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Prevent crashing when processing content stream (#291)

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* Skip invalid pop operation on empty graphics state stacks
* Fix clipping input values to size for Type 0 Functions
* Do not pass invalid Q content stream operator to external handlers
This commit is contained in:
Adrian-George Bostan 2020-04-01 23:08:41 +03:00 committed by GitHub
parent c582323a8f
commit 64a43b38d2
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2 changed files with 6 additions and 3 deletions
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4
contentstream/processor.go
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@ -230,6 +230,10 @@ func (proc *ContentStreamProcessor) Process(resources *model.PdfPageResources) e
case "q":
proc.graphicsStack.Push(proc.graphicsState)
case "Q":
if len(proc.graphicsStack) == 0 {
common.Log.Debug("WARN: invalid `Q` operator. Graphics state stack is empty. Skipping.")
continue
}
proc.graphicsState = proc.graphicsStack.Pop()
// Color operations (Table 74 p. 179)

5
model/functions.go
View File

@ -306,10 +306,10 @@ func (f *PdfFunctionType0) Evaluate(x []float64) ([]float64, error) {
for i := 0; i < len(x); i++ {
xi := x[i]
// See section 7.10.2 Type 0 (Sampled) Functions (pp. 93-94 PDF32000_2008).
xip := math.Min(math.Max(xi, f.Domain[2*i]), f.Domain[2*i+1])
ei := interpolate(xip, f.Domain[2*i], f.Domain[2*i+1], encode[2*i], encode[2*i+1])
eip := math.Min(math.Max(ei, 0), float64(f.Size[i]))
eip := math.Min(math.Max(ei, 0), float64(f.Size[i]-1))
// eip represents coordinate into the data table.
// At this point it is real values.
@ -325,7 +325,6 @@ func (f *PdfFunctionType0) Evaluate(x []float64) ([]float64, error) {
index = f.Size[i] - 1
}
indices = append(indices, index)
}
// Calculate the index