Minor cleanup.

[wxWidgets.git] / src / common / gifdecod.cpp

diff --git a/src/common/gifdecod.cpp b/src/common/gifdecod.cpp
index c9cfe9b16ec1e2fbea84df6901e7d6a2c77d6ffa..4b3e6ddc87660a5747cff14f5c4e03d3fc38e6b3 100644 (file)
--- a/src/common/gifdecod.cpp
+++ b/src/common/gifdecod.cpp
@@ -1,5 +1,5 @@
 /////////////////////////////////////////////////////////////////////////////
-// Name:        gifdecod.cpp
+// Name:        src/common/gifdecod.cpp
 // Purpose:     wxGIFDecoder, GIF reader for wxImage and wxAnimation
 // Author:      Guillermo Rodriguez Garcia <guille@iies.es>
 // Version:     3.04
@@ -8,24 +8,19 @@
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 
-#if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
-#pragma implementation "gifdecod.h"
-#endif
-
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
 #ifdef __BORLANDC__
-#  pragma hdrstop
+    #pragma hdrstop
 #endif
 
+#if wxUSE_STREAMS && wxUSE_GIF
+
 #ifndef WX_PRECOMP
-#  include "wx/defs.h"
-#  include "wx/palette.h"
+    #include "wx/palette.h"
 #endif
 
-#if wxUSE_STREAMS && wxUSE_GIF
-
 #include <stdlib.h>
 #include <string.h>
 #include "wx/gifdecod.h"
@@ -146,21 +141,18 @@ bool wxGIFDecoder::ConvertToImage(wxImage *image) const
         image->SetMask(false);
 
 #if wxUSE_PALETTE
-    if (pal)
-    {
-        unsigned char r[256];
-        unsigned char g[256];
-        unsigned char b[256];
-
-        for (i = 0; i < 256; i++)
-        {
-            r[i] = pal[3*i + 0];
-            g[i] = pal[3*i + 1];
-            b[i] = pal[3*i + 2];
-        }
+    unsigned char r[256];
+    unsigned char g[256];
+    unsigned char b[256];
 
-        image->SetPalette(wxPalette(256, r, g, b));
+    for (i = 0; i < 256; i++)
+    {
+        r[i] = pal[3*i + 0];
+        g[i] = pal[3*i + 1];
+        b[i] = pal[3*i + 2];
     }
+
+    image->SetPalette(wxPalette(256, r, g, b));
 #endif // wxUSE_PALETTE
 
     /* copy image data */
@@ -271,17 +263,19 @@ bool wxGIFDecoder::GoPrevFrame(bool cyclic)
 
 bool wxGIFDecoder::GoFrame(int which)
 {
-    int i;
-
     if (!IsAnimation())
         return false;
 
     if ((which >= 1) && (which <= m_nimages))
     {
+        m_image = 1;
         m_pimage = m_pfirst;
 
-        for (i = 0; i < which; i++)
+        while (m_image < which)
+        {
+            m_image++;
             m_pimage = m_pimage->next;
+        }
 
         return true;
     }
@@ -472,6 +466,25 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
         /* make new entry in alphabet (only if NOT just cleared) */
         if (lastcode != -1)
         {
+            // Normally, after the alphabet is full and can't grow any
+            // further (ab_free == 4096), encoder should (must?) emit CLEAR
+            // to reset it. This checks whether we really got it, otherwise
+            // the GIF is damaged.
+            if (ab_free > ab_max)
+            {
+                delete[] ab_prefix;
+                delete[] ab_tail;
+                delete[] stack;
+                return wxGIF_INVFORMAT;
+            }
+
+            // This assert seems unnecessary since the condition above
+            // eliminates the only case in which it went false. But I really
+            // don't like being forced to ask "Who in .text could have
+            // written there?!" And I wouldn't have been forced to ask if
+            // this line had already been here.
+            wxASSERT(ab_free < allocSize);
+
             ab_prefix[ab_free] = lastcode;
             ab_tail[ab_free]   = code;
             ab_free++;
@@ -507,7 +520,7 @@ int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
                     /* loop until a valid y coordinate has been
                     found, Or if the maximum number of passes has
                     been reached, exit the loop, and stop image
-                    decoding (At this point the image is succesfully
+                    decoding (At this point the image is successfully
                     decoded).
                     If we don't loop, but merely set y to some other
                     value, that new value might still be invalid depending
@@ -677,6 +690,11 @@ int wxGIFDecoder::ReadGIF()
     m_screenw = buf[0] + 256 * buf[1];
     m_screenh = buf[2] + 256 * buf[3];
 
+    if ((m_screenw == 0) || (m_screenh == 0))
+    {
+        return wxGIF_INVFORMAT;
+    }
+
     /* load global color map if available */
     if ((buf[4] & 0x80) == 0x80)
     {
@@ -703,7 +721,7 @@ int wxGIFDecoder::ReadGIF()
 
     bool done = false;
 
-    while(!done)
+    while (!done)
     {
         type = (unsigned char)m_f->GetC();
 
@@ -752,7 +770,7 @@ int wxGIFDecoder::ReadGIF()
                     transparent = buf[4];
 
                 /* read disposal method */
-                disposal = (buf[1] & 0x1C) - 1;
+                disposal = ((buf[1] & 0x1C) >> 2) - 1;
             }
             else
             /* other extension, skip */
@@ -799,7 +817,7 @@ int wxGIFDecoder::ReadGIF()
             pimg->w = buf[4] + 256 * buf[5];
             pimg->h = buf[6] + 256 * buf[7];
 
-            if (pimg->w == 0 || pimg->h == 0)
+            if ((pimg->w == 0) || (pimg->w > m_screenw) || (pimg->h == 0) || (pimg->h > m_screenh))
             {
                 Destroy();
                 return wxGIF_INVFORMAT;
@@ -845,6 +863,11 @@ int wxGIFDecoder::ReadGIF()
 
             /* get initial code size from first byte in raster data */
             bits = (unsigned char)m_f->GetC();
+            if (bits == 0)
+            {
+                Destroy();
+                return wxGIF_INVFORMAT;
+            }
 
             /* decode image */
             int result = dgif(pimg, interl, bits);
@@ -861,7 +884,7 @@ int wxGIFDecoder::ReadGIF()
         }
     }
 
-    if (m_nimages == 0)
+    if (m_nimages <= 0)
     {
         Destroy();
         return wxGIF_INVFORMAT;