Andrew's git / gitweb.git / commit.c
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commit.con commit [PATCH] Add a topological sort procedure to commit.c (ab580ac)
   1#include <ctype.h>
   2#include "tag.h"
   3#include "commit.h"
   4#include "cache.h"
   5
   6struct sort_node
   7{
   8        /*
   9         * the number of children of the associated commit
  10         * that also occur in the list being sorted.
  11         */
  12        unsigned int indegree;
  13
  14        /*
  15         * reference to original list item that we will re-use
  16         * on output.
  17         */
  18        struct commit_list * list_item;
  19
  20};
  21
  22const char *commit_type = "commit";
  23
  24enum cmit_fmt get_commit_format(const char *arg)
  25{
  26        if (!*arg)
  27                return CMIT_FMT_DEFAULT;
  28        if (!strcmp(arg, "=raw"))
  29                return CMIT_FMT_RAW;
  30        if (!strcmp(arg, "=medium"))
  31                return CMIT_FMT_MEDIUM;
  32        if (!strcmp(arg, "=short"))
  33                return CMIT_FMT_SHORT;
  34        if (!strcmp(arg, "=full"))
  35                return CMIT_FMT_FULL;
  36        die("invalid --pretty format");
  37}
  38
  39static struct commit *check_commit(struct object *obj, const unsigned char *sha1)
  40{
  41        if (obj->type != commit_type) {
  42                error("Object %s is a %s, not a commit", 
  43                      sha1_to_hex(sha1), obj->type);
  44                return NULL;
  45        }
  46        return (struct commit *) obj;
  47}
  48
  49struct commit *lookup_commit_reference(const unsigned char *sha1)
  50{
  51        struct object *obj = parse_object(sha1);
  52
  53        if (!obj)
  54                return NULL;
  55        if (obj->type == tag_type)
  56                obj = ((struct tag *)obj)->tagged;
  57        return check_commit(obj, sha1);
  58}
  59
  60struct commit *lookup_commit(const unsigned char *sha1)
  61{
  62        struct object *obj = lookup_object(sha1);
  63        if (!obj) {
  64                struct commit *ret = xmalloc(sizeof(struct commit));
  65                memset(ret, 0, sizeof(struct commit));
  66                created_object(sha1, &ret->object);
  67                ret->object.type = commit_type;
  68                return ret;
  69        }
  70        if (!obj->type)
  71                obj->type = commit_type;
  72        return check_commit(obj, sha1);
  73}
  74
  75static unsigned long parse_commit_date(const char *buf)
  76{
  77        unsigned long date;
  78
  79        if (memcmp(buf, "author", 6))
  80                return 0;
  81        while (*buf++ != '\n')
  82                /* nada */;
  83        if (memcmp(buf, "committer", 9))
  84                return 0;
  85        while (*buf++ != '>')
  86                /* nada */;
  87        date = strtoul(buf, NULL, 10);
  88        if (date == ULONG_MAX)
  89                date = 0;
  90        return date;
  91}
  92
  93int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
  94{
  95        void *bufptr = buffer;
  96        unsigned char parent[20];
  97        struct commit_list **pptr;
  98
  99        if (item->object.parsed)
 100                return 0;
 101        item->object.parsed = 1;
 102        get_sha1_hex(bufptr + 5, parent);
 103        item->tree = lookup_tree(parent);
 104        if (item->tree)
 105                add_ref(&item->object, &item->tree->object);
 106        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
 107        pptr = &item->parents;
 108        while (!memcmp(bufptr, "parent ", 7) &&
 109               !get_sha1_hex(bufptr + 7, parent)) {
 110                struct commit *new_parent = lookup_commit(parent);
 111                if (new_parent) {
 112                        pptr = &commit_list_insert(new_parent, pptr)->next;
 113                        add_ref(&item->object, &new_parent->object);
 114                }
 115                bufptr += 48;
 116        }
 117        item->date = parse_commit_date(bufptr);
 118        return 0;
 119}
 120
 121int parse_commit(struct commit *item)
 122{
 123        char type[20];
 124        void *buffer;
 125        unsigned long size;
 126        int ret;
 127
 128        if (item->object.parsed)
 129                return 0;
 130        buffer = read_sha1_file(item->object.sha1, type, &size);
 131        if (!buffer)
 132                return error("Could not read %s",
 133                             sha1_to_hex(item->object.sha1));
 134        if (strcmp(type, commit_type)) {
 135                free(buffer);
 136                return error("Object %s not a commit",
 137                             sha1_to_hex(item->object.sha1));
 138        }
 139        ret = parse_commit_buffer(item, buffer, size);
 140        if (!ret) {
 141                item->buffer = buffer;
 142                return 0;
 143        }
 144        free(buffer);
 145        return ret;
 146}
 147
 148struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
 149{
 150        struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
 151        new_list->item = item;
 152        new_list->next = *list_p;
 153        *list_p = new_list;
 154        return new_list;
 155}
 156
 157void free_commit_list(struct commit_list *list)
 158{
 159        while (list) {
 160                struct commit_list *temp = list;
 161                list = temp->next;
 162                free(temp);
 163        }
 164}
 165
 166struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
 167{
 168        struct commit_list **pp = list;
 169        struct commit_list *p;
 170        while ((p = *pp) != NULL) {
 171                if (p->item->date < item->date) {
 172                        break;
 173                }
 174                pp = &p->next;
 175        }
 176        return commit_list_insert(item, pp);
 177}
 178
 179        
 180void sort_by_date(struct commit_list **list)
 181{
 182        struct commit_list *ret = NULL;
 183        while (*list) {
 184                insert_by_date((*list)->item, &ret);
 185                *list = (*list)->next;
 186        }
 187        *list = ret;
 188}
 189
 190struct commit *pop_most_recent_commit(struct commit_list **list,
 191                                      unsigned int mark)
 192{
 193        struct commit *ret = (*list)->item;
 194        struct commit_list *parents = ret->parents;
 195        struct commit_list *old = *list;
 196
 197        *list = (*list)->next;
 198        free(old);
 199
 200        while (parents) {
 201                struct commit *commit = parents->item;
 202                parse_commit(commit);
 203                if (!(commit->object.flags & mark)) {
 204                        commit->object.flags |= mark;
 205                        insert_by_date(commit, list);
 206                }
 207                parents = parents->next;
 208        }
 209        return ret;
 210}
 211
 212/*
 213 * Generic support for pretty-printing the header
 214 */
 215static int get_one_line(const char *msg, unsigned long len)
 216{
 217        int ret = 0;
 218
 219        while (len--) {
 220                char c = *msg++;
 221                ret++;
 222                if (c == '\n')
 223                        break;
 224                if (!c)
 225                        return 0;
 226        }
 227        return ret;
 228}
 229
 230static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf, const char *line)
 231{
 232        char *date;
 233        unsigned int namelen;
 234        unsigned long time;
 235        int tz, ret;
 236
 237        date = strchr(line, '>');
 238        if (!date)
 239                return 0;
 240        namelen = ++date - line;
 241        time = strtoul(date, &date, 10);
 242        tz = strtol(date, NULL, 10);
 243
 244        ret = sprintf(buf, "%s: %.*s\n", what, namelen, line);
 245        if (fmt == CMIT_FMT_MEDIUM)
 246                ret += sprintf(buf + ret, "Date:   %s\n", show_date(time, tz));
 247        return ret;
 248}
 249
 250static int is_empty_line(const char *line, int len)
 251{
 252        while (len && isspace(line[len-1]))
 253                len--;
 254        return !len;
 255}
 256
 257static int add_parent_info(enum cmit_fmt fmt, char *buf, const char *line, int parents)
 258{
 259        int offset = 0;
 260        switch (parents) {
 261        case 1:
 262                break;
 263        case 2:
 264                /* Go back to the previous line: 40 characters of previous parent, and one '\n' */
 265                offset = sprintf(buf, "Merge: %.40s\n", line-41);
 266                /* Fallthrough */
 267        default:
 268                /* Replace the previous '\n' with a space */
 269                buf[offset-1] = ' ';
 270                offset += sprintf(buf + offset, "%.40s\n", line+7);
 271        }
 272        return offset;
 273}
 274
 275unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, unsigned long len, char *buf, unsigned long space)
 276{
 277        int hdr = 1, body = 0;
 278        unsigned long offset = 0;
 279        int parents = 0;
 280
 281        for (;;) {
 282                const char *line = msg;
 283                int linelen = get_one_line(msg, len);
 284
 285                if (!linelen)
 286                        break;
 287
 288                /*
 289                 * We want some slop for indentation and a possible
 290                 * final "...". Thus the "+ 20".
 291                 */
 292                if (offset + linelen + 20 > space) {
 293                        memcpy(buf + offset, "    ...\n", 8);
 294                        offset += 8;
 295                        break;
 296                }
 297
 298                msg += linelen;
 299                len -= linelen;
 300                if (hdr) {
 301                        if (linelen == 1) {
 302                                hdr = 0;
 303                                buf[offset++] = '\n';
 304                                continue;
 305                        }
 306                        if (fmt == CMIT_FMT_RAW) {
 307                                memcpy(buf + offset, line, linelen);
 308                                offset += linelen;
 309                                continue;
 310                        }
 311                        if (!memcmp(line, "parent ", 7)) {
 312                                if (linelen != 48)
 313                                        die("bad parent line in commit");
 314                                offset += add_parent_info(fmt, buf + offset, line, ++parents);
 315                        }
 316                        if (!memcmp(line, "author ", 7))
 317                                offset += add_user_info("Author", fmt, buf + offset, line + 7);
 318                        if (fmt == CMIT_FMT_FULL) {
 319                                if (!memcmp(line, "committer ", 10))
 320                                        offset += add_user_info("Commit", fmt, buf + offset, line + 10);
 321                        }
 322                        continue;
 323                }
 324
 325                if (is_empty_line(line, linelen)) {
 326                        if (!body)
 327                                continue;
 328                        if (fmt == CMIT_FMT_SHORT)
 329                                break;
 330                } else {
 331                        body = 1;
 332                }
 333                memset(buf + offset, ' ', 4);
 334                memcpy(buf + offset + 4, line, linelen);
 335                offset += linelen + 4;
 336        }
 337        /* Make sure there is an EOLN */
 338        if (buf[offset - 1] != '\n')
 339                buf[offset++] = '\n';
 340        buf[offset] = '\0';
 341        return offset;
 342}
 343
 344struct commit *pop_commit(struct commit_list **stack)
 345{
 346        struct commit_list *top = *stack;
 347        struct commit *item = top ? top->item : NULL;
 348
 349        if (top) {
 350                *stack = top->next;
 351                free(top);
 352        }
 353        return item;
 354}
 355
 356int count_parents(struct commit * commit)
 357{
 358        int count = 0;
 359        struct commit_list * parents = commit->parents;
 360        for (count=0;parents; parents=parents->next,count++)
 361          ;
 362        return count;
 363}
 364
 365/*
 366 * Performs an in-place topological sort on the list supplied.
 367 */
 368void sort_in_topological_order(struct commit_list ** list)
 369{
 370        struct commit_list * next = *list;
 371        struct commit_list * work = NULL;
 372        struct commit_list ** pptr = list;
 373        struct sort_node * nodes;
 374        struct sort_node * next_nodes;
 375        int count = 0;
 376
 377        /* determine the size of the list */
 378        while (next) {
 379                next = next->next;
 380                count++;
 381        }
 382        /* allocate an array to help sort the list */
 383        nodes = xcalloc(count, sizeof(*nodes));
 384        /* link the list to the array */
 385        next_nodes = nodes;
 386        next=*list;
 387        while (next) {
 388                next_nodes->list_item = next;
 389                next->item->object.util = next_nodes;
 390                next_nodes++;
 391                next = next->next;
 392        }
 393        /* update the indegree */
 394        next=*list;
 395        while (next) {
 396                struct commit_list * parents = next->item->parents;
 397                while (parents) {
 398                        struct commit * parent=parents->item;
 399                        struct sort_node * pn = (struct sort_node *)parent->object.util;
 400                        
 401                        if (pn)
 402                                pn->indegree++;
 403                        parents=parents->next;
 404                }
 405                next=next->next;
 406        }
 407        /* 
 408         * find the tips
 409         *
 410         * tips are nodes not reachable from any other node in the list 
 411         * 
 412         * the tips serve as a starting set for the work queue.
 413         */
 414        next=*list;
 415        while (next) {
 416                struct sort_node * node = (struct sort_node *)next->item->object.util;
 417
 418                if (node->indegree == 0) {
 419                        commit_list_insert(next->item, &work);
 420                }
 421                next=next->next;
 422        }
 423        /* process the list in topological order */
 424        while (work) {
 425                struct commit * work_item = pop_commit(&work);
 426                struct sort_node * work_node = (struct sort_node *)work_item->object.util;
 427                struct commit_list * parents = work_item->parents;
 428
 429                while (parents) {
 430                        struct commit * parent=parents->item;
 431                        struct sort_node * pn = (struct sort_node *)parent->object.util;
 432                        
 433                        if (pn) {
 434                                /* 
 435                                 * parents are only enqueued for emission 
 436                                 * when all their children have been emitted thereby
 437                                 * guaranteeing topological order.
 438                                 */
 439                                pn->indegree--;
 440                                if (!pn->indegree) 
 441                                        commit_list_insert(parent, &work);
 442                        }
 443                        parents=parents->next;
 444                }
 445                /*
 446                 * work_item is a commit all of whose children
 447                 * have already been emitted. we can emit it now.
 448                 */
 449                *pptr = work_node->list_item;
 450                pptr = &(*pptr)->next;
 451                *pptr = NULL;
 452                work_item->object.util = NULL;
 453        }
 454        free(nodes);
 455}