pdftopdf: Honor inherited MediaBox, CropBox and Rotate attributes

Makefile.am

@@ -95,7 +95,8 @@ check_SCRIPTS = \
 	cupsfilters/testfilters.sh \
 	cupsfilters/test-pclm-overflow.sh \
 	cupsfilters/test-pwgtopdf-bit-row.sh \
-	cupsfilters/test-pdftoraster-copy-height.sh
+	cupsfilters/test-pdftoraster-copy-height.sh \
+	cupsfilters/test-pdftopdf-inherited-mediabox.sh
 
 check_PROGRAMS = \
 	testcmyk \
@@ -122,7 +123,8 @@ TESTS = \
 	cupsfilters/testfilters.sh \
 	cupsfilters/test-pclm-overflow.sh \
 	cupsfilters/test-pwgtopdf-bit-row.sh \
-	cupsfilters/test-pdftoraster-copy-height.sh
+	cupsfilters/test-pdftoraster-copy-height.sh \
+	cupsfilters/test-pdftopdf-inherited-mediabox.sh
 
 #	testcmyk # fails as it opens some image.ppm which is nowerhe to be found.
 #	testimage # requires also some ppm file as argument
@@ -358,6 +360,7 @@ EXTRA_DIST += cupsfilters/gen-lorem-text.c
 # (not a check_PROGRAM, so it can skip when ASan is absent); named here so it
 # ships in "make dist".
 EXTRA_DIST += cupsfilters/test-pdftoraster-copy-height.c
+EXTRA_DIST += cupsfilters/test-pdftopdf-inherited-mediabox.c
 # Generated deterministic lorem text for texttopdf tests
 BUILT_SOURCES = cupsfilters/test_files/test_text_lorem.txt
 CLEANFILES   = cupsfilters/test_files/test_text_lorem.txt
@@ -375,6 +378,7 @@ EXTRA_DIST += \
 	cupsfilters/test-filter-cases.txt \
 	cupsfilters/test_files/filled-2.pdf \
 	cupsfilters/test_files/form_english.pdf \
+	cupsfilters/test_files/inherited_mediabox.pdf \
 	cupsfilters/test_files/malformed.pdf \
 	cupsfilters/test_files/onepage-a4-adobe-rgb-8-150dpi.pwg \
 	cupsfilters/test_files/test_file_1pg.pdf \

cupsfilters/pdftopdf.c

@@ -250,6 +250,80 @@ media_to_rect(cups_media_t *size,       // I - CUPS media (size) information
   crop->y2  = 72.0 * (size->length - size->top) / 2540.0;
 }
 
+//
+// 'page_get_rect()' - Look up an inheritable rectangle attribute ("MediaBox"
+//                     or "CropBox") for a page.
+//
+// Page attributes may be inherited from ancestor /Pages nodes (ISO 32000-1
+// section 7.7.3.4), so walk up the /Parent chain.  Also resolve an indirect
+// reference to the rectangle array, which pdfioDictGetRect() does not do.
+//
+
+static bool                             // O - `true` if found, `false` otherwise
+page_get_rect(pdfio_obj_t  *page,       // I - Page object
+              const char   *key,        // I - Key ("MediaBox" or "CropBox")
+              pdfio_rect_t *rect)       // O - Rectangle
+{
+  pdfio_obj_t   *obj = page;            // Current page/pages node
+  pdfio_dict_t  *dict;                  // Current dictionary
+  pdfio_obj_t   *ref;                   // Indirect rectangle array object
+  pdfio_array_t *array;                 // Rectangle array
+  int           depth;                  // Loop guard against cyclic /Parent
+
+
+  for (depth = 0; obj && depth < 64; depth ++)
+  {
+    if ((dict = pdfioObjGetDict(obj)) == NULL)
+      break;
+
+    if (pdfioDictGetRect(dict, key, rect))
+      return (true);
+
+    if ((ref = pdfioDictGetObj(dict, key)) != NULL && (array = pdfioObjGetArray(ref)) != NULL && pdfioArrayGetSize(array) == 4)
+    {
+      rect->x1 = pdfioArrayGetNumber(array, 0);
+      rect->y1 = pdfioArrayGetNumber(array, 1);
+      rect->x2 = pdfioArrayGetNumber(array, 2);
+      rect->y2 = pdfioArrayGetNumber(array, 3);
+      return (true);
+    }
+
+    obj = pdfioDictGetObj(dict, "Parent");
+  }
+
+  memset(rect, 0, sizeof(pdfio_rect_t));
+  return (false);
+}
+
+
+//
+// 'page_get_rotate()' - Look up the inheritable /Rotate attribute for a page,
+//                       walking up the /Parent chain.
+//
+
+static int                              // O - Rotation in degrees (0 if unset)
+page_get_rotate(pdfio_obj_t *page)      // I - Page object
+{
+  pdfio_obj_t   *obj = page;            // Current page/pages node
+  pdfio_dict_t  *dict;                  // Current dictionary
+  int           depth;                  // Loop guard against cyclic /Parent
+
+
+  for (depth = 0; obj && depth < 64; depth ++)
+  {
+    if ((dict = pdfioObjGetDict(obj)) == NULL)
+      break;
+
+    if (pdfioDictGetType(dict, "Rotate") == PDFIO_VALTYPE_NUMBER)
+      return ((int)pdfioDictGetNumber(dict, "Rotate"));
+
+    obj = pdfioDictGetObj(dict, "Parent");
+  }
+
+  return (0);
+}
+
+
 //
 // 'prepare_log()' - Log an informational or error message while preparing
 //                   documents for printing.
@@ -1518,7 +1592,7 @@ flatten_pdf(xform_prepare_t *p,			// I - Preparation data
   idict = pdfioObjGetDict(outpage->input[pg]); 
 
   annotsArray = pdfioDictGetArray(idict, "Annots"); 
-  rotate_val = (int)pdfioDictGetNumber(idict, "Rotate"); 
+  rotate_val = page_get_rotate(outpage->input[pg]);
   count = pdfioArrayGetSize(annotsArray); 
 
   p->annotation_contents = (char**)malloc(count * sizeof(char*)); 
@@ -2044,10 +2118,10 @@ copy_page(xform_prepare_t *p,		// I - Preparation data
   // Transform input page to output cell...
   idict = pdfioObjGetDict(outpage->input[layout]);
 
-  if (!pdfioDictGetRect(idict, "CropBox", &irect))
+  if (!page_get_rect(outpage->input[layout], "CropBox", &irect))
   {
     // No crop box, use media box...
-    if (!pdfioDictGetRect(idict, "MediaBox", &irect))
+    if (!page_get_rect(outpage->input[layout], "MediaBox", &irect))
     {
       // No media box, use output page size...
       irect = p->media;

cupsfilters/test-pdftopdf-inherited-mediabox.c

@@ -0,0 +1,127 @@
+//
+// Checker for test-pdftopdf-inherited-mediabox.sh: read back the PDF that
+// cfFilterPDFToPDF() produced from test_files/inherited_mediabox.pdf and
+// inspect the transformation applied to the input page.
+//
+// The input page is 2970x2100 pt with its MediaBox inherited from the
+// /Pages node; printed on Letter with print-scaling=auto it has to be
+// scaled down (by about 0.26) and rotated by 90 degrees.  When the
+// inherited MediaBox is ignored, pdftopdf assumes the input page is already
+// Letter-sized and emits a ~0.97 scale without rotation.
+//
+// Copyright © 2026 by OpenPrinting
+//
+// Licensed under Apache License v2.0.  See the file "LICENSE" for more
+// information.
+//
+
+#include <pdfio.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+//
+// 'main()' - Check the first "cm" operator of page 1.
+//
+
+int					// O - 0 on success, 1 on failure
+main(int  argc,				// I - Number of command-line arguments
+     char *argv[])			// I - Command-line arguments
+{
+  pdfio_file_t	*pdf;			// Output PDF from pdftopdf
+  pdfio_obj_t	*page;			// First page
+  pdfio_stream_t *st;			// Content stream
+  size_t	i,			// Looping var
+		num_streams;		// Number of content streams
+  char		token[256],		// Current token
+		*end;			// End of numeric token
+  double	value,			// Numeric token value
+		matrix[6];		// Last six numbers seen
+  int		num_values = 0,		// Number of numbers in the window
+		found = 0;		// Found a "cm" operator?
+  double	scale;			// Scale factor of the matrix
+
+
+  if (argc != 2)
+  {
+    fputs("Usage: test-pdftopdf-inherited-mediabox OUTPUT.pdf\n", stderr);
+    return (1);
+  }
+
+  if ((pdf = pdfioFileOpen(argv[1], NULL, NULL, NULL, NULL)) == NULL)
+  {
+    fprintf(stderr, "Unable to open \"%s\".\n", argv[1]);
+    return (1);
+  }
+
+  if (pdfioFileGetNumPages(pdf) != 1)
+  {
+    fprintf(stderr, "Expected 1 output page, got %u.\n", (unsigned)pdfioFileGetNumPages(pdf));
+    return (1);
+  }
+
+  page        = pdfioFileGetPage(pdf, 0);
+  num_streams = pdfioPageGetNumStreams(page);
+
+  for (i = 0; i < num_streams && !found; i ++)
+  {
+    if ((st = pdfioPageOpenStream(page, i, true)) == NULL)
+    {
+      fprintf(stderr, "Unable to open content stream %u.\n", (unsigned)i);
+      return (1);
+    }
+
+    while (pdfioStreamGetToken(st, token, sizeof(token)))
+    {
+      value = strtod(token, &end);
+
+      if (end > token && !*end)
+      {
+        // Number: keep the last six...
+        if (num_values == 6)
+          memmove(matrix, matrix + 1, 5 * sizeof(double));
+        else
+          num_values ++;
+
+        matrix[num_values - 1] = value;
+      }
+      else if (!strcmp(token, "cm") && num_values == 6)
+      {
+        found = 1;
+        break;
+      }
+      else
+        num_values = 0;
+    }
+
+    pdfioStreamClose(st);
+  }
+
+  pdfioFileClose(pdf);
+
+  if (!found)
+  {
+    fputs("No \"cm\" operator found on page 1.\n", stderr);
+    return (1);
+  }
+
+  scale = hypot(matrix[0], matrix[1]);
+
+  printf("cm = [%g %g %g %g %g %g], scale = %g\n", matrix[0], matrix[1], matrix[2], matrix[3], matrix[4], matrix[5], scale);
+
+  if (scale < 0.1 || scale > 0.5)
+  {
+    fputs("Input page was not scaled to fit: inherited MediaBox ignored?\n", stderr);
+    return (1);
+  }
+
+  if (fabs(matrix[0]) > 1e-6 || fabs(matrix[3]) > 1e-6)
+  {
+    fputs("Input page was not rotated to fit: inherited MediaBox ignored?\n", stderr);
+    return (1);
+  }
+
+  return (0);
+}

cupsfilters/test-pdftopdf-inherited-mediabox.sh

@@ -0,0 +1,71 @@
+#!/usr/bin/env bash
+#
+# Regression test: cfFilterPDFToPDF() must honor inheritable page attributes.
+#
+# /MediaBox, /CropBox and /Rotate may be defined on an ancestor /Pages node
+# instead of on the /Page itself (ISO 32000-1, 7.7.3.4), and the value may
+# be an indirect reference.  The PDFio-based pdftopdf used to read these
+# keys only from the page dictionary, so a page with an inherited MediaBox
+# was taken to be the output page size already: no scaling, no
+# auto-rotation, and an oversized page came out cropped to its lower-left
+# corner.
+#
+# test_files/inherited_mediabox.pdf is a single 2970x2100 pt page whose
+# MediaBox is only defined, as an indirect array, on the /Pages node.  We
+# run it through pdftopdf for Letter with print-scaling=auto via the
+# testfilters harness and then read the output back with PDFio (see
+# test-pdftopdf-inherited-mediabox.c): the page transform must scale by
+# roughly 0.26 and rotate by 90 degrees.
+#
+# Like testfilters.sh, this runs from the top-level build directory and
+# passes file names relative to it: testfilters copies the case file names
+# into 100-byte buffers, so long absolute paths must be avoided.
+#
+set -euo pipefail
+
+CC="${CC:-cc}"
+
+TESTFILTERS="./testfilters"
+if [[ ! -x "${TESTFILTERS}" ]]; then
+  echo "testfilters harness not found at ${TESTFILTERS}" >&2
+  exit 99
+fi
+
+FIXTURE="cupsfilters/test_files/inherited_mediabox.pdf"
+CHECKER_SRC="cupsfilters/test-pdftopdf-inherited-mediabox.c"
+for f in "${FIXTURE}" "${CHECKER_SRC}"; do
+  if [[ ! -f "${f}" ]]; then
+    echo "test file not found: ${f}" >&2
+    exit 99
+  fi
+done
+
+PKG_CFLAGS="$(pkg-config --cflags pdfio 2>/dev/null || true)"
+PKG_LIBS="$(pkg-config --libs pdfio 2>/dev/null || true)"
+if [[ -z "${PKG_LIBS}" ]]; then
+  echo "pkg-config cannot find pdfio; skipping." >&2
+  exit 77
+fi
+
+WORKDIR="$(mktemp -d ./inherited-mediabox.XXXXXX)"
+cleanup() { rm -rf "${WORKDIR}"; }
+trap cleanup EXIT
+
+CASES="${WORKDIR}/cases.txt"
+OUTPUT="${WORKDIR}/output.pdf"
+CHECKER="${WORKDIR}/check"
+
+# One testfilters case: fixture -> pdftopdf -> Letter PDF.
+printf '%s\tapplication/pdf\t%s\tapplication/pdf\tGeneric\tPDF Color 2\t1\t1\tapplication/pdf\t42\tinherited-user\tinherited-mediabox\t1\tmedia-size=letter print-scaling=auto\tpdftopdf\n' \
+  "${FIXTURE}" "${OUTPUT}" > "${CASES}"
+
+"${TESTFILTERS}" "${CASES}"
+
+if [[ ! -s "${OUTPUT}" ]]; then
+  echo "pdftopdf produced no output" >&2
+  exit 1
+fi
+
+"${CC}" -std=gnu11 -O0 ${PKG_CFLAGS} "${CHECKER_SRC}" ${PKG_LIBS} -lm -o "${CHECKER}"
+
+"${CHECKER}" "${OUTPUT}"