Fix object map to use unique file hash instead of pointer values (Issue #125)

CHANGES.md

@@ -27,6 +27,8 @@ v1.5.3 - YYYY-MM-DD
 - Fixed decryption of UTF-16 strings (Issue #42)
 - Fixed decryption of PDF files with large permission values.
 - Fixed support for EncryptMetadata key in the encryption dictionary.
+- Fixed `pdfioObjCopy` and `pdfioPageCopy` to properly identify the source PDF
+  file being used (Issue #125)
 
 
 v1.5.2 - 2025-04-12

examples/pdfiomerge.c

@@ -8,8 +8,8 @@
 //
 // Usage:
 //
-//   ./pdfmerge [-o OUTPUT.pdf] INPUT.pdf [... INPUT.pdf]
+//   ./pdfiomerge [-o OUTPUT.pdf] INPUT.pdf [... INPUT.pdf]
-//   ./pdfmerge INPUT.pdf [... INPUT.pdf] >OUTPUT.pdf
+//   ./pdfiomerge INPUT.pdf [... INPUT.pdf] >OUTPUT.pdf
 //
 
 #include <pdfio.h>
@@ -47,7 +47,7 @@ main(int  argc,				// I - Number of command-line arguments
     }
     else if (!strncmp(argv[i], "--", 2))
     {
-      fprintf(stderr, "pdfmerge: Unknown option '%s'.\n", argv[i]);
+      fprintf(stderr, "pdfiomerge: Unknown option '%s'.\n", argv[i]);
       return (usage(stderr));
     }
     else if (argv[i][0] == '-')
@@ -59,14 +59,14 @@ main(int  argc,				// I - Number of command-line arguments
           case 'o' : // -o OUTPUT.pdf
               if (outpdf)
               {
-                fputs("pdfmerge: Only one output file can be specified.\n", stderr);
+                fputs("pdfiomerge: Only one output file can be specified.\n", stderr);
                 return (usage(stderr));
               }
 
               i ++;
               if (i >= argc)
               {
-                fputs("pdfmerge: Missing output filename after '-o'.\n", stderr);
+                fputs("pdfiomerge: Missing output filename after '-o'.\n", stderr);
                 return (usage(stderr));
               }
 
@@ -75,7 +75,7 @@ main(int  argc,				// I - Number of command-line arguments
               break;
 
           default :
-              fprintf(stderr, "pdfmerge: Unknown option '-%c'.\n", *opt);
+              fprintf(stderr, "pdfiomerge: Unknown option '-%c'.\n", *opt);
               return (usage(stderr));
         }
       }

pdfio-file.c

@@ -64,9 +64,10 @@ _pdfioFileAddMappedObj(
   pdf->num_objmaps ++;
 
   map->obj        = dst_obj;
-  map->src_pdf    = src_obj->pdf;
   map->src_number = src_obj->number;
 
+  memcpy(map->src_id, src_obj->pdf->file_id, sizeof(map->src_id));
+
   // Sort as needed...
   if (pdf->num_objmaps > 1 && compare_objmaps(map, pdf->objmaps + pdf->num_objmaps - 2) < 0)
     qsort(pdf->objmaps, pdf->num_objmaps, sizeof(_pdfio_objmap_t), (int (*)(const void *, const void *))compare_objmaps);
@@ -685,7 +686,7 @@ _pdfioFileFindMappedObj(
     return (NULL);
 
   // Otherwise search for a match...
-  key.src_pdf    = src_pdf;
+  memcpy(key.src_id, src_pdf->file_id, sizeof(key.src_id));
   key.src_number = src_number;
 
   if ((match = (_pdfio_objmap_t *)bsearch(&key, pdf->objmaps, pdf->num_objmaps, sizeof(_pdfio_objmap_t), (int (*)(const void *, const void *))compare_objmaps)) != NULL)
@@ -1046,6 +1047,10 @@ pdfioFileOpen(
 		*end;			// End of line
   ssize_t	bytes;			// Bytes read
   off_t		xref_offset;		// Offset to xref table
+  time_t	curtime;		// Creation date/time
+  unsigned char	*id_value;		// ID value
+  size_t	id_valuelen;		// Length of ID value
+  _pdfio_sha256_t ctx;			// Hashing context
 
 
   PDFIO_DEBUG("pdfioFileOpen(filename=\"%s\", password_cb=%p, password_cbdata=%p, error_cb=%p, error_cbdata=%p)\n", filename, (void *)password_cb, (void *)password_cbdata, (void *)error_cb, (void *)error_cbdata);
@@ -1146,6 +1151,18 @@ pdfioFileOpen(
       goto error;
   }
 
+  // Create the unique file identifier string for the object map...
+  curtime = pdfioFileGetCreationDate(pdf);
+
+  _pdfioCryptoSHA256Init(&ctx);
+  _pdfioCryptoSHA256Append(&ctx, (uint8_t *)pdf->filename, strlen(pdf->filename));
+  _pdfioCryptoSHA256Append(&ctx, (uint8_t *)&curtime, sizeof(curtime));
+  if ((id_value = pdfioArrayGetBinary(pdf->id_array, 0, &id_valuelen)) != NULL)
+    _pdfioCryptoSHA256Append(&ctx, id_value, id_valuelen);
+  if ((id_value = pdfioArrayGetBinary(pdf->id_array, 1, &id_valuelen)) != NULL)
+    _pdfioCryptoSHA256Append(&ctx, id_value, id_valuelen);
+  _pdfioCryptoSHA256Finish(&ctx, pdf->file_id);
+
   return (pdf);
 
 
@@ -1420,10 +1437,11 @@ static int				// O - Result of comparison
 compare_objmaps(_pdfio_objmap_t *a,	// I - First object map
                 _pdfio_objmap_t *b)	// I - Second object map
 {
-  if (a->src_pdf < b->src_pdf)
+  int	ret = memcmp(a->src_id, b->src_id, sizeof(a->src_id));
-    return (-1);
+					// Result of comparison
-  else if (a->src_pdf > b->src_pdf)
+
-    return (1);
+  if (ret)
+    return (ret);
   else if (a->src_number < b->src_number)
     return (-1);
   else if (a->src_number > b->src_number)
@@ -1452,6 +1470,8 @@ create_common(
   pdfio_file_t	*pdf;			// New PDF file
   pdfio_dict_t	*dict;			// Dictionary
   unsigned char	id_value[16];		// File ID value
+  time_t	curtime;		// Creation date/time
+  _pdfio_sha256_t ctx;			// Hashing context
 
 
   PDFIO_DEBUG("create_common(filename=\"%s\", fd=%d, output_cb=%p, output_cbdata=%p, version=\"%s\", media_box=%p, crop_box=%p, error_cb=%p, error_cbdata=%p)\n", filename, fd, (void *)output_cb, (void *)output_cbdata, version, (void *)media_box, (void *)crop_box, (void *)error_cb, (void *)error_cbdata);
@@ -1542,7 +1562,9 @@ create_common(
   if ((dict = pdfioDictCreate(pdf)) == NULL)
     goto error;
 
-  pdfioDictSetDate(dict, "CreationDate", time(NULL));
+  curtime = time(NULL);
+
+  pdfioDictSetDate(dict, "CreationDate", curtime);
   pdfioDictSetString(dict, "Producer", "pdfio/" PDFIO_VERSION);
 
   if ((pdf->info_obj = pdfioFileCreateObj(pdf, dict)) == NULL)
@@ -1567,6 +1589,14 @@ create_common(
     pdfioArrayAppendBinary(pdf->id_array, id_value, sizeof(id_value));
   }
 
+  // Create the unique file identifier string for the object map...
+  _pdfioCryptoSHA256Init(&ctx);
+  _pdfioCryptoSHA256Append(&ctx, (uint8_t *)pdf->filename, strlen(pdf->filename));
+  _pdfioCryptoSHA256Append(&ctx, (uint8_t *)&curtime, sizeof(curtime));
+  _pdfioCryptoSHA256Append(&ctx, id_value, sizeof(id_value));
+  _pdfioCryptoSHA256Append(&ctx, id_value, sizeof(id_value));
+  _pdfioCryptoSHA256Finish(&ctx, pdf->file_id);
+
   return (pdf);
 
   // Common error handling code...

pdfio-object.c

@@ -79,6 +79,10 @@ pdfioObjCopy(pdfio_file_t *pdf,		// I - PDF file
   if (srcobj->value.type == PDFIO_VALTYPE_NONE)
     _pdfioObjLoad(srcobj);
 
+  // See if we have already mapped this object...
+  if ((dstobj = _pdfioFileFindMappedObj(pdf, srcobj->pdf, srcobj->number)) != NULL)
+    return (dstobj);			// Yes, return that one...
+
   // Create the new object...
   if ((dstobj = _pdfioFileCreateObj(pdf, srcobj->pdf, NULL)) == NULL)
     return (NULL);

pdfio-private.h

@@ -221,7 +221,7 @@ struct _pdfio_dict_s			// Dictionary
 typedef struct _pdfio_objmap_s		// PDF object map
 {
   pdfio_obj_t	*obj;			// Object for this file
-  pdfio_file_t	*src_pdf;		// Source PDF file
+  unsigned char	src_id[32];		// Source PDF file file identifier
   size_t	src_number;		// Source object number
 } _pdfio_objmap_t;
 
@@ -236,6 +236,7 @@ typedef struct _pdfio_strbuf_s		// PDF string buffer
 struct _pdfio_file_s			// PDF file structure
 {
   char		*filename;		// Filename
+  unsigned char	file_id[32];		// File identifier bytes
   struct lconv	*loc;			// Locale data
   char		*version;		// Version number
   pdfio_rect_t	media_box,		// Default MediaBox value