lha: Precalculate CRC16 tables

This avoids all possible concurrency issues.

As a bonus, turn the whole array const to move it into read-only
section.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>

diff --git a/libarchive/archive_read_support_format_lha.c b/libarchive/archive_read_support_format_lha.c
index ff6dbb8df1cd4d2cba42ee479d7f2d9bed1025a8..3e6c15fff13e4f93f90348b88d8d84a88c1a702f 100644 (file)
--- a/libarchive/archive_read_support_format_lha.c
+++ b/libarchive/archive_read_support_format_lha.c
@@ -239,7 +239,6 @@ static int  lha_read_data_none(struct archive_read *, const void **,
                    size_t *, int64_t *);
 static int     lha_read_data_lzh(struct archive_read *, const void **,
                    size_t *, int64_t *);
-static void    lha_crc16_init(void);
 static uint16_t lha_crc16(uint16_t, const void *, size_t);
 static int     lzh_decode_init(struct lzh_stream *, const char *);
 static void    lzh_decode_free(struct lzh_stream *);
@@ -483,8 +482,6 @@ archive_read_format_lha_read_header(struct archive_read *a,
        struct archive_mstring conv_buffer;
        const wchar_t *conv_buffer_p;
 
-       lha_crc16_init();
-
        a->archive.archive_format = ARCHIVE_FORMAT_LHA;
        if (a->archive.archive_format_name == NULL)
                a->archive.archive_format_name = "lha";
@@ -1733,30 +1730,86 @@ lha_calcsum(unsigned char sum, const void *pp, int offset, size_t size)
        return (sum);
 }
 
-static uint16_t crc16tbl[2][256];
-static void
-lha_crc16_init(void)
-{
-       unsigned int i;
-       static int crc16init = 0;
-
-       if (crc16init)
-               return;
-       crc16init = 1;
-
-       for (i = 0; i < 256; i++) {
-               unsigned int j;
-               uint16_t crc = (uint16_t)i;
-               for (j = 8; j; j--)
-                       crc = (crc >> 1) ^ ((crc & 1) * 0xA001);
-               crc16tbl[0][i] = crc;
-       }
-
-       for (i = 0; i < 256; i++) {
-               crc16tbl[1][i] = (crc16tbl[0][i] >> 8)
-                       ^ crc16tbl[0][crc16tbl[0][i] & 0xff];
+static const uint16_t crc16tbl[2][256] = {
+       {
+               0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280,
+               0xc241, 0xc601, 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1,
+               0xc481, 0x0440, 0xcc01, 0x0cc0, 0x0d80, 0xcd41, 0x0f00,
+               0xcfc1, 0xce81, 0x0e40, 0x0a00, 0xcac1, 0xcb81, 0x0b40,
+               0xc901, 0x09c0, 0x0880, 0xc841, 0xd801, 0x18c0, 0x1980,
+               0xd941, 0x1b00, 0xdbc1, 0xda81, 0x1a40, 0x1e00, 0xdec1,
+               0xdf81, 0x1f40, 0xdd01, 0x1dc0, 0x1c80, 0xdc41, 0x1400,
+               0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0, 0x1680, 0xd641,
+               0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081,
+               0x1040, 0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1,
+               0xf281, 0x3240, 0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501,
+               0x35c0, 0x3480, 0xf441, 0x3c00, 0xfcc1, 0xfd81, 0x3d40,
+               0xff01, 0x3fc0, 0x3e80, 0xfe41, 0xfa01, 0x3ac0, 0x3b80,
+               0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840, 0x2800, 0xe8c1,
+               0xe981, 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41, 0xee01,
+               0x2ec0, 0x2f80, 0xef41, 0x2d00, 0xedc1, 0xec81, 0x2c40,
+               0xe401, 0x24c0, 0x2580, 0xe541, 0x2700, 0xe7c1, 0xe681,
+               0x2640, 0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0,
+               0x2080, 0xe041, 0xa001, 0x60c0, 0x6180, 0xa141, 0x6300,
+               0xa3c1, 0xa281, 0x6240, 0x6600, 0xa6c1, 0xa781, 0x6740,
+               0xa501, 0x65c0, 0x6480, 0xa441, 0x6c00, 0xacc1, 0xad81,
+               0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41, 0xaa01, 0x6ac0,
+               0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840, 0x7800,
+               0xb8c1, 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41,
+               0xbe01, 0x7ec0, 0x7f80, 0xbf41, 0x7d00, 0xbdc1, 0xbc81,
+               0x7c40, 0xb401, 0x74c0, 0x7580, 0xb541, 0x7700, 0xb7c1,
+               0xb681, 0x7640, 0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101,
+               0x71c0, 0x7080, 0xb041, 0x5000, 0x90c1, 0x9181, 0x5140,
+               0x9301, 0x53c0, 0x5280, 0x9241, 0x9601, 0x56c0, 0x5780,
+               0x9741, 0x5500, 0x95c1, 0x9481, 0x5440, 0x9c01, 0x5cc0,
+               0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40, 0x5a00,
+               0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841,
+               0x8801, 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81,
+               0x4a40, 0x4e00, 0x8ec1, 0x8f81, 0x4f40, 0x8d01, 0x4dc0,
+               0x4c80, 0x8c41, 0x4400, 0x84c1, 0x8581, 0x4540, 0x8701,
+               0x47c0, 0x4680, 0x8641, 0x8201, 0x42c0, 0x4380, 0x8341,
+               0x4100, 0x81c1, 0x8081, 0x4040
+       },
+       {
+               0x0000, 0x9001, 0x6001, 0xf000, 0xc002, 0x5003, 0xa003,
+               0x3002, 0xc007, 0x5006, 0xa006, 0x3007, 0x0005, 0x9004,
+               0x6004, 0xf005, 0xc00d, 0x500c, 0xa00c, 0x300d, 0x000f,
+               0x900e, 0x600e, 0xf00f, 0x000a, 0x900b, 0x600b, 0xf00a,
+               0xc008, 0x5009, 0xa009, 0x3008, 0xc019, 0x5018, 0xa018,
+               0x3019, 0x001b, 0x901a, 0x601a, 0xf01b, 0x001e, 0x901f,
+               0x601f, 0xf01e, 0xc01c, 0x501d, 0xa01d, 0x301c, 0x0014,
+               0x9015, 0x6015, 0xf014, 0xc016, 0x5017, 0xa017, 0x3016,
+               0xc013, 0x5012, 0xa012, 0x3013, 0x0011, 0x9010, 0x6010,
+               0xf011, 0xc031, 0x5030, 0xa030, 0x3031, 0x0033, 0x9032,
+               0x6032, 0xf033, 0x0036, 0x9037, 0x6037, 0xf036, 0xc034,
+               0x5035, 0xa035, 0x3034, 0x003c, 0x903d, 0x603d, 0xf03c,
+               0xc03e, 0x503f, 0xa03f, 0x303e, 0xc03b, 0x503a, 0xa03a,
+               0x303b, 0x0039, 0x9038, 0x6038, 0xf039, 0x0028, 0x9029,
+               0x6029, 0xf028, 0xc02a, 0x502b, 0xa02b, 0x302a, 0xc02f,
+               0x502e, 0xa02e, 0x302f, 0x002d, 0x902c, 0x602c, 0xf02d,
+               0xc025, 0x5024, 0xa024, 0x3025, 0x0027, 0x9026, 0x6026,
+               0xf027, 0x0022, 0x9023, 0x6023, 0xf022, 0xc020, 0x5021,
+               0xa021, 0x3020, 0xc061, 0x5060, 0xa060, 0x3061, 0x0063,
+               0x9062, 0x6062, 0xf063, 0x0066, 0x9067, 0x6067, 0xf066,
+               0xc064, 0x5065, 0xa065, 0x3064, 0x006c, 0x906d, 0x606d,
+               0xf06c, 0xc06e, 0x506f, 0xa06f, 0x306e, 0xc06b, 0x506a,
+               0xa06a, 0x306b, 0x0069, 0x9068, 0x6068, 0xf069, 0x0078,
+               0x9079, 0x6079, 0xf078, 0xc07a, 0x507b, 0xa07b, 0x307a,
+               0xc07f, 0x507e, 0xa07e, 0x307f, 0x007d, 0x907c, 0x607c,
+               0xf07d, 0xc075, 0x5074, 0xa074, 0x3075, 0x0077, 0x9076,
+               0x6076, 0xf077, 0x0072, 0x9073, 0x6073, 0xf072, 0xc070,
+               0x5071, 0xa071, 0x3070, 0x0050, 0x9051, 0x6051, 0xf050,
+               0xc052, 0x5053, 0xa053, 0x3052, 0xc057, 0x5056, 0xa056,
+               0x3057, 0x0055, 0x9054, 0x6054, 0xf055, 0xc05d, 0x505c,
+               0xa05c, 0x305d, 0x005f, 0x905e, 0x605e, 0xf05f, 0x005a,
+               0x905b, 0x605b, 0xf05a, 0xc058, 0x5059, 0xa059, 0x3058,
+               0xc049, 0x5048, 0xa048, 0x3049, 0x004b, 0x904a, 0x604a,
+               0xf04b, 0x004e, 0x904f, 0x604f, 0xf04e, 0xc04c, 0x504d,
+               0xa04d, 0x304c, 0x0044, 0x9045, 0x6045, 0xf044, 0xc046,
+               0x5047, 0xa047, 0x3046, 0xc043, 0x5042, 0xa042, 0x3043,
+               0x0041, 0x9040, 0x6040, 0xf041
        }
-}
+};
 
 static uint16_t
 lha_crc16(uint16_t crc, const void *pp, size_t len)