change: decompress the hashed section too

laumann

Aug 22, 2022, 8:54 PM

OBKF6SIIFFHHY7YWKPPX75N23NAVUD5662DKIHXSSIDPKKXQ5ZDQC

Dependencies

• [2] KDJUAAAL change: prefix function names with change_
• [3] Q7TKZCJP Add initial support for reading the offsets from a (fixed) change
• [4] QEFCNNVC change: display offsets for given change file
• [5] AEMTSEJX change: simplify readout of offsets
• [6] RIWSVVAS change: decompress the 'contents' with zstd_seekable

Change contents

• edit in change.c at line 12
  [3.1212]

  [3.1488]
  +

  + void

  + dump_buf(const char *name, uint8_t *buf, size_t len)

  + {

  + int i;
• edit in change.c at line 18
  [3.1489]

  [3.1489]
  + if (len == 0) {

  + printf("%s = []\n", name);

  + return;

  + }

  +

  + printf("%s = [%02x", name, buf[0]);

  + for (i = 1; i < len; i++)

  + printf(", %02x", buf[i]);

  + printf("]\n");

  + }

  +
• edit in change.c at line 59
  [3.2195]→[3.67:303](∅→∅)
  − }

  −

  − void

  − dump_buf(const char *name, uint8_t *buf, size_t len)

  − {

  − int i;

  −

  − if (len == 0) {

  − printf("%s = []\n", name);

  − return;

  − }

  −

  − printf("%s = [%u", name, buf[0]);

  − for (i = 1; i < len; i++)

  − printf(", %u", buf[i]);

  − printf("]\n");
• replacement in change.c at line 62
  [3.4]→[3.304:608](∅→∅)
  − * Read the contents section of the open change file, decompress it and return

  − * the raw bytes.

  − *

  − * Returns a malloc()'ed byte buffer that the caller is responsible for

  − * deallocating. Returns NULL if the full contents could not be read, or the

  − * decompression failed, or some other error occurred.
  [3.4]

  [3.608]
  + * Read in an expected amount of bytes (or die failing), and decompress with

  + * zstd-seekable. Return a malloc()'ed byte buffer that the caller is in charge

  + * of free()'ing.
• replacement in change.c at line 66
  [3.612]→[3.612:622](∅→∅),[3.622]→[2.52:102](∅→∅)
  − uint8_t *

  − change_read_contents(int fd, struct offsets *off)
  [3.612]

  [3.665]
  + static uint8_t *

  + decompress_segment(

  + int fd,

  + size_t compressed_len,

  + uint64_t expected_len

  + )
• edit in change.c at line 73
  [3.667]→[3.667:813](∅→∅)
  − /**

  − * Allocate two buffers: one for compressed data, and one for

  − * decompressed data. The decompressed data buffer is the return value.

  − */
• edit in change.c at line 75
  [3.850]→[3.850:878](∅→∅)
  − size_t compressed_to_read;
• replacement in change.c at line 79
  [3.941]→[3.941:1129](∅→∅)
  − compressed_to_read = off->total - off->contents_off;

  − printf("expecting to read %lu bytes (compressed)\n", compressed_to_read);

  − compressed = calloc(sizeof(uint8_t), compressed_to_read);
  [3.941]

  [3.1129]
  + printf("expecting to read %lu bytes (compressed)\n", compressed_len);

  + compressed = calloc(sizeof(uint8_t), compressed_len);
• replacement in change.c at line 85
  [3.1201]→[3.1201:1252](∅→∅)
  − buf = calloc(sizeof(uint8_t), off->contents_len);
  [3.1201]

  [3.1252]
  + buf = calloc(sizeof(uint8_t), expected_len);
• replacement in change.c at line 92
  [3.1344]→[3.1344:1451](∅→∅)
  − compressed_read = read(fd, compressed, compressed_to_read);

  − if (compressed_read != compressed_to_read) {
  [3.1344]

  [3.1451]
  + compressed_read = read(fd, compressed, compressed_len);

  + if (compressed_read != compressed_len) {
• replacement in change.c at line 95
  [3.1517]→[3.1517:1559](∅→∅)
  − compressed_to_read, compressed_read);
  [3.1517]

  [3.1559]
  + compressed_len, compressed_read);
• replacement in change.c at line 106
  [3.1752]→[3.1752:1822](∅→∅)
  − result = ZSTD_seekable_initBuff(zs, compressed, compressed_to_read);
  [3.1752]

  [3.1822]
  + result = ZSTD_seekable_initBuff(zs, compressed, compressed_len);
• replacement in change.c at line 113
  [3.1959]→[3.1959:2026](∅→∅)
  − result = ZSTD_seekable_decompress(zs, buf, off->contents_len, 0);
  [3.1959]

  [3.2026]
  + result = ZSTD_seekable_decompress(zs, buf, expected_len, 0);
• replacement in change.c at line 120
  [3.2213]→[3.2213:2330](∅→∅)
  − if (result != off->contents_len) {

  − fprintf(stderr, "decoded %lu bytes, wanted %lu\n", result, off->contents_len);
  [3.2213]

  [3.2330]
  + if (result != expected_len) {

  + fprintf(stderr, "decoded %lu bytes, wanted %lu\n", result, expected_len);
• edit in change.c at line 136
  [3.2591]

  [3.2591]
  + }

  +

  + /**

  + *

  + */

  + int

  + change_decode_hashed(int fd, size_t comp_hashed_len, size_t hashed_len)

  + {

  + uint8_t *buf;
• edit in change.c at line 146
  [3.2592]

  [3.2592]
  + buf = decompress_segment(fd, comp_hashed_len, hashed_len);

  + if (buf == NULL) {

  + fprintf(stderr, "error: failed to decompress hashed segment\n");

  + return 1;

  + }

  + dump_buf("hashed", buf, hashed_len);

  + free(buf);

  +

  + return 0;

  + }

  +

  + /**

  + * Read the contents section of the open change file, decompress it and return

  + * the raw bytes.

  + *

  + * Returns a malloc()'ed byte buffer that the caller is responsible for

  + * deallocating. Returns NULL if the full contents could not be read, or the

  + * decompression failed, or some other error occurred.

  + */

  + uint8_t *

  + change_read_contents(int fd, struct offsets *off)

  + {

  + return decompress_segment(fd, off->total - off->contents_off, off->contents_len);
• edit in change.c at line 205
  [3.2572]

  [3.2572]
  + goto out;

  + }

  +

  + err = change_decode_hashed(fd, off.unhashed_off - OFFSETS_SIZE, off.hashed_len);

  + if (err != 0) {

  + printf("error: failed to decode hashed\n");
• edit in change.c at line 217
  [3.2730]→[3.2730:2778](∅→∅)
  − *

  − * seek to off.contents_off - OFFSETS_SIZE