1 files changed, 94 insertions, 26 deletions

diff --git a/fsmonitor.c b/fsmonitor.c
index 868cca01e2..932bd9012d 100644
--- a/fsmonitor.c
+++ b/fsmonitor.c
@@ -6,8 +6,10 @@
 #include "run-command.h"
 #include "strbuf.h"
 
-#define INDEX_EXTENSION_VERSION	(1)
-#define HOOK_INTERFACE_VERSION	(1)
+#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);
 
@@ -24,6 +26,22 @@ static void fsmonitor_ewah_callback(size_t pos, void *is)
 	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)
 {
@@ -32,17 +50,26 @@ int read_fsmonitor_extension(struct index_state *istate, const void *data,
 	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) + sizeof(uint64_t) + sizeof(uint32_t))
+	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_VERSION)
+	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 = get_be64(index);
-	index += sizeof(uint64_t);
+	istate->fsmonitor_last_update = strbuf_detach(&last_update, NULL);
 
 	ewah_size = get_be32(index);
 	index += sizeof(uint32_t);
@@ -79,7 +106,6 @@ void fill_fsmonitor_bitmap(struct index_state *istate)
 void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
 {
 	uint32_t hdr_version;
-	uint64_t tm;
 	uint32_t ewah_start;
 	uint32_t ewah_size = 0;
 	int fixup = 0;
@@ -89,11 +115,12 @@ void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
 		BUG("fsmonitor_dirty has more entries than the index (%"PRIuMAX" > %u)",
 		    (uintmax_t)istate->fsmonitor_dirty->bit_size, istate->cache_nr);
 
-	put_be32(&hdr_version, INDEX_EXTENSION_VERSION);
+	put_be32(&hdr_version, INDEX_EXTENSION_VERSION2);
 	strbuf_add(sb, &hdr_version, sizeof(uint32_t));
 
-	put_be64(&tm, istate->fsmonitor_last_update);
-	strbuf_add(sb, &tm, sizeof(uint64_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 */
 
@@ -110,9 +137,9 @@ void write_fsmonitor_extension(struct strbuf *sb, struct index_state *istate)
 }
 
 /*
- * Call the query-fsmonitor hook passing the time of the last saved results.
+ * Call the query-fsmonitor hook passing the last update token of the saved results.
  */
-static int query_fsmonitor(int version, uint64_t last_update, struct strbuf *query_result)
+static int query_fsmonitor(int version, const char *last_update, struct strbuf *query_result)
 {
 	struct child_process cp = CHILD_PROCESS_INIT;
 
@@ -121,7 +148,7 @@ static int query_fsmonitor(int version, uint64_t last_update, struct strbuf *que
 
 	argv_array_push(&cp.args, core_fsmonitor);
 	argv_array_pushf(&cp.args, "%d", version);
-	argv_array_pushf(&cp.args, "%" PRIuMAX, (uintmax_t)last_update);
+	argv_array_pushf(&cp.args, "%s", last_update);
 	cp.use_shell = 1;
 	cp.dir = get_git_work_tree();
 
@@ -148,14 +175,18 @@ static void fsmonitor_refresh_callback(struct index_state *istate, const char *n
 void refresh_fsmonitor(struct index_state *istate)
 {
 	struct strbuf query_result = STRBUF_INIT;
-	int query_success = 0;
-	size_t bol; /* beginning of line */
+	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;
 
 	if (!core_fsmonitor || istate->fsmonitor_has_run_once)
 		return;
+
+	hook_version = fsmonitor_hook_version();
+
 	istate->fsmonitor_has_run_once = 1;
 
 	trace_printf_key(&trace_fsmonitor, "refresh fsmonitor");
@@ -164,26 +195,60 @@ void refresh_fsmonitor(struct index_state *istate)
 	 * 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 time, call query_fsmonitor for the set of
-	 * changes since that time, else assume everything is possibly dirty
+	 * If we have a last update token, call query_fsmonitor for the set of
+	 * changes since that token, else assume everything is possibly dirty
 	 * and check it all.
 	 */
 	if (istate->fsmonitor_last_update) {
-		query_success = !query_fsmonitor(HOOK_INTERFACE_VERSION,
-			istate->fsmonitor_last_update, &query_result);
+		if (hook_version == -1 || hook_version == HOOK_INTERFACE_VERSION2) {
+			query_success = !query_fsmonitor(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 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;
+				}
+			} 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_INTERFACE_VERSION1,
+				istate->fsmonitor_last_update, &query_result);
+		}
+
 		trace_performance_since(last_update, "fsmonitor process '%s'", core_fsmonitor);
 		trace_printf_key(&trace_fsmonitor, "fsmonitor process '%s' returned %s",
 			core_fsmonitor, query_success ? "success" : "failure");
 	}
 
 	/* a fsmonitor process can return '/' to indicate all entries are invalid */
-	if (query_success && query_result.buf[0] != '/') {
+	if (query_success && query_result.buf[bol] != '/') {
 		/* Mark all entries returned by the monitor as dirty */
 		buf = query_result.buf;
-		bol = 0;
-		for (i = 0; i < query_result.len; i++) {
+		for (i = bol; i < query_result.len; i++) {
 			if (buf[i] != '\0')
 				continue;
 			fsmonitor_refresh_callback(istate, buf + bol);
@@ -217,18 +282,21 @@ void refresh_fsmonitor(struct index_state *istate)
 	}
 	strbuf_release(&query_result);
 
-	/* Now that we've updated istate, save the last_update time */
-	istate->fsmonitor_last_update = last_update;
+	/* 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);
 }
 
 void add_fsmonitor(struct index_state *istate)
 {
 	unsigned int i;
+	struct strbuf last_update = STRBUF_INIT;
 
 	if (!istate->fsmonitor_last_update) {
 		trace_printf_key(&trace_fsmonitor, "add fsmonitor");
 		istate->cache_changed |= FSMONITOR_CHANGED;
-		istate->fsmonitor_last_update = getnanotime();
+		strbuf_addf(&last_update, "%"PRIu64"", getnanotime());
+		istate->fsmonitor_last_update = strbuf_detach(&last_update, NULL);
 
 		/* reset the fsmonitor state */
 		for (i = 0; i < istate->cache_nr; i++)
@@ -250,7 +318,7 @@ void remove_fsmonitor(struct index_state *istate)
 	if (istate->fsmonitor_last_update) {
 		trace_printf_key(&trace_fsmonitor, "remove fsmonitor");
 		istate->cache_changed |= FSMONITOR_CHANGED;
-		istate->fsmonitor_last_update = 0;
+		FREE_AND_NULL(istate->fsmonitor_last_update);
 	}
 }