bulk-checkin.c

   1 /*
   2  * Copyright (c) 2011, Google Inc.
   3  */
   4 #include "bulk-checkin.h"
   5 #include "csum-file.h"
   6 #include "pack.h"
   7
   8 static int pack_compression_level = Z_DEFAULT_COMPRESSION;
   9
  10 static struct bulk_checkin_state {
  11         unsigned plugged:1;
  12
  13         char *pack_tmp_name;
  14         struct sha1file *f;
  15         off_t offset;
  16         struct pack_idx_option pack_idx_opts;
  17
  18         struct pack_idx_entry **written;
  19         uint32_t alloc_written;
  20         uint32_t nr_written;
  21 } state;
  22
  23 static void finish_bulk_checkin(struct bulk_checkin_state *state)
  24 {
  25         unsigned char sha1[20];
  26         char packname[PATH_MAX];
  27         int i;
  28
  29         if (!state->f)
  30                 return;
  31
  32         if (state->nr_written == 0) {
  33                 close(state->f->fd);
  34                 unlink(state->pack_tmp_name);
  35                 goto clear_exit;
  36         } else if (state->nr_written == 1) {
  37                 sha1close(state->f, sha1, CSUM_FSYNC);
  38         } else {
  39                 int fd = sha1close(state->f, sha1, 0);
  40                 fixup_pack_header_footer(fd, sha1, state->pack_tmp_name,
  41                                          state->nr_written, sha1,
  42                                          state->offset);
  43                 close(fd);
  44         }
  45
  46         sprintf(packname, "%s/pack/pack-", get_object_directory());
  47         finish_tmp_packfile(packname, state->pack_tmp_name,
  48                             state->written, state->nr_written,
  49                             &state->pack_idx_opts, sha1);
  50         for (i = 0; i < state->nr_written; i++)
  51                 free(state->written[i]);
  52
  53 clear_exit:
  54         free(state->written);
  55         memset(state, 0, sizeof(*state));
  56
  57         /* Make objects we just wrote available to ourselves */
  58         reprepare_packed_git();
  59 }
  60
  61 static int already_written(struct bulk_checkin_state *state, unsigned char sha1[])
  62 {
  63         int i;
  64
  65         /* The object may already exist in the repository */
  66         if (has_sha1_file(sha1))
  67                 return 1;
  68
  69         /* Might want to keep the list sorted */
  70         for (i = 0; i < state->nr_written; i++)
  71                 if (!hashcmp(state->written[i]->sha1, sha1))
  72                         return 1;
  73
  74         /* This is a new object we need to keep */
  75         return 0;
  76 }
  77
  78 /*
  79  * Read the contents from fd for size bytes, streaming it to the
  80  * packfile in state while updating the hash in ctx. Signal a failure
  81  * by returning a negative value when the resulting pack would exceed
  82  * the pack size limit and this is not the first object in the pack,
  83  * so that the caller can discard what we wrote from the current pack
  84  * by truncating it and opening a new one. The caller will then call
  85  * us again after rewinding the input fd.
  86  *
  87  * The already_hashed_to pointer is kept untouched by the caller to
  88  * make sure we do not hash the same byte when we are called
  89  * again. This way, the caller does not have to checkpoint its hash
  90  * status before calling us just in case we ask it to call us again
  91  * with a new pack.
  92  */
  93 static int stream_to_pack(struct bulk_checkin_state *state,
  94                           git_SHA_CTX *ctx, off_t *already_hashed_to,
  95                           int fd, size_t size, enum object_type type,
  96                           const char *path, unsigned flags)
  97 {
  98         git_zstream s;
  99         unsigned char obuf[16384];
 100         unsigned hdrlen;
 101         int status = Z_OK;
 102         int write_object = (flags & HASH_WRITE_OBJECT);
 103         off_t offset = 0;
 104
 105         memset(&s, 0, sizeof(s));
 106         git_deflate_init(&s, pack_compression_level);
 107
 108         hdrlen = encode_in_pack_object_header(type, size, obuf);
 109         s.next_out = obuf + hdrlen;
 110         s.avail_out = sizeof(obuf) - hdrlen;
 111
 112         while (status != Z_STREAM_END) {
 113                 unsigned char ibuf[16384];
 114
 115                 if (size && !s.avail_in) {
 116                         ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
 117                         if (xread(fd, ibuf, rsize) != rsize)
 118                                 die("failed to read %d bytes from '%s'",
 119                                     (int)rsize, path);
 120                         offset += rsize;
 121                         if (*already_hashed_to < offset) {
 122                                 size_t hsize = offset - *already_hashed_to;
 123                                 if (rsize < hsize)
 124                                         hsize = rsize;
 125                                 if (hsize)
 126                                         git_SHA1_Update(ctx, ibuf, hsize);
 127                                 *already_hashed_to = offset;
 128                         }
 129                         s.next_in = ibuf;
 130                         s.avail_in = rsize;
 131                         size -= rsize;
 132                 }
 133
 134                 status = git_deflate(&s, size ? 0 : Z_FINISH);
 135
 136                 if (!s.avail_out || status == Z_STREAM_END) {
 137                         if (write_object) {
 138                                 size_t written = s.next_out - obuf;
 139
 140                                 /* would we bust the size limit? */
 141                                 if (state->nr_written &&
 142                                     pack_size_limit_cfg &&
 143                                     pack_size_limit_cfg < state->offset + written) {
 144                                         git_deflate_abort(&s);
 145                                         return -1;
 146                                 }
 147
 148                                 sha1write(state->f, obuf, written);
 149                                 state->offset += written;
 150                         }
 151                         s.next_out = obuf;
 152                         s.avail_out = sizeof(obuf);
 153                 }
 154
 155                 switch (status) {
 156                 case Z_OK:
 157                 case Z_BUF_ERROR:
 158                 case Z_STREAM_END:
 159                         continue;
 160                 default:
 161                         die("unexpected deflate failure: %d", status);
 162                 }
 163         }
 164         git_deflate_end(&s);
 165         return 0;
 166 }
 167
 168 /* Lazily create backing packfile for the state */
 169 static void prepare_to_stream(struct bulk_checkin_state *state,
 170                               unsigned flags)
 171 {
 172         if (!(flags & HASH_WRITE_OBJECT) || state->f)
 173                 return;
 174
 175         state->f = create_tmp_packfile(&state->pack_tmp_name);
 176         reset_pack_idx_option(&state->pack_idx_opts);
 177
 178         /* Pretend we are going to write only one object */
 179         state->offset = write_pack_header(state->f, 1);
 180         if (!state->offset)
 181                 die_errno("unable to write pack header");
 182 }
 183
 184 static int deflate_to_pack(struct bulk_checkin_state *state,
 185                            unsigned char result_sha1[],
 186                            int fd, size_t size,
 187                            enum object_type type, const char *path,
 188                            unsigned flags)
 189 {
 190         off_t seekback, already_hashed_to;
 191         git_SHA_CTX ctx;
 192         unsigned char obuf[16384];
 193         unsigned header_len;
 194         struct sha1file_checkpoint checkpoint;
 195         struct pack_idx_entry *idx = NULL;
 196
 197         seekback = lseek(fd, 0, SEEK_CUR);
 198         if (seekback == (off_t) -1)
 199                 return error("cannot find the current offset");
 200
 201         header_len = sprintf((char *)obuf, "%s %" PRIuMAX,
 202                              typename(type), (uintmax_t)size) + 1;
 203         git_SHA1_Init(&ctx);
 204         git_SHA1_Update(&ctx, obuf, header_len);
 205
 206         /* Note: idx is non-NULL when we are writing */
 207         if ((flags & HASH_WRITE_OBJECT) != 0)
 208                 idx = xcalloc(1, sizeof(*idx));
 209
 210         already_hashed_to = 0;
 211
 212         while (1) {
 213                 prepare_to_stream(state, flags);
 214                 if (idx) {
 215                         sha1file_checkpoint(state->f, &checkpoint);
 216                         idx->offset = state->offset;
 217                         crc32_begin(state->f);
 218                 }
 219                 if (!stream_to_pack(state, &ctx, &already_hashed_to,
 220                                     fd, size, type, path, flags))
 221                         break;
 222                 /*
 223                  * Writing this object to the current pack will make
 224                  * it too big; we need to truncate it, start a new
 225                  * pack, and write into it.
 226                  */
 227                 if (!idx)
 228                         die("BUG: should not happen");
 229                 sha1file_truncate(state->f, &checkpoint);
 230                 state->offset = checkpoint.offset;
 231                 finish_bulk_checkin(state);
 232                 if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
 233                         return error("cannot seek back");
 234         }
 235         git_SHA1_Final(result_sha1, &ctx);
 236         if (!idx)
 237                 return 0;
 238
 239         idx->crc32 = crc32_end(state->f);
 240         if (already_written(state, result_sha1)) {
 241                 sha1file_truncate(state->f, &checkpoint);
 242                 state->offset = checkpoint.offset;
 243                 free(idx);
 244         } else {
 245                 hashcpy(idx->sha1, result_sha1);
 246                 ALLOC_GROW(state->written,
 247                            state->nr_written + 1,
 248                            state->alloc_written);
 249                 state->written[state->nr_written++] = idx;
 250         }
 251         return 0;
 252 }
 253
 254 int index_bulk_checkin(unsigned char *sha1,
 255                        int fd, size_t size, enum object_type type,
 256                        const char *path, unsigned flags)
 257 {
 258         int status = deflate_to_pack(&state, sha1, fd, size, type,
 259                                      path, flags);
 260         if (!state.plugged)
 261                 finish_bulk_checkin(&state);
 262         return status;
 263 }
 264
 265 void plug_bulk_checkin(void)
 266 {
 267         state.plugged = 1;
 268 }
 269
 270 void unplug_bulk_checkin(void)
 271 {
 272         state.plugged = 0;
 273         if (state.f)
 274                 finish_bulk_checkin(&state);
 275 }