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   1 /*
   2  * rev-parse.c
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  */
   6 #include "cache.h"
   7 #include "commit.h"
   8
   9 static int get_extended_sha1(char *name, unsigned char *sha1);
  10
  11 /*
  12  * Some arguments are relevant "revision" arguments,
  13  * others are about output format or other details.
  14  * This sorts it all out.
  15  */
  16 static int is_rev_argument(const char *arg)
  17 {
  18         static const char *rev_args[] = {
  19                 "--max-count=",
  20                 "--max-age=",
  21                 "--min-age=",
  22                 "--merge-order",
  23                 NULL
  24         };
  25         const char **p = rev_args;
  26
  27         for (;;) {
  28                 const char *str = *p++;
  29                 int len;
  30                 if (!str)
  31                         return 0;
  32                 len = strlen(str);
  33                 if (!strncmp(arg, str, len))
  34                         return 1;
  35         }
  36 }
  37
  38 static int get_parent(char *name, unsigned char *result, int idx)
  39 {
  40         unsigned char sha1[20];
  41         int ret = get_extended_sha1(name, sha1);
  42         struct commit *commit;
  43         struct commit_list *p;
  44
  45         if (ret)
  46                 return ret;
  47         commit = lookup_commit_reference(sha1);
  48         if (!commit)
  49                 return -1;
  50         if (parse_commit(commit))
  51                 return -1;
  52         p = commit->parents;
  53         while (p) {
  54                 if (!--idx) {
  55                         memcpy(result, p->item->object.sha1, 20);
  56                         return 0;
  57                 }
  58                 p = p->next;
  59         }
  60         return -1;
  61 }
  62
  63 /*
  64  * This is like "get_sha1()", except it allows "sha1 expressions",
  65  * notably "xyz^" for "parent of xyz"
  66  */
  67 static int get_extended_sha1(char *name, unsigned char *sha1)
  68 {
  69         int parent;
  70         int len = strlen(name);
  71
  72         parent = 1;
  73         if (len > 2 && name[len-1] >= '1' && name[len-1] <= '9') {
  74                 parent = name[len-1] - '0';
  75                 len--;
  76         }
  77         if (len > 1 && name[len-1] == '^') {
  78                 int ret;
  79                 name[len-1] = 0;
  80                 ret = get_parent(name, sha1, parent);
  81                 name[len-1] = '^';
  82                 if (!ret)
  83                         return 0;
  84         }
  85         return get_sha1(name, sha1);
  86 }
  87
  88 int main(int argc, char **argv)
  89 {
  90         int i, as_is = 0, revs_only = 0, no_revs = 0;
  91         char *def = NULL;
  92         unsigned char sha1[20];
  93
  94         for (i = 1; i < argc; i++) {
  95                 char *arg = argv[i];
  96                 char *dotdot;
  97
  98                 if (as_is) {
  99                         printf("%s\n", arg);
 100                         continue;
 101                 }
 102                 if (*arg == '-') {
 103                         if (!strcmp(arg, "--")) {
 104                                 if (def) {
 105                                         printf("%s\n", def);
 106                                         def = NULL;
 107                                 }
 108                                 if (revs_only)
 109                                         break;
 110                                 as_is = 1;
 111                         }
 112                         if (!strcmp(arg, "--default")) {
 113                                 if (def)
 114                                         printf("%s\n", def);
 115                                 def = argv[i+1];
 116                                 i++;
 117                                 continue;
 118                         }
 119                         if (!strcmp(arg, "--revs-only")) {
 120                                 revs_only = 1;
 121                                 continue;
 122                         }
 123                         if (!strcmp(arg, "--no-revs")) {
 124                                 no_revs = 1;
 125                                 continue;
 126                         }
 127                         if (revs_only | no_revs) {
 128                                 if (is_rev_argument(arg) != revs_only)
 129                                         continue;
 130                         }
 131                         printf("%s\n", arg);
 132                         continue;
 133                 }
 134                 dotdot = strstr(arg, "..");
 135                 if (dotdot) {
 136                         unsigned char end[20];
 137                         char *n = dotdot+2;
 138                         *dotdot = 0;
 139                         if (!get_extended_sha1(arg, sha1)) {
 140                                 if (!*n)
 141                                         n = "HEAD";
 142                                 if (!get_extended_sha1(n, end)) {
 143                                         if (no_revs)
 144                                                 continue;
 145                                         def = NULL;
 146                                         printf("%s\n", sha1_to_hex(end));
 147                                         printf("^%s\n", sha1_to_hex(sha1));
 148                                         continue;
 149                                 }
 150                         }
 151                         *dotdot = '.';
 152                 }
 153                 if (!get_extended_sha1(arg, sha1)) {
 154                         if (no_revs)
 155                                 continue;
 156                         def = NULL;
 157                         printf("%s\n", sha1_to_hex(sha1));
 158                         continue;
 159                 }
 160                 if (*arg == '^' && !get_extended_sha1(arg+1, sha1)) {
 161                         if (no_revs)
 162                                 continue;
 163                         def = NULL;
 164                         printf("^%s\n", sha1_to_hex(sha1));
 165                         continue;
 166                 }
 167                 if (def) {
 168                         printf("%s\n", def);
 169                         def = NULL;
 170                 }
 171                 if (revs_only)
 172                         continue;
 173                 printf("%s\n", arg);
 174         }
 175         if (def)
 176                 printf("%s\n", def);
 177         return 0;
 178 }