1/* pngimage.c
2 *
3 * Copyright (c) 2014 John Cunningham Bowler
4 *
5 * Last changed in libpng 1.6.10 [March 6, 2014]
6 *
7 * This code is released under the libpng license.
8 * For conditions of distribution and use, see the disclaimer
9 * and license in png.h
10 *
11 * Test the png_read_png and png_write_png interfaces.  Given a PNG file load it
12 * using png_read_png and then write with png_write_png.  Test all possible
13 * transforms.
14 */
15#include <stdarg.h>
16#include <stdlib.h>
17#include <string.h>
18#include <errno.h>
19#include <stdio.h>
20#include <assert.h>
21
22#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
23#  include <config.h>
24#endif
25
26/* Define the following to use this test against your installed libpng, rather
27 * than the one being built here:
28 */
29#ifdef PNG_FREESTANDING_TESTS
30#  include <png.h>
31#else
32#  include "../../png.h"
33#endif
34
35#ifndef PNG_SETJMP_SUPPORTED
36#  include <setjmp.h> /* because png.h did *not* include this */
37#endif
38
39#if defined(PNG_INFO_IMAGE_SUPPORTED) && defined(PNG_SEQUENTIAL_READ_SUPPORTED)
40/* If a transform is valid on both read and write this implies that if the
41 * transform is applied to read it must also be applied on write to produce
42 * meaningful data.  This is because these transforms when performed on read
43 * produce data with a memory format that does not correspond to a PNG format.
44 *
45 * Most of these transforms are invertible; after applying the transform on
46 * write the result is the original PNG data that would have would have been
47 * read if no transform were applied.
48 *
49 * The exception is _SHIFT, which destroys the low order bits marked as not
50 * significant in a PNG with the sBIT chunk.
51 *
52 * The following table lists, for each transform, the conditions under which it
53 * is expected to do anything.  Conditions are defined as follows:
54 *
55 * 1) Color mask bits required - simply a mask to AND with color_type; one of
56 *    these must be present for the transform to fire, except that 0 means
57 *    'always'.
58 * 2) Color mask bits which must be absent - another mask - none of these must
59 *    be present.
60 * 3) Bit depths - a mask of component bit depths for the transform to fire.
61 * 4) 'read' - the transform works in png_read_png.
62 * 5) 'write' - the transform works in png_write_png.
63 * 6) PNG_INFO_chunk; a mask of the chunks that must be present for the
64 *    transform to fire.  All must be present - the requirement is that
65 *    png_get_valid() & mask == mask, so if mask is 0 there is no requirement.
66 *
67 * The condition refers to the original image state - if multiple transforms are
68 * used together it is possible to cause a transform that wouldn't fire on the
69 * original image to fire.
70 */
71static struct transform_info
72{
73   const char *name;
74   int         transform;
75   png_uint_32 valid_chunks;
76#     define CHUNK_NONE 0
77#     define CHUNK_sBIT PNG_INFO_sBIT
78#     define CHUNK_tRNS PNG_INFO_tRNS
79   png_byte    color_mask_required;
80   png_byte    color_mask_absent;
81#     define COLOR_MASK_X   0
82#     define COLOR_MASK_P   PNG_COLOR_MASK_PALETTE
83#     define COLOR_MASK_C   PNG_COLOR_MASK_COLOR
84#     define COLOR_MASK_A   PNG_COLOR_MASK_ALPHA
85#     define COLOR_MASK_ALL (PALETTE+COLOR+ALPHA)  /* absent = gray, no alpha */
86   png_byte    bit_depths;
87#     define BD_ALL  (1 + 2 + 4 + 8 + 16)
88#     define BD_PAL  (1 + 2 + 4 + 8)
89#     define BD_LOW  (1 + 2 + 4)
90#     define BD_16   16
91#     define BD_TRUE (8+16) /* i.e. true-color depths */
92   png_byte    when;
93#     define TRANSFORM_R  1
94#     define TRANSFORM_W  2
95#     define TRANSFORM_RW 3
96   png_byte    tested; /* the transform was tested somewhere */
97} transform_info[] =
98{
99   /* List ALL the PNG_TRANSFORM_ macros here.  Check for support using the READ
100    * macros; even if the transform is supported on write it cannot be tested
101    * without the read support.
102    */
103#  define T(name,chunk,cm_required,cm_absent,bd,when)\
104   {  #name, PNG_TRANSFORM_ ## name, CHUNK_ ## chunk,\
105      COLOR_MASK_ ## cm_required, COLOR_MASK_ ## cm_absent, BD_ ## bd,\
106      TRANSFORM_ ## when, 0/*!tested*/ }
107
108#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
109   T(STRIP_16,            NONE, X,   X,   16,  R),
110      /* drops the bottom 8 bits when bit depth is 16 */
111#endif
112#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
113   T(STRIP_ALPHA,         NONE, A,   X,  ALL,  R),
114      /* removes the alpha channel if present */
115#endif
116#ifdef PNG_WRITE_PACK_SUPPORTED
117#  define TRANSFORM_RW_PACK TRANSFORM_RW
118#else
119#  define TRANSFORM_RW_PACK TRANSFORM_R
120#endif
121#ifdef PNG_READ_PACK_SUPPORTED
122   T(PACKING,             NONE, X,   X,  LOW, RW_PACK),
123      /* unpacks low-bit-depth components into 1 byte per component on read,
124       * reverses this on write.
125       */
126#endif
127#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
128#  define TRANSFORM_RW_PACKSWAP TRANSFORM_RW
129#else
130#  define TRANSFORM_RW_PACKSWAP TRANSFORM_R
131#endif
132#ifdef PNG_READ_PACKSWAP_SUPPORTED
133   T(PACKSWAP,            NONE, X,   X,  LOW, RW_PACKSWAP),
134      /* reverses the order of low-bit-depth components packed into a byte */
135#endif
136#ifdef PNG_READ_EXPAND_SUPPORTED
137   T(EXPAND,              NONE, P,   X,  ALL,  R),
138      /* expands PLTE PNG files to RGB (no tRNS) or RGBA (tRNS) *
139       * Note that the 'EXPAND' transform does lots of different things: */
140   T(EXPAND,              NONE, X,   C,  ALL,  R),
141      /* expands grayscale PNG files to RGB, or RGBA */
142   T(EXPAND,              tRNS, X,   A,  ALL,  R),
143      /* expands the tRNS chunk in files without alpha */
144#endif
145#ifdef PNG_WRITE_INVERT_SUPPORTED
146#  define TRANSFORM_RW_INVERT TRANSFORM_RW
147#else
148#  define TRANSFORM_RW_INVERT TRANSFORM_R
149#endif
150#ifdef PNG_READ_INVERT_SUPPORTED
151   T(INVERT_MONO,         NONE, X,   C,  ALL, RW_INVERT),
152      /* converts gray-scale components to 1..0 from 0..1 */
153#endif
154#ifdef PNG_WRITE_SHIFT_SUPPORTED
155#  define TRANSFORM_RW_SHIFT TRANSFORM_RW
156#else
157#  define TRANSFORM_RW_SHIFT TRANSFORM_R
158#endif
159#ifdef PNG_READ_SHIFT_SUPPORTED
160   T(SHIFT,               sBIT, X,   X,  ALL, RW_SHIFT),
161      /* reduces component values to the original range based on the sBIT chunk,
162       * this is only partially reversible - the low bits are lost and cannot be
163       * recovered on write.  In fact write code replicates the bits to generate
164       * new low-order bits.
165       */
166#endif
167#ifdef PNG_WRITE_BGR_SUPPORTED
168#  define TRANSFORM_RW_BGR TRANSFORM_RW
169#else
170#  define TRANSFORM_RW_BGR TRANSFORM_R
171#endif
172#ifdef PNG_READ_BGR_SUPPORTED
173   T(BGR,                 NONE, C,   P, TRUE, RW_BGR),
174      /* reverses the rgb component values of true-color pixels */
175#endif
176#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
177#  define TRANSFORM_RW_SWAP_ALPHA TRANSFORM_RW
178#else
179#  define TRANSFORM_RW_SWAP_ALPHA TRANSFORM_R
180#endif
181#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
182   T(SWAP_ALPHA,          NONE, A,   X, TRUE, RW_SWAP_ALPHA),
183      /* swaps the alpha channel of RGBA or GA pixels to the front - ARGB or
184       * AG, on write reverses the process.
185       */
186#endif
187#ifdef PNG_WRITE_SWAP_SUPPORTED
188#  define TRANSFORM_RW_SWAP TRANSFORM_RW
189#else
190#  define TRANSFORM_RW_SWAP TRANSFORM_R
191#endif
192#ifdef PNG_READ_SWAP_SUPPORTED
193   T(SWAP_ENDIAN,         NONE, X,   P,   16, RW_SWAP),
194      /* byte-swaps 16-bit component values */
195#endif
196#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
197#  define TRANSFORM_RW_INVERT_ALPHA TRANSFORM_RW
198#else
199#  define TRANSFORM_RW_INVERT_ALPHA TRANSFORM_R
200#endif
201#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
202   T(INVERT_ALPHA,        NONE, A,   X, TRUE, RW_INVERT_ALPHA),
203      /* converts an alpha channel from 0..1 to 1..0 */
204#endif
205#ifdef PNG_WRITE_FILLER_SUPPORTED
206   T(STRIP_FILLER_BEFORE, NONE, A,   P, TRUE,  W), /* 'A' for a filler! */
207      /* on write skips a leading filler channel; testing requires data with a
208       * filler channel so this is produced from RGBA or GA images by removing
209       * the 'alpha' flag from the color type in place.
210       */
211   T(STRIP_FILLER_AFTER,  NONE, A,   P, TRUE,  W),
212      /* on write strips a trailing filler channel */
213#endif
214#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
215   T(GRAY_TO_RGB,         NONE, X,   C,  ALL,  R),
216      /* expands grayscale images to RGB, also causes the palette part of
217       * 'EXPAND' to happen.  Low bit depth grayscale images are expanded to
218       * 8-bits per component and no attempt is made to convert the image to a
219       * palette image.  While this transform is partially reversible
220       * png_write_png does not currently support this.
221       */
222   T(GRAY_TO_RGB,         NONE, P,   X,  ALL,  R),
223      /* The 'palette' side effect mentioned above; a bit bogus but this is the
224       * way the libpng code works.
225       */
226#endif
227#ifdef PNG_READ_EXPAND_16_SUPPORTED
228   T(EXPAND_16,           NONE, X,   X,  PAL,  R),
229      /* expands images to 16-bits per component, as a side effect expands
230       * palette images to RGB and expands the tRNS chunk if present, so it can
231       * modify 16-bit per component images as well:
232       */
233   T(EXPAND_16,           tRNS, X,   A,   16,  R),
234      /* side effect of EXPAND_16 - expands the tRNS chunk in an RGB or G 16-bit
235       * image.
236       */
237#endif
238#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
239   T(SCALE_16,            NONE, X,   X,   16,  R)
240      /* scales 16-bit components to 8-bits. */
241#endif
242
243#undef T
244};
245
246#define ARRAY_SIZE(a) ((sizeof a)/(sizeof a[0]))
247#define TTABLE_SIZE ARRAY_SIZE(transform_info)
248
249/* Some combinations of options that should be reversible are not; these cases
250 * are bugs.
251 */
252static int known_bad_combos[][2] =
253{
254   /* problem, antidote */
255   { PNG_TRANSFORM_SHIFT | PNG_TRANSFORM_INVERT_ALPHA, 0/*antidote*/ }
256};
257
258static int
259is_combo(int transforms)
260{
261   return transforms & (transforms-1); /* non-zero if more than one set bit */
262}
263
264static int
265first_transform(int transforms)
266{
267   return transforms & -transforms; /* lowest set bit */
268}
269
270static int
271is_bad_combo(int transforms)
272{
273   unsigned int i;
274
275   for (i=0; i<ARRAY_SIZE(known_bad_combos); ++i)
276   {
277      int combo = known_bad_combos[i][0];
278
279      if ((combo & transforms) == combo &&
280         (transforms & known_bad_combos[i][1]) == 0)
281         return 1;
282   }
283
284   return 0; /* combo is ok */
285}
286
287static const char *
288transform_name(int t)
289   /* The name, if 't' has multiple bits set the name of the lowest set bit is
290    * returned.
291    */
292{
293   unsigned int i;
294
295   t &= -t; /* first set bit */
296
297   for (i=0; i<TTABLE_SIZE; ++i)
298   {
299      if ((transform_info[i].transform & t) != 0)
300         return transform_info[i].name;
301   }
302
303   return "invalid transform";
304}
305
306/* Variables calculated by validate_T below and used to record all the supported
307 * transforms.  Need (unsigned int) here because of the places where these
308 * values are used (unsigned compares in the 'exhaustive' iterator.)
309 */
310static unsigned int read_transforms, write_transforms, rw_transforms;
311
312static void
313validate_T(void)
314   /* Validate the above table - this just builds the above values */
315{
316   unsigned int i;
317
318   for (i=0; i<TTABLE_SIZE; ++i)
319   {
320      if (transform_info[i].when & TRANSFORM_R)
321         read_transforms |= transform_info[i].transform;
322
323      if (transform_info[i].when & TRANSFORM_W)
324         write_transforms |= transform_info[i].transform;
325   }
326
327   /* Reversible transforms are those which are supported on both read and
328    * write.
329    */
330   rw_transforms = read_transforms & write_transforms;
331}
332
333/* FILE DATA HANDLING
334 *    The original file is cached in memory.  During write the output file is
335 *    written to memory.
336 *
337 *    In both cases the file data is held in a linked list of buffers - not all
338 *    of these are in use at any time.
339 */
340struct buffer_list
341{
342   struct buffer_list *next;         /* next buffer in list */
343   png_byte            buffer[1024]; /* the actual buffer */
344};
345
346struct buffer
347{
348   struct buffer_list  *last;       /* last buffer in use */
349   size_t               end_count;  /* bytes in the last buffer */
350   struct buffer_list  *current;    /* current buffer being read */
351   size_t               read_count; /* count of bytes read from current */
352   struct buffer_list   first;      /* the very first buffer */
353};
354
355static void
356buffer_init(struct buffer *buffer)
357   /* Call this only once for a given buffer */
358{
359   buffer->first.next = NULL;
360   buffer->last = NULL;
361   buffer->current = NULL;
362}
363
364#ifdef PNG_WRITE_SUPPORTED
365static void
366buffer_start_write(struct buffer *buffer)
367{
368   buffer->last = &buffer->first;
369   buffer->end_count = 0;
370   buffer->current = NULL;
371}
372#endif
373
374static void
375buffer_start_read(struct buffer *buffer)
376{
377   buffer->current = &buffer->first;
378   buffer->read_count = 0;
379}
380
381#ifdef ENOMEM /* required by POSIX 1003.1 */
382#  define MEMORY ENOMEM
383#else
384#  define MEMORY ERANGE /* required by ANSI-C */
385#endif
386static struct buffer *
387get_buffer(png_structp pp)
388   /* Used from libpng callbacks to get the current buffer */
389{
390   return (struct buffer*)png_get_io_ptr(pp);
391}
392
393#define NEW(type) ((type *)malloc(sizeof (type)))
394
395static struct buffer_list *
396buffer_extend(struct buffer_list *current)
397{
398   struct buffer_list *add;
399
400   assert(current->next == NULL);
401
402   add = NEW(struct buffer_list);
403   if (add == NULL)
404      return NULL;
405
406   add->next = NULL;
407   current->next = add;
408
409   return add;
410}
411
412/* Load a buffer from a file; does the equivalent of buffer_start_write.  On a
413 * read error returns an errno value, else returns 0.
414 */
415static int
416buffer_from_file(struct buffer *buffer, FILE *fp)
417{
418   struct buffer_list *last = &buffer->first;
419   size_t count = 0;
420
421   for (;;)
422   {
423      size_t r = fread(last->buffer+count, 1/*size*/,
424         (sizeof last->buffer)-count, fp);
425
426      if (r > 0)
427      {
428         count += r;
429
430         if (count >= sizeof last->buffer)
431         {
432            assert(count == sizeof last->buffer);
433            count = 0;
434
435            if (last->next == NULL)
436            {
437               last = buffer_extend(last);
438               if (last == NULL)
439                  return MEMORY;
440            }
441
442            else
443               last = last->next;
444         }
445      }
446
447      else /* fread failed - probably end of file */
448      {
449         if (feof(fp))
450         {
451            buffer->last = last;
452            buffer->end_count = count;
453            return 0; /* no error */
454         }
455
456         /* Some kind of funky error; errno should be non-zero */
457         return errno == 0 ? ERANGE : errno;
458      }
459   }
460}
461
462/* This structure is used to control the test of a single file. */
463typedef enum
464{
465   VERBOSE,        /* switches on all messages */
466   INFORMATION,
467   WARNINGS,       /* switches on warnings */
468   LIBPNG_WARNING,
469   APP_WARNING,
470   ERRORS,         /* just errors */
471   APP_FAIL,       /* continuable error - no need to longjmp */
472   LIBPNG_ERROR,   /* this and higher cause a longjmp */
473   LIBPNG_BUG,     /* erroneous behavior in libpng */
474   APP_ERROR,      /* such as out-of-memory in a callback */
475   QUIET,          /* no normal messages */
476   USER_ERROR,     /* such as file-not-found */
477   INTERNAL_ERROR
478} error_level;
479#define LEVEL_MASK      0xf   /* where the level is in 'options' */
480
481#define EXHAUSTIVE      0x010 /* Test all combinations of active options */
482#define STRICT          0x020 /* Fail on warnings as well as errors */
483#define LOG             0x040 /* Log pass/fail to stdout */
484#define CONTINUE        0x080 /* Continue on APP_FAIL errors */
485#define SKIP_BUGS       0x100 /* Skip over known bugs */
486#define LOG_SKIPPED     0x200 /* Log skipped bugs */
487#define FIND_BAD_COMBOS 0x400 /* Attempt to deduce bad combos */
488
489/* Result masks apply to the result bits in the 'results' field below; these
490 * bits are simple 1U<<error_level.  A pass requires either nothing worse than
491 * warnings (--relaxes) or nothing worse than information (--strict)
492 */
493#define RESULT_STRICT(r)   (((r) & ~((1U<<WARNINGS)-1)) == 0)
494#define RESULT_RELAXED(r)  (((r) & ~((1U<<ERRORS)-1)) == 0)
495
496struct display
497{
498   jmp_buf        error_return;      /* Where to go to on error */
499
500   const char    *filename;          /* The name of the original file */
501   const char    *operation;         /* Operation being performed */
502   int            transforms;        /* Transform used in operation */
503   png_uint_32    options;           /* See display_log below */
504   png_uint_32    results;           /* A mask of errors seen */
505
506
507   png_structp    original_pp;       /* used on the original read */
508   png_infop      original_ip;       /* set by the original read */
509
510   png_size_t     original_rowbytes; /* of the original rows: */
511   png_bytepp     original_rows;     /* from the original read */
512
513   /* Original chunks valid */
514   png_uint_32    chunks;
515
516   /* Original IHDR information */
517   png_uint_32    width;
518   png_uint_32    height;
519   int            bit_depth;
520   int            color_type;
521   int            interlace_method;
522   int            compression_method;
523   int            filter_method;
524
525   /* Derived information for the original image. */
526   int            active_transforms;  /* transforms that do something on read */
527   int            ignored_transforms; /* transforms that should do nothing */
528
529   /* Used on a read, both the original read and when validating a written
530    * image.
531    */
532   png_structp    read_pp;
533   png_infop      read_ip;
534
535#  ifdef PNG_WRITE_SUPPORTED
536      /* Used to write a new image (the original info_ptr is used) */
537      png_structp   write_pp;
538      struct buffer written_file;   /* where the file gets written */
539#  endif
540
541   struct buffer  original_file;     /* Data read from the original file */
542};
543
544static void
545display_init(struct display *dp)
546   /* Call this only once right at the start to initialize the control
547    * structure, the (struct buffer) lists are maintained across calls - the
548    * memory is not freed.
549    */
550{
551   memset(dp, 0, sizeof *dp);
552   dp->options = WARNINGS; /* default to !verbose, !quiet */
553   dp->filename = NULL;
554   dp->operation = NULL;
555   dp->original_pp = NULL;
556   dp->original_ip = NULL;
557   dp->original_rows = NULL;
558   dp->read_pp = NULL;
559   dp->read_ip = NULL;
560   buffer_init(&dp->original_file);
561
562#  ifdef PNG_WRITE_SUPPORTED
563      dp->write_pp = NULL;
564      buffer_init(&dp->written_file);
565#  endif
566}
567
568static void
569display_clean_read(struct display *dp)
570{
571   if (dp->read_pp != NULL)
572      png_destroy_read_struct(&dp->read_pp, &dp->read_ip, NULL);
573}
574
575#ifdef PNG_WRITE_SUPPORTED
576static void
577display_clean_write(struct display *dp)
578{
579      if (dp->write_pp != NULL)
580         png_destroy_write_struct(&dp->write_pp, NULL);
581}
582#endif
583
584static void
585display_clean(struct display *dp)
586{
587#  ifdef PNG_WRITE_SUPPORTED
588      display_clean_write(dp);
589#  endif
590   display_clean_read(dp);
591
592   dp->original_rowbytes = 0;
593   dp->original_rows = NULL;
594   dp->chunks = 0;
595
596   png_destroy_read_struct(&dp->original_pp, &dp->original_ip, NULL);
597   /* leave the filename for error detection */
598   dp->results = 0; /* reset for next time */
599}
600
601static struct display *
602get_dp(png_structp pp)
603   /* The display pointer is always stored in the png_struct error pointer */
604{
605   struct display *dp = (struct display*)png_get_error_ptr(pp);
606
607   if (dp == NULL)
608   {
609      fprintf(stderr, "pngimage: internal error (no display)\n");
610      exit(99); /* prevents a crash */
611   }
612
613   return dp;
614}
615
616/* error handling */
617#ifdef __GNUC__
618#  define VGATTR __attribute__((__format__ (__printf__,3,4)))
619   /* Required to quiet GNUC warnings when the compiler sees a stdarg function
620    * that calls one of the stdio v APIs.
621    */
622#else
623#  define VGATTR
624#endif
625static void VGATTR
626display_log(struct display *dp, error_level level, const char *fmt, ...)
627   /* 'level' is as above, fmt is a stdio style format string.  This routine
628    * does not return if level is above LIBPNG_WARNING
629    */
630{
631   dp->results |= 1U << level;
632
633   if (level > (error_level)(dp->options & LEVEL_MASK))
634   {
635      const char *lp;
636      va_list ap;
637
638      switch (level)
639      {
640         case INFORMATION:    lp = "information"; break;
641         case LIBPNG_WARNING: lp = "warning(libpng)"; break;
642         case APP_WARNING:    lp = "warning(pngimage)"; break;
643         case APP_FAIL:       lp = "error(continuable)"; break;
644         case LIBPNG_ERROR:   lp = "error(libpng)"; break;
645         case LIBPNG_BUG:     lp = "bug(libpng)"; break;
646         case APP_ERROR:      lp = "error(pngimage)"; break;
647         case USER_ERROR:     lp = "error(user)"; break;
648
649         case INTERNAL_ERROR: /* anything unexpected is an internal error: */
650         case VERBOSE: case WARNINGS: case ERRORS: case QUIET:
651         default:             lp = "bug(pngimage)"; break;
652      }
653
654      fprintf(stderr, "%s: %s: %s",
655         dp->filename != NULL ? dp->filename : "<stdin>", lp, dp->operation);
656
657      if (dp->transforms != 0)
658      {
659         int tr = dp->transforms;
660
661         if (is_combo(tr))
662            fprintf(stderr, "(0x%x)", tr);
663
664         else
665            fprintf(stderr, "(%s)", transform_name(tr));
666      }
667
668      fprintf(stderr, ": ");
669
670      va_start(ap, fmt);
671      vfprintf(stderr, fmt, ap);
672      va_end(ap);
673
674      fputc('\n', stderr);
675   }
676   /* else do not output any message */
677
678   /* Errors cause this routine to exit to the fail code */
679   if (level > APP_FAIL || (level > ERRORS && !(dp->options & CONTINUE)))
680      longjmp(dp->error_return, level);
681}
682
683/* error handler callbacks for libpng */
684static void PNGCBAPI
685display_warning(png_structp pp, png_const_charp warning)
686{
687   display_log(get_dp(pp), LIBPNG_WARNING, "%s", warning);
688}
689
690static void PNGCBAPI
691display_error(png_structp pp, png_const_charp error)
692{
693   struct display *dp = get_dp(pp);
694
695   display_log(dp, LIBPNG_ERROR, "%s", error);
696}
697
698static void
699display_cache_file(struct display *dp, const char *filename)
700   /* Does the initial cache of the file. */
701{
702   FILE *fp;
703   int ret;
704
705   dp->filename = filename;
706
707   if (filename != NULL)
708   {
709      fp = fopen(filename, "rb");
710      if (fp == NULL)
711         display_log(dp, USER_ERROR, "open failed: %s", strerror(errno));
712   }
713
714   else
715      fp = stdin;
716
717   ret = buffer_from_file(&dp->original_file, fp);
718
719   fclose(fp);
720
721   if (ret != 0)
722      display_log(dp, APP_ERROR, "read failed: %s", strerror(ret));
723}
724
725static void
726buffer_read(struct display *dp, struct buffer *bp, png_bytep data,
727   png_size_t size)
728{
729   struct buffer_list *last = bp->current;
730   size_t read_count = bp->read_count;
731
732   while (size > 0)
733   {
734      size_t avail;
735
736      if (last == NULL ||
737         (last == bp->last && read_count >= bp->end_count))
738      {
739         display_log(dp, USER_ERROR, "file truncated (%lu bytes)",
740            (unsigned long)size);
741         /*NOTREACHED*/
742         break;
743      }
744
745      else if (read_count >= sizeof last->buffer)
746      {
747         /* Move to the next buffer: */
748         last = last->next;
749         read_count = 0;
750         bp->current = last; /* Avoid update outside the loop */
751
752         /* And do a sanity check (the EOF case is caught above) */
753         if (last == NULL)
754         {
755            display_log(dp, INTERNAL_ERROR, "damaged buffer list");
756            /*NOTREACHED*/
757            break;
758         }
759      }
760
761      avail = (sizeof last->buffer) - read_count;
762      if (avail > size)
763         avail = size;
764
765      memcpy(data, last->buffer + read_count, avail);
766      read_count += avail;
767      size -= avail;
768      data += avail;
769   }
770
771   bp->read_count = read_count;
772}
773
774static void PNGCBAPI
775read_function(png_structp pp, png_bytep data, png_size_t size)
776{
777   buffer_read(get_dp(pp), get_buffer(pp), data, size);
778}
779
780static void
781read_png(struct display *dp, struct buffer *bp, const char *operation,
782   int transforms)
783{
784   png_structp pp;
785   png_infop   ip;
786
787   /* This cleans out any previous read and sets operation and transforms to
788    * empty.
789    */
790   display_clean_read(dp);
791
792   if (operation != NULL) /* else this is a verify and do not overwrite info */
793   {
794      dp->operation = operation;
795      dp->transforms = transforms;
796   }
797
798   dp->read_pp = pp = png_create_read_struct(PNG_LIBPNG_VER_STRING, dp,
799      display_error, display_warning);
800   if (pp == NULL)
801      display_log(dp, LIBPNG_ERROR, "failed to create read struct");
802
803   /* The png_read_png API requires us to make the info struct, but it does the
804    * call to png_read_info.
805    */
806   dp->read_ip = ip = png_create_info_struct(pp);
807   if (ip == NULL)
808      display_log(dp, LIBPNG_ERROR, "failed to create info struct");
809
810#  ifdef PNG_SET_USER_LIMITS_SUPPORTED
811      /* Remove the user limits, if any */
812      png_set_user_limits(pp, 0x7fffffff, 0x7fffffff);
813#  endif
814
815   /* Set the IO handling */
816   buffer_start_read(bp);
817   png_set_read_fn(pp, bp, read_function);
818
819   png_read_png(pp, ip, transforms, NULL/*params*/);
820
821#if 0 /* crazy debugging */
822   {
823      png_bytep pr = png_get_rows(pp, ip)[0];
824      size_t rb = png_get_rowbytes(pp, ip);
825      size_t cb;
826      char c = ' ';
827
828      fprintf(stderr, "%.4x %2d (%3lu bytes):", transforms, png_get_bit_depth(pp,ip), (unsigned long)rb);
829
830      for (cb=0; cb<rb; ++cb)
831         fputc(c, stderr), fprintf(stderr, "%.2x", pr[cb]), c='.';
832
833      fputc('\n', stderr);
834   }
835#endif
836}
837
838static void
839update_display(struct display *dp)
840   /* called once after the first read to update all the info, original_pp and
841    * original_ip must have been filled in.
842    */
843{
844   png_structp pp;
845   png_infop   ip;
846
847   /* Now perform the initial read with a 0 tranform. */
848   read_png(dp, &dp->original_file, "original read", 0/*no transform*/);
849
850   /* Move the result to the 'original' fields */
851   dp->original_pp = pp = dp->read_pp, dp->read_pp = NULL;
852   dp->original_ip = ip = dp->read_ip, dp->read_ip = NULL;
853
854   dp->original_rowbytes = png_get_rowbytes(pp, ip);
855   if (dp->original_rowbytes == 0)
856      display_log(dp, LIBPNG_BUG, "png_get_rowbytes returned 0");
857
858   dp->chunks = png_get_valid(pp, ip, 0xffffffff);
859   if ((dp->chunks & PNG_INFO_IDAT) == 0) /* set by png_read_png */
860      display_log(dp, LIBPNG_BUG, "png_read_png did not set IDAT flag");
861
862   dp->original_rows = png_get_rows(pp, ip);
863   if (dp->original_rows == NULL)
864      display_log(dp, LIBPNG_BUG, "png_read_png did not create row buffers");
865
866   if (!png_get_IHDR(pp, ip,
867      &dp->width, &dp->height, &dp->bit_depth, &dp->color_type,
868      &dp->interlace_method, &dp->compression_method, &dp->filter_method))
869      display_log(dp, LIBPNG_BUG, "png_get_IHDR failed");
870
871   /* 'active' transforms are discovered based on the original image format;
872    * running one active transform can activate others.  At present the code
873    * does not attempt to determine the closure.
874    */
875   {
876      png_uint_32 chunks = dp->chunks;
877      int active = 0, inactive = 0;
878      int ct = dp->color_type;
879      int bd = dp->bit_depth;
880      unsigned int i;
881
882      for (i=0; i<TTABLE_SIZE; ++i)
883      {
884         int transform = transform_info[i].transform;
885
886         if ((transform_info[i].valid_chunks == 0 ||
887               (transform_info[i].valid_chunks & chunks) != 0) &&
888            (transform_info[i].color_mask_required & ct) ==
889               transform_info[i].color_mask_required &&
890            (transform_info[i].color_mask_absent & ct) == 0 &&
891            (transform_info[i].bit_depths & bd) != 0 &&
892            (transform_info[i].when & TRANSFORM_R) != 0)
893            active |= transform;
894
895         else if ((transform_info[i].when & TRANSFORM_R) != 0)
896            inactive |= transform;
897      }
898
899      /* Some transforms appear multiple times in the table; the 'active' status
900       * is the logical OR of these and the inactive status must be adjusted to
901       * take this into account.
902       */
903      inactive &= ~active;
904
905      dp->active_transforms = active;
906      dp->ignored_transforms = inactive; /* excluding write-only transforms */
907
908      if (active == 0)
909         display_log(dp, INTERNAL_ERROR, "bad transform table");
910   }
911}
912
913static int
914compare_read(struct display *dp, int applied_transforms)
915{
916   /* Compare the png_info from read_ip with original_info */
917   size_t rowbytes;
918   png_uint_32 width, height;
919   int bit_depth, color_type;
920   int interlace_method, compression_method, filter_method;
921   const char *e = NULL;
922
923   png_get_IHDR(dp->read_pp, dp->read_ip, &width, &height, &bit_depth,
924      &color_type, &interlace_method, &compression_method, &filter_method);
925
926#  define C(item) if (item != dp->item) \
927      display_log(dp, APP_WARNING, "IHDR " #item "(%lu) changed to %lu",\
928         (unsigned long)dp->item, (unsigned long)item), e = #item
929
930   /* The IHDR should be identical: */
931   C(width);
932   C(height);
933   C(bit_depth);
934   C(color_type);
935   C(interlace_method);
936   C(compression_method);
937   C(filter_method);
938
939   /* 'e' remains set to the name of the last thing changed: */
940   if (e)
941      display_log(dp, APP_ERROR, "IHDR changed (%s)", e);
942
943   /* All the chunks from the original PNG should be preserved in the output PNG
944    * because the PNG format has not been changed.
945    */
946   {
947      unsigned long chunks =
948         png_get_valid(dp->read_pp, dp->read_ip, 0xffffffff);
949
950      if (chunks != dp->chunks)
951         display_log(dp, APP_FAIL, "PNG chunks changed from 0x%lx to 0x%lx",
952            (unsigned long)dp->chunks, chunks);
953   }
954
955   /* rowbytes should be the same */
956   rowbytes = png_get_rowbytes(dp->read_pp, dp->read_ip);
957
958   /* NOTE: on 64-bit systems this may trash the top bits of rowbytes,
959    * which could lead to weird error messages.
960    */
961   if (rowbytes != dp->original_rowbytes)
962      display_log(dp, APP_ERROR, "PNG rowbytes changed from %lu to %lu",
963         (unsigned long)dp->original_rowbytes, (unsigned long)rowbytes);
964
965   /* The rows should be the same too, unless the applied transforms includes
966    * the shift transform, in which case low bits may have been lost.
967    */
968   {
969      png_bytepp rows = png_get_rows(dp->read_pp, dp->read_ip);
970      unsigned int mask;  /* mask (if not zero) for the final byte */
971
972      if (bit_depth < 8)
973      {
974         /* Need the stray bits at the end, this depends only on the low bits
975          * of the image width; overflow does not matter.  If the width is an
976          * exact multiple of 8 bits this gives a mask of 0, not 0xff.
977          */
978         mask = 0xff & (0xff00 >> ((bit_depth * width) & 7));
979      }
980
981      else
982         mask = 0;
983
984      if (rows == NULL)
985         display_log(dp, LIBPNG_BUG, "png_get_rows returned NULL");
986
987      if ((applied_transforms & PNG_TRANSFORM_SHIFT) == 0 ||
988         (dp->active_transforms & PNG_TRANSFORM_SHIFT) == 0 ||
989         color_type == PNG_COLOR_TYPE_PALETTE)
990      {
991         unsigned long y;
992
993         for (y=0; y<height; ++y)
994         {
995            png_bytep row = rows[y];
996            png_bytep orig = dp->original_rows[y];
997
998            if (memcmp(row, orig, rowbytes-(mask != 0)) != 0 || (mask != 0 &&
999               ((row[rowbytes-1] & mask) != (orig[rowbytes-1] & mask))))
1000            {
1001               size_t x;
1002
1003               /* Find the first error */
1004               for (x=0; x<rowbytes-1; ++x) if (row[x] != orig[x])
1005                  break;
1006
1007               display_log(dp, APP_FAIL,
1008                  "byte(%lu,%lu) changed 0x%.2x -> 0x%.2x",
1009                  (unsigned long)x, (unsigned long)y, orig[x], row[x]);
1010               return 0; /* don't keep reporting failed rows on 'continue' */
1011            }
1012         }
1013      }
1014
1015      else
1016      {
1017         unsigned long y;
1018         int bpp;   /* bits-per-pixel then bytes-per-pixel */
1019         /* components are up to 8 bytes in size */
1020         png_byte sig_bits[8];
1021         png_color_8p sBIT;
1022
1023         if (png_get_sBIT(dp->read_pp, dp->read_ip, &sBIT) != PNG_INFO_sBIT)
1024            display_log(dp, INTERNAL_ERROR,
1025               "active shift transform but no sBIT in file");
1026
1027         switch (color_type)
1028         {
1029            case PNG_COLOR_TYPE_GRAY:
1030               sig_bits[0] = sBIT->gray;
1031               bpp = bit_depth;
1032               break;
1033
1034            case PNG_COLOR_TYPE_GA:
1035               sig_bits[0] = sBIT->gray;
1036               sig_bits[1] = sBIT->alpha;
1037               bpp = 2 * bit_depth;
1038               break;
1039
1040            case PNG_COLOR_TYPE_RGB:
1041               sig_bits[0] = sBIT->red;
1042               sig_bits[1] = sBIT->green;
1043               sig_bits[2] = sBIT->blue;
1044               bpp = 3 * bit_depth;
1045               break;
1046
1047            case PNG_COLOR_TYPE_RGBA:
1048               sig_bits[0] = sBIT->red;
1049               sig_bits[1] = sBIT->green;
1050               sig_bits[2] = sBIT->blue;
1051               sig_bits[3] = sBIT->alpha;
1052               bpp = 4 * bit_depth;
1053               break;
1054
1055            default:
1056               display_log(dp, LIBPNG_ERROR, "invalid colour type %d",
1057                  color_type);
1058               /*NOTREACHED*/
1059               bpp = 0;
1060               break;
1061         }
1062
1063         {
1064            int b;
1065
1066            for (b=0; 8*b<bpp; ++b)
1067            {
1068               /* libpng should catch this; if not there is a security issue
1069                * because an app (like this one) may overflow an array. In fact
1070                * libpng doesn't catch this at present.
1071                */
1072               if (sig_bits[b] == 0 || sig_bits[b] > bit_depth/*!palette*/)
1073                  display_log(dp, LIBPNG_BUG,
1074                     "invalid sBIT[%u]  value %d returned for PNG bit depth %d",
1075                     b, sig_bits[b], bit_depth);
1076            }
1077         }
1078
1079         if (bpp < 8 && bpp != bit_depth)
1080         {
1081            /* sanity check; this is a grayscale PNG; something is wrong in the
1082             * code above.
1083             */
1084            display_log(dp, INTERNAL_ERROR, "invalid bpp %u for bit_depth %u",
1085               bpp, bit_depth);
1086         }
1087
1088         switch (bit_depth)
1089         {
1090            int b;
1091
1092            case 16: /* Two bytes per component, bit-endian */
1093               for (b = (bpp >> 4); b > 0; )
1094               {
1095                  unsigned int sig = (unsigned int)(0xffff0000 >> sig_bits[b]);
1096
1097                  sig_bits[2*b+1] = (png_byte)sig;
1098                  sig_bits[2*b+0] = (png_byte)(sig >> 8); /* big-endian */
1099               }
1100               break;
1101
1102            case 8: /* One byte per component */
1103               for (b=0; b*8 < bpp; ++b)
1104                  sig_bits[b] = (png_byte)(0xff00 >> sig_bits[b]);
1105               break;
1106
1107            case 1: /* allowed, but dumb */
1108               /* Value is 1 */
1109               sig_bits[0] = 0xff;
1110               break;
1111
1112            case 2: /* Replicate 4 times */
1113               /* Value is 1 or 2 */
1114               b = 0x3 & ((0x3<<2) >> sig_bits[0]);
1115               b |= b << 2;
1116               b |= b << 4;
1117               sig_bits[0] = (png_byte)b;
1118               break;
1119
1120            case 4: /* Relicate twice */
1121               /* Value is 1, 2, 3 or 4 */
1122               b = 0xf & ((0xf << 4) >> sig_bits[0]);
1123               b |= b << 4;
1124               sig_bits[0] = (png_byte)b;
1125               break;
1126
1127            default:
1128               display_log(dp, LIBPNG_BUG, "invalid bit depth %d", bit_depth);
1129               break;
1130         }
1131
1132         /* Convert bpp to bytes; this gives '1' for low-bit depth grayscale,
1133          * where there are multiple pixels per byte.
1134          */
1135         bpp = (bpp+7) >> 3;
1136
1137         /* The mask can be combined with sig_bits[0] */
1138         if (mask != 0)
1139         {
1140            mask &= sig_bits[0];
1141
1142            if (bpp != 1 || mask == 0)
1143               display_log(dp, INTERNAL_ERROR, "mask calculation error %u, %u",
1144                  bpp, mask);
1145         }
1146
1147         for (y=0; y<height; ++y)
1148         {
1149            png_bytep row = rows[y];
1150            png_bytep orig = dp->original_rows[y];
1151            unsigned long x;
1152
1153            for (x=0; x<(width-(mask!=0)); ++x)
1154            {
1155               int b;
1156
1157               for (b=0; b<bpp; ++b)
1158               {
1159                  if ((*row++ & sig_bits[b]) != (*orig++ & sig_bits[b]))
1160                  {
1161                     display_log(dp, APP_FAIL,
1162                        "significant bits at (%lu[%u],%lu) changed %.2x->%.2x",
1163                        x, b, y, orig[-1], row[-1]);
1164                     return 0;
1165                  }
1166               }
1167            }
1168
1169            if (mask != 0 && (*row & mask) != (*orig & mask))
1170            {
1171               display_log(dp, APP_FAIL,
1172                  "significant bits at (%lu[end],%lu) changed", x, y);
1173               return 0;
1174            }
1175         } /* for y */
1176      }
1177   }
1178
1179   return 1; /* compare succeeded */
1180}
1181
1182#ifdef PNG_WRITE_SUPPORTED
1183static void
1184buffer_write(struct display *dp, struct buffer *buffer, png_bytep data,
1185   png_size_t size)
1186   /* Generic write function used both from the write callback provided to
1187    * libpng and from the generic read code.
1188    */
1189{
1190   /* Write the data into the buffer, adding buffers as required */
1191   struct buffer_list *last = buffer->last;
1192   size_t end_count = buffer->end_count;
1193
1194   while (size > 0)
1195   {
1196      size_t avail;
1197
1198      if (end_count >= sizeof last->buffer)
1199      {
1200         if (last->next == NULL)
1201         {
1202            last = buffer_extend(last);
1203
1204            if (last == NULL)
1205               display_log(dp, APP_ERROR, "out of memory saving file");
1206         }
1207
1208         else
1209            last = last->next;
1210
1211         buffer->last = last; /* avoid the need to rewrite every time */
1212         end_count = 0;
1213      }
1214
1215      avail = (sizeof last->buffer) - end_count;
1216      if (avail > size)
1217         avail = size;
1218
1219      memcpy(last->buffer + end_count, data, avail);
1220      end_count += avail;
1221      size -= avail;
1222      data += avail;
1223   }
1224
1225   buffer->end_count = end_count;
1226}
1227
1228static void PNGCBAPI
1229write_function(png_structp pp, png_bytep data, png_size_t size)
1230{
1231   buffer_write(get_dp(pp), get_buffer(pp), data, size);
1232}
1233
1234static void
1235write_png(struct display *dp, png_infop ip, int transforms)
1236{
1237   display_clean_write(dp); /* safety */
1238
1239   buffer_start_write(&dp->written_file);
1240   dp->operation = "write";
1241   dp->transforms = transforms;
1242
1243   dp->write_pp = png_create_write_struct(PNG_LIBPNG_VER_STRING, dp,
1244      display_error, display_warning);
1245
1246   if (dp->write_pp == NULL)
1247      display_log(dp, APP_ERROR, "failed to create write png_struct");
1248
1249   png_set_write_fn(dp->write_pp, &dp->written_file, write_function,
1250      NULL/*flush*/);
1251
1252#  ifdef PNG_SET_USER_LIMITS_SUPPORTED
1253      /* Remove the user limits, if any */
1254      png_set_user_limits(dp->write_pp, 0x7fffffff, 0x7fffffff);
1255#  endif
1256
1257   /* Certain transforms require the png_info to be zapped to allow the
1258    * transform to work correctly.
1259    */
1260   if (transforms & (PNG_TRANSFORM_PACKING|
1261                     PNG_TRANSFORM_STRIP_FILLER|
1262                     PNG_TRANSFORM_STRIP_FILLER_BEFORE))
1263   {
1264      int ct = dp->color_type;
1265
1266      if (transforms & (PNG_TRANSFORM_STRIP_FILLER|
1267                        PNG_TRANSFORM_STRIP_FILLER_BEFORE))
1268         ct &= ~PNG_COLOR_MASK_ALPHA;
1269
1270      png_set_IHDR(dp->write_pp, ip, dp->width, dp->height, dp->bit_depth, ct,
1271         dp->interlace_method, dp->compression_method, dp->filter_method);
1272   }
1273
1274   png_write_png(dp->write_pp, ip, transforms, NULL/*params*/);
1275
1276   /* Clean it on the way out - if control returns to the caller then the
1277    * written_file contains the required data.
1278    */
1279   display_clean_write(dp);
1280}
1281#endif /* WRITE_SUPPORTED */
1282
1283static int
1284skip_transform(struct display *dp, int tr)
1285   /* Helper to test for a bad combo and log it if it is skipped */
1286{
1287   if ((dp->options & SKIP_BUGS) != 0 && is_bad_combo(tr))
1288   {
1289      /* Log this to stdout if logging is on, otherwise just do an information
1290       * display_log.
1291       */
1292      if ((dp->options & LOG_SKIPPED) != 0)
1293      {
1294         printf("SKIP: %s transforms ", dp->filename);
1295
1296         while (tr != 0)
1297         {
1298            int next = first_transform(tr);
1299            tr &= ~next;
1300
1301            printf("%s", transform_name(next));
1302            if (tr != 0)
1303               putchar('+');
1304         }
1305
1306         putchar('\n');
1307      }
1308
1309      else
1310         display_log(dp, INFORMATION, "%s: skipped known bad combo 0x%x",
1311            dp->filename, tr);
1312
1313      return 1; /* skip */
1314   }
1315
1316   return 0; /* don't skip */
1317}
1318
1319static void
1320test_one_file(struct display *dp, const char *filename)
1321{
1322   /* First cache the file and update the display original file
1323    * information for the new file.
1324    */
1325   dp->operation = "cache file";
1326   dp->transforms = 0;
1327   display_cache_file(dp, filename);
1328   update_display(dp);
1329
1330   /* First test: if there are options that should be ignored for this file
1331    * verify that they really are ignored.
1332    */
1333   if (dp->ignored_transforms != 0)
1334   {
1335      read_png(dp, &dp->original_file, "ignored transforms",
1336         dp->ignored_transforms);
1337
1338      /* The result should be identical to the original_rows */
1339      if (!compare_read(dp, 0/*transforms applied*/))
1340         return; /* no point testing more */
1341   }
1342
1343#ifdef PNG_WRITE_SUPPORTED
1344   /* Second test: write the original PNG data out to a new file (to test the
1345    * write side) then read the result back in and make sure that it hasn't
1346    * changed.
1347    */
1348   dp->operation = "write";
1349   write_png(dp, dp->original_ip, 0/*transforms*/);
1350   read_png(dp, &dp->written_file, NULL, 0/*transforms*/);
1351   if (!compare_read(dp, 0/*transforms applied*/))
1352      return;
1353#endif
1354
1355   /* Third test: the active options.  Test each in turn, or, with the
1356    * EXHAUSTIVE option, test all possible combinations.
1357    */
1358   {
1359      /* Use unsigned int here because the code below to increment through all
1360       * the possibilities exhaustively has to use a compare and that must be
1361       * unsigned, because some transforms are negative on a 16-bit system.
1362       */
1363      unsigned int active = dp->active_transforms;
1364      const int exhaustive = (dp->options & EXHAUSTIVE) != 0;
1365      unsigned int current = first_transform(active);
1366      unsigned int bad_transforms = 0;
1367      unsigned int bad_combo = ~0U;    /* bitwise AND of failing transforms */
1368      unsigned int bad_combo_list = 0; /* bitwise OR of failures */
1369
1370      for (;;)
1371      {
1372         read_png(dp, &dp->original_file, "active transforms", current);
1373
1374         /* If this involved any irreversible transformations then if we write
1375          * it out with just the reversible transformations and read it in again
1376          * with the same transforms we should get the same thing.  At present
1377          * this isn't done - it just seems like a waste of time and it would
1378          * require two sets of read png_struct/png_info.
1379          *
1380          * If there were no irreversible transformations then if we write it
1381          * out and read it back in again (without the reversible transforms)
1382          * we should get back to the place where we started.
1383          */
1384#ifdef PNG_WRITE_SUPPORTED
1385         if ((current & write_transforms) == current)
1386         {
1387            /* All transforms reversible: write the PNG with the transformations
1388             * reversed, then read it back in with no transformations.  The
1389             * result should be the same as the original apart from the loss of
1390             * low order bits because of the SHIFT/sBIT transform.
1391             */
1392            dp->operation = "reversible transforms";
1393            write_png(dp, dp->read_ip, current);
1394
1395            /* And if this is read back in, because all the transformations were
1396             * reversible, the result should be the same.
1397             */
1398            read_png(dp, &dp->written_file, NULL, 0);
1399            if (!compare_read(dp, current/*for the SHIFT/sBIT transform*/))
1400            {
1401               /* This set of transforms failed.  If a single bit is set - if
1402                * there is just one transform - don't include this in further
1403                * 'exhaustive' tests.  Notice that each transform is tested on
1404                * its own before testing combos in the exhaustive case.
1405                */
1406               if (is_combo(current))
1407               {
1408                  bad_combo &= current;
1409                  bad_combo_list |= current;
1410               }
1411
1412               else
1413                  bad_transforms |= current;
1414            }
1415         }
1416#endif
1417
1418         /* Now move to the next transform */
1419         if (exhaustive) /* all combinations */
1420         {
1421            unsigned int next = current;
1422
1423            do
1424            {
1425               if (next == read_transforms) /* Everything tested */
1426                  goto combo;
1427
1428               ++next;
1429            }  /* skip known bad combos if the relevant option is set; skip
1430                * combos involving known bad single transforms in all cases.
1431                */
1432            while (  (next & read_transforms) <= current
1433                  || (next & active) == 0 /* skip cases that do nothing */
1434                  || (next & bad_transforms) != 0
1435                  || skip_transform(dp, next));
1436
1437            assert((next & read_transforms) == next);
1438            current = next;
1439         }
1440
1441         else /* one at a time */
1442         {
1443            active &= ~current;
1444
1445            if (active == 0)
1446               goto combo;
1447
1448            current = first_transform(active);
1449         }
1450      }
1451
1452combo:
1453      if (dp->options & FIND_BAD_COMBOS)
1454      {
1455         /* bad_combos identifies the combos that occur in all failing cases;
1456          * bad_combo_list identifies transforms that do not prevent the
1457          * failure.
1458          */
1459         if (bad_combo != ~0U)
1460            printf("%s[0x%x]: PROBLEM: 0x%x[0x%x] ANTIDOTE: 0x%x\n",
1461               dp->filename, active, bad_combo, bad_combo_list,
1462               rw_transforms & ~bad_combo_list);
1463
1464         else
1465            printf("%s: no %sbad combos found\n", dp->filename,
1466               (dp->options & SKIP_BUGS) ? "additional " : "");
1467      }
1468   }
1469}
1470
1471static int
1472do_test(struct display *dp, const char *file)
1473   /* Exists solely to isolate the setjmp clobbers */
1474{
1475   int ret = setjmp(dp->error_return);
1476
1477   if (ret == 0)
1478   {
1479      test_one_file(dp, file);
1480      return 0;
1481   }
1482
1483   else if (ret < ERRORS) /* shouldn't longjmp on warnings */
1484      display_log(dp, INTERNAL_ERROR, "unexpected return code %d", ret);
1485
1486   return ret;
1487}
1488
1489int
1490main(const int argc, const char * const * const argv)
1491{
1492   /* For each file on the command line test it with a range of transforms */
1493   int option_end, ilog = 0;
1494   struct display d;
1495
1496   validate_T();
1497   display_init(&d);
1498
1499   for (option_end=1; option_end<argc; ++option_end)
1500   {
1501      const char *name = argv[option_end];
1502
1503      if (strcmp(name, "--verbose") == 0)
1504         d.options = (d.options & ~LEVEL_MASK) | VERBOSE;
1505
1506      else if (strcmp(name, "--warnings") == 0)
1507         d.options = (d.options & ~LEVEL_MASK) | WARNINGS;
1508
1509      else if (strcmp(name, "--errors") == 0)
1510         d.options = (d.options & ~LEVEL_MASK) | ERRORS;
1511
1512      else if (strcmp(name, "--quiet") == 0)
1513         d.options = (d.options & ~LEVEL_MASK) | QUIET;
1514
1515      else if (strcmp(name, "--exhaustive") == 0)
1516         d.options |= EXHAUSTIVE;
1517
1518      else if (strcmp(name, "--fast") == 0)
1519         d.options &= ~EXHAUSTIVE;
1520
1521      else if (strcmp(name, "--strict") == 0)
1522         d.options |= STRICT;
1523
1524      else if (strcmp(name, "--relaxed") == 0)
1525         d.options &= ~STRICT;
1526
1527      else if (strcmp(name, "--log") == 0)
1528      {
1529         ilog = option_end; /* prevent display */
1530         d.options |= LOG;
1531      }
1532
1533      else if (strcmp(name, "--nolog") == 0)
1534         d.options &= ~LOG;
1535
1536      else if (strcmp(name, "--continue") == 0)
1537         d.options |= CONTINUE;
1538
1539      else if (strcmp(name, "--stop") == 0)
1540         d.options &= ~CONTINUE;
1541
1542      else if (strcmp(name, "--skip-bugs") == 0)
1543         d.options |= SKIP_BUGS;
1544
1545      else if (strcmp(name, "--test-all") == 0)
1546         d.options &= ~SKIP_BUGS;
1547
1548      else if (strcmp(name, "--log-skipped") == 0)
1549         d.options |= LOG_SKIPPED;
1550
1551      else if (strcmp(name, "--nolog-skipped") == 0)
1552         d.options &= ~LOG_SKIPPED;
1553
1554      else if (strcmp(name, "--find-bad-combos") == 0)
1555         d.options |= FIND_BAD_COMBOS;
1556
1557      else if (strcmp(name, "--nofind-bad-combos") == 0)
1558         d.options &= ~FIND_BAD_COMBOS;
1559
1560      else if (name[0] == '-' && name[1] == '-')
1561      {
1562         fprintf(stderr, "pngimage: %s: unknown option\n", name);
1563         return 99;
1564      }
1565
1566      else
1567         break; /* Not an option */
1568   }
1569
1570   {
1571      int i;
1572      int errors = 0;
1573
1574      for (i=option_end; i<argc; ++i)
1575      {
1576         {
1577            int ret = do_test(&d, argv[i]);
1578
1579            if (ret > QUIET) /* abort on user or internal error */
1580               return 99;
1581         }
1582
1583         /* Here on any return, including failures, except user/internal issues
1584          */
1585         {
1586            const int pass = (d.options & STRICT) ?
1587               RESULT_STRICT(d.results) : RESULT_RELAXED(d.results);
1588
1589            if (!pass)
1590               ++errors;
1591
1592            if (d.options & LOG)
1593            {
1594               int j;
1595
1596               printf("%s: pngimage ", pass ? "PASS" : "FAIL");
1597
1598               for (j=1; j<option_end; ++j) if (j != ilog)
1599                  printf("%s ", argv[j]);
1600
1601               printf("%s\n", d.filename);
1602            }
1603         }
1604
1605         display_clean(&d);
1606      }
1607
1608      return errors != 0;
1609   }
1610}
1611#else /* !PNG_INFO_IMAGE_SUPPORTED || !PNG_READ_SUPPORTED */
1612int
1613main(void)
1614{
1615   fprintf(stderr, "pngimage: no support for png_read/write_image\n");
1616   return 77;
1617}
1618#endif
1619