mirror of https://github.com/berdav/snappy-fox
CRC calculation (crc32c) and consideration
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f524a05782
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52b475b4e0
110
snappy-fox.c
110
snappy-fox.c
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@ -51,6 +51,89 @@ static uint32_t ignore_offset_errors = 0;
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static uint8_t offset_dummy_byte = 0xff;
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/* Read offset */
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static uint32_t read_offset = 0;
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/* Consider CRC Errors */
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static uint32_t consider_crc_errors = 0;
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/* CRC related functions */
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static const uint32_t crc32c_table[] = {
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0x00000000, 0xf26b8303, 0xe13b70f7, 0x1350f3f4, 0xc79a971f,
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0x35f1141c, 0x26a1e7e8, 0xd4ca64eb, 0x8ad958cf, 0x78b2dbcc,
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0x6be22838, 0x9989ab3b, 0x4d43cfd0, 0xbf284cd3, 0xac78bf27,
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0x5e133c24, 0x105ec76f, 0xe235446c, 0xf165b798, 0x030e349b,
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0xd7c45070, 0x25afd373, 0x36ff2087, 0xc494a384, 0x9a879fa0,
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0x68ec1ca3, 0x7bbcef57, 0x89d76c54, 0x5d1d08bf, 0xaf768bbc,
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0xbc267848, 0x4e4dfb4b, 0x20bd8ede, 0xd2d60ddd, 0xc186fe29,
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0x33ed7d2a, 0xe72719c1, 0x154c9ac2, 0x061c6936, 0xf477ea35,
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0xaa64d611, 0x580f5512, 0x4b5fa6e6, 0xb93425e5, 0x6dfe410e,
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0x9f95c20d, 0x8cc531f9, 0x7eaeb2fa, 0x30e349b1, 0xc288cab2,
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0xd1d83946, 0x23b3ba45, 0xf779deae, 0x05125dad, 0x1642ae59,
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0xe4292d5a, 0xba3a117e, 0x4851927d, 0x5b016189, 0xa96ae28a,
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0x7da08661, 0x8fcb0562, 0x9c9bf696, 0x6ef07595, 0x417b1dbc,
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0xb3109ebf, 0xa0406d4b, 0x522bee48, 0x86e18aa3, 0x748a09a0,
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0x67dafa54, 0x95b17957, 0xcba24573, 0x39c9c670, 0x2a993584,
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0xd8f2b687, 0x0c38d26c, 0xfe53516f, 0xed03a29b, 0x1f682198,
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0x5125dad3, 0xa34e59d0, 0xb01eaa24, 0x42752927, 0x96bf4dcc,
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0x64d4cecf, 0x77843d3b, 0x85efbe38, 0xdbfc821c, 0x2997011f,
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0x3ac7f2eb, 0xc8ac71e8, 0x1c661503, 0xee0d9600, 0xfd5d65f4,
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0x0f36e6f7, 0x61c69362, 0x93ad1061, 0x80fde395, 0x72966096,
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0xa65c047d, 0x5437877e, 0x4767748a, 0xb50cf789, 0xeb1fcbad,
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0x197448ae, 0x0a24bb5a, 0xf84f3859, 0x2c855cb2, 0xdeeedfb1,
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0xcdbe2c45, 0x3fd5af46, 0x7198540d, 0x83f3d70e, 0x90a324fa,
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0x62c8a7f9, 0xb602c312, 0x44694011, 0x5739b3e5, 0xa55230e6,
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0xfb410cc2, 0x092a8fc1, 0x1a7a7c35, 0xe811ff36, 0x3cdb9bdd,
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0xceb018de, 0xdde0eb2a, 0x2f8b6829, 0x82f63b78, 0x709db87b,
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0x63cd4b8f, 0x91a6c88c, 0x456cac67, 0xb7072f64, 0xa457dc90,
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0x563c5f93, 0x082f63b7, 0xfa44e0b4, 0xe9141340, 0x1b7f9043,
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0xcfb5f4a8, 0x3dde77ab, 0x2e8e845f, 0xdce5075c, 0x92a8fc17,
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0x60c37f14, 0x73938ce0, 0x81f80fe3, 0x55326b08, 0xa759e80b,
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0xb4091bff, 0x466298fc, 0x1871a4d8, 0xea1a27db, 0xf94ad42f,
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0x0b21572c, 0xdfeb33c7, 0x2d80b0c4, 0x3ed04330, 0xccbbc033,
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0xa24bb5a6, 0x502036a5, 0x4370c551, 0xb11b4652, 0x65d122b9,
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0x97baa1ba, 0x84ea524e, 0x7681d14d, 0x2892ed69, 0xdaf96e6a,
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0xc9a99d9e, 0x3bc21e9d, 0xef087a76, 0x1d63f975, 0x0e330a81,
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0xfc588982, 0xb21572c9, 0x407ef1ca, 0x532e023e, 0xa145813d,
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0x758fe5d6, 0x87e466d5, 0x94b49521, 0x66df1622, 0x38cc2a06,
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0xcaa7a905, 0xd9f75af1, 0x2b9cd9f2, 0xff56bd19, 0x0d3d3e1a,
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0x1e6dcdee, 0xec064eed, 0xc38d26c4, 0x31e6a5c7, 0x22b65633,
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0xd0ddd530, 0x0417b1db, 0xf67c32d8, 0xe52cc12c, 0x1747422f,
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0x49547e0b, 0xbb3ffd08, 0xa86f0efc, 0x5a048dff, 0x8ecee914,
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0x7ca56a17, 0x6ff599e3, 0x9d9e1ae0, 0xd3d3e1ab, 0x21b862a8,
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0x32e8915c, 0xc083125f, 0x144976b4, 0xe622f5b7, 0xf5720643,
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0x07198540, 0x590ab964, 0xab613a67, 0xb831c993, 0x4a5a4a90,
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0x9e902e7b, 0x6cfbad78, 0x7fab5e8c, 0x8dc0dd8f, 0xe330a81a,
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0x115b2b19, 0x020bd8ed, 0xf0605bee, 0x24aa3f05, 0xd6c1bc06,
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0xc5914ff2, 0x37faccf1, 0x69e9f0d5, 0x9b8273d6, 0x88d28022,
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0x7ab90321, 0xae7367ca, 0x5c18e4c9, 0x4f48173d, 0xbd23943e,
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0xf36e6f75, 0x0105ec76, 0x12551f82, 0xe03e9c81, 0x34f4f86a,
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0xc69f7b69, 0xd5cf889d, 0x27a40b9e, 0x79b737ba, 0x8bdcb4b9,
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0x988c474d, 0x6ae7c44e, 0xbe2da0a5, 0x4c4623a6, 0x5f16d052,
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0xad7d5351
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};
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static uint32_t crc32c_lookup(uint8_t index) {
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return crc32c_table[index & 0xff];
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}
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static void crc32c(uint32_t *crc, const uint8_t *data, size_t len)
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{
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int i = 0;
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for (i = 0 ; i < len; ++i) {
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uint32_t tabval = crc32c_lookup(*crc ^ data[i]);
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*crc = tabval ^ (*crc >> 8);
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}
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}
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static void crc32c_init(uint32_t *crc) {
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/* Initial value is 0 */
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*crc = 0xffffffff;
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}
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static void crc32c_fini(uint32_t *crc) {
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/* Final step is to reverse the CRC Value */
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*crc ^= 0xffffffff;
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/* Mask the CRC */
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*crc = ((*crc >> 15) | (*crc << 17)) + 0xa282ead8;
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}
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/* Logarithm base two of the number */
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static uint32_t log2_32(uint32_t n) {
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@ -249,13 +332,15 @@ static int32_t parse_compressed_type(uint8_t compressed_type,
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}
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static int snappy_uncompress(FILE *out, uint8_t *cdata, size_t clength,
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uint8_t *data, size_t length, uint32_t *idx) {
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uint8_t *data, size_t length, uint32_t *idx, uint32_t *crc) {
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int32_t off = 0;
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uint32_t cidx = 0;
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uint32_t bytes = 0;
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uint32_t len = 0;
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uint8_t ctype = 0;
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crc32c_init(crc);
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*idx = 0;
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prdebug("Decompressing %ld bytes\n", clength);
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@ -273,6 +358,9 @@ static int snappy_uncompress(FILE *out, uint8_t *cdata, size_t clength,
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off = parse_compressed_type(ctype, cdata, cidx, clength,
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data, idx, len);
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if (off < 0) {
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/* Calculate CRC */
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crc32c(crc, data, *idx);
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crc32c_fini(crc);
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if (fwrite(data, 1, *idx, out) != *idx)
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return off;
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return off;
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@ -282,6 +370,9 @@ static int snappy_uncompress(FILE *out, uint8_t *cdata, size_t clength,
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cidx += off;
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}
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crc32c(crc, data, *idx);
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crc32c_fini(crc);
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return 0;
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}
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@ -348,6 +439,7 @@ static int parse_compressed_data_chunk(FILE *in, FILE *out) {
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uint32_t c_read_length = 0;
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uint32_t crc = 0;
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uint32_t idx = 0;
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uint32_t uncompressed_crc = 0;
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c_data = malloc(MAX_COMPRESSED_DATA_SIZE);
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if (c_data == NULL) {
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@ -396,12 +488,20 @@ static int parse_compressed_data_chunk(FILE *in, FILE *out) {
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c_read_length = fread(c_data, 1, c_length - 3, in);
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if ((ret = snappy_uncompress(out, c_data, c_read_length,
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data, MAX_UNCOMPRESSED_DATA_SIZE, &idx)) != 0) {
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data, MAX_UNCOMPRESSED_DATA_SIZE, &idx,
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&uncompressed_crc)) != 0) {
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goto return_point;
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}
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prinfo("End of decompression %lx\n", ftell(in));
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if (crc != uncompressed_crc) {
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prinfo("Corrupted File! Expected CRC: %08x Calculated CRC: %08x\n", crc, uncompressed_crc);
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if (consider_crc_errors) {
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ret = -1;
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goto return_point;
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}
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}
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if (fwrite(data, 1, idx, out) < idx) {
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perror("fwrite");
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@ -542,6 +642,7 @@ int main(int argc, char **argv) {
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int option_idx = 0;
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static struct option flags[] = {
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{"consider_crc_errors", no_argument, 0, 'C'},
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{"ignore_offset_errors", optional_argument, 0, 'E'},
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{"read_offset", required_argument, 0, 'O'},
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{"unframed", no_argument, 0, 'u'},
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@ -551,8 +652,11 @@ int main(int argc, char **argv) {
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};
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while (c != -1) {
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c = getopt_long(argc, argv, "O:E::uhv", flags, &option_idx);
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c = getopt_long(argc, argv, "CO:E::uhv", flags, &option_idx);
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switch (c) {
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case 'C':
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consider_crc_errors = 1;
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break;
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case 'E':
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ignore_offset_errors = 1;
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/* Set the dummy byte to the passed value */
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