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