diff options
Diffstat (limited to 'unpack.c')
-rw-r--r-- | unpack.c | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/unpack.c b/unpack.c new file mode 100644 index 0000000..2617e9a --- /dev/null +++ b/unpack.c @@ -0,0 +1,123 @@ +#include <ctype.h> +#include <stdarg.h> +#include <stdbool.h> +#include <stdint.h> +#include <limits.h> + +#include <stdio.h> + +#include "common.h" +#include "pack.h" + +typedef enum pack_status unpacker(void *buf, size_t size, va_list ap); + +enum endian { BIG, LITTLE }; + +uintmax_t read_val(unsigned char *buf, size_t size, enum endian e) +{ + unsigned long long val = 0; + + for (size_t i = 0; i < size; i++) + val |= (buf[i] & 0xff) << (e == LITTLE ? i : size - i - 1) * 8; + + return val; +} +#define X(M) \ + M(b, signed char ) \ + M(B, unsigned char ) \ + M(h, short ) \ + M(H, unsigned short ) \ + M(i, int ) \ + M(I, unsigned ) \ + M(l, long ) \ + M(L, unsigned long ) \ + M(q, long long) \ + M(Q, unsigned long long) + +enum pack_status unpack(void *buf_, size_t size, const char *fmt, ...) +{ + enum endian endianness = BIG; + unsigned char *buf = buf_; + size_t offset = 0; + va_list ap; + + va_start(ap, fmt); + + for (int i = 0; fmt[i] != '\0'; i++) { + bool sign = islower(fmt[i]); + size_t s; + union { + signed char *b; + unsigned char *B; + short *h; + unsigned short *H; + int *i; + unsigned int *I; + long *l; + unsigned long *L; + long long *q; + unsigned long long *Q; + } arg; + /*void *arg;*/ + union { uintmax_t u; intmax_t s; } val; + switch (fmt[i]) { + case '>': endianness = BIG; continue; + case '<': endianness = LITTLE; continue; + case 'b': arg.b = va_arg(ap, signed char *); + case 'B': arg.B = va_arg(ap, unsigned char *); + case 'h': arg.h = va_arg(ap, short *); + case 'H': arg.H = va_arg(ap, unsigned short *); + case 'i': arg.i = va_arg(ap, int *); + case 'I': arg.I = va_arg(ap, unsigned *); + case 'l': arg.l = va_arg(ap, long *); + case 'L': arg.L = va_arg(ap, unsigned long *); + case 'q': arg.q = va_arg(ap, long long *); + case 'Q': arg.Q = va_arg(ap, unsigned long long *); + case 'x': break; + return PACK_FMTINVAL; + } + + s = getsize(fmt[i]); + if (s == (size_t)-1) return PACK_FMTINVAL; + + if (size - offset < s) return PACK_TOOSMALL; + + if (fmt[i] == 'x') goto skip; + + val.u = read_val(buf, s, endianness); + + fprintf(stderr, "%zu, %llu\n", s, val.u); + + if (sign) { + intmax_t vals; + if (!(val.u & (1llu << (s * 8 - 1)))) { + vals = val.u; + } else { + uintmax_t offt = UINTMAX_MAX >> (sizeof offt * CHAR_BIT - s * 8); + vals = val.u - offt - 1; + } + val.s = vals; + fprintf(stderr, "signed %lld\n", val.s); + } + + switch (fmt[i]) { +#define D(t, f) fprintf(stderr, "(%p) "#t " = %" #f "\n", (void *)arg.t, *arg.t) + case 'b': *arg.b = val.s; D(b, d); break; + case 'B': *arg.B = val.u; D(B, u); break; + case 'h': *arg.h = val.s; D(h, d); break; + case 'H': *arg.H = val.u; D(H, u); break; + case 'i': *arg.i = val.s; D(i, d); break; + case 'I': *arg.I = val.u; D(I, u); break; + case 'l': *arg.l = val.s; D(l, ld); break; + case 'L': *arg.L = val.u; D(L, lu); break; + case 'q': *arg.q = val.s; D(q, lld); break; + case 'Q': *arg.Q = val.u; D(Q, llu); break; + } +skip: + offset += s; + } + + va_end(ap); + + return PACK_OK; +} |