fast-export: avoid NULL pointer arithmetic
[git] / builtin / read-tree.c
1 /*
2  * GIT - The information manager from hell
3  *
4  * Copyright (C) Linus Torvalds, 2005
5  */
6
7 #include "cache.h"
8 #include "lockfile.h"
9 #include "object.h"
10 #include "tree.h"
11 #include "tree-walk.h"
12 #include "cache-tree.h"
13 #include "unpack-trees.h"
14 #include "dir.h"
15 #include "builtin.h"
16 #include "parse-options.h"
17 #include "resolve-undo.h"
18
19 static int nr_trees;
20 static int read_empty;
21 static struct tree *trees[MAX_UNPACK_TREES];
22
23 static int list_tree(unsigned char *sha1)
24 {
25         struct tree *tree;
26
27         if (nr_trees >= MAX_UNPACK_TREES)
28                 die("I cannot read more than %d trees", MAX_UNPACK_TREES);
29         tree = parse_tree_indirect(sha1);
30         if (!tree)
31                 return -1;
32         trees[nr_trees++] = tree;
33         return 0;
34 }
35
36 static const char * const read_tree_usage[] = {
37         N_("git read-tree [(-m [--trivial] [--aggressive] | --reset | --prefix=<prefix>) [-u [--exclude-per-directory=<gitignore>] | -i]] [--no-sparse-checkout] [--index-output=<file>] (--empty | <tree-ish1> [<tree-ish2> [<tree-ish3>]])"),
38         NULL
39 };
40
41 static int index_output_cb(const struct option *opt, const char *arg,
42                                  int unset)
43 {
44         set_alternate_index_output(arg);
45         return 0;
46 }
47
48 static int exclude_per_directory_cb(const struct option *opt, const char *arg,
49                                     int unset)
50 {
51         struct dir_struct *dir;
52         struct unpack_trees_options *opts;
53
54         opts = (struct unpack_trees_options *)opt->value;
55
56         if (opts->dir)
57                 die("more than one --exclude-per-directory given.");
58
59         dir = xcalloc(1, sizeof(*opts->dir));
60         dir->flags |= DIR_SHOW_IGNORED;
61         dir->exclude_per_dir = arg;
62         opts->dir = dir;
63         /* We do not need to nor want to do read-directory
64          * here; we are merely interested in reusing the
65          * per directory ignore stack mechanism.
66          */
67         return 0;
68 }
69
70 static void debug_stage(const char *label, const struct cache_entry *ce,
71                         struct unpack_trees_options *o)
72 {
73         printf("%s ", label);
74         if (!ce)
75                 printf("(missing)\n");
76         else if (ce == o->df_conflict_entry)
77                 printf("(conflict)\n");
78         else
79                 printf("%06o #%d %s %.8s\n",
80                        ce->ce_mode, ce_stage(ce), ce->name,
81                        sha1_to_hex(ce->sha1));
82 }
83
84 static int debug_merge(const struct cache_entry * const *stages,
85                        struct unpack_trees_options *o)
86 {
87         int i;
88
89         printf("* %d-way merge\n", o->merge_size);
90         debug_stage("index", stages[0], o);
91         for (i = 1; i <= o->merge_size; i++) {
92                 char buf[24];
93                 xsnprintf(buf, sizeof(buf), "ent#%d", i);
94                 debug_stage(buf, stages[i], o);
95         }
96         return 0;
97 }
98
99 static struct lock_file lock_file;
100
101 int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
102 {
103         int i, stage = 0;
104         unsigned char sha1[20];
105         struct tree_desc t[MAX_UNPACK_TREES];
106         struct unpack_trees_options opts;
107         int prefix_set = 0;
108         const struct option read_tree_options[] = {
109                 { OPTION_CALLBACK, 0, "index-output", NULL, N_("file"),
110                   N_("write resulting index to <file>"),
111                   PARSE_OPT_NONEG, index_output_cb },
112                 OPT_SET_INT(0, "empty", &read_empty,
113                             N_("only empty the index"), 1),
114                 OPT__VERBOSE(&opts.verbose_update, N_("be verbose")),
115                 OPT_GROUP(N_("Merging")),
116                 OPT_SET_INT('m', NULL, &opts.merge,
117                             N_("perform a merge in addition to a read"), 1),
118                 OPT_SET_INT(0, "trivial", &opts.trivial_merges_only,
119                             N_("3-way merge if no file level merging required"), 1),
120                 OPT_SET_INT(0, "aggressive", &opts.aggressive,
121                             N_("3-way merge in presence of adds and removes"), 1),
122                 OPT_SET_INT(0, "reset", &opts.reset,
123                             N_("same as -m, but discard unmerged entries"), 1),
124                 { OPTION_STRING, 0, "prefix", &opts.prefix, N_("<subdirectory>/"),
125                   N_("read the tree into the index under <subdirectory>/"),
126                   PARSE_OPT_NONEG | PARSE_OPT_LITERAL_ARGHELP },
127                 OPT_SET_INT('u', NULL, &opts.update,
128                             N_("update working tree with merge result"), 1),
129                 { OPTION_CALLBACK, 0, "exclude-per-directory", &opts,
130                   N_("gitignore"),
131                   N_("allow explicitly ignored files to be overwritten"),
132                   PARSE_OPT_NONEG, exclude_per_directory_cb },
133                 OPT_SET_INT('i', NULL, &opts.index_only,
134                             N_("don't check the working tree after merging"), 1),
135                 OPT__DRY_RUN(&opts.dry_run, N_("don't update the index or the work tree")),
136                 OPT_SET_INT(0, "no-sparse-checkout", &opts.skip_sparse_checkout,
137                             N_("skip applying sparse checkout filter"), 1),
138                 OPT_SET_INT(0, "debug-unpack", &opts.debug_unpack,
139                             N_("debug unpack-trees"), 1),
140                 OPT_END()
141         };
142
143         memset(&opts, 0, sizeof(opts));
144         opts.head_idx = -1;
145         opts.src_index = &the_index;
146         opts.dst_index = &the_index;
147
148         git_config(git_default_config, NULL);
149
150         argc = parse_options(argc, argv, unused_prefix, read_tree_options,
151                              read_tree_usage, 0);
152
153         hold_locked_index(&lock_file, 1);
154
155         prefix_set = opts.prefix ? 1 : 0;
156         if (1 < opts.merge + opts.reset + prefix_set)
157                 die("Which one? -m, --reset, or --prefix?");
158
159         /*
160          * NEEDSWORK
161          *
162          * The old index should be read anyway even if we're going to
163          * destroy all index entries because we still need to preserve
164          * certain information such as index version or split-index
165          * mode.
166          */
167
168         if (opts.reset || opts.merge || opts.prefix) {
169                 if (read_cache_unmerged() && (opts.prefix || opts.merge))
170                         die("You need to resolve your current index first");
171                 stage = opts.merge = 1;
172         }
173         resolve_undo_clear();
174
175         for (i = 0; i < argc; i++) {
176                 const char *arg = argv[i];
177
178                 if (get_sha1(arg, sha1))
179                         die("Not a valid object name %s", arg);
180                 if (list_tree(sha1) < 0)
181                         die("failed to unpack tree object %s", arg);
182                 stage++;
183         }
184         if (nr_trees == 0 && !read_empty)
185                 warning("read-tree: emptying the index with no arguments is deprecated; use --empty");
186         else if (nr_trees > 0 && read_empty)
187                 die("passing trees as arguments contradicts --empty");
188
189         if (1 < opts.index_only + opts.update)
190                 die("-u and -i at the same time makes no sense");
191         if ((opts.update || opts.index_only) && !opts.merge)
192                 die("%s is meaningless without -m, --reset, or --prefix",
193                     opts.update ? "-u" : "-i");
194         if ((opts.dir && !opts.update))
195                 die("--exclude-per-directory is meaningless unless -u");
196         if (opts.merge && !opts.index_only)
197                 setup_work_tree();
198
199         if (opts.merge) {
200                 if (stage < 2)
201                         die("just how do you expect me to merge %d trees?", stage-1);
202                 switch (stage - 1) {
203                 case 1:
204                         opts.fn = opts.prefix ? bind_merge : oneway_merge;
205                         break;
206                 case 2:
207                         opts.fn = twoway_merge;
208                         opts.initial_checkout = is_cache_unborn();
209                         break;
210                 case 3:
211                 default:
212                         opts.fn = threeway_merge;
213                         break;
214                 }
215
216                 if (stage - 1 >= 3)
217                         opts.head_idx = stage - 2;
218                 else
219                         opts.head_idx = 1;
220         }
221
222         if (opts.debug_unpack)
223                 opts.fn = debug_merge;
224
225         cache_tree_free(&active_cache_tree);
226         for (i = 0; i < nr_trees; i++) {
227                 struct tree *tree = trees[i];
228                 parse_tree(tree);
229                 init_tree_desc(t+i, tree->buffer, tree->size);
230         }
231         if (unpack_trees(nr_trees, t, &opts))
232                 return 128;
233
234         if (opts.debug_unpack || opts.dry_run)
235                 return 0; /* do not write the index out */
236
237         /*
238          * When reading only one tree (either the most basic form,
239          * "-m ent" or "--reset ent" form), we can obtain a fully
240          * valid cache-tree because the index must match exactly
241          * what came from the tree.
242          */
243         if (nr_trees == 1 && !opts.prefix)
244                 prime_cache_tree(&the_index, trees[0]);
245
246         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
247                 die("unable to write new index file");
248         return 0;
249 }