Subject: [PATCH 05/16] fsmonitor--daemon: refactor cookie handling for readability

From: "Jeff Hostetler via GitGitGadget" <[email-masked]>
Date: Fri, 11 Mar 2022 21:14:52 +0000

From: Jeff Hostetler <[email-masked]>

fixup! fsmonitor--daemon: use a cookie file to sync with file system

Use implicit definitions for FCIR_ enum values.

Remove const from cookie->name.

Reverse if then and else branches around open() to ease readability.

Document that we don't care about errors from close() and unlink().

Signed-off-by: Jeff Hostetler <[email-masked]>
---
 builtin/fsmonitor--daemon.c | 53 +++++++++++++++++++++----------------
 1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/builtin/fsmonitor--daemon.c b/builtin/fsmonitor--daemon.c
index 97ca2a356e5..02a99ce98a2 100644
--- a/builtin/fsmonitor--daemon.c
+++ b/builtin/fsmonitor--daemon.c
@@ -109,14 +109,14 @@ static int do_as_client__status(void)
 
 enum fsmonitor_cookie_item_result {
 	FCIR_ERROR = -1, /* could not create cookie file ? */
-	FCIR_INIT = 0,
+	FCIR_INIT,
 	FCIR_SEEN,
 	FCIR_ABORT,
 };
 
 struct fsmonitor_cookie_item {
 	struct hashmap_entry entry;
-	const char *name;
+	char *name;
 	enum fsmonitor_cookie_item_result result;
 };
 
@@ -166,37 +166,44 @@ static enum fsmonitor_cookie_item_result with_lock__wait_for_cookie(
 	 * that the listener thread has seen it.
 	 */
 	fd = open(cookie_pathname.buf, O_WRONLY | O_CREAT | O_EXCL, 0600);
-	if (fd >= 0) {
-		close(fd);
-		unlink(cookie_pathname.buf);
-
-		/*
-		 * Technically, this is an infinite wait (well, unless another
-		 * thread sends us an abort).  I'd like to change this to
-		 * use `pthread_cond_timedwait()` and return an error/timeout
-		 * and let the caller do the trivial response thing, but we
-		 * don't have that routine in our thread-utils.
-		 *
-		 * After extensive beta testing I'm not really worried about
-		 * this.  Also note that the above open() and unlink() calls
-		 * will cause at least two FS events on that path, so the odds
-		 * of getting stuck are pretty slim.
-		 */
-		while (cookie->result == FCIR_INIT)
-			pthread_cond_wait(&state->cookies_cond,
-					  &state->main_lock);
-	} else {
+	if (fd < 0) {
 		error_errno(_("could not create fsmonitor cookie '%s'"),
 			    cookie->name);
 
 		cookie->result = FCIR_ERROR;
+		goto done;
 	}
 
+	/*
+	 * Technically, close() and unlink() can fail, but we don't
+	 * care here.  We only created the file to trigger a watch
+	 * event from the FS to know that when we're up to date.
+	 */
+	close(fd);
+	unlink(cookie_pathname.buf);
+
+	/*
+	 * Technically, this is an infinite wait (well, unless another
+	 * thread sends us an abort).  I'd like to change this to
+	 * use `pthread_cond_timedwait()` and return an error/timeout
+	 * and let the caller do the trivial response thing, but we
+	 * don't have that routine in our thread-utils.
+	 *
+	 * After extensive beta testing I'm not really worried about
+	 * this.  Also note that the above open() and unlink() calls
+	 * will cause at least two FS events on that path, so the odds
+	 * of getting stuck are pretty slim.
+	 */
+	while (cookie->result == FCIR_INIT)
+		pthread_cond_wait(&state->cookies_cond,
+				  &state->main_lock);
+
+done:
 	hashmap_remove(&state->cookies, &cookie->entry, NULL);
 
 	result = cookie->result;
 
-	free((char*)cookie->name);
+	free(cookie->name);
 	free(cookie);
 	strbuf_release(&cookie_pathname);
 
-- 
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