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FIX: set max row count to avoid iterating off the end of the data buffer #22

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FIX: set max row count to avoid iterating off the end of the data buffer #22

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a6f27c7
FIX: set max row count to avoid iterating off the end of the data buffer
ZLLentz Dec 18, 2024
bd0c62c
ENH: add a warning for buffer size mismatch
ZLLentz Dec 19, 2024
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31 changes: 20 additions & 11 deletions pycaqtimage/pycaqtimage.sip
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Original file line number Diff line number Diff line change
Expand Up @@ -349,8 +349,17 @@ static int rowIncMult1[8] = { 0, 0, -1, -1, 0, 0, 1, 1}; /* Scaled
static int rowIncMult2[8] = { 0, 2, 0, 0, 0, -2, 0, 0}; /* Scaled by srcwidth */
static int rowIncK[8] = { 0, 0, -1, 1, 0, 0, 1, -1}; /* Constant */

int _max_row(ImageBuffer *imageBuffer, long count)
{
if (imageBuffer->imgwidth > 0) {
return std::min(imageBuffer->imgheight, (int) std::floor(count / imageBuffer->imgwidth));
} else {
return 0;
}
}

Comment on lines +352 to +360
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@janeliu-slac janeliu-slac Dec 19, 2024 •
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This is minor but if using a modern C++ approach I think a smart pointer is considered best practice. Raw pointers should be used only when performance/memory management are critical.

If only one pointer for ImageBuffer is needed, std::unique_ptr would work.

#include <memory> 

int _max_row(unique_ptr<ImageBuffer> imageBuffer, long count)
{
    if (imageBuffer->imgwidth > 0) {
        return std::min(imageBuffer->imgheight, (int) std::floor(count / imageBuffer->imgwidth));
    } else {
        return 0;
    }
}

Regarding the buffer overflow problem--if the program uses std::vector, std::array or other dynamically sized containers similar to a python list maybe this issue can be avoided. Raw arrays is probably one of the major reasons the world moved away from C.

template <class T>
void _pyDoAvg(ImageBuffer *imageBuffer, T *cadata)
void _pyDoAvg(ImageBuffer *imageBuffer, T *cadata, long count)
{
T *src = cadata;
uint32_t *dst = imageBuffer->imageData;
Expand All @@ -365,10 +374,11 @@ void _pyDoAvg(ImageBuffer *imageBuffer, T *cadata)
int col_inc = imageBuffer->srcwidth * colIncMult[orientation] +
colIncK[orientation];
int iNewAverage = imageBuffer->iNumAveraged + 1;
int row_max = _max_row(imageBuffer, count);

src += init_offset;
if (iNewAverage == 1) {
for (int iRow = 0; iRow < imageBuffer->imgheight; ++iRow) {
for (int iRow = 0; iRow < row_max; ++iRow) {
for (int iCol = 0; iCol < imageBuffer->imgwidth; ++iCol) {
*dstF++ = *src;
*dst++ = *src;
Expand All @@ -377,7 +387,7 @@ void _pyDoAvg(ImageBuffer *imageBuffer, T *cadata)
src += row_inc;
}
} else {
for (int iRow = 0; iRow < imageBuffer->imgheight; ++iRow) {
for (int iRow = 0; iRow < row_max; ++iRow) {
for (int iCol = 0; iCol < imageBuffer->imgwidth; ++iCol) {
*dstF += (*src - *dstF) / iNewAverage;
*dst++ = *dstF++;
Expand Down Expand Up @@ -408,14 +418,14 @@ static void _pyColorImagePvCallback(void* cadata, long count, size_t size, void*
int col_inc = imageBuffer->srcwidth * colIncMult[orientation] +
colIncK[orientation];
int iNewAverage = imageBuffer->iNumAveraged + 1;
int row_max = _max_row(imageBuffer, count);

UNUSED(count);
UNUSED(size);

/* If we're using the color image, don't average, just copy and we're done! */
if (!imageBuffer->useGray) {
src += 3 * init_offset;
for (int iRow = 0; iRow < imageBuffer->imgheight; ++iRow) {
for (int iRow = 0; iRow < row_max; ++iRow) {
for (int iCol = 0; iCol < imageBuffer->imgwidth; ++iCol) {
*dst++ = RGB(src);
src += 3 * col_inc;
Expand All @@ -426,7 +436,7 @@ static void _pyColorImagePvCallback(void* cadata, long count, size_t size, void*
} else {
if (iNewAverage == 1) {
src += 3 * init_offset;
for (int iRow = 0; iRow < imageBuffer->imgheight; ++iRow) {
for (int iRow = 0; iRow < row_max; ++iRow) {
for (int iCol = 0; iCol < imageBuffer->imgwidth; ++iCol) {
*dstF = GRAY(src);
*dst++ = *dstF++;
Expand All @@ -436,7 +446,7 @@ static void _pyColorImagePvCallback(void* cadata, long count, size_t size, void*
}
} else {
src += 3 * init_offset;
for (int iRow = 0; iRow < imageBuffer->imgheight; ++iRow) {
for (int iRow = 0; iRow < row_max; ++iRow) {
for (int iCol = 0; iCol < imageBuffer->imgwidth; ++iCol) {
*dstF += (GRAY(src) - *dstF) / iNewAverage;
*dst++ = *dstF++;
Expand All @@ -456,16 +466,15 @@ static void _pyImagePvCallback(void* cadata, long count, size_t size, void* usr)
{
ImageBuffer* imageBuffer = reinterpret_cast<ImageBuffer*>(usr);

UNUSED(count);
switch (size) {
case 4:
_pyDoAvg(imageBuffer, reinterpret_cast<uint32_t*>(cadata));
_pyDoAvg(imageBuffer, reinterpret_cast<uint32_t*>(cadata), count);
break;
case 2:
_pyDoAvg(imageBuffer, reinterpret_cast<uint16_t*>(cadata));
_pyDoAvg(imageBuffer, reinterpret_cast<uint16_t*>(cadata), count);
break;
case 1:
_pyDoAvg(imageBuffer, reinterpret_cast<uint8_t*>(cadata));
_pyDoAvg(imageBuffer, reinterpret_cast<uint8_t*>(cadata), count);
break;
default:
fprintf(stderr, "Image pixel size is %d bytes?\n", (int) size);
Expand Down