#include "wx/gifdecod.h"
+//---------------------------------------------------------------------------
+// GIFImage constructor
+//---------------------------------------------------------------------------
+GIFImage::GIFImage()
+{
+ w = 0;
+ h = 0;
+ left = 0;
+ top = 0;
+ transparent = 0;
+ disposal = 0;
+ delay = -1;
+ p = (unsigned char *) NULL;
+ pal = (unsigned char *) NULL;
+ next = (GIFImage *) NULL;
+ prev = (GIFImage *) NULL;
+}
+
//---------------------------------------------------------------------------
// wxGIFDecoder constructor and destructor
//---------------------------------------------------------------------------
while (pimg != NULL)
{
- paux = pimg->next;
- free(pimg->p);
- free(pimg->pal);
- delete pimg;
- pimg = paux;
+ paux = pimg->next;
+ free(pimg->p);
+ free(pimg->pal);
+ delete pimg;
+ pimg = paux;
}
m_pimage = NULL;
image->Create(GetWidth(), GetHeight());
if (!image->Ok())
- return FALSE;
+ return FALSE;
pal = GetPalette();
src = GetData();
/* set transparent colour mask */
if (transparent != -1)
{
- for (i = 0; i < 256; i++)
- {
- if ((pal[3 * i + 0] == 255) &&
- (pal[3 * i + 1] == 0) &&
- (pal[3 * i + 2] == 255))
- {
- pal[3 * i + 2] = 254;
- }
- }
-
- pal[3 * transparent + 0] = 255,
- pal[3 * transparent + 1] = 0,
- pal[3 * transparent + 2] = 255;
-
- image->SetMaskColour(255, 0, 255);
+ for (i = 0; i < 256; i++)
+ {
+ if ((pal[3 * i + 0] == 255) &&
+ (pal[3 * i + 1] == 0) &&
+ (pal[3 * i + 2] == 255))
+ {
+ pal[3 * i + 2] = 254;
+ }
+ }
+
+ pal[3 * transparent + 0] = 255,
+ pal[3 * transparent + 1] = 0,
+ pal[3 * transparent + 2] = 255;
+
+ image->SetMaskColour(255, 0, 255);
}
else
- image->SetMask(FALSE);
+ image->SetMask(FALSE);
+#if wxUSE_PALETTE
if (pal)
{
- unsigned char* r = new unsigned char[256];
- unsigned char* g = new unsigned char[256];
- unsigned char* b = new unsigned char[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];
- }
- image->SetPalette(wxPalette(256, r, g, b));
- delete[] r; delete[] g; delete[] b;
+ 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];
+ }
+
+ image->SetPalette(wxPalette(256, r, g, b));
}
+#endif // wxUSE_PALETTE
/* copy image data */
for (i = 0; i < (GetWidth() * GetHeight()); i++, src++)
{
- *(dst++) = pal[3 * (*src) + 0];
- *(dst++) = pal[3 * (*src) + 1];
- *(dst++) = pal[3 * (*src) + 2];
+ *(dst++) = pal[3 * (*src) + 0];
+ *(dst++) = pal[3 * (*src) + 1];
+ *(dst++) = pal[3 * (*src) + 2];
}
return TRUE;
bool wxGIFDecoder::GoFirstFrame()
{
if (!IsAnimation())
- return FALSE;
+ return FALSE;
m_image = 1;
m_pimage = m_pfirst;
bool wxGIFDecoder::GoLastFrame()
{
if (!IsAnimation())
- return FALSE;
+ return FALSE;
m_image = m_nimages;
m_pimage = m_plast;
bool wxGIFDecoder::GoNextFrame(bool cyclic)
{
if (!IsAnimation())
- return FALSE;
+ return FALSE;
if ((m_image < m_nimages) || (cyclic))
{
- m_pimage = m_pimage->next;
- m_image++;
+ m_pimage = m_pimage->next;
+ m_image++;
- if (!m_pimage)
- {
- m_image = 1;
- m_pimage = m_pfirst;
- }
+ if (!m_pimage)
+ {
+ m_image = 1;
+ m_pimage = m_pfirst;
+ }
- return TRUE;
+ return TRUE;
}
else
- return FALSE;
+ return FALSE;
}
bool wxGIFDecoder::GoPrevFrame(bool cyclic)
{
if (!IsAnimation())
- return FALSE;
+ return FALSE;
if ((m_image > 1) || (cyclic))
{
- m_pimage = m_pimage->prev;
- m_image--;
+ m_pimage = m_pimage->prev;
+ m_image--;
- if (!m_pimage)
- {
- m_image = m_nimages;
- m_pimage = m_plast;
- }
+ if (!m_pimage)
+ {
+ m_image = m_nimages;
+ m_pimage = m_plast;
+ }
- return TRUE;
+ return TRUE;
}
else
- return FALSE;
+ return FALSE;
}
bool wxGIFDecoder::GoFrame(int which)
int i;
if (!IsAnimation())
- return FALSE;
+ return FALSE;
if ((which >= 1) && (which <= m_nimages))
{
- m_pimage = m_pfirst;
+ m_pimage = m_pfirst;
- for (i = 1; i < which; i++)
- m_pimage = m_pimage->next;
+ for (i = 1; i < which; i++)
+ m_pimage = m_pimage->next;
- return TRUE;
+ return TRUE;
}
else
- return FALSE;
+ return FALSE;
}
/* keep reading new bytes while needed */
while (bits > m_restbits)
{
- /* if no bytes left in this block, read the next block */
- if (m_restbyte == 0)
- {
- m_restbyte = (unsigned char)m_f->GetC();
-
- /* Some encoders are a bit broken: instead of issuing
- * an end-of-image symbol (ab_fin) they come up with
- * a zero-length subblock!! We catch this here so
- * that the decoder sees an ab_fin code.
- */
- if (m_restbyte == 0)
- {
- code = ab_fin;
- break;
- }
-
- /* prefetch data */
- m_f->Read((void *) m_buffer, m_restbyte);
- m_bufp = m_buffer;
- }
-
- /* read next byte and isolate the bits we need */
- m_lastbyte = (unsigned char) (*m_bufp++);
- mask = (1 << (bits - m_restbits)) - 1;
- code = code + ((m_lastbyte & mask) << m_restbits);
- m_restbyte--;
-
- /* adjust total number of bits extracted from the buffer */
- m_restbits = m_restbits + 8;
+ /* if no bytes left in this block, read the next block */
+ if (m_restbyte == 0)
+ {
+ m_restbyte = (unsigned char)m_f->GetC();
+
+ /* Some encoders are a bit broken: instead of issuing
+ * an end-of-image symbol (ab_fin) they come up with
+ * a zero-length subblock!! We catch this here so
+ * that the decoder sees an ab_fin code.
+ */
+ if (m_restbyte == 0)
+ {
+ code = ab_fin;
+ break;
+ }
+
+ /* prefetch data */
+ m_f->Read((void *) m_buffer, m_restbyte);
+ if (m_f->LastRead() != m_restbyte)
+ {
+ code = ab_fin;
+ return code;
+ }
+ m_bufp = m_buffer;
+ }
+
+ /* read next byte and isolate the bits we need */
+ m_lastbyte = (unsigned char) (*m_bufp++);
+ mask = (1 << (bits - m_restbits)) - 1;
+ code = code + ((m_lastbyte & mask) << m_restbits);
+ m_restbyte--;
+
+ /* adjust total number of bits extracted from the buffer */
+ m_restbits = m_restbits + 8;
}
/* find number of bits remaining for next code */
// dgif:
// GIF decoding function. The initial code size (aka root size)
// is 'bits'. Supports interlaced images (interl == 1).
-//
+// Returns wxGIF_OK (== 0) on success, or an error code if something
+// fails (see header file for details)
int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits)
{
- int *ab_prefix = new int[4096]; /* alphabet (prefixes) */
- int *ab_tail = new int[4096]; /* alphabet (tails) */
- int *stack = new int[4096]; /* decompression stack */
+ static const int allocSize = 4096 + 1;
+ int *ab_prefix = new int[allocSize]; /* alphabet (prefixes) */
+ if (ab_prefix == NULL)
+ {
+ return wxGIF_MEMERR;
+ }
+
+ int *ab_tail = new int[allocSize]; /* alphabet (tails) */
+ if (ab_tail == NULL)
+ {
+ delete[] ab_prefix;
+ return wxGIF_MEMERR;
+ }
+
+ int *stack = new int[allocSize]; /* decompression stack */
+ if (stack == NULL)
+ {
+ delete[] ab_prefix;
+ delete[] ab_tail;
+ return wxGIF_MEMERR;
+ }
+
int ab_clr; /* clear code */
int ab_fin; /* end of info code */
int ab_bits; /* actual symbol width, in bits */
do
{
- /* get next code */
- readcode = code = getcode(ab_bits, ab_fin);
-
- /* end of image? */
- if (code == ab_fin) break;
-
- /* reset alphabet? */
- if (code == ab_clr)
- {
- /* reset main variables */
- ab_bits = bits + 1;
- ab_free = (1 << bits) + 2;
- ab_max = (1 << ab_bits) - 1;
- lastcode = -1;
- abcabca = -1;
-
- /* skip to next code */
- continue;
- }
-
- /* unknown code: special case (like in ABCABCA) */
- if (code >= ab_free)
- {
- code = lastcode; /* take last string */
- stack[pos++] = abcabca; /* add first character */
- }
-
- /* build the string for this code in the stack */
- while (code > ab_clr)
- {
- stack[pos++] = ab_tail[code];
- code = ab_prefix[code];
- }
- stack[pos] = code; /* push last code into the stack */
- abcabca = code; /* save for special case */
-
- /* make new entry in alphabet (only if NOT just cleared) */
- if (lastcode != -1)
- {
- ab_prefix[ab_free] = lastcode;
- ab_tail[ab_free] = code;
- ab_free++;
-
- if ((ab_free > ab_max) && (ab_bits < 12))
- {
- ab_bits++;
- ab_max = (1 << ab_bits) - 1;
- }
- }
-
- /* dump stack data to the buffer */
- while (pos >= 0)
- {
- (img->p)[x + (y * (img->w))] = (char)stack[pos--];
-
- if (++x >= (img->w))
- {
- x = 0;
-
- if (interl)
- {
- /* support for interlaced images */
- switch (pass)
- {
- case 1: y += 8; break;
- case 2: y += 8; break;
- case 3: y += 4; break;
- case 4: y += 2; break;
- }
- if (y >= (img->h))
- {
- switch (++pass)
- {
- case 2: y = 4; break;
- case 3: y = 2; break;
- case 4: y = 1; break;
- }
- }
- }
- else
- {
- /* non-interlaced */
- y++;
- }
- }
- }
-
- pos = 0;
- lastcode = readcode;
+ /* get next code */
+ readcode = code = getcode(ab_bits, ab_fin);
+
+ /* end of image? */
+ if (code == ab_fin) break;
+
+ /* reset alphabet? */
+ if (code == ab_clr)
+ {
+ /* reset main variables */
+ ab_bits = bits + 1;
+ ab_free = (1 << bits) + 2;
+ ab_max = (1 << ab_bits) - 1;
+ lastcode = -1;
+ abcabca = -1;
+
+ /* skip to next code */
+ continue;
+ }
+
+ /* unknown code: special case (like in ABCABCA) */
+ if (code >= ab_free)
+ {
+ code = lastcode; /* take last string */
+ stack[pos++] = abcabca; /* add first character */
+ }
+
+ /* build the string for this code in the stack */
+ while (code > ab_clr)
+ {
+ stack[pos++] = ab_tail[code];
+ code = ab_prefix[code];
+
+ // Don't overflow. This shouldn't happen with normal
+ // GIF files, the allocSize of 4096+1 is enough. This
+ // will only happen with badly formed GIFs.
+ if (pos >= allocSize)
+ {
+ delete[] ab_prefix;
+ delete[] ab_tail;
+ delete[] stack;
+ return wxGIF_INVFORMAT;
+ }
+ }
+ stack[pos] = code; /* push last code into the stack */
+ abcabca = code; /* save for special case */
+
+ /* make new entry in alphabet (only if NOT just cleared) */
+ if (lastcode != -1)
+ {
+ ab_prefix[ab_free] = lastcode;
+ ab_tail[ab_free] = code;
+ ab_free++;
+
+ if ((ab_free > ab_max) && (ab_bits < 12))
+ {
+ ab_bits++;
+ ab_max = (1 << ab_bits) - 1;
+ }
+ }
+
+ /* dump stack data to the buffer */
+ while (pos >= 0)
+ {
+ if (pos >= allocSize)
+ {
+ delete[] ab_prefix;
+ delete[] ab_tail;
+ delete[] stack;
+ return wxGIF_INVFORMAT;
+ }
+
+ (img->p)[x + (y * (img->w))] = (char)stack[pos--];
+
+ if (++x >= (img->w))
+ {
+ x = 0;
+
+ if (interl)
+ {
+ /* support for interlaced images */
+ switch (pass)
+ {
+ case 1: y += 8; break;
+ case 2: y += 8; break;
+ case 3: y += 4; break;
+ case 4: y += 2; break;
+ }
+ if (y >= (img->h))
+ {
+ switch (++pass)
+ {
+ case 2: y = 4; break;
+ case 3: y = 2; break;
+ case 4: y = 1; break;
+ }
+ }
+ }
+ else
+ {
+ /* non-interlaced */
+ y++;
+/*
+Normally image decoding is finished when an End of Information code is
+encountered (code == ab_fin) however some broken encoders write wrong
+"block byte counts" (The first byte value after the "code size" byte),
+being one value too high. It might very well be possible other variants
+of this problem occur as well. The only sensible solution seems to
+be to check for clipping.
+Example of wrong encoding:
+(1 * 1 B/W image, raster data stream follows in hex bytes)
+
+02 << B/W images have a code size of 2
+02 << Block byte count
+44 << LZW packed
+00 << Zero byte count (terminates data stream)
+
+Because the block byte count is 2, the zero byte count is used in the
+decoding process, and decoding is continued after this byte. (While it
+should signal an end of image)
+
+It should be:
+02
+02
+44
+01 << When decoded this correctly includes the End of Information code
+00
+
+Or (Worse solution):
+02
+01
+44
+00
+(The 44 doesn't include an End of Information code, but at least the
+decoder correctly skips to 00 now after decoding, and signals this
+as an End of Information itself)
+*/
+ if (y >= img->h)
+ {
+ code = ab_fin;
+ break;
+ }
+ }
+ }
+ }
+
+ pos = 0;
+ lastcode = readcode;
}
while (code != ab_fin);
delete [] ab_tail ;
delete [] stack ;
- return 0;
+ return wxGIF_OK;
}
//
int wxGIFDecoder::ReadGIF()
{
- int ncolors, bits, interl, transparent, disposal, i;
+ unsigned int ncolors;
+ int bits, interl, transparent, disposal, i;
long size;
long delay;
unsigned char type = 0;
unsigned char pal[768];
unsigned char buf[16];
GIFImage **ppimg;
- GIFImage *pimg, *pprev;
+ GIFImage *pimg, *pprev;
/* check GIF signature */
if (!CanRead())
- return wxGIF_INVFORMAT;
+ return wxGIF_INVFORMAT;
/* check for animated GIF support (ver. >= 89a) */
- m_f->Read(buf, 6);
+
+ static const size_t headerSize = (3 + 3);
+ m_f->Read(buf, headerSize);
+ if (m_f->LastRead() != headerSize)
+ {
+ return wxGIF_INVFORMAT;
+ }
if (memcmp(buf + 3, "89a", 3) < 0)
- m_anim = FALSE;
+ {
+ m_anim = FALSE;
+ }
/* read logical screen descriptor block (LSDB) */
- m_f->Read(buf, 7);
+ static const size_t lsdbSize = (2 + 2 + 1 + 1 + 1);
+ m_f->Read(buf, lsdbSize);
+ if (m_f->LastRead() != lsdbSize)
+ {
+ return wxGIF_INVFORMAT;
+ }
+
m_screenw = buf[0] + 256 * buf[1];
m_screenh = buf[2] + 256 * buf[3];
/* load global color map if available */
if ((buf[4] & 0x80) == 0x80)
{
- m_background = buf[5];
-
- ncolors = 2 << (buf[4] & 0x07);
- m_f->Read(pal, 3 * ncolors);
+ m_background = buf[5];
+
+ ncolors = 2 << (buf[4] & 0x07);
+ size_t numBytes = 3 * ncolors;
+ m_f->Read(pal, numBytes);
+ if (m_f->LastRead() != numBytes)
+ {
+ return wxGIF_INVFORMAT;
+ }
}
/* transparent colour, disposal method and delay default to unused */
while(!done)
{
- type = (unsigned char)m_f->GetC();
-
- /* end of data? */
- if (type == 0x3B)
- {
- done = TRUE;
- }
- else
- /* extension block? */
- if (type == 0x21)
- {
- if (((unsigned char)m_f->GetC()) == 0xF9)
- /* graphics control extension, parse it */
- {
- m_f->Read(buf, 6);
-
- /* read delay and convert from 1/100 of a second to ms */
- delay = 10 * (buf[2] + 256 * buf[3]);
-
- /* read transparent colour index, if used */
- if (buf[1] & 0x01)
- transparent = buf[4];
-
- /* read disposal method */
- disposal = (buf[1] & 0x1C) - 1;
- }
- else
- /* other extension, skip */
- {
- while ((i = (unsigned char)m_f->GetC()) != 0)
- {
- m_f->SeekI(i, wxFromCurrent);
- }
- }
- }
- else
- /* image descriptor block? */
- if (type == 0x2C)
- {
- /* allocate memory for IMAGEN struct */
- pimg = (*ppimg) = new GIFImage();
-
- if (pimg == NULL)
- {
- Destroy();
- return wxGIF_MEMERR;
- }
-
- /* fill in the data */
- m_f->Read(buf, 9);
- pimg->left = buf[0] + 256 * buf[1];
- pimg->top = buf[2] + 256 * buf[3];
+ type = (unsigned char)m_f->GetC();
+
+ /*
+ If the end of file has been reached (or an error) and a ";"
+ (0x3B) hasn't been encountered yet, exit the loop. (Without this
+ check the while loop would loop endlessly.) Later on, in the next while
+ loop, the file will be treated as being truncated (But still
+ be decoded as far as possible). returning wxGIF_TRUNCATED is not
+ possible here since some init code is done after this loop.
+ */
+ if (m_f->Eof())// || !m_f->IsOk())
+ {
+ /*
+ type is set to some bogus value, so there's no
+ need to continue evaluating it.
+ */
+ break; // Alternative : "return wxGIF_INVFORMAT;"
+ }
+
+ /* end of data? */
+ if (type == 0x3B)
+ {
+ done = TRUE;
+ }
+ else
+ /* extension block? */
+ if (type == 0x21)
+ {
+ if (((unsigned char)m_f->GetC()) == 0xF9)
+ /* graphics control extension, parse it */
+ {
+ static const size_t gceSize = 6;
+ m_f->Read(buf, gceSize);
+ if (m_f->LastRead() != gceSize)
+ {
+ Destroy();
+ return wxGIF_INVFORMAT;
+ }
+
+ /* read delay and convert from 1/100 of a second to ms */
+ delay = 10 * (buf[2] + 256 * buf[3]);
+
+ /* read transparent colour index, if used */
+ if (buf[1] & 0x01)
+ transparent = buf[4];
+
+ /* read disposal method */
+ disposal = (buf[1] & 0x1C) - 1;
+ }
+ else
+ /* other extension, skip */
+ {
+ while ((i = (unsigned char)m_f->GetC()) != 0)
+ {
+ m_f->SeekI(i, wxFromCurrent);
+ if (m_f->Eof())
+ {
+ done = TRUE;
+ break;
+ }
+ }
+ }
+ }
+ else
+ /* image descriptor block? */
+ if (type == 0x2C)
+ {
+ /* allocate memory for IMAGEN struct */
+ pimg = (*ppimg) = new GIFImage();
+
+ if (pimg == NULL)
+ {
+ Destroy();
+ return wxGIF_MEMERR;
+ }
+
+ /* fill in the data */
+ static const size_t idbSize = (2 + 2 + 2 + 2 + 1);
+ m_f->Read(buf, idbSize);
+ if (m_f->LastRead() != idbSize)
+ {
+ Destroy();
+ return wxGIF_INVFORMAT;
+ }
+
+ pimg->left = buf[0] + 256 * buf[1];
+ pimg->top = buf[2] + 256 * buf[3];
/*
- pimg->left = buf[4] + 256 * buf[5];
- pimg->top = buf[4] + 256 * buf[5];
+ pimg->left = buf[4] + 256 * buf[5];
+ pimg->top = buf[4] + 256 * buf[5];
*/
- pimg->w = buf[4] + 256 * buf[5];
- pimg->h = buf[6] + 256 * buf[7];
- interl = ((buf[8] & 0x40)? 1 : 0);
- size = pimg->w * pimg->h;
-
- pimg->transparent = transparent;
- pimg->disposal = disposal;
- pimg->delay = delay;
- pimg->next = NULL;
- pimg->prev = pprev;
- pprev = pimg;
- ppimg = &pimg->next;
-
- /* allocate memory for image and palette */
- pimg->p = (unsigned char *) malloc((size_t)size);
- pimg->pal = (unsigned char *) malloc(768);
-
- if ((!pimg->p) || (!pimg->pal))
- {
- Destroy();
- return wxGIF_MEMERR;
- }
-
- /* load local color map if available, else use global map */
- if ((buf[8] & 0x80) == 0x80)
- {
- ncolors = 2 << (buf[8] & 0x07);
- m_f->Read(pimg->pal, 3 * ncolors);
- }
- else
- memcpy(pimg->pal, pal, 768);
-
- /* get initial code size from first byte in raster data */
- bits = (unsigned char)m_f->GetC();
-
- /* decode image */
- dgif(pimg, interl, bits);
- m_nimages++;
-
- /* if this is not an animated GIF, exit after first image */
- if (!m_anim)
- done = TRUE;
- }
+ pimg->w = buf[4] + 256 * buf[5];
+ pimg->h = buf[6] + 256 * buf[7];
+
+ if (pimg->w == 0 || pimg->h == 0)
+ {
+ Destroy();
+ return wxGIF_INVFORMAT;
+ }
+
+ interl = ((buf[8] & 0x40)? 1 : 0);
+ size = pimg->w * pimg->h;
+
+ pimg->transparent = transparent;
+ pimg->disposal = disposal;
+ pimg->delay = delay;
+ pimg->next = NULL;
+ pimg->prev = pprev;
+ pprev = pimg;
+ ppimg = &pimg->next;
+
+ /* allocate memory for image and palette */
+ pimg->p = (unsigned char *) malloc((size_t)size);
+ pimg->pal = (unsigned char *) malloc(768);
+
+ if ((!pimg->p) || (!pimg->pal))
+ {
+ Destroy();
+ return wxGIF_MEMERR;
+ }
+
+ /* load local color map if available, else use global map */
+ if ((buf[8] & 0x80) == 0x80)
+ {
+ ncolors = 2 << (buf[8] & 0x07);
+ size_t numBytes = 3 * ncolors;
+ m_f->Read(pimg->pal, numBytes);
+ if (m_f->LastRead() != numBytes)
+ {
+ Destroy();
+ return wxGIF_INVFORMAT;
+ }
+ }
+ else
+ {
+ memcpy(pimg->pal, pal, 768);
+ }
+
+ /* get initial code size from first byte in raster data */
+ bits = (unsigned char)m_f->GetC();
+
+ /* decode image */
+ int result = dgif(pimg, interl, bits);
+ if (result != wxGIF_OK)
+ {
+ Destroy();
+ return result;
+ }
+ m_nimages++;
+
+ /* if this is not an animated GIF, exit after first image */
+ if (!m_anim)
+ done = TRUE;
+ }
}
- /* setup image pointers */
- if (m_nimages != 0)
+ if (m_nimages == 0)
{
- m_image = 1;
- m_plast = pimg;
- m_pimage = m_pfirst;
+ Destroy();
+ return wxGIF_INVFORMAT;
}
+ /* setup image pointers */
+ m_image = 1;
+ m_plast = pimg;
+ m_pimage = m_pfirst;
+
/* try to read to the end of the stream */
while (type != 0x3B)
{
- type = (unsigned char)m_f->GetC();
-
- if (type == 0x21)
- {
- /* extension type */
- (void) m_f->GetC();
-
- /* skip all data */
- while ((i = (unsigned char)m_f->GetC()) != 0)
- {
- m_f->SeekI(i, wxFromCurrent);
- }
- }
- else if (type == 0x2C)
- {
- /* image descriptor block */
- m_f->Read(buf, 9);
-
- /* local color map */
- if ((buf[8] & 0x80) == 0x80)
- {
- ncolors = 2 << (buf[8] & 0x07);
- m_f->SeekI(3 * ncolors, wxFromCurrent);
- }
-
- /* initial code size */
- (void) m_f->GetC();
-
- /* skip all data */
- while ((i = (unsigned char)m_f->GetC()) != 0)
- {
- m_f->SeekI(i, wxFromCurrent);
- }
- }
- else if ((type != 0x3B) && (type != 00)) /* testing */
- {
- /* images are OK, but couldn't read to the end of the stream */
- return wxGIF_TRUNCATED;
- }
+ if (!m_f->IsOk())
+ return wxGIF_TRUNCATED;
+
+ type = (unsigned char)m_f->GetC();
+
+ if (type == 0x21)
+ {
+ /* extension type */
+ (void) m_f->GetC();
+
+ /* skip all data */
+ while ((i = (unsigned char)m_f->GetC()) != 0)
+ {
+ m_f->SeekI(i, wxFromCurrent);
+ }
+ }
+ else if (type == 0x2C)
+ {
+ /* image descriptor block */
+ static const size_t idbSize = (2 + 2 + 2 + 2 + 1);
+ m_f->Read(buf, idbSize);
+ if (m_f->LastRead() != idbSize)
+ {
+ Destroy();
+ return wxGIF_INVFORMAT;
+ }
+
+ /* local color map */
+ if ((buf[8] & 0x80) == 0x80)
+ {
+ ncolors = 2 << (buf[8] & 0x07);
+ off_t pos = m_f->TellI();
+ off_t numBytes = 3 * ncolors;
+ m_f->SeekI(numBytes, wxFromCurrent);
+ if (m_f->TellI() != (pos + numBytes))
+ {
+ Destroy();
+ return wxGIF_INVFORMAT;
+ }
+ }
+
+ /* initial code size */
+ (void) m_f->GetC();
+
+ /* skip all data */
+ while ((i = (unsigned char)m_f->GetC()) != 0)
+ {
+ m_f->SeekI(i, wxFromCurrent);
+ }
+ }
+ else if ((type != 0x3B) && (type != 00)) /* testing */
+ {
+ /* images are OK, but couldn't read to the end of the stream */
+ return wxGIF_TRUNCATED;
+ }
}
return wxGIF_OK;
projects / wxWidgets.git / blobdiff