bulk-checkin.c

   1 /*
   2  * Copyright (c) 2011, Google Inc.
   3  */
   4 #include "cache.h"
   5 #include "bulk-checkin.h"
   6 #include "csum-file.h"
   7 #include "pack.h"
   8 #include "strbuf.h"
   9 #include "packfile.h"
  10
  11 static struct bulk_checkin_state {
  12         unsigned plugged:1;
  13
  14         char *pack_tmp_name;
  15         struct sha1file *f;
  16         off_t offset;
  17         struct pack_idx_option pack_idx_opts;
  18
  19         struct pack_idx_entry **written;
  20         uint32_t alloc_written;
  21         uint32_t nr_written;
  22 } state;
  23
  24 static void finish_bulk_checkin(struct bulk_checkin_state *state)
  25 {
  26         struct object_id oid;
  27         struct strbuf packname = STRBUF_INIT;
  28         int i;
  29
  30         if (!state->f)
  31                 return;
  32
  33         if (state->nr_written == 0) {
  34                 close(state->f->fd);
  35                 unlink(state->pack_tmp_name);
  36                 goto clear_exit;
  37         } else if (state->nr_written == 1) {
  38                 sha1close(state->f, oid.hash, CSUM_FSYNC);
  39         } else {
  40                 int fd = sha1close(state->f, oid.hash, 0);
  41                 fixup_pack_header_footer(fd, oid.hash, state->pack_tmp_name,
  42                                          state->nr_written, oid.hash,
  43                                          state->offset);
  44                 close(fd);
  45         }
  46
  47         strbuf_addf(&packname, "%s/pack/pack-", get_object_directory());
  48         finish_tmp_packfile(&packname, state->pack_tmp_name,
  49                             state->written, state->nr_written,
  50                             &state->pack_idx_opts, oid.hash);
  51         for (i = 0; i < state->nr_written; i++)
  52                 free(state->written[i]);
  53
  54 clear_exit:
  55         free(state->written);
  56         memset(state, 0, sizeof(*state));
  57
  58         strbuf_release(&packname);
  59         /* Make objects we just wrote available to ourselves */
  60         reprepare_packed_git();
  61 }
  62
  63 static int already_written(struct bulk_checkin_state *state, unsigned char sha1[])
  64 {
  65         int i;
  66
  67         /* The object may already exist in the repository */
  68         if (has_sha1_file(sha1))
  69                 return 1;
  70
  71         /* Might want to keep the list sorted */
  72         for (i = 0; i < state->nr_written; i++)
  73                 if (!hashcmp(state->written[i]->oid.hash, sha1))
  74                         return 1;
  75
  76         /* This is a new object we need to keep */
  77         return 0;
  78 }
  79
  80 /*
  81  * Read the contents from fd for size bytes, streaming it to the
  82  * packfile in state while updating the hash in ctx. Signal a failure
  83  * by returning a negative value when the resulting pack would exceed
  84  * the pack size limit and this is not the first object in the pack,
  85  * so that the caller can discard what we wrote from the current pack
  86  * by truncating it and opening a new one. The caller will then call
  87  * us again after rewinding the input fd.
  88  *
  89  * The already_hashed_to pointer is kept untouched by the caller to
  90  * make sure we do not hash the same byte when we are called
  91  * again. This way, the caller does not have to checkpoint its hash
  92  * status before calling us just in case we ask it to call us again
  93  * with a new pack.
  94  */
  95 static int stream_to_pack(struct bulk_checkin_state *state,
  96                           git_SHA_CTX *ctx, off_t *already_hashed_to,
  97                           int fd, size_t size, enum object_type type,
  98                           const char *path, unsigned flags)
  99 {
 100         git_zstream s;
 101         unsigned char obuf[16384];
 102         unsigned hdrlen;
 103         int status = Z_OK;
 104         int write_object = (flags & HASH_WRITE_OBJECT);
 105         off_t offset = 0;
 106
 107         git_deflate_init(&s, pack_compression_level);
 108
 109         hdrlen = encode_in_pack_object_header(obuf, sizeof(obuf), type, size);
 110         s.next_out = obuf + hdrlen;
 111         s.avail_out = sizeof(obuf) - hdrlen;
 112
 113         while (status != Z_STREAM_END) {
 114                 unsigned char ibuf[16384];
 115
 116                 if (size && !s.avail_in) {
 117                         ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
 118                         ssize_t read_result = read_in_full(fd, ibuf, rsize);
 119                         if (read_result < 0)
 120                                 die_errno("failed to read from '%s'", path);
 121                         if (read_result != rsize)
 122                                 die("failed to read %d bytes from '%s'",
 123                                     (int)rsize, path);
 124                         offset += rsize;
 125                         if (*already_hashed_to < offset) {
 126                                 size_t hsize = offset - *already_hashed_to;
 127                                 if (rsize < hsize)
 128                                         hsize = rsize;
 129                                 if (hsize)
 130                                         git_SHA1_Update(ctx, ibuf, hsize);
 131                                 *already_hashed_to = offset;
 132                         }
 133                         s.next_in = ibuf;
 134                         s.avail_in = rsize;
 135                         size -= rsize;
 136                 }
 137
 138                 status = git_deflate(&s, size ? 0 : Z_FINISH);
 139
 140                 if (!s.avail_out || status == Z_STREAM_END) {
 141                         if (write_object) {
 142                                 size_t written = s.next_out - obuf;
 143
 144                                 /* would we bust the size limit? */
 145                                 if (state->nr_written &&
 146                                     pack_size_limit_cfg &&
 147                                     pack_size_limit_cfg < state->offset + written) {
 148                                         git_deflate_abort(&s);
 149                                         return -1;
 150                                 }
 151
 152                                 sha1write(state->f, obuf, written);
 153                                 state->offset += written;
 154                         }
 155                         s.next_out = obuf;
 156                         s.avail_out = sizeof(obuf);
 157                 }
 158
 159                 switch (status) {
 160                 case Z_OK:
 161                 case Z_BUF_ERROR:
 162                 case Z_STREAM_END:
 163                         continue;
 164                 default:
 165                         die("unexpected deflate failure: %d", status);
 166                 }
 167         }
 168         git_deflate_end(&s);
 169         return 0;
 170 }
 171
 172 /* Lazily create backing packfile for the state */
 173 static void prepare_to_stream(struct bulk_checkin_state *state,
 174                               unsigned flags)
 175 {
 176         if (!(flags & HASH_WRITE_OBJECT) || state->f)
 177                 return;
 178
 179         state->f = create_tmp_packfile(&state->pack_tmp_name);
 180         reset_pack_idx_option(&state->pack_idx_opts);
 181
 182         /* Pretend we are going to write only one object */
 183         state->offset = write_pack_header(state->f, 1);
 184         if (!state->offset)
 185                 die_errno("unable to write pack header");
 186 }
 187
 188 static int deflate_to_pack(struct bulk_checkin_state *state,
 189                            unsigned char result_sha1[],
 190                            int fd, size_t size,
 191                            enum object_type type, const char *path,
 192                            unsigned flags)
 193 {
 194         off_t seekback, already_hashed_to;
 195         git_SHA_CTX ctx;
 196         unsigned char obuf[16384];
 197         unsigned header_len;
 198         struct sha1file_checkpoint checkpoint;
 199         struct pack_idx_entry *idx = NULL;
 200
 201         seekback = lseek(fd, 0, SEEK_CUR);
 202         if (seekback == (off_t) -1)
 203                 return error("cannot find the current offset");
 204
 205         header_len = xsnprintf((char *)obuf, sizeof(obuf), "%s %" PRIuMAX,
 206                                typename(type), (uintmax_t)size) + 1;
 207         git_SHA1_Init(&ctx);
 208         git_SHA1_Update(&ctx, obuf, header_len);
 209
 210         /* Note: idx is non-NULL when we are writing */
 211         if ((flags & HASH_WRITE_OBJECT) != 0)
 212                 idx = xcalloc(1, sizeof(*idx));
 213
 214         already_hashed_to = 0;
 215
 216         while (1) {
 217                 prepare_to_stream(state, flags);
 218                 if (idx) {
 219                         sha1file_checkpoint(state->f, &checkpoint);
 220                         idx->offset = state->offset;
 221                         crc32_begin(state->f);
 222                 }
 223                 if (!stream_to_pack(state, &ctx, &already_hashed_to,
 224                                     fd, size, type, path, flags))
 225                         break;
 226                 /*
 227                  * Writing this object to the current pack will make
 228                  * it too big; we need to truncate it, start a new
 229                  * pack, and write into it.
 230                  */
 231                 if (!idx)
 232                         die("BUG: should not happen");
 233                 sha1file_truncate(state->f, &checkpoint);
 234                 state->offset = checkpoint.offset;
 235                 finish_bulk_checkin(state);
 236                 if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
 237                         return error("cannot seek back");
 238         }
 239         git_SHA1_Final(result_sha1, &ctx);
 240         if (!idx)
 241                 return 0;
 242
 243         idx->crc32 = crc32_end(state->f);
 244         if (already_written(state, result_sha1)) {
 245                 sha1file_truncate(state->f, &checkpoint);
 246                 state->offset = checkpoint.offset;
 247                 free(idx);
 248         } else {
 249                 hashcpy(idx->oid.hash, result_sha1);
 250                 ALLOC_GROW(state->written,
 251                            state->nr_written + 1,
 252                            state->alloc_written);
 253                 state->written[state->nr_written++] = idx;
 254         }
 255         return 0;
 256 }
 257
 258 int index_bulk_checkin(unsigned char *sha1,
 259                        int fd, size_t size, enum object_type type,
 260                        const char *path, unsigned flags)
 261 {
 262         int status = deflate_to_pack(&state, sha1, fd, size, type,
 263                                      path, flags);
 264         if (!state.plugged)
 265                 finish_bulk_checkin(&state);
 266         return status;
 267 }
 268
 269 void plug_bulk_checkin(void)
 270 {
 271         state.plugged = 1;
 272 }
 273
 274 void unplug_bulk_checkin(void)
 275 {
 276         state.plugged = 0;
 277         if (state.f)
 278                 finish_bulk_checkin(&state);
 279 }