From 033a4a8263b4658c50d36b2830ca63060e85e1d9 Mon Sep 17 00:00:00 2001
From: Nicolas Pennequin <nicolas.pennequin@free.fr>
Date: Sun, 5 Aug 2007 20:17:29 +0200
Subject: [PATCH] bufseek: Changed specification and improved range checking.

It makes more sense to seek within the file than within the available data,
(that would be overly complicated for the caller anyway).
Seeking to a point before the available data should now trigger a rebuffer
(required for the case of rewinding to the start of an audio track), but I
haven't tested this yet.
---
 testplugin.c | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/testplugin.c b/testplugin.c
index 109b10e..5348c50 100644
--- a/testplugin.c
+++ b/testplugin.c
@@ -544,23 +544,50 @@ int bufclose(int handle_id)
     return 0;
 }
 
-/* Set reading index in handle (relatively to the start of the handle data).
-   Return 0 for success and < 0 for failure */
-int bufseek(int handle_id, size_t offset)
+/* Set reading index in handle (relatively to the start of the file).
+   Access before the available data will trigger a rebuffer.
+   TODO: Test this
+   TODO: Maybe force an immediate rebuffer by calling buffer_handle() ?
+   Return 0 for success and < 0 for failure:
+     -1 if the handle wasn't found
+     -2 if there is no data available at the new position
+        (the reading index is still moved)
+     -3 if the new requested position was beyond the end of the file
+*/
+int bufseek(int handle_id, size_t newpos)
 {
+    int ret = 0;
     struct memory_handle *h = find_handle(handle_id);
     if (!h)
         return -1;
 
-    if (offset > h->available)
-        return -2;
+    if (newpos > h->filesize) {
+        /* access beyond the end of the file */
+        return -3;
+    }
 
-    h->ridx = RINGBUF_ADD(h->data, offset);
-    return 0;
+    else if (newpos < h->offset) {
+        /* access before what we currently have. A rebuffer is needed. */
+        h->offset = newpos;
+        h->available = 0;
+        h->filerem = h->filesize - newpos;
+        /* having changed filerem should be enough to trigger the rebuffer. */
+        h->widx = h->data;
+        ret = -2;
+    }
+
+    else if (newpos > h->offset + h->available) {
+        /* data isn't available yet. */
+        ret = -2;
+    }
+
+    h->ridx = RINGBUF_ADD(h->data, newpos);
+    return ret;
 }
 
 /* Advance the reading index in a handle (relatively to its current position).
-   Return 0 for success and < 0 for failure */
+   Return 0 for success and < 0 for failure
+   TODO: Add some rebuffering like in bufseek */
 int bufadvance(int handle_id, off_t offset)
 {
     struct memory_handle *h = find_handle(handle_id);
-- 
2.11.4.GIT