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/*
* Copyright (C) 2020 Tomasz Kramkowski <tk@the-tk.com>
* SPDX-License-Identifier: MIT
*/
#include <ctype.h>
#include <inttypes.h>
#include <limits.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include "common.h"
#include "pack.h"
#include "trace.h"
enum endian { BIG, LITTLE };
static uintmax_t read_val(unsigned char *buf, size_t size, enum endian e)
{
uintmax_t val = 0;
for (size_t i = 0; i < size; i++) {
val |= (uintmax_t)(buf[i] & 0xff) << (e == LITTLE ? i : size - i - 1) * 8;
}
return val;
}
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;
tr_call("unpack(%p, %zu, %s, ...)", buf, size, fmt);
va_start(ap, fmt);
for (int i = 0; fmt[i] != '\0'; i++) {
bool sign = islower(fmt[i]);
unsigned long long count = 1;
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;
union { uintmax_t u; intmax_t s; } val;
tr_debug("i: %d, fmt[i]: %c, sign: %ssigned", i, fmt[i], sign ? "" : "un");
switch (fmt[i]) {
case '>': endianness = BIG; continue;
case '<': endianness = LITTLE; continue;
case 'b': arg.b = va_arg(ap, signed char *); break;
case 'B': arg.B = va_arg(ap, unsigned char *); break;
case 'h': arg.h = va_arg(ap, short *); break;
case 'H': arg.H = va_arg(ap, unsigned short *); break;
case 'i': arg.i = va_arg(ap, int *); break;
case 'I': arg.I = va_arg(ap, unsigned *); break;
case 'l': arg.l = va_arg(ap, long *); break;
case 'L': arg.L = va_arg(ap, unsigned long *); break;
case 'q': arg.q = va_arg(ap, long long *); break;
case 'Q': arg.Q = va_arg(ap, unsigned long long *); break;
case 'x': break;
return PACK_FMTINVAL;
}
s = getsize(fmt[i]);
tr_debug("s: %zu", s);
if (s == (size_t)-1) return PACK_FMTINVAL;
if (size - offset < s * count) return PACK_TOOSMALL;
if (fmt[i] == 'x') goto skip;
for (unsigned long long j = 0; j < count; j++) {
val.u = read_val(buf + s * j, s, endianness);
tr_debug("val.u: %" PRIuMAX, val.u);
if (sign) {
intmax_t vals;
if (!(val.u & (UINTMAX_C(1) << (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;
tr_debug("val.s: %" PRIdMAX, val.s);
}
switch (fmt[i]) {
case 'b': arg.b[j] = val.s; break;
case 'B': arg.B[j] = val.u; break;
case 'h': arg.h[j] = val.s; break;
case 'H': arg.H[j] = val.u; break;
case 'i': arg.i[j] = val.s; break;
case 'I': arg.I[j] = val.u; break;
case 'l': arg.l[j] = val.s; break;
case 'L': arg.L[j] = val.u; break;
case 'q': arg.q[j] = val.s; break;
case 'Q': arg.Q[j] = val.u; break;
}
}
skip:
offset += s * count;
}
va_end(ap);
return PACK_OK;
}
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