Andrew's git - gitweb.git/blob

   1/*
   2 * Copyright (c) 2011, Google Inc.
   3 */
   4#include "bulk-checkin.h"
   5#include "csum-file.h"
   6#include "pack.h"
   7#include "strbuf.h"
   8
   9static int pack_compression_level = Z_DEFAULT_COMPRESSION;
  10
  11static 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
  24static void finish_bulk_checkin(struct bulk_checkin_state *state)
  25{
  26        unsigned char sha1[20];
  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, sha1, CSUM_FSYNC);
  39        } else {
  40                int fd = sha1close(state->f, sha1, 0);
  41                fixup_pack_header_footer(fd, sha1, state->pack_tmp_name,
  42                                         state->nr_written, sha1,
  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, sha1);
  51        for (i = 0; i < state->nr_written; i++)
  52                free(state->written[i]);
  53
  54clear_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
  63static 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]->sha1, 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 */
  95static 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        memset(&s, 0, sizeof(s));
 108        git_deflate_init(&s, pack_compression_level);
 109
 110        hdrlen = encode_in_pack_object_header(type, size, obuf);
 111        s.next_out = obuf + hdrlen;
 112        s.avail_out = sizeof(obuf) - hdrlen;
 113
 114        while (status != Z_STREAM_END) {
 115                unsigned char ibuf[16384];
 116
 117                if (size && !s.avail_in) {
 118                        ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
 119                        if (read_in_full(fd, ibuf, rsize) != rsize)
 120                                die("failed to read %d bytes from '%s'",
 121                                    (int)rsize, path);
 122                        offset += rsize;
 123                        if (*already_hashed_to < offset) {
 124                                size_t hsize = offset - *already_hashed_to;
 125                                if (rsize < hsize)
 126                                        hsize = rsize;
 127                                if (hsize)
 128                                        git_SHA1_Update(ctx, ibuf, hsize);
 129                                *already_hashed_to = offset;
 130                        }
 131                        s.next_in = ibuf;
 132                        s.avail_in = rsize;
 133                        size -= rsize;
 134                }
 135
 136                status = git_deflate(&s, size ? 0 : Z_FINISH);
 137
 138                if (!s.avail_out || status == Z_STREAM_END) {
 139                        if (write_object) {
 140                                size_t written = s.next_out - obuf;
 141
 142                                /* would we bust the size limit? */
 143                                if (state->nr_written &&
 144                                    pack_size_limit_cfg &&
 145                                    pack_size_limit_cfg < state->offset + written) {
 146                                        git_deflate_abort(&s);
 147                                        return -1;
 148                                }
 149
 150                                sha1write(state->f, obuf, written);
 151                                state->offset += written;
 152                        }
 153                        s.next_out = obuf;
 154                        s.avail_out = sizeof(obuf);
 155                }
 156
 157                switch (status) {
 158                case Z_OK:
 159                case Z_BUF_ERROR:
 160                case Z_STREAM_END:
 161                        continue;
 162                default:
 163                        die("unexpected deflate failure: %d", status);
 164                }
 165        }
 166        git_deflate_end(&s);
 167        return 0;
 168}
 169
 170/* Lazily create backing packfile for the state */
 171static void prepare_to_stream(struct bulk_checkin_state *state,
 172                              unsigned flags)
 173{
 174        if (!(flags & HASH_WRITE_OBJECT) || state->f)
 175                return;
 176
 177        state->f = create_tmp_packfile(&state->pack_tmp_name);
 178        reset_pack_idx_option(&state->pack_idx_opts);
 179
 180        /* Pretend we are going to write only one object */
 181        state->offset = write_pack_header(state->f, 1);
 182        if (!state->offset)
 183                die_errno("unable to write pack header");
 184}
 185
 186static int deflate_to_pack(struct bulk_checkin_state *state,
 187                           unsigned char result_sha1[],
 188                           int fd, size_t size,
 189                           enum object_type type, const char *path,
 190                           unsigned flags)
 191{
 192        off_t seekback, already_hashed_to;
 193        git_SHA_CTX ctx;
 194        unsigned char obuf[16384];
 195        unsigned header_len;
 196        struct sha1file_checkpoint checkpoint;
 197        struct pack_idx_entry *idx = NULL;
 198
 199        seekback = lseek(fd, 0, SEEK_CUR);
 200        if (seekback == (off_t) -1)
 201                return error("cannot find the current offset");
 202
 203        header_len = sprintf((char *)obuf, "%s %" PRIuMAX,
 204                             typename(type), (uintmax_t)size) + 1;
 205        git_SHA1_Init(&ctx);
 206        git_SHA1_Update(&ctx, obuf, header_len);
 207
 208        /* Note: idx is non-NULL when we are writing */
 209        if ((flags & HASH_WRITE_OBJECT) != 0)
 210                idx = xcalloc(1, sizeof(*idx));
 211
 212        already_hashed_to = 0;
 213
 214        while (1) {
 215                prepare_to_stream(state, flags);
 216                if (idx) {
 217                        sha1file_checkpoint(state->f, &checkpoint);
 218                        idx->offset = state->offset;
 219                        crc32_begin(state->f);
 220                }
 221                if (!stream_to_pack(state, &ctx, &already_hashed_to,
 222                                    fd, size, type, path, flags))
 223                        break;
 224                /*
 225                 * Writing this object to the current pack will make
 226                 * it too big; we need to truncate it, start a new
 227                 * pack, and write into it.
 228                 */
 229                if (!idx)
 230                        die("BUG: should not happen");
 231                sha1file_truncate(state->f, &checkpoint);
 232                state->offset = checkpoint.offset;
 233                finish_bulk_checkin(state);
 234                if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
 235                        return error("cannot seek back");
 236        }
 237        git_SHA1_Final(result_sha1, &ctx);
 238        if (!idx)
 239                return 0;
 240
 241        idx->crc32 = crc32_end(state->f);
 242        if (already_written(state, result_sha1)) {
 243                sha1file_truncate(state->f, &checkpoint);
 244                state->offset = checkpoint.offset;
 245                free(idx);
 246        } else {
 247                hashcpy(idx->sha1, result_sha1);
 248                ALLOC_GROW(state->written,
 249                           state->nr_written + 1,
 250                           state->alloc_written);
 251                state->written[state->nr_written++] = idx;
 252        }
 253        return 0;
 254}
 255
 256int index_bulk_checkin(unsigned char *sha1,
 257                       int fd, size_t size, enum object_type type,
 258                       const char *path, unsigned flags)
 259{
 260        int status = deflate_to_pack(&state, sha1, fd, size, type,
 261                                     path, flags);
 262        if (!state.plugged)
 263                finish_bulk_checkin(&state);
 264        return status;
 265}
 266
 267void plug_bulk_checkin(void)
 268{
 269        state.plugged = 1;
 270}
 271
 272void unplug_bulk_checkin(void)
 273{
 274        state.plugged = 0;
 275        if (state.f)
 276                finish_bulk_checkin(&state);
 277}