From 9821cce484b14f6f7ecbfa6367c26ceab7ebe87e Mon Sep 17 00:00:00 2001
From: Brandon Low <lostlogic@rockbox.org>
Date: Tue, 6 Nov 2007 16:49:30 +0000
Subject: Pull the size range checking and disk request into a separate
 function that both bufread and bufgetdata can use.  Do better range checking
 to ensure that we don't get 'stuck' in the calls and warn with a logf if
 requests are made for which we cannot guarantee satisfaction.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@15495 a1c6a512-1295-4272-9138-f99709370657
---
 apps/buffering.c | 85 +++++++++++++++++++++++++++-----------------------------
 1 file changed, 41 insertions(+), 44 deletions(-)

(limited to 'apps')

diff --git a/apps/buffering.c b/apps/buffering.c
index 18f3ba6900..5fd8c24122 100644
--- a/apps/buffering.c
+++ b/apps/buffering.c
@@ -970,51 +970,70 @@ int bufadvance(int handle_id, off_t offset)
     return bufseek(handle_id, newpos);
 }
 
-/* Copy data from the given handle to the dest buffer.
-   Return the number of bytes copied or < 0 for failure (handle not found).
-   The caller is blocked until the requested amount of data is available.
-*/
-ssize_t bufread(int handle_id, size_t size, void *dest)
+/* Used by bufread and bufgetdata to prepare the buffer and retrieve the
+ * actual amount of data available for reading.  This function explicitly
+ * does not check the validity of the input handle.  It does do range checks
+ * on size and returns a valid (and explicit) amount of data for reading */
+static size_t prep_bufdata(const struct memory_handle *h, size_t size)
 {
-    const struct memory_handle *h = find_handle(handle_id);
-    if (!h)
-        return ERR_HANDLE_NOT_FOUND;
-
-    size_t ret;
     size_t avail = RINGBUF_SUB(h->widx, h->ridx);
 
     if (avail == 0 && h->filerem == 0)
         /* File is finished reading */
         return 0;
 
-    if (h->filerem > 0 && (avail == 0 || avail < size))
+    if (size == 0 || size > h->available + h->filerem)
+        size = h->available + h->filerem;
+
+    if (h->type == TYPE_PACKET_AUDIO && size > BUFFERING_DEFAULT_FILECHUNK)
+    {
+        /* If more than a filechunk is requested, log it and provide no more
+         * than the amount of data on buffer or one file chunk */
+        logf("data request > filechunk");
+        size = MAX(avail,BUFFERING_DEFAULT_FILECHUNK);
+    }
+
+    if (h->filerem > 0 && avail < size)
     {
         /* Data isn't ready. Request buffering */
-        buf_request_buffer_handle(handle_id);
+        buf_request_buffer_handle(h->id);
         /* Wait for the data to be ready */
         do
         {
             sleep(1);
             avail = RINGBUF_SUB(h->widx, h->ridx);
         }
-        while (h->filerem > 0 && (avail == 0 || avail < size));
+        while (h->filerem > 0 && avail < size);
     }
 
-    ret = MIN(size, avail);
+    return MIN(size,avail);
+}
 
-    if (h->ridx + ret > buffer_len)
+/* Copy data from the given handle to the dest buffer.
+   Return the number of bytes copied or < 0 for failure (handle not found).
+   The caller is blocked until the requested amount of data is available.
+*/
+ssize_t bufread(int handle_id, size_t size, void *dest)
+{
+    const struct memory_handle *h = find_handle(handle_id);
+    if (!h)
+        return ERR_HANDLE_NOT_FOUND;
+
+    size = prep_bufdata(h, size);
+
+    if (h->ridx + size > buffer_len)
     {
         /* the data wraps around the end of the buffer */
         size_t read = buffer_len - h->ridx;
         memcpy(dest, &buffer[h->ridx], read);
-        memcpy(dest+read, buffer, ret - read);
+        memcpy(dest+read, buffer, size - read);
     }
     else
     {
-        memcpy(dest, &buffer[h->ridx], ret);
+        memcpy(dest, &buffer[h->ridx], size);
     }
 
-    return ret;
+    return size;
 }
 
 /* Update the "data" pointer to make the handle's data available to the caller.
@@ -1032,41 +1051,19 @@ ssize_t bufgetdata(int handle_id, size_t size, void **data)
     if (!h)
         return ERR_HANDLE_NOT_FOUND;
 
-    ssize_t ret;
-    size_t avail = RINGBUF_SUB(h->widx, h->ridx);
+    size = prep_bufdata(h, size);
 
-    if (avail == 0 && h->filerem == 0)
-        /* File is finished reading */
-        return 0;
-
-    if (h->filerem > 0 && (avail == 0 || avail < size))
-    {
-        /* Data isn't ready. Request buffering */
-        buf_request_buffer_handle(handle_id);
-        /* Wait for the data to be ready */
-        do
-        {
-            sleep(1);
-            avail = RINGBUF_SUB(h->widx, h->ridx);
-        }
-        while (h->filerem > 0 && (avail == 0 || avail < size));
-    }
-
-    if (h->ridx + size > buffer_len && avail >= size)
+    if (h->ridx + size > buffer_len)
     {
         /* the data wraps around the end of the buffer :
            use the guard buffer to provide the requested amount of data. */
         size_t copy_n = MIN(h->ridx + size - buffer_len, GUARD_BUFSIZE);
         memcpy(guard_buffer, (unsigned char *)buffer, copy_n);
-        ret = buffer_len - h->ridx + copy_n;
-    }
-    else
-    {
-        ret = MIN(avail, buffer_len - h->ridx);
+        size = buffer_len - h->ridx + copy_n;
     }
 
     *data = &buffer[h->ridx];
-    return ret;
+    return size;
 }
 
 /*
-- 
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