1// Copyright 2017 Google Inc. All Rights Reserved.
2//
3// Use of this source code is governed by a BSD-style license
4// that can be found in the COPYING file in the root of the source
5// tree. An additional intellectual property rights grant can be found
6// in the file PATENTS. All contributing project authors may
7// be found in the AUTHORS file in the root of the source tree.
8// -----------------------------------------------------------------------------
9//
10// (limited) PNM decoder
11
12#include "./pnmdec.h"
13
14#include <assert.h>
15#include <ctype.h>
16#include <stdio.h>
17#include <stdlib.h>
18#include <string.h>
19
20#include "webp/encode.h"
21#include "./imageio_util.h"
22
23typedef enum {
24  WIDTH_FLAG      = 1 << 0,
25  HEIGHT_FLAG     = 1 << 1,
26  DEPTH_FLAG      = 1 << 2,
27  MAXVAL_FLAG     = 1 << 3,
28  TUPLE_FLAG      = 1 << 4,
29  ALL_NEEDED_FLAGS = WIDTH_FLAG | HEIGHT_FLAG | DEPTH_FLAG | MAXVAL_FLAG
30} PNMFlags;
31
32typedef struct {
33  const uint8_t* data;
34  size_t data_size;
35  int width, height;
36  int bytes_per_px;
37  int depth;          // 1 (grayscale), 2 (grayscale + alpha), 3 (rgb), 4 (rgba)
38  int max_value;
39  int type;           // 5, 6 or 7
40  int seen_flags;
41} PNMInfo;
42
43// -----------------------------------------------------------------------------
44// PNM decoding
45
46#define MAX_LINE_SIZE 1024
47static const size_t kMinPNMHeaderSize = 3;
48
49static size_t ReadLine(const uint8_t* const data, size_t off, size_t data_size,
50                       char out[MAX_LINE_SIZE + 1], size_t* const out_size) {
51  size_t i = 0;
52  *out_size = 0;
53 redo:
54  for (i = 0; i < MAX_LINE_SIZE && off < data_size; ++i) {
55    out[i] = data[off++];
56    if (out[i] == '\n') break;
57  }
58  if (off < data_size) {
59    if (i == 0) goto redo;         // empty line
60    if (out[0] == '#') goto redo;  // skip comment
61  }
62  out[i] = 0;   // safety sentinel
63  *out_size = i;
64  return off;
65}
66
67static size_t FlagError(const char flag[]) {
68  fprintf(stderr, "PAM header error: flags '%s' already seen.\n", flag);
69  return 0;
70}
71
72// inspired from http://netpbm.sourceforge.net/doc/pam.html
73static size_t ReadPAMFields(PNMInfo* const info, size_t off) {
74  char out[MAX_LINE_SIZE + 1];
75  size_t out_size;
76  int tmp;
77  int expected_depth = -1;
78  assert(info != NULL);
79  while (1) {
80    off = ReadLine(info->data, off, info->data_size, out, &out_size);
81    if (off == 0) return 0;
82    if (sscanf(out, "WIDTH %d", &tmp) == 1) {
83      if (info->seen_flags & WIDTH_FLAG) return FlagError("WIDTH");
84      info->seen_flags |= WIDTH_FLAG;
85      info->width = tmp;
86    } else if (sscanf(out, "HEIGHT %d", &tmp) == 1) {
87      if (info->seen_flags & HEIGHT_FLAG) return FlagError("HEIGHT");
88      info->seen_flags |= HEIGHT_FLAG;
89      info->height = tmp;
90    } else if (sscanf(out, "DEPTH %d", &tmp) == 1) {
91      if (info->seen_flags & DEPTH_FLAG) return FlagError("DEPTH");
92      info->seen_flags |= DEPTH_FLAG;
93      info->depth = tmp;
94    } else if (sscanf(out, "MAXVAL %d", &tmp) == 1) {
95      if (info->seen_flags & MAXVAL_FLAG) return FlagError("MAXVAL");
96      info->seen_flags |= MAXVAL_FLAG;
97      info->max_value = tmp;
98    } else if (!strcmp(out, "TUPLTYPE RGB_ALPHA")) {
99      expected_depth = 4;
100      info->seen_flags |= TUPLE_FLAG;
101    } else if (!strcmp(out, "TUPLTYPE RGB")) {
102      expected_depth = 3;
103      info->seen_flags |= TUPLE_FLAG;
104    } else if (!strcmp(out, "TUPLTYPE GRAYSCALE_ALPHA")) {
105      expected_depth = 2;
106      info->seen_flags |= TUPLE_FLAG;
107    } else if (!strcmp(out, "TUPLTYPE GRAYSCALE")) {
108      expected_depth = 1;
109      info->seen_flags |= TUPLE_FLAG;
110    } else if (!strcmp(out, "ENDHDR")) {
111      break;
112    } else {
113      static const char kEllipsis[] = " ...";
114      int i;
115      if (out_size > 20) sprintf(out + 20 - strlen(kEllipsis), kEllipsis);
116      for (i = 0; i < (int)strlen(out); ++i) {
117        // isprint() might trigger a "char-subscripts" warning if given a char.
118        if (!isprint((int)out[i])) out[i] = ' ';
119      }
120      fprintf(stderr, "PAM header error: unrecognized entry [%s]\n", out);
121      return 0;
122    }
123  }
124  if (!(info->seen_flags & ALL_NEEDED_FLAGS)) {
125    fprintf(stderr, "PAM header error: missing tags%s%s%s%s\n",
126            (info->seen_flags & WIDTH_FLAG) ? "" : " WIDTH",
127            (info->seen_flags & HEIGHT_FLAG) ? "" : " HEIGHT",
128            (info->seen_flags & DEPTH_FLAG) ? "" : " DEPTH",
129            (info->seen_flags & MAXVAL_FLAG) ? "" : " MAXVAL");
130    return 0;
131  }
132  if (expected_depth != -1 && info->depth != expected_depth) {
133    fprintf(stderr, "PAM header error: expected DEPTH %d but got DEPTH %d\n",
134            expected_depth, info->depth);
135    return 0;
136  }
137  return off;
138}
139
140static size_t ReadHeader(PNMInfo* const info) {
141  size_t off = 0;
142  char out[MAX_LINE_SIZE + 1];
143  size_t out_size;
144  if (info == NULL) return 0;
145  if (info->data == NULL || info->data_size < kMinPNMHeaderSize) return 0;
146
147  info->width = info->height = 0;
148  info->type = -1;
149  info->seen_flags = 0;
150  info->bytes_per_px = 0;
151  info->depth = 0;
152  info->max_value = 0;
153
154  off = ReadLine(info->data, off, info->data_size, out, &out_size);
155  if (off == 0 || sscanf(out, "P%d", &info->type) != 1) return 0;
156  if (info->type == 7) {
157    off = ReadPAMFields(info, off);
158  } else {
159    off = ReadLine(info->data, off, info->data_size, out, &out_size);
160    if (off == 0 || sscanf(out, "%d %d", &info->width, &info->height) != 2) {
161      return 0;
162    }
163    off = ReadLine(info->data, off, info->data_size, out, &out_size);
164    if (off == 0 || sscanf(out, "%d", &info->max_value) != 1) return 0;
165
166    // finish initializing missing fields
167    info->depth = (info->type == 5) ? 1 : 3;
168  }
169  // perform some basic numerical validation
170  if (info->width <= 0 || info->height <= 0 ||
171      info->type <= 0 || info->type >= 9 ||
172      info->depth <= 0 || info->depth > 4 ||
173      info->max_value <= 0 || info->max_value >= 65536) {
174    return 0;
175  }
176  info->bytes_per_px = info->depth * (info->max_value > 255 ? 2 : 1);
177  return off;
178}
179
180int ReadPNM(const uint8_t* const data, size_t data_size,
181            WebPPicture* const pic, int keep_alpha,
182            struct Metadata* const metadata) {
183  int ok = 0;
184  int i, j;
185  uint64_t stride, pixel_bytes, sample_size, depth;
186  uint8_t* rgb = NULL, *tmp_rgb;
187  size_t offset;
188  PNMInfo info;
189
190  info.data = data;
191  info.data_size = data_size;
192  offset = ReadHeader(&info);
193  if (offset == 0) {
194    fprintf(stderr, "Error parsing PNM header.\n");
195    goto End;
196  }
197
198  if (info.type < 5 || info.type > 7) {
199    fprintf(stderr, "Unsupported P%d PNM format.\n", info.type);
200    goto End;
201  }
202
203  // Some basic validations.
204  if (pic == NULL) goto End;
205  if (info.width > WEBP_MAX_DIMENSION || info.height > WEBP_MAX_DIMENSION) {
206    fprintf(stderr, "Invalid %dx%d dimension for PNM\n",
207                    info.width, info.height);
208    goto End;
209  }
210
211  pixel_bytes = (uint64_t)info.width * info.height * info.bytes_per_px;
212  if (data_size < offset + pixel_bytes) {
213    fprintf(stderr, "Truncated PNM file (P%d).\n", info.type);
214    goto End;
215  }
216  sample_size = (info.max_value > 255) ? 2 : 1;
217  // final depth
218  depth = (info.depth == 1 || info.depth == 3 || !keep_alpha) ? 3 : 4;
219  stride = depth * info.width;
220  if (stride != (size_t)stride ||
221      !ImgIoUtilCheckSizeArgumentsOverflow(stride, info.height)) {
222    goto End;
223  }
224
225  rgb = (uint8_t*)malloc((size_t)stride * info.height);
226  if (rgb == NULL) goto End;
227
228  // Convert input.
229  // We only optimize for the sample_size=1, max_value=255, depth=1 case.
230  tmp_rgb = rgb;
231  for (j = 0; j < info.height; ++j) {
232    const uint8_t* in = data + offset;
233    offset += info.bytes_per_px * info.width;
234    assert(offset <= data_size);
235    if (info.max_value == 255 && info.depth >= 3) {
236      // RGB or RGBA
237      if (info.depth == 3 || keep_alpha) {
238        memcpy(tmp_rgb, in, info.depth * info.width * sizeof(*in));
239      } else {
240        assert(info.depth == 4 && !keep_alpha);
241        for (i = 0; i < info.width; ++i) {
242          tmp_rgb[3 * i + 0] = in[4 * i + 0];
243          tmp_rgb[3 * i + 1] = in[4 * i + 1];
244          tmp_rgb[3 * i + 2] = in[4 * i + 2];
245        }
246      }
247    } else {
248      // Unoptimized case, we need to handle non-trivial operations:
249      //   * convert 16b to 8b (if max_value > 255)
250      //   * rescale to [0..255] range (if max_value != 255)
251      //   * drop the alpha channel (if keep_alpha is false)
252      const uint32_t round = info.max_value / 2;
253      int k = 0;
254      for (i = 0; i < info.width * info.depth; ++i) {
255        uint32_t v = (sample_size == 2) ? 256u * in[2 * i + 0] + in[2 * i + 1]
256                   : in[i];
257        if (info.max_value != 255) v = (v * 255u + round) / info.max_value;
258        if (v > 255u) v = 255u;
259        if (info.depth > 2) {
260          if (!keep_alpha && info.depth == 4 && (i % 4) == 3) {
261            // skip alpha
262          } else {
263            tmp_rgb[k] = v;
264            k += 1;
265          }
266        } else if (info.depth == 1 || (i % 2) == 0) {
267          tmp_rgb[k + 0] = tmp_rgb[k + 1] = tmp_rgb[k + 2] = v;
268          k += 3;
269        } else if (keep_alpha && info.depth == 2) {
270          tmp_rgb[k] = v;
271          k += 1;
272        } else {
273          // skip alpha
274        }
275      }
276    }
277    tmp_rgb += stride;
278  }
279
280  // WebP conversion.
281  pic->width = info.width;
282  pic->height = info.height;
283  ok = (depth == 4) ? WebPPictureImportRGBA(pic, rgb, (int)stride)
284                    : WebPPictureImportRGB(pic, rgb, (int)stride);
285  if (!ok) goto End;
286
287  ok = 1;
288 End:
289  free((void*)rgb);
290
291  (void)metadata;
292  (void)keep_alpha;
293  return ok;
294}
295
296// -----------------------------------------------------------------------------
297