cairo: fix raster_fuzzer — remove PDF API calls that prevent acquire callback

[OwenSanzas]

Summary

The raster_fuzzer harness is intended to test cairo's raster source pattern mechanism (the acquire/release callbacks). However, two misplaced calls to PDF-surface-specific APIs on an image surface contaminate the surface's error state, causing cairo_paint() to short-circuit. As a result, the acquire callback is never triggered, and the harness's core testing target is completely dead code.

Root Cause

In raster_fuzzer.c, lines 61–62:

cairo_pdf_surface_set_page_label(surface, buf);
cairo_pdf_surface_set_metadata(surface, CAIRO_PDF_METADATA_KEYWORDS, buf);

Here, surface is an image surface created by cairo_image_surface_create_from_png(). These two functions are designed exclusively for PDF surfaces. Internally, they call _extract_pdf_surface(), which checks whether the surface is paginated. When it is not, it sets the surface's error status to CAIRO_STATUS_SURFACE_TYPE_MISMATCH:

// cairo-pdf-surface.c: _extract_pdf_surface()
if (! _cairo_surface_is_paginated (surface)) {
    status_ignored = _cairo_surface_set_error (surface,
                       _cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH));
    return FALSE;
}

Once the surface enters this error state, cairo_paint() checks the target surface status and short-circuits without performing any drawing — so the raster source acquire callback is never invoked.

Verification

I wrote a standalone test program that isolates the issue:

Without PDF calls:

Surface status before paint: no error has occurred
ACQUIRE CALLBACK TRIGGERED (call #1)
RELEASE CALLBACK TRIGGERED
acquire_called after paint: 1

With PDF calls on image surface:

Surface status AFTER pdf_set_page_label: the surface type is not appropriate for the operation
acquire_called after paint: 0

The acquire callback fires normally without the PDF calls, but is never triggered when the PDF calls are present.

Coverage Comparison (600s each)

Metric	Original	Fixed	Diff
Line coverage	0.57%	0.65%	+0.08
Function coverage	1.12%	1.28%	+0.16
Branch coverage	0.27%	0.30%	+0.03

Fix

Remove the two PDF-specific calls and the unnecessary #include <cairo-pdf.h>. This allows cairo_paint() to proceed normally, triggering the acquire/release callbacks as intended.

[github-actions]

OwenSanzas is a new contributor to projects/cairo. The PR must be approved by known contributors before it can be merged. The past contributors are: hunsche, Teemperor, tysmith, DonggeLiu, salmonx, Google-Autofuzz, inferno-chromium, ecalp-tps