lib/diff_output.c

   1 /* Common parts for printing diff output */
   2 /*
   3  * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #include <ctype.h>
  19 #include <errno.h>
  20 #include <stdbool.h>
  21 #include <stdint.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include <arraylist.h>
  28 #include <diff_main.h>
  29 #include <diff_output.h>
  30
  31 #include "diff_internal.h"
  32
  33 static int
  34 get_atom_byte(int *ch, struct diff_atom *atom, off_t off)
  35 {
  36         off_t cur;
  37
  38         if (atom->at != NULL) {
  39                 *ch = atom->at[off];
  40                 return 0;
  41         }
  42
  43         cur = ftello(atom->root->f);
  44         if (cur == -1)
  45                 return errno;
  46
  47         if (cur != atom->pos + off &&
  48             fseeko(atom->root->f, atom->pos + off, SEEK_SET) == -1)
  49                 return errno;
  50
  51         *ch = fgetc(atom->root->f);
  52         if (*ch == EOF && ferror(atom->root->f))
  53                 return errno;
  54
  55         return 0;
  56 }
  57
  58 #define DIFF_OUTPUT_BUF_SIZE    512
  59
  60 int
  61 diff_output_lines(struct diff_output_info *outinfo, FILE *dest,
  62                   const char *prefix, struct diff_atom *start_atom,
  63                   unsigned int count)
  64 {
  65         struct diff_atom *atom;
  66         off_t outoff = 0, *offp;
  67         int rc;
  68
  69         if (outinfo && outinfo->line_offsets.len > 0) {
  70                 unsigned int idx = outinfo->line_offsets.len - 1;
  71                 outoff = outinfo->line_offsets.head[idx];
  72         }
  73
  74         foreach_diff_atom(atom, start_atom, count) {
  75                 off_t outlen = 0;
  76                 int i, ch, nbuf = 0;
  77                 unsigned int len = atom->len;
  78                 unsigned char buf[DIFF_OUTPUT_BUF_SIZE + 1 /* '\n' */];
  79                 size_t n;
  80
  81                 n = strlcpy(buf, prefix, sizeof(buf));
  82                 if (n >= DIFF_OUTPUT_BUF_SIZE) /* leave room for '\n' */
  83                         return ENOBUFS;
  84                 nbuf += n;
  85
  86                 if (len) {
  87                         rc = get_atom_byte(&ch, atom, len - 1);
  88                         if (rc)
  89                                 return rc;
  90                         if (ch == '\n')
  91                                 len--;
  92                         if (len) {
  93                                 rc = get_atom_byte(&ch, atom, len - 1);
  94                                 if (rc)
  95                                         return rc;
  96                                 if (ch == '\r')
  97                                         len--;
  98                         }
  99                 }
 100
 101                 for (i = 0; i < len; i++) {
 102                         rc = get_atom_byte(&ch, atom, i);
 103                         if (rc)
 104                                 return rc;
 105                         if (nbuf >= DIFF_OUTPUT_BUF_SIZE) {
 106                                 rc = fwrite(buf, 1, nbuf, dest);
 107                                 if (rc != nbuf)
 108                                         return errno;
 109                                 outlen += rc;
 110                                 nbuf = 0;
 111                         }
 112                         buf[nbuf++] = ch;
 113                 }
 114                 buf[nbuf++] = '\n';
 115                 rc = fwrite(buf, 1, nbuf, dest);
 116                 if (rc != nbuf)
 117                         return errno;
 118                 outlen += rc;
 119                 if (outinfo) {
 120                         ARRAYLIST_ADD(offp, outinfo->line_offsets);
 121                         if (offp == NULL)
 122                                 return ENOMEM;
 123                         outoff += outlen;
 124                         *offp = outoff;
 125                 }
 126         }
 127
 128         return DIFF_RC_OK;
 129 }
 130
 131 int
 132 diff_output_chunk_left_version(struct diff_output_info **output_info,
 133                                FILE *dest,
 134                                const struct diff_input_info *info,
 135                                const struct diff_result *result,
 136                                const struct diff_chunk_context *cc)
 137 {
 138         int rc, c_idx;
 139         struct diff_output_info *outinfo = NULL;
 140
 141         if (diff_range_empty(&cc->left))
 142                 return DIFF_RC_OK;
 143
 144         if (output_info) {
 145                 *output_info = diff_output_info_alloc();
 146                 if (*output_info == NULL)
 147                         return ENOMEM;
 148                 outinfo = *output_info;
 149         }
 150
 151         /* Write out all chunks on the left side. */
 152         for (c_idx = cc->chunk.start; c_idx < cc->chunk.end; c_idx++) {
 153                 const struct diff_chunk *c = &result->chunks.head[c_idx];
 154
 155                 if (c->left_count) {
 156                         rc = diff_output_lines(outinfo, dest, "",
 157                             c->left_start, c->left_count);
 158                         if (rc)
 159                                 return rc;
 160                 }
 161         }
 162
 163         return DIFF_RC_OK;
 164 }
 165
 166 int
 167 diff_output_chunk_right_version(struct diff_output_info **output_info,
 168                                 FILE *dest,
 169                                 const struct diff_input_info *info,
 170                                 const struct diff_result *result,
 171                                 const struct diff_chunk_context *cc)
 172 {
 173         int rc, c_idx;
 174         struct diff_output_info *outinfo = NULL;
 175
 176         if (diff_range_empty(&cc->right))
 177                 return DIFF_RC_OK;
 178
 179         if (output_info) {
 180                 *output_info = diff_output_info_alloc();
 181                 if (*output_info == NULL)
 182                         return ENOMEM;
 183                 outinfo = *output_info;
 184         }
 185
 186         /* Write out all chunks on the right side. */
 187         for (c_idx = cc->chunk.start; c_idx < cc->chunk.end; c_idx++) {
 188                 const struct diff_chunk *c = &result->chunks.head[c_idx];
 189
 190                 if (c->right_count) {
 191                         rc = diff_output_lines(outinfo, dest, "", c->right_start,
 192                             c->right_count);
 193                         if (rc)
 194                                 return rc;
 195                 }
 196         }
 197
 198         return DIFF_RC_OK;
 199 }
 200
 201 int
 202 diff_output_trailing_newline_msg(struct diff_output_info *outinfo, FILE *dest,
 203                                  const struct diff_chunk *c)
 204 {
 205         enum diff_chunk_type chunk_type = diff_chunk_type(c);
 206         struct diff_atom *atom, *start_atom;
 207         unsigned int atom_count;
 208         int rc, ch;
 209         off_t outoff = 0, *offp;
 210
 211         if (chunk_type == CHUNK_MINUS || chunk_type == CHUNK_SAME) {
 212                 start_atom = c->left_start;
 213                 atom_count = c->left_count;
 214         } else if (chunk_type == CHUNK_PLUS) {
 215                 start_atom = c->right_start;
 216                 atom_count = c->right_count;
 217         } else
 218                 return EINVAL;
 219
 220         /* Locate the last atom. */
 221         if (atom_count == 0)
 222                 return EINVAL;
 223         atom = &start_atom[atom_count - 1];
 224
 225         rc = get_atom_byte(&ch, atom, atom->len - 1);
 226         if (rc != DIFF_RC_OK)
 227                 return rc;
 228
 229         if (ch != '\n') {
 230                 if (outinfo && outinfo->line_offsets.len > 0) {
 231                         unsigned int idx = outinfo->line_offsets.len - 1;
 232                         outoff = outinfo->line_offsets.head[idx];
 233                 }
 234                 rc = fprintf(dest, "\\ No newline at end of file\n");
 235                 if (rc < 0)
 236                         return errno;
 237                 if (outinfo) {
 238                         ARRAYLIST_ADD(offp, outinfo->line_offsets);
 239                         if (offp == NULL)
 240                                 return ENOMEM;
 241                         outoff += rc;
 242                         *offp = outoff;
 243                 }
 244         }
 245
 246         return DIFF_RC_OK;
 247 }
 248
 249 static bool
 250 is_function_prototype(unsigned char ch)
 251 {
 252         return (isalpha(ch) || ch == '_' || ch == '$');
 253 }
 254
 255 #define begins_with(s, pre) (strncmp(s, pre, sizeof(pre)-1) == 0)
 256
 257 int
 258 diff_output_match_function_prototype(char *prototype, size_t prototype_size,
 259     int *last_prototype_idx, const struct diff_result *result,
 260     const struct diff_chunk_context *cc)
 261 {
 262         struct diff_atom *start_atom, *atom;
 263         const struct diff_data *data;
 264         unsigned char buf[DIFF_FUNCTION_CONTEXT_SIZE];
 265         const char *state = NULL;
 266         int rc, i, ch;
 267
 268         if (result->left->atoms.len > 0 && cc->left.start > 0) {
 269                 data = result->left;
 270                 start_atom = &data->atoms.head[cc->left.start - 1];
 271         } else
 272                 return DIFF_RC_OK;
 273
 274         diff_data_foreach_atom_backwards_from(start_atom, atom, data) {
 275                 int atom_idx = diff_atom_root_idx(data, atom);
 276                 if (atom_idx < *last_prototype_idx)
 277                         break;
 278                 rc = get_atom_byte(&ch, atom, 0);
 279                 if (rc)
 280                         return rc;
 281                 buf[0] = (unsigned char)ch;
 282                 if (!is_function_prototype(buf[0]))
 283                         continue;
 284                 for (i = 1; i < atom->len && i < sizeof(buf) - 1; i++) {
 285                         rc = get_atom_byte(&ch, atom, i);
 286                         if (rc)
 287                                 return rc;
 288                         if (ch == '\n')
 289                                 break;
 290                         buf[i] = (unsigned char)ch;
 291                 }
 292                 buf[i] = '\0';
 293                 if (begins_with(buf, "private:")) {
 294                         if (!state)
 295                                 state = " (private)";
 296                 } else if (begins_with(buf, "protected:")) {
 297                         if (!state)
 298                                 state = " (protected)";
 299                 } else if (begins_with(buf, "public:")) {
 300                         if (!state)
 301                                 state = " (public)";
 302                 } else {
 303                         if (state)  /* don't care about truncation */
 304                                 strlcat(buf, state, sizeof(buf));
 305                         strlcpy(prototype, buf, prototype_size);
 306                         break;
 307                 }
 308         }
 309
 310         *last_prototype_idx = diff_atom_root_idx(data, start_atom);
 311         return DIFF_RC_OK;
 312 }
 313
 314 struct diff_output_info *
 315 diff_output_info_alloc(void)
 316 {
 317         struct diff_output_info *output_info;
 318         off_t *offp;
 319
 320         output_info = malloc(sizeof(*output_info));
 321         if (output_info != NULL) {
 322                 ARRAYLIST_INIT(output_info->line_offsets, 128);
 323                 ARRAYLIST_ADD(offp, output_info->line_offsets);
 324                 if (offp == NULL) {
 325                         diff_output_info_free(output_info);
 326                         return NULL;
 327                 }
 328                 *offp = 0;
 329         }
 330         return output_info;
 331 }
 332
 333 void
 334 diff_output_info_free(struct diff_output_info *output_info)
 335 {
 336         ARRAYLIST_FREE(output_info->line_offsets);
 337         free(output_info);
 338 }
 339
 340 const char *
 341 diff_output_get_label_left(const struct diff_input_info *info)
 342 {
 343         if (info->flags & DIFF_INPUT_LEFT_NONEXISTENT)
 344                 return "/dev/null";
 345
 346         return info->left_path ? : "a";
 347 }
 348
 349 const char *
 350 diff_output_get_label_right(const struct diff_input_info *info)
 351 {
 352         if (info->flags & DIFF_INPUT_RIGHT_NONEXISTENT)
 353                 return "/dev/null";
 354
 355         return info->right_path ? : "b";
 356 }