Adding upstream version 1:2.39.2.upstream/1%2.39.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 612 insertions, 0 deletions

diff --git a/fsmonitor.c b/fsmonitor.c
new file mode 100644
index 0000000..08af00c
--- /dev/null
+++ b/fsmonitor.c
@@ -0,0 +1,612 @@
+#include "cache.h"
+#include "config.h"
+#include "dir.h"
+#include "ewah/ewok.h"
+#include "fsmonitor.h"
+#include "fsmonitor-ipc.h"
+#include "run-command.h"
+#include "strbuf.h"
+
+#define INDEX_EXTENSION_VERSION1	(1)
+#define INDEX_EXTENSION_VERSION2	(2)
+#define HOOK_INTERFACE_VERSION1		(1)
+#define HOOK_INTERFACE_VERSION2		(2)
+
+struct trace_key trace_fsmonitor = TRACE_KEY_INIT(FSMONITOR);
+
+static void assert_index_minimum(struct index_state *istate, size_t pos)
+{
+	if (pos > istate->cache_nr)
+		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
+		    (uintmax_t)pos, istate->cache_nr);
+}
+
+static void fsmonitor_ewah_callback(size_t pos, void *is)
+{
+	struct index_state *istate = (struct index_state *)is;
+	struct cache_entry *ce;
+
+	assert_index_minimum(istate, pos + 1);
+
+	ce = istate->cache[pos];
+	ce->ce_flags &= ~CE_FSMONITOR_VALID;
+}
+
+static int fsmonitor_hook_version(void)
+{
+	int hook_version;
+
+	if (git_config_get_int("core.fsmonitorhookversion", &hook_version))
+		return -1;
+
+	if (hook_version == HOOK_INTERFACE_VERSION1 ||
+	    hook_version == HOOK_INTERFACE_VERSION2)
+		return hook_version;
+
+	warning("Invalid hook version '%i' in core.fsmonitorhookversion. "
+		"Must be 1 or 2.", hook_version);
+	return -1;
+}
+
+int read_fsmonitor_extension(struct index_state *istate, const void *data,
+	unsigned long sz)
+{
+	const char *index = data;
+	uint32_t hdr_version;
+	uint32_t ewah_size;
+	struct ewah_bitmap *fsmonitor_dirty;
+	int ret;
+	uint64_t timestamp;
+	struct strbuf last_update = STRBUF_INIT;
+
+	if (sz < sizeof(uint32_t) + 1 + sizeof(uint32_t))
+		return error("corrupt fsmonitor extension (too short)");
+
+	hdr_version = get_be32(index);
+	index += sizeof(uint32_t);
+	if (hdr_version == INDEX_EXTENSION_VERSION1) {
+		timestamp = get_be64(index);
+		strbuf_addf(&last_update, "%"PRIu64"", timestamp);
+		index += sizeof(uint64_t);
+	} else if (hdr_version == INDEX_EXTENSION_VERSION2) {
+		strbuf_addstr(&last_update, index);
+		index += last_update.len + 1;
+	} else {
+		return error("bad fsmonitor version %d", hdr_version);
+	}
+
+	istate->fsmonitor_last_update = strbuf_detach(&last_update, NULL);
+
+	ewah_size = get_be32(index);
+	index += sizeof(uint32_t);
+
+	fsmonitor_dirty = ewah_new();
+	ret = ewah_read_mmap(fsmonitor_dirty, index, ewah_size);
+	if (ret != ewah_size) {
+		ewah_free(fsmonitor_dirty);
+		return error("failed to parse ewah bitmap reading fsmonitor index extension");
+	}
+	istate->fsmonitor_dirty = fsmonitor_dirty;
+
+	if (!istate->split_index)
+		assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
+
+	trace2_data_string("index", NULL, "extension/fsmn/read/token",
+			   istate->fsmonitor_last_update);
+	trace_printf_key(&trace_fsmonitor,
+			 "read fsmonitor extension successful '%s'",
+			 istate->fsmonitor_last_update);
+	return 0;
+}
+
+void fill_fsmonitor_bitmap(struct index_state *istate)
+{
+	unsigned int i, skipped = 0;
+	istate->fsmonitor_dirty = ewah_new();
+	for (i = 0; i < istate->cache_nr; i++) {
+		if (istate->cache[i]->ce_flags & CE_REMOVE)
+			skipped++;
+		else if (!(istate->cache[i]->ce_flags & CE_FSMONITOR_VALID))
+			ewah_set(istate->fsmonitor_dirty, i - skipped);
+	}
+}
+
+void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
+{
+	uint32_t hdr_version;
+	uint32_t ewah_start;
+	uint32_t ewah_size = 0;
+	int fixup = 0;
+
+	if (!istate->split_index)
+		assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
+
+	put_be32(&hdr_version, INDEX_EXTENSION_VERSION2);
+	strbuf_add(sb, &hdr_version, sizeof(uint32_t));
+
+	strbuf_addstr(sb, istate->fsmonitor_last_update);
+	strbuf_addch(sb, 0); /* Want to keep a NUL */
+
+	fixup = sb->len;
+	strbuf_add(sb, &ewah_size, sizeof(uint32_t)); /* we'll fix this up later */
+
+	ewah_start = sb->len;
+	ewah_serialize_strbuf(istate->fsmonitor_dirty, sb);
+	ewah_free(istate->fsmonitor_dirty);
+	istate->fsmonitor_dirty = NULL;
+
+	/* fix up size field */
+	put_be32(&ewah_size, sb->len - ewah_start);
+	memcpy(sb->buf + fixup, &ewah_size, sizeof(uint32_t));
+
+	trace2_data_string("index", NULL, "extension/fsmn/write/token",
+			   istate->fsmonitor_last_update);
+	trace_printf_key(&trace_fsmonitor,
+			 "write fsmonitor extension successful '%s'",
+			 istate->fsmonitor_last_update);
+}
+
+/*
+ * Call the query-fsmonitor hook passing the last update token of the saved results.
+ */
+static int query_fsmonitor_hook(struct repository *r,
+				int version,
+				const char *last_update,
+				struct strbuf *query_result)
+{
+	struct child_process cp = CHILD_PROCESS_INIT;
+	int result;
+
+	if (fsm_settings__get_mode(r) != FSMONITOR_MODE_HOOK)
+		return -1;
+
+	strvec_push(&cp.args, fsm_settings__get_hook_path(r));
+	strvec_pushf(&cp.args, "%d", version);
+	strvec_pushf(&cp.args, "%s", last_update);
+	cp.use_shell = 1;
+	cp.dir = get_git_work_tree();
+
+	trace2_region_enter("fsm_hook", "query", NULL);
+
+	result = capture_command(&cp, query_result, 1024);
+
+	if (result)
+		trace2_data_intmax("fsm_hook", NULL, "query/failed", result);
+	else
+		trace2_data_intmax("fsm_hook", NULL, "query/response-length",
+				   query_result->len);
+
+	trace2_region_leave("fsm_hook", "query", NULL);
+
+	return result;
+}
+
+static void fsmonitor_refresh_callback(struct index_state *istate, char *name)
+{
+	int i, len = strlen(name);
+	int pos = index_name_pos(istate, name, len);
+
+	trace_printf_key(&trace_fsmonitor,
+			 "fsmonitor_refresh_callback '%s' (pos %d)",
+			 name, pos);
+
+	if (name[len - 1] == '/') {
+		/*
+		 * The daemon can decorate directory events, such as
+		 * moves or renames, with a trailing slash if the OS
+		 * FS Event contains sufficient information, such as
+		 * MacOS.
+		 *
+		 * Use this to invalidate the entire cone under that
+		 * directory.
+		 *
+		 * We do not expect an exact match because the index
+		 * does not normally contain directory entries, so we
+		 * start at the insertion point and scan.
+		 */
+		if (pos < 0)
+			pos = -pos - 1;
+
+		/* Mark all entries for the folder invalid */
+		for (i = pos; i < istate->cache_nr; i++) {
+			if (!starts_with(istate->cache[i]->name, name))
+				break;
+			istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
+		}
+
+		/*
+		 * We need to remove the traling "/" from the path
+		 * for the untracked cache.
+		 */
+		name[len - 1] = '\0';
+	} else if (pos >= 0) {
+		/*
+		 * We have an exact match for this path and can just
+		 * invalidate it.
+		 */
+		istate->cache[pos]->ce_flags &= ~CE_FSMONITOR_VALID;
+	} else {
+		/*
+		 * The path is not a tracked file -or- it is a
+		 * directory event on a platform that cannot
+		 * distinguish between file and directory events in
+		 * the event handler, such as Windows.
+		 *
+		 * Scan as if it is a directory and invalidate the
+		 * cone under it.  (But remember to ignore items
+		 * between "name" and "name/", such as "name-" and
+		 * "name.".
+		 */
+		pos = -pos - 1;
+
+		for (i = pos; i < istate->cache_nr; i++) {
+			if (!starts_with(istate->cache[i]->name, name))
+				break;
+			if ((unsigned char)istate->cache[i]->name[len] > '/')
+				break;
+			if (istate->cache[i]->name[len] == '/')
+				istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
+		}
+	}
+
+	/*
+	 * Mark the untracked cache dirty even if it wasn't found in the index
+	 * as it could be a new untracked file.
+	 */
+	untracked_cache_invalidate_path(istate, name, 0);
+}
+
+/*
+ * The number of pathnames that we need to receive from FSMonitor
+ * before we force the index to be updated.
+ *
+ * Note that any pathname within the set of received paths MAY cause
+ * cache-entry or istate flag bits to be updated and thus cause the
+ * index to be updated on disk.
+ *
+ * However, the response may contain many paths (such as ignored
+ * paths) that will not update any flag bits.  And thus not force the
+ * index to be updated.  (This is fine and normal.)  It also means
+ * that the token will not be updated in the FSMonitor index
+ * extension.  So the next Git command will find the same token in the
+ * index, make the same token-relative request, and receive the same
+ * response (plus any newly changed paths).  If this response is large
+ * (and continues to grow), performance could be impacted.
+ *
+ * For example, if the user runs a build and it writes 100K object
+ * files but doesn't modify any source files, the index would not need
+ * to be updated.  The FSMonitor response (after the build and
+ * relative to a pre-build token) might be 5MB.  Each subsequent Git
+ * command will receive that same 100K/5MB response until something
+ * causes the index to be updated.  And `refresh_fsmonitor()` will
+ * have to iterate over those 100K paths each time.
+ *
+ * Performance could be improved if we optionally force update the
+ * index after a very large response and get an updated token into
+ * the FSMonitor index extension.  This should allow subsequent
+ * commands to get smaller and more current responses.
+ *
+ * The value chosen here does not need to be precise.  The index
+ * will be updated automatically the first time the user touches
+ * a tracked file and causes a command like `git status` to
+ * update an mtime to be updated and/or set a flag bit.
+ */
+static int fsmonitor_force_update_threshold = 100;
+
+void refresh_fsmonitor(struct index_state *istate)
+{
+	static int warn_once = 0;
+	struct strbuf query_result = STRBUF_INIT;
+	int query_success = 0, hook_version = -1;
+	size_t bol = 0; /* beginning of line */
+	uint64_t last_update;
+	struct strbuf last_update_token = STRBUF_INIT;
+	char *buf;
+	unsigned int i;
+	int is_trivial = 0;
+	struct repository *r = istate->repo ? istate->repo : the_repository;
+	enum fsmonitor_mode fsm_mode = fsm_settings__get_mode(r);
+	enum fsmonitor_reason reason = fsm_settings__get_reason(r);
+
+	if (!warn_once && reason > FSMONITOR_REASON_OK) {
+		char *msg = fsm_settings__get_incompatible_msg(r, reason);
+		warn_once = 1;
+		warning("%s", msg);
+		free(msg);
+	}
+
+	if (fsm_mode <= FSMONITOR_MODE_DISABLED ||
+	    istate->fsmonitor_has_run_once)
+		return;
+
+	istate->fsmonitor_has_run_once = 1;
+
+	trace_printf_key(&trace_fsmonitor, "refresh fsmonitor");
+
+	if (fsm_mode == FSMONITOR_MODE_IPC) {
+		query_success = !fsmonitor_ipc__send_query(
+			istate->fsmonitor_last_update ?
+			istate->fsmonitor_last_update : "builtin:fake",
+			&query_result);
+		if (query_success) {
+			/*
+			 * The response contains a series of nul terminated
+			 * strings.  The first is the new token.
+			 *
+			 * Use `char *buf` as an interlude to trick the CI
+			 * static analysis to let us use `strbuf_addstr()`
+			 * here (and only copy the token) rather than
+			 * `strbuf_addbuf()`.
+			 */
+			buf = query_result.buf;
+			strbuf_addstr(&last_update_token, buf);
+			bol = last_update_token.len + 1;
+			is_trivial = query_result.buf[bol] == '/';
+			if (is_trivial)
+				trace2_data_intmax("fsm_client", NULL,
+						   "query/trivial-response", 1);
+		} else {
+			/*
+			 * The builtin daemon is not available on this
+			 * platform -OR- we failed to get a response.
+			 *
+			 * Generate a fake token (rather than a V1
+			 * timestamp) for the index extension.  (If
+			 * they switch back to the hook API, we don't
+			 * want ambiguous state.)
+			 */
+			strbuf_addstr(&last_update_token, "builtin:fake");
+		}
+
+		goto apply_results;
+	}
+
+	assert(fsm_mode == FSMONITOR_MODE_HOOK);
+
+	hook_version = fsmonitor_hook_version();
+
+	/*
+	 * This could be racy so save the date/time now and query_fsmonitor_hook
+	 * should be inclusive to ensure we don't miss potential changes.
+	 */
+	last_update = getnanotime();
+	if (hook_version == HOOK_INTERFACE_VERSION1)
+		strbuf_addf(&last_update_token, "%"PRIu64"", last_update);
+
+	/*
+	 * If we have a last update token, call query_fsmonitor_hook for the set of
+	 * changes since that token, else assume everything is possibly dirty
+	 * and check it all.
+	 */
+	if (istate->fsmonitor_last_update) {
+		if (hook_version == -1 || hook_version == HOOK_INTERFACE_VERSION2) {
+			query_success = !query_fsmonitor_hook(
+				r, HOOK_INTERFACE_VERSION2,
+				istate->fsmonitor_last_update, &query_result);
+
+			if (query_success) {
+				if (hook_version < 0)
+					hook_version = HOOK_INTERFACE_VERSION2;
+
+				/*
+				 * First entry will be the last update token
+				 * Need to use a char * variable because static
+				 * analysis was suggesting to use strbuf_addbuf
+				 * but we don't want to copy the entire strbuf
+				 * only the chars up to the first NUL
+				 */
+				buf = query_result.buf;
+				strbuf_addstr(&last_update_token, buf);
+				if (!last_update_token.len) {
+					warning("Empty last update token.");
+					query_success = 0;
+				} else {
+					bol = last_update_token.len + 1;
+					is_trivial = query_result.buf[bol] == '/';
+				}
+			} else if (hook_version < 0) {
+				hook_version = HOOK_INTERFACE_VERSION1;
+				if (!last_update_token.len)
+					strbuf_addf(&last_update_token, "%"PRIu64"", last_update);
+			}
+		}
+
+		if (hook_version == HOOK_INTERFACE_VERSION1) {
+			query_success = !query_fsmonitor_hook(
+				r, HOOK_INTERFACE_VERSION1,
+				istate->fsmonitor_last_update, &query_result);
+			if (query_success)
+				is_trivial = query_result.buf[0] == '/';
+		}
+
+		if (is_trivial)
+			trace2_data_intmax("fsm_hook", NULL,
+					   "query/trivial-response", 1);
+
+		trace_performance_since(last_update, "fsmonitor process '%s'",
+					fsm_settings__get_hook_path(r));
+		trace_printf_key(&trace_fsmonitor,
+				 "fsmonitor process '%s' returned %s",
+				 fsm_settings__get_hook_path(r),
+				 query_success ? "success" : "failure");
+	}
+
+apply_results:
+	/*
+	 * The response from FSMonitor (excluding the header token) is
+	 * either:
+	 *
+	 * [a] a (possibly empty) list of NUL delimited relative
+	 *     pathnames of changed paths.  This list can contain
+	 *     files and directories.  Directories have a trailing
+	 *     slash.
+	 *
+	 * [b] a single '/' to indicate the provider had no
+	 *     information and that we should consider everything
+	 *     invalid.  We call this a trivial response.
+	 */
+	trace2_region_enter("fsmonitor", "apply_results", istate->repo);
+
+	if (query_success && !is_trivial) {
+		/*
+		 * Mark all pathnames returned by the monitor as dirty.
+		 *
+		 * This updates both the cache-entries and the untracked-cache.
+		 */
+		int count = 0;
+
+		buf = query_result.buf;
+		for (i = bol; i < query_result.len; i++) {
+			if (buf[i] != '\0')
+				continue;
+			fsmonitor_refresh_callback(istate, buf + bol);
+			bol = i + 1;
+			count++;
+		}
+		if (bol < query_result.len) {
+			fsmonitor_refresh_callback(istate, buf + bol);
+			count++;
+		}
+
+		/* Now mark the untracked cache for fsmonitor usage */
+		if (istate->untracked)
+			istate->untracked->use_fsmonitor = 1;
+
+		if (count > fsmonitor_force_update_threshold)
+			istate->cache_changed |= FSMONITOR_CHANGED;
+
+		trace2_data_intmax("fsmonitor", istate->repo, "apply_count",
+				   count);
+
+	} else {
+		/*
+		 * We failed to get a response or received a trivial response,
+		 * so invalidate everything.
+		 *
+		 * We only want to run the post index changed hook if
+		 * we've actually changed entries, so keep track if we
+		 * actually changed entries or not.
+		 */
+		int is_cache_changed = 0;
+
+		for (i = 0; i < istate->cache_nr; i++) {
+			if (istate->cache[i]->ce_flags & CE_FSMONITOR_VALID) {
+				is_cache_changed = 1;
+				istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
+			}
+		}
+
+		/*
+		 * If we're going to check every file, ensure we save
+		 * the results.
+		 */
+		if (is_cache_changed)
+			istate->cache_changed |= FSMONITOR_CHANGED;
+
+		if (istate->untracked)
+			istate->untracked->use_fsmonitor = 0;
+	}
+	trace2_region_leave("fsmonitor", "apply_results", istate->repo);
+
+	strbuf_release(&query_result);
+
+	/* Now that we've updated istate, save the last_update_token */
+	FREE_AND_NULL(istate->fsmonitor_last_update);
+	istate->fsmonitor_last_update = strbuf_detach(&last_update_token, NULL);
+}
+
+/*
+ * The caller wants to turn on FSMonitor.  And when the caller writes
+ * the index to disk, a FSMonitor extension should be included.  This
+ * requires that `istate->fsmonitor_last_update` not be NULL.  But we
+ * have not actually talked to a FSMonitor process yet, so we don't
+ * have an initial value for this field.
+ *
+ * For a protocol V1 FSMonitor process, this field is a formatted
+ * "nanoseconds since epoch" field.  However, for a protocol V2
+ * FSMonitor process, this field is an opaque token.
+ *
+ * Historically, `add_fsmonitor()` has initialized this field to the
+ * current time for protocol V1 processes.  There are lots of race
+ * conditions here, but that code has shipped...
+ *
+ * The only true solution is to use a V2 FSMonitor and get a current
+ * or default token value (that it understands), but we cannot do that
+ * until we have actually talked to an instance of the FSMonitor process
+ * (but the protocol requires that we send a token first...).
+ *
+ * For simplicity, just initialize like we have a V1 process and require
+ * that V2 processes adapt.
+ */
+static void initialize_fsmonitor_last_update(struct index_state *istate)
+{
+	struct strbuf last_update = STRBUF_INIT;
+
+	strbuf_addf(&last_update, "%"PRIu64"", getnanotime());
+	istate->fsmonitor_last_update = strbuf_detach(&last_update, NULL);
+}
+
+void add_fsmonitor(struct index_state *istate)
+{
+	unsigned int i;
+
+	if (!istate->fsmonitor_last_update) {
+		trace_printf_key(&trace_fsmonitor, "add fsmonitor");
+		istate->cache_changed |= FSMONITOR_CHANGED;
+		initialize_fsmonitor_last_update(istate);
+
+		/* reset the fsmonitor state */
+		for (i = 0; i < istate->cache_nr; i++)
+			istate->cache[i]->ce_flags &= ~CE_FSMONITOR_VALID;
+
+		/* reset the untracked cache */
+		if (istate->untracked) {
+			add_untracked_cache(istate);
+			istate->untracked->use_fsmonitor = 1;
+		}
+
+		/* Update the fsmonitor state */
+		refresh_fsmonitor(istate);
+	}
+}
+
+void remove_fsmonitor(struct index_state *istate)
+{
+	if (istate->fsmonitor_last_update) {
+		trace_printf_key(&trace_fsmonitor, "remove fsmonitor");
+		istate->cache_changed |= FSMONITOR_CHANGED;
+		FREE_AND_NULL(istate->fsmonitor_last_update);
+	}
+}
+
+void tweak_fsmonitor(struct index_state *istate)
+{
+	unsigned int i;
+	int fsmonitor_enabled = (fsm_settings__get_mode(istate->repo)
+				 > FSMONITOR_MODE_DISABLED);
+
+	if (istate->fsmonitor_dirty) {
+		if (fsmonitor_enabled) {
+			/* Mark all entries valid */
+			for (i = 0; i < istate->cache_nr; i++) {
+				if (S_ISGITLINK(istate->cache[i]->ce_mode))
+					continue;
+				istate->cache[i]->ce_flags |= CE_FSMONITOR_VALID;
+			}
+
+			/* Mark all previously saved entries as dirty */
+			assert_index_minimum(istate, istate->fsmonitor_dirty->bit_size);
+			ewah_each_bit(istate->fsmonitor_dirty, fsmonitor_ewah_callback, istate);
+
+			refresh_fsmonitor(istate);
+		}
+
+		ewah_free(istate->fsmonitor_dirty);
+		istate->fsmonitor_dirty = NULL;
+	}
+
+	if (fsmonitor_enabled)
+		add_fsmonitor(istate);
+	else
+		remove_fsmonitor(istate);
+}