/*=export_func ao_string_cook_escape_char
* private:
*
* what: escape-process a string fragment
* arg: + char const * + pzScan + points to character after the escape +
* arg: + char * + pRes + Where to put the result byte +
* arg: + unsigned int + nl_ch + replacement char if scanned char is \n +
*
* ret-type: unsigned int
* ret-desc: The number of bytes consumed processing the escaped character.
*
* doc:
*
* This function converts "t" into "\t" and all your other favorite
* escapes, including numeric ones: hex and ocatal, too.
* The returned result tells the caller how far to advance the
* scan pointer (passed in). The default is to just pass through the
* escaped character and advance the scan by one.
*
* Some applications need to keep an escaped newline, others need to
* suppress it. This is accomplished by supplying a '\n' replacement
* character that is different from \n, if need be. For example, use
* 0x7F and never emit a 0x7F.
*
* err: @code{NULL} is returned if the string is mal-formed.
=*/
unsigned int
ao_string_cook_escape_char(char const * pzIn, char * pRes, uint_t nl)
{
unsigned int res = 1;
switch (*pRes = *pzIn++) {
case NUL: /* NUL - end of input string */
return 0;
case '\r':
if (*pzIn != NL)
return 1;
res++;
/* FALLTHROUGH */
case NL: /* NL - emit newline */
*pRes = (char)nl;
return res;
case 'a': *pRes = '\a'; break;
case 'b': *pRes = '\b'; break;
case 'f': *pRes = '\f'; break;
case 'n': *pRes = NL; break;
case 'r': *pRes = '\r'; break;
case 't': *pRes = '\t'; break;
case 'v': *pRes = '\v'; break;
case 'x':
case 'X': /* HEX Escape */
if (IS_HEX_DIGIT_CHAR(*pzIn)) {
char z[4];
unsigned int ct = 0;
do {
z[ct] = pzIn[ct];
if (++ct >= 2)
break;
} while (IS_HEX_DIGIT_CHAR(pzIn[ct]));
z[ct] = NUL;
*pRes = (char)strtoul(z, NULL, 16);
return ct + 1;
}
break;
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
{
/*
* IF the character copied was an octal digit,
* THEN set the output character to an octal value.
* The 3 octal digit result might exceed 0xFF, so check it.
*/
char z[4];
unsigned long val;
unsigned int ct = 0;
z[ct++] = *--pzIn;
while (IS_OCT_DIGIT_CHAR(pzIn[ct])) {
z[ct] = pzIn[ct];
if (++ct >= 3)
break;
}
z[ct] = NUL;
val = strtoul(z, NULL, 8);
if (val > 0xFF)
val = 0xFF;
*pRes = (char)val;
return ct;
}
default: /* quoted character is result character */;
}
return res;
}
/*=export_func ao_string_cook_escape_char
* private:
*
* what: escape-process a string fragment
* arg: + char const* + pzScan + points to character after the escape +
* arg: + char* + pRes + Where to put the result byte +
* arg: + unsigned int + nl_ch + replacement char if scanned char is \n +
*
* ret-type: unsigned int
* ret-desc: The number of bytes consumed processing the escaped character.
*
* doc:
*
* This function converts "t" into "\t" and all your other favorite
* escapes, including numeric ones: hex and ocatal, too.
* The returned result tells the caller how far to advance the
* scan pointer (passed in). The default is to just pass through the
* escaped character and advance the scan by one.
*
* Some applications need to keep an escaped newline, others need to
* suppress it. This is accomplished by supplying a '\n' replacement
* character that is different from \n, if need be. For example, use
* 0x7F and never emit a 0x7F.
*
* err: @code{NULL} is returned if the string is mal-formed.
=*/
unsigned int
ao_string_cook_escape_char( char const* pzIn, char* pRes, u_int nl )
{
unsigned int res = 1;
switch (*pRes = *pzIn++) {
case NUL: /* NUL - end of input string */
return 0;
case '\r':
if (*pzIn != '\n')
return 1;
res++;
/* FALLTHROUGH */
case '\n': /* NL - emit newline */
*pRes = (char)nl;
return res;
case 'a': *pRes = '\a'; break;
case 'b': *pRes = '\b'; break;
case 'f': *pRes = '\f'; break;
case 'n': *pRes = '\n'; break;
case 'r': *pRes = '\r'; break;
case 't': *pRes = '\t'; break;
case 'v': *pRes = '\v'; break;
case 'x':
case 'X': /* HEX Escape */
if (IS_HEX_DIGIT_CHAR(*pzIn)) {
char z[4], *pz = z;
do *(pz++) = *(pzIn++);
while (IS_HEX_DIGIT_CHAR(*pzIn) && (pz < z + 2));
*pz = NUL;
*pRes = (unsigned char)strtoul(z, NULL, 16);
res += pz - z;
}
break;
case '0': case '1': case '2': case '3':
case '4': case '5': case '6': case '7':
{
/*
* IF the character copied was an octal digit,
* THEN set the output character to an octal value
*/
char z[4], *pz = z + 1;
unsigned long val;
z[0] = *pRes;
while (IS_OCT_DIGIT_CHAR(*pzIn) && (pz < z + 3))
*(pz++) = *(pzIn++);
*pz = NUL;
val = strtoul(z, NULL, 8);
if (val > 0xFF)
val = 0xFF;
*pRes = (unsigned char)val;
res = pz - z;
break;
}
default: ;
}
return res;
}
