summaryrefslogtreecommitdiffstats
path: root/apps/buffering.c
diff options
context:
space:
mode:
authorRafaël Carré <rafael.carre@gmail.com>2009-10-25 11:03:59 +0000
committerRafaël Carré <rafael.carre@gmail.com>2009-10-25 11:03:59 +0000
commitf3944cb694b46052975f0a1f1ec9b0aebe047679 (patch)
treecfb4dc9916bc077e8a9659f00ffca2b65ef57366 /apps/buffering.c
parent0b302f0cb9e9cf5d308e5d89a16c661ff6bc604f (diff)
downloadrockbox-f3944cb694b46052975f0a1f1ec9b0aebe047679.tar.gz
rockbox-f3944cb694b46052975f0a1f1ec9b0aebe047679.tar.bz2
rockbox-f3944cb694b46052975f0a1f1ec9b0aebe047679.zip
buffering: leave a comment to explain what is broken in the code and link to FS#10605
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@23344 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'apps/buffering.c')
-rw-r--r--apps/buffering.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/apps/buffering.c b/apps/buffering.c
index e66e95d66d..22ec821a30 100644
--- a/apps/buffering.c
+++ b/apps/buffering.c
@@ -486,6 +486,31 @@ static bool move_handle(struct memory_handle **h, size_t *delta,
cur_handle = dest;
if (overlap > 0) {
+ /* FIXME : this code is broken and can leave the data corrupted when
+ * the amount of data to move is close to the whole buffer size.
+ *
+ * Example : ('S' is the source data, '-' is empty buffer)
+ * Size of the buffer is 8 bytes, starts at 0.
+ * Size of the data to move is 7 bytes.
+ *
+ * -SSSSSSS
+ * ^-------- start of source data == 1
+ *
+ * DD-DDDDD ('D' is desired destination data)
+ * ^------ start of destination data == 3
+ *
+ * memmove(3, 1, 5);
+ * memmove(0, 7, 2);
+ *
+ * First memmove() call will leave the buffer in this state:
+ *
+ * -SSDDDDD
+ * ^^
+ * \--- data to be moved by the second memmove() call, but
+ * overwritten by the first call.
+ *
+ * See FS#10605 for more details
+ */
size_t first_part = size_to_move - overlap;
memmove(dest, src, first_part);
memmove(buffer, (const char *)src + first_part, overlap);