + CloseHandle(data->hEventShutdown); + destroy_watch(data->watch_worktree); + destroy_watch(data->watch_gitdir); + + FREE_AND_NULL(state->backend_data); }