Buflib: Clarification about invalid handles

* Enhance allocation function comments to better state the return value and what an invalid value is
* Change clients to check for "< 0" instead of "<= 0" or "== 0"
* Return -1 or -2 depending on the exact failure in buflib_alloc_ex.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30469 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 4 insertions, 2 deletions

diff --git a/apps/plugins/pictureflow/pictureflow.c b/apps/plugins/pictureflow/pictureflow.c
index c13aca1a95..a572586886 100644
--- a/apps/plugins/pictureflow/pictureflow.c
+++ b/apps/plugins/pictureflow/pictureflow.c
@@ -1520,9 +1520,11 @@ int read_pfraw(char* filename, int prio)
                 sizeof( pix_t ) * bmph.width * bmph.height;
 
     int hid;
-    while (!(hid = rb->buflib_alloc(&buf_ctx, size)) && free_slide_prio(prio));
+    do {
+        hid = rb->buflib_alloc(&buf_ctx, size);
+    } while (hid < 0 && free_slide_prio(prio));
 
-    if (!hid) {
+    if (hid < 0) {
         rb->close( fh );
         return 0;
     }