update: fix multiple deletes from *vec iterators

{song,dir}vec_for_each each failed to gracefully handle deleted files when iterating through. While we were thread-safe, we were not safe within the calling thread. If a callback we passed caused sv->nr to shring, our index would still increment; causing files to stay in the database. A way to test this is to remove 10 or so contiguous songs from a >10 song directory.

update: fix multiple deletes from *vec iterators
d52437d4 · Eric Wong · Max Kellermann · 9aeacdef · d52437d4 · d52437d4
Commit d52437d4 authored Oct 21, 2008 by Eric Wong Committed by Max Kellermann Oct 21, 2008
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Showing with 10 additions and 2 deletions

dirvec.c src/dirvec.c +5 -1

songvec.c src/songvec.c +5 -1

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--- a/src/dirvec.c
+++ b/src/dirvec.c
@@ -98,16 +98,20 @@ int dirvec_for_each(const struct dirvec *dv,
                    int (*fn)(struct directory *, void *), void *arg)
 {
 	size_t i;
+	size_t prev_nr;

 	pthread_mutex_lock(&nr_lock);
-	for (i = 0; i < dv->nr; ++i) {
+	for (i = 0; i < dv->nr; ) {
 		struct directory *dir = dv->base[i];

 		assert(dir);
+		prev_nr = dv->nr;
 		pthread_mutex_unlock(&nr_lock);
 		if (fn(dir, arg) < 0)
 			return -1;
 		pthread_mutex_lock(&nr_lock); /* dv->nr may change in fn() */
+		if (prev_nr == dv->nr)
+			++i;
 	}
 	pthread_mutex_unlock(&nr_lock);


--- a/src/songvec.c
+++ b/src/songvec.c
@@ -96,18 +96,22 @@ songvec_for_each(const struct songvec *sv,
 		 int (*fn)(struct song *, void *), void *arg)
 {
 	size_t i;
+	size_t prev_nr;

 	pthread_mutex_lock(&nr_lock);
-	for (i = 0; i < sv->nr; ++i) {
+	for (i = 0; i < sv->nr; ) {
 		struct song *song = sv->base[i];

 		assert(song);
 		assert(*song->url);

+		prev_nr = sv->nr;
 		pthread_mutex_unlock(&nr_lock); /* fn() may block */
 		if (fn(song, arg) < 0)
 			return -1;
 		pthread_mutex_lock(&nr_lock); /* sv->nr may change in fn() */
+		if (prev_nr == sv->nr)
+			++i;
 	}
 	pthread_mutex_unlock(&nr_lock);