range-diff.c

   1 #include "cache.h"
   2 #include "range-diff.h"
   3 #include "string-list.h"
   4 #include "run-command.h"
   5 #include "argv-array.h"
   6 #include "hashmap.h"
   7 #include "xdiff-interface.h"
   8 #include "linear-assignment.h"
   9 #include "diffcore.h"
  10
  11 struct patch_util {
  12         /* For the search for an exact match */
  13         struct hashmap_entry e;
  14         const char *diff, *patch;
  15
  16         int i, shown;
  17         int diffsize;
  18         size_t diff_offset;
  19         /* the index of the matching item in the other branch, or -1 */
  20         int matching;
  21         struct object_id oid;
  22 };
  23
  24 /*
  25  * Reads the patches into a string list, with the `util` field being populated
  26  * as struct object_id (will need to be free()d).
  27  */
  28 static int read_patches(const char *range, struct string_list *list)
  29 {
  30         struct child_process cp = CHILD_PROCESS_INIT;
  31         FILE *in;
  32         struct strbuf buf = STRBUF_INIT, line = STRBUF_INIT;
  33         struct patch_util *util = NULL;
  34         int in_header = 1;
  35
  36         argv_array_pushl(&cp.args, "log", "--no-color", "-p", "--no-merges",
  37                         "--reverse", "--date-order", "--decorate=no",
  38                         "--no-abbrev-commit", range,
  39                         NULL);
  40         cp.out = -1;
  41         cp.no_stdin = 1;
  42         cp.git_cmd = 1;
  43
  44         if (start_command(&cp))
  45                 return error_errno(_("could not start `log`"));
  46         in = fdopen(cp.out, "r");
  47         if (!in) {
  48                 error_errno(_("could not read `log` output"));
  49                 finish_command(&cp);
  50                 return -1;
  51         }
  52
  53         while (strbuf_getline(&line, in) != EOF) {
  54                 const char *p;
  55
  56                 if (skip_prefix(line.buf, "commit ", &p)) {
  57                         if (util) {
  58                                 string_list_append(list, buf.buf)->util = util;
  59                                 strbuf_reset(&buf);
  60                         }
  61                         util = xcalloc(sizeof(*util), 1);
  62                         if (get_oid(p, &util->oid)) {
  63                                 error(_("could not parse commit '%s'"), p);
  64                                 free(util);
  65                                 string_list_clear(list, 1);
  66                                 strbuf_release(&buf);
  67                                 strbuf_release(&line);
  68                                 fclose(in);
  69                                 finish_command(&cp);
  70                                 return -1;
  71                         }
  72                         util->matching = -1;
  73                         in_header = 1;
  74                         continue;
  75                 }
  76
  77                 if (starts_with(line.buf, "diff --git")) {
  78                         in_header = 0;
  79                         strbuf_addch(&buf, '\n');
  80                         if (!util->diff_offset)
  81                                 util->diff_offset = buf.len;
  82                         strbuf_addbuf(&buf, &line);
  83                 } else if (in_header) {
  84                         if (starts_with(line.buf, "Author: ")) {
  85                                 strbuf_addbuf(&buf, &line);
  86                                 strbuf_addstr(&buf, "\n\n");
  87                         } else if (starts_with(line.buf, "    ")) {
  88                                 strbuf_rtrim(&line);
  89                                 strbuf_addbuf(&buf, &line);
  90                                 strbuf_addch(&buf, '\n');
  91                         }
  92                         continue;
  93                 } else if (starts_with(line.buf, "@@ "))
  94                         strbuf_addstr(&buf, "@@");
  95                 else if (!line.buf[0] || starts_with(line.buf, "index "))
  96                         /*
  97                          * A completely blank (not ' \n', which is context)
  98                          * line is not valid in a diff.  We skip it
  99                          * silently, because this neatly handles the blank
 100                          * separator line between commits in git-log
 101                          * output.
 102                          *
 103                          * We also want to ignore the diff's `index` lines
 104                          * because they contain exact blob hashes in which
 105                          * we are not interested.
 106                          */
 107                         continue;
 108                 else
 109                         strbuf_addbuf(&buf, &line);
 110
 111                 strbuf_addch(&buf, '\n');
 112                 util->diffsize++;
 113         }
 114         fclose(in);
 115         strbuf_release(&line);
 116
 117         if (util)
 118                 string_list_append(list, buf.buf)->util = util;
 119         strbuf_release(&buf);
 120
 121         if (finish_command(&cp))
 122                 return -1;
 123
 124         return 0;
 125 }
 126
 127 static int patch_util_cmp(const void *dummy, const struct patch_util *a,
 128                      const struct patch_util *b, const char *keydata)
 129 {
 130         return strcmp(a->diff, keydata ? keydata : b->diff);
 131 }
 132
 133 static void find_exact_matches(struct string_list *a, struct string_list *b)
 134 {
 135         struct hashmap map;
 136         int i;
 137
 138         hashmap_init(&map, (hashmap_cmp_fn)patch_util_cmp, NULL, 0);
 139
 140         /* First, add the patches of a to a hash map */
 141         for (i = 0; i < a->nr; i++) {
 142                 struct patch_util *util = a->items[i].util;
 143
 144                 util->i = i;
 145                 util->patch = a->items[i].string;
 146                 util->diff = util->patch + util->diff_offset;
 147                 hashmap_entry_init(util, strhash(util->diff));
 148                 hashmap_add(&map, util);
 149         }
 150
 151         /* Now try to find exact matches in b */
 152         for (i = 0; i < b->nr; i++) {
 153                 struct patch_util *util = b->items[i].util, *other;
 154
 155                 util->i = i;
 156                 util->patch = b->items[i].string;
 157                 util->diff = util->patch + util->diff_offset;
 158                 hashmap_entry_init(util, strhash(util->diff));
 159                 other = hashmap_remove(&map, util, NULL);
 160                 if (other) {
 161                         if (other->matching >= 0)
 162                                 BUG("already assigned!");
 163
 164                         other->matching = i;
 165                         util->matching = other->i;
 166                 }
 167         }
 168
 169         hashmap_free(&map, 0);
 170 }
 171
 172 static void diffsize_consume(void *data, char *line, unsigned long len)
 173 {
 174         (*(int *)data)++;
 175 }
 176
 177 static int diffsize(const char *a, const char *b)
 178 {
 179         xpparam_t pp = { 0 };
 180         xdemitconf_t cfg = { 0 };
 181         mmfile_t mf1, mf2;
 182         int count = 0;
 183
 184         mf1.ptr = (char *)a;
 185         mf1.size = strlen(a);
 186         mf2.ptr = (char *)b;
 187         mf2.size = strlen(b);
 188
 189         cfg.ctxlen = 3;
 190         if (!xdi_diff_outf(&mf1, &mf2, diffsize_consume, &count, &pp, &cfg))
 191                 return count;
 192
 193         error(_("failed to generate diff"));
 194         return COST_MAX;
 195 }
 196
 197 static void get_correspondences(struct string_list *a, struct string_list *b,
 198                                 int creation_factor)
 199 {
 200         int n = a->nr + b->nr;
 201         int *cost, c, *a2b, *b2a;
 202         int i, j;
 203
 204         ALLOC_ARRAY(cost, st_mult(n, n));
 205         ALLOC_ARRAY(a2b, n);
 206         ALLOC_ARRAY(b2a, n);
 207
 208         for (i = 0; i < a->nr; i++) {
 209                 struct patch_util *a_util = a->items[i].util;
 210
 211                 for (j = 0; j < b->nr; j++) {
 212                         struct patch_util *b_util = b->items[j].util;
 213
 214                         if (a_util->matching == j)
 215                                 c = 0;
 216                         else if (a_util->matching < 0 && b_util->matching < 0)
 217                                 c = diffsize(a_util->diff, b_util->diff);
 218                         else
 219                                 c = COST_MAX;
 220                         cost[i + n * j] = c;
 221                 }
 222
 223                 c = a_util->matching < 0 ?
 224                         a_util->diffsize * creation_factor / 100 : COST_MAX;
 225                 for (j = b->nr; j < n; j++)
 226                         cost[i + n * j] = c;
 227         }
 228
 229         for (j = 0; j < b->nr; j++) {
 230                 struct patch_util *util = b->items[j].util;
 231
 232                 c = util->matching < 0 ?
 233                         util->diffsize * creation_factor / 100 : COST_MAX;
 234                 for (i = a->nr; i < n; i++)
 235                         cost[i + n * j] = c;
 236         }
 237
 238         for (i = a->nr; i < n; i++)
 239                 for (j = b->nr; j < n; j++)
 240                         cost[i + n * j] = 0;
 241
 242         compute_assignment(n, n, cost, a2b, b2a);
 243
 244         for (i = 0; i < a->nr; i++)
 245                 if (a2b[i] >= 0 && a2b[i] < b->nr) {
 246                         struct patch_util *a_util = a->items[i].util;
 247                         struct patch_util *b_util = b->items[a2b[i]].util;
 248
 249                         a_util->matching = a2b[i];
 250                         b_util->matching = i;
 251                 }
 252
 253         free(cost);
 254         free(a2b);
 255         free(b2a);
 256 }
 257
 258 static const char *short_oid(struct patch_util *util)
 259 {
 260         return find_unique_abbrev(&util->oid, DEFAULT_ABBREV);
 261 }
 262
 263 static struct diff_filespec *get_filespec(const char *name, const char *p)
 264 {
 265         struct diff_filespec *spec = alloc_filespec(name);
 266
 267         fill_filespec(spec, &null_oid, 0, 0644);
 268         spec->data = (char *)p;
 269         spec->size = strlen(p);
 270         spec->should_munmap = 0;
 271         spec->is_stdin = 1;
 272
 273         return spec;
 274 }
 275
 276 static void patch_diff(const char *a, const char *b,
 277                               struct diff_options *diffopt)
 278 {
 279         diff_queue(&diff_queued_diff,
 280                    get_filespec("a", a), get_filespec("b", b));
 281
 282         diffcore_std(diffopt);
 283         diff_flush(diffopt);
 284 }
 285
 286 static void output(struct string_list *a, struct string_list *b,
 287                    struct diff_options *diffopt)
 288 {
 289         int i = 0, j = 0;
 290
 291         /*
 292          * We assume the user is really more interested in the second argument
 293          * ("newer" version). To that end, we print the output in the order of
 294          * the RHS (the `b` parameter). To put the LHS (the `a` parameter)
 295          * commits that are no longer in the RHS into a good place, we place
 296          * them once we have shown all of their predecessors in the LHS.
 297          */
 298
 299         while (i < a->nr || j < b->nr) {
 300                 struct patch_util *a_util, *b_util;
 301                 a_util = i < a->nr ? a->items[i].util : NULL;
 302                 b_util = j < b->nr ? b->items[j].util : NULL;
 303
 304                 /* Skip all the already-shown commits from the LHS. */
 305                 while (i < a->nr && a_util->shown)
 306                         a_util = ++i < a->nr ? a->items[i].util : NULL;
 307
 308                 /* Show unmatched LHS commit whose predecessors were shown. */
 309                 if (i < a->nr && a_util->matching < 0) {
 310                         printf("%d: %s < -: --------\n",
 311                                i + 1, short_oid(a_util));
 312                         i++;
 313                         continue;
 314                 }
 315
 316                 /* Show unmatched RHS commits. */
 317                 while (j < b->nr && b_util->matching < 0) {
 318                         printf("-: -------- > %d: %s\n",
 319                                j + 1, short_oid(b_util));
 320                         b_util = ++j < b->nr ? b->items[j].util : NULL;
 321                 }
 322
 323                 /* Show matching LHS/RHS pair. */
 324                 if (j < b->nr) {
 325                         a_util = a->items[b_util->matching].util;
 326                         printf("%d: %s ! %d: %s\n",
 327                                b_util->matching + 1, short_oid(a_util),
 328                                j + 1, short_oid(b_util));
 329                         if (!(diffopt->output_format & DIFF_FORMAT_NO_OUTPUT))
 330                                 patch_diff(a->items[b_util->matching].string,
 331                                            b->items[j].string, diffopt);
 332                         a_util->shown = 1;
 333                         j++;
 334                 }
 335         }
 336 }
 337
 338 int show_range_diff(const char *range1, const char *range2,
 339                     int creation_factor, struct diff_options *diffopt)
 340 {
 341         int res = 0;
 342
 343         struct string_list branch1 = STRING_LIST_INIT_DUP;
 344         struct string_list branch2 = STRING_LIST_INIT_DUP;
 345
 346         if (read_patches(range1, &branch1))
 347                 res = error(_("could not parse log for '%s'"), range1);
 348         if (!res && read_patches(range2, &branch2))
 349                 res = error(_("could not parse log for '%s'"), range2);
 350
 351         if (!res) {
 352                 find_exact_matches(&branch1, &branch2);
 353                 get_correspondences(&branch1, &branch2, creation_factor);
 354                 output(&branch1, &branch2, diffopt);
 355         }
 356
 357         string_list_clear(&branch1, 1);
 358         string_list_clear(&branch2, 1);
 359
 360         return res;
 361 }