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