hex.c

/*
 * This file is Copyright (c) 2010 by the GPSD project
 * BSD terms apply: see the file COPYING in the distribution root for details.
 */
#include <string.h>
#include <ctype.h>
#include <assert.h>

#include "gpsd.h"

char /*@ observer @*/ *gpsd_hexdump(char *binbuf, size_t binbuflen)
{
    char *cp;
    bool printable = true;

    assert(binbuf != NULL);
    for (cp = binbuf; cp < binbuf + binbuflen; cp++)
	if (!isprint(*cp) && !isspace(*cp))
	    printable = false;
    if (printable)
	return binbuf;
    else {
	static char hexbuf[MAX_PACKET_LENGTH * 2 + 1];
#ifndef SQUELCH_ENABLE
	size_t i, j = 0;
	size_t len =
	    (size_t) ((binbuflen >
		       MAX_PACKET_LENGTH) ? MAX_PACKET_LENGTH : binbuflen);
	const char *ibuf = (const char *)binbuf;
	const char *hexchar = "0123456789abcdef";

	if (NULL == binbuf || 0 == binbuflen)
	    return "";

	/*@ -shiftimplementation @*/
	for (i = 0; i < len; i++) {
	    hexbuf[j++] = hexchar[(ibuf[i] & 0xf0) >> 4];
	    hexbuf[j++] = hexchar[ibuf[i] & 0x0f];
	}
	/*@ +shiftimplementation @*/
	hexbuf[j] = '\0';
#else /* SQUELCH defined */
	hexbuf[0] = '\0';
#endif /* SQUELCH_ENABLE */
	return hexbuf;
    }
}

int gpsd_hexpack( /*@in@*/ const char *src, /*@out@ */ char *dst, size_t len)
{
/* hex2bin source string to destination - destination can be same as source */
    int i, k, l;

    /*@ -mustdefine @*/
    l = (int)(strlen(src) / 2);
    if ((l < 1) || ((size_t) l > len))
	return -2;

    for (i = 0; i < l; i++)
	if ((k = hex2bin(src + i * 2)) != -1)
	    dst[i] = (char)(k & 0xff);
	else
	    return -1;
    (void)memset(dst + i, '\0', (size_t) (len - i));
    return l;
    /*@ +mustdefine @*/
}

/*@ +charint -shiftimplementation @*/
int hex2bin(const char *s)
{
    int a, b;

    a = s[0] & 0xff;
    b = s[1] & 0xff;

    if ((a >= 'a') && (a <= 'f'))
	a = a + 10 - 'a';
    else if ((a >= 'A') && (a <= 'F'))
	a = a + 10 - 'A';
    else if ((a >= '0') && (a <= '9'))
	a -= '0';
    else
	return -1;

    if ((b >= 'a') && (b <= 'f'))
	b = b + 10 - 'a';
    else if ((b >= 'A') && (b <= 'F'))
	b = b + 10 - 'A';
    else if ((b >= '0') && (b <= '9'))
	b -= '0';
    else
	return -1;

    return ((a << 4) + b);
}

/*@ -charint +shiftimplementation @*/

ssize_t hex_escapes( /*@out@*/ char *cooked, const char *raw)
/* interpret C-style hex escapes */
{
    char c, *cookend;

    /*@ +charint -mustdefine -compdef @*/
    for (cookend = cooked; *raw != '\0'; raw++)
	if (*raw != '\\')
	    *cookend++ = *raw;
	else {
	    switch (*++raw) {
	    case 'b':
		*cookend++ = '\b';
		break;
	    case 'e':
		*cookend++ = '\x1b';
		break;
	    case 'f':
		*cookend++ = '\f';
		break;
	    case 'n':
		*cookend++ = '\n';
		break;
	    case 'r':
		*cookend++ = '\r';
		break;
	    case 't':
		*cookend++ = '\r';
		break;
	    case 'v':
		*cookend++ = '\v';
		break;
	    case 'x':
		switch (*++raw) {
		case '0':
		    c = (char)0x00;
		    break;
		case '1':
		    c = (char)0x10;
		    break;
		case '2':
		    c = (char)0x20;
		    break;
		case '3':
		    c = (char)0x30;
		    break;
		case '4':
		    c = (char)0x40;
		    break;
		case '5':
		    c = (char)0x50;
		    break;
		case '6':
		    c = (char)0x60;
		    break;
		case '7':
		    c = (char)0x70;
		    break;
		case '8':
		    c = (char)0x80;
		    break;
		case '9':
		    c = (char)0x90;
		    break;
		case 'A':
		case 'a':
		    c = (char)0xa0;
		    break;
		case 'B':
		case 'b':
		    c = (char)0xb0;
		    break;
		case 'C':
		case 'c':
		    c = (char)0xc0;
		    break;
		case 'D':
		case 'd':
		    c = (char)0xd0;
		    break;
		case 'E':
		case 'e':
		    c = (char)0xe0;
		    break;
		case 'F':
		case 'f':
		    c = (char)0xf0;
		    break;
		default:
		    return -1;
		}
		switch (*++raw) {
		case '0':
		    c += 0x00;
		    break;
		case '1':
		    c += 0x01;
		    break;
		case '2':
		    c += 0x02;
		    break;
		case '3':
		    c += 0x03;
		    break;
		case '4':
		    c += 0x04;
		    break;
		case '5':
		    c += 0x05;
		    break;
		case '6':
		    c += 0x06;
		    break;
		case '7':
		    c += 0x07;
		    break;
		case '8':
		    c += 0x08;
		    break;
		case '9':
		    c += 0x09;
		    break;
		case 'A':
		case 'a':
		    c += 0x0a;
		    break;
		case 'B':
		case 'b':
		    c += 0x0b;
		    break;
		case 'C':
		case 'c':
		    c += 0x0c;
		    break;
		case 'D':
		case 'd':
		    c += 0x0d;
		    break;
		case 'E':
		case 'e':
		    c += 0x0e;
		    break;
		case 'F':
		case 'f':
		    c += 0x0f;
		    break;
		default:
		    return -2;
		}
		*cookend++ = c;
		break;
	    case '\\':
		*cookend++ = '\\';
		break;
	    default:
		return -3;
	    }
	}
    return (ssize_t) (cookend - cooked);
    /*@ +charint +mustdefine +compdef @*/
}