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fix(preview): Hardening against errors and silent DB corruptions #58857

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solracsf wants to merge 2 commits into from
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fix(preview): Hardening against errors and silent DB corruptions #58857

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bde504b
fix(preview): Hardening against errors and silent DB corruptions
solracsf Mar 11, 2026
3023b33
fix
solracsf Mar 11, 2026
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149 changes: 100 additions & 49 deletions lib/private/Preview/Generator.php
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Original file line number Diff line number Diff line change
Expand Up @@ -418,81 +418,113 @@ private function generateProviderPreview(File $file, int $width, int $height, bo
* @return int[]
*/
private function calculateSize(int $width, int $height, bool $crop, string $mode, int $maxWidth, int $maxHeight): array {
// Prevent fatal DivisionByZeroError
if ($maxWidth === 0 || $maxHeight === 0) {
return [0, 0];
}

// Use float variables for JIT optimization to prevent type juggling overhead
$calcWidth = (float)$width;
$calcHeight = (float)$height;

// Handle the edge case where both dimensions are -1 (auto).
// Prevents cascading negative values in the logic below.
if ($width === -1 && $height === -1) {
$calcWidth = (float)$maxWidth;
$calcHeight = (float)$maxHeight;
}

/*
* If we are not cropping we have to make sure the requested image
* respects the aspect ratio of the original.
*/
if (!$crop) {
$ratio = $maxHeight / $maxWidth;

if ($width === -1) {
$width = $height / $ratio;
// If both dimensions are provided and > 0, calculate the ratio from the requested
// dimensions to preserve the intended aspect ratio. Fallback to max bounds ratio otherwise.
if ($width !== -1 && $height !== -1 && $calcWidth > 0 && $calcHeight > 0) {
$ratio = $calcHeight / $calcWidth;
} else {
$ratio = $maxHeight / $maxWidth;
}
if ($height === -1) {
$height = $width * $ratio;

// Clean control flow preventing redundant logic and division by zero
if ($width === -1 && $height !== -1) {
$calcWidth = $calcHeight / $ratio;
} elseif ($height === -1 && $width !== -1) {
$calcHeight = $calcWidth * $ratio;
}

$ratioH = $height / $maxHeight;
$ratioW = $width / $maxWidth;
$ratioH = $calcHeight / $maxHeight;
$ratioW = $calcWidth / $maxWidth;

/*
* Fill means that the $height and $width are the max
* Cover means min.
*/
if ($mode === IPreview::MODE_FILL) {
if ($ratioH > $ratioW) {
$height = $width * $ratio;
$calcHeight = $calcWidth * $ratio;
} else {
$width = $height / $ratio;
$calcWidth = $calcHeight / $ratio;
}
} elseif ($mode === IPreview::MODE_COVER) {
if ($ratioH > $ratioW) {
$width = $height / $ratio;
$calcWidth = $calcHeight / $ratio;
} else {
$height = $width * $ratio;
$calcHeight = $calcWidth * $ratio;
}
}
}

if ($height !== $maxHeight && $width !== $maxWidth) {
/*
* Safe float comparison. Using (int)round() prevents false
* positives caused by float precision issues (e.g. 100.0000001 !== 100.0)
*/
if ((int)round($calcHeight) !== $maxHeight && ((int)round($calcWidth) !== $maxWidth)) {

// Protect log() and subsequent divisions against <= 0 values
$safeHeight = max(1.0, $calcHeight);
$safeWidth = max(1.0, $calcWidth);

/*
* Scale to the nearest power of four
* Scale to the nearest power of four.
*/
$pow4height = 4 ** ceil(log($height) / log(4));
$pow4width = 4 ** ceil(log($width) / log(4));
$pow4height = 4 ** ceil(log($safeHeight, 4));
$pow4width = 4 ** ceil(log($safeWidth, 4));

// Minimum size is 64
$pow4height = max($pow4height, 64);
$pow4width = max($pow4width, 64);
$pow4height = max($pow4height, 64.0);
$pow4width = max($pow4width, 64.0);

$ratioH = $height / $pow4height;
$ratioW = $width / $pow4width;
$ratioH = $safeHeight / $pow4height;
$ratioW = $safeWidth / $pow4width;

if ($ratioH < $ratioW) {
$width = $pow4width;
$height /= $ratioW;
$calcWidth = $pow4width;
$calcHeight /= $ratioW;
} else {
$height = $pow4height;
$width /= $ratioH;
$calcHeight = $pow4height;
$calcWidth /= $ratioH;
}
}

/*
* Make sure the requested height and width fall within the max
* of the preview.
*/
if ($height > $maxHeight) {
$ratio = $height / $maxHeight;
$height = $maxHeight;
$width /= $ratio;
if ($calcHeight > $maxHeight) {
$ratio = $calcHeight / $maxHeight;
$calcHeight = $maxHeight;
$calcWidth /= $ratio;
}
if ($width > $maxWidth) {
$ratio = $width / $maxWidth;
$width = $maxWidth;
$height /= $ratio;

if ($calcWidth > $maxWidth) {
$ratio = $calcWidth / $maxWidth;
$calcWidth = $maxWidth;
$calcHeight /= $ratio;
}

return [(int)round($width), (int)round($height)];
return [(int)round($calcWidth), (int)round($calcHeight)];
}

/**
Expand All @@ -511,30 +543,42 @@ private function generatePreview(
bool $cacheResult,
): ISimpleFile {
$preview = $maxPreview;
if (!$preview->valid()) {
throw new \InvalidArgumentException('Failed to generate preview, failed to load image');

// Check for valid dimensions to prevent DivisionByZeroError later
if (!$preview->valid() || $preview->width() <= 0 || $preview->height() <= 0) {
throw new \InvalidArgumentException('Failed to generate preview, invalid image dimensions');
}

// Protection against fatal DivisionByZeroError
if ($width <= 0 || $height <= 0) {
throw new \InvalidArgumentException('Target preview dimensions must be strictly positive');
}

$previewConcurrency = $this->getNumConcurrentPreviews('preview_concurrency_new');
$sem = self::guardWithSemaphore(self::SEMAPHORE_ID_NEW, $previewConcurrency);
try {
if ($crop) {
if ($height !== $preview->height() && $width !== $preview->width()) {
//Resize
$widthR = $preview->width() / $width;
$heightR = $preview->height() / $height;
// Resize
$widthR = (float)$preview->width() / (float)$width;
$heightR = (float)$preview->height() / (float)$height;

if ($widthR > $heightR) {
$scaleH = $height;
$scaleW = $maxWidth / $heightR;
$scaleH = (float)$height;
// Use $preview->width() instead of $maxWidth to calculate proportional scale.
$scaleW = (float)$preview->width() / $heightR;
} else {
$scaleH = $maxHeight / $widthR;
$scaleW = $width;
// Use $preview->height() instead of $maxHeight
$scaleH = (float)$preview->height() / $widthR;
$scaleW = (float)$width;
}
$preview = $preview->preciseResizeCopy((int)round($scaleW), (int)round($scaleH));
}
$cropX = (int)floor(abs($width - $preview->width()) * 0.5);
$cropY = (int)floor(abs($height - $preview->height()) * 0.5);

// Use max(0, excess) instead of abs() to prevent out-of-bounds
// crop if scaled image is slightly smaller than target due to float rounding.
$cropX = (int)floor(max(0.0, (float)$preview->width() - (float)$width) * 0.5);
$cropY = (int)floor(max(0.0, (float)$preview->height() - (float)$height) * 0.5);
$preview = $preview->cropCopy($cropX, $cropY, $width, $height);
} else {
$preview = $maxPreview->resizeCopy(max($width, $height));
Expand All @@ -543,13 +587,19 @@ private function generatePreview(
self::unguardWithSemaphore($sem);
}

if (!$preview->valid() || $preview->dataMimeType() === null) {
throw new \InvalidArgumentException('Preview generation failed: invalid or null MIME type');
$mime = $preview->dataMimeType();
if (!$preview->valid() || empty($mime)) {
throw new \InvalidArgumentException('Preview generation failed: invalid or empty MIME type');
}

$fileId = $file->getId();
if ($fileId === null) {
throw new \InvalidArgumentException('Cannot generate preview for an unpersisted file (null ID)');
}

$previewEntry = new Preview();
$previewEntry->generateId();
$previewEntry->setFileId($file->getId());
$previewEntry->setFileId($fileId);
$previewEntry->setStorageId($file->getMountPoint()->getNumericStorageId());
$previewEntry->setWidth($width);
$previewEntry->setSourceMimeType($file->getMimeType());
Expand All @@ -558,9 +608,10 @@ private function generatePreview(
$previewEntry->setMax(false);
$previewEntry->setCropped($crop);
$previewEntry->setEncrypted(false);
$previewEntry->setMimeType($preview->dataMimeType());
$previewEntry->setMimeType($mime);
$previewEntry->setEtag($file->getEtag());
$previewEntry->setMtime((new \DateTime())->getTimestamp());

$previewEntry->setMtime((new \DateTimeImmutable())->getTimestamp());

if ($cacheResult) {
$previewEntry = $this->savePreview($previewEntry, $preview);
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