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escapes() revamp

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Partial rewrite of escapes(), mostly changing its if-then-else
logic so that end-of-string can be checked once instead for each case.
The previous version had a bug if the input string ended with backslash
and one decimal digit (due to being lumped together with the handling
for trailing \X or \O).
This commit is contained in:
nethack.rankin
2011-08-04 02:41:44 +00:00
parent 50e12a87aa
commit 612755bfb5
1 changed files with 47 additions and 33 deletions
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80
src/options.c
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@@ -753,40 +753,58 @@ nmcpy(dest, src, maxlen)
* has the effect of 'meta'-ing the value which follows (so that the
* alternate character set will be enabled).
*
* For 3.4.3 and earlier, ending with "\M", backslash, or caret prior
* to terminating '\0' would pull that '\0' into the output and then
* keep processing past it. Now, a trailing escape will be handled
* as if it was preceded with its own backslash and be kept as is,
* with end of string terminator always honored as end of input.
* For 3.4.3 and earlier, input ending with "\M", backslash, or caret
* prior to terminating '\0' would pull that '\0' into the output and then
* keep processing past it, potentially overflowing the output buffer.
* Now, trailing \ or ^ will act like \\ or \^ and add '\\' or '^' to the
* output and stop there; trailing \M will fall through to \<other> and
* yield 'M', then stop. Any \X or \O followed by something other than
* an appropriate digit will also fall through to \<other> and yield 'X'
* or 'O', plus stop if the non-digit is end-of-string.
*/
STATIC_OVL void
escapes(cp, tp)
const char *cp;
char *tp;
{
static NEARDATA const char
oct[] = "01234567", dec[] = "0123456789",
hex[] = "00112233445566778899aAbBcCdDeEfF";
const char *dp;
int cval, meta, dcount;
while (*cp) {
int cval = 0, meta = 0;
/* \M has to be followed by something to do meta conversion,
otherwise it will just be \M which ultimately yields 'M' */
meta = (*cp == '\\' && (cp[1] == 'm' || cp[1] == 'M') && cp[2]);
if (meta) cp += 2;
if (*cp == '\\' && cp[1] && index("mM", cp[1]) && cp[2]) {
meta = 1;
cp += 2;
}
if (*cp == '\\' && cp[1] && index("0123456789xXoO", cp[1]) && cp[2]) {
NEARDATA const char hex[] = "00112233445566778899aAbBcCdDeEfF";
const char *dp;
int dcount = 0;
cp++;
if (*cp == 'x' || *cp == 'X')
for (++cp; *cp && (dp = index(hex, *cp)) && (dcount++ < 2); cp++)
cval = (cval * 16) + ((int)(dp - hex) / 2);
else if (*cp == 'o' || *cp == 'O')
for (++cp; *cp && (index("01234567",*cp)) && (dcount++ < 3); cp++)
cval = (cval * 8) + (*cp - '0');
else
for (; *cp && (index("0123456789",*cp)) && (dcount++ < 3); cp++)
cval = (cval * 10) + (*cp - '0');
} else if (*cp == '\\' && cp[1]) { /* C-style character escapes */
cval = dcount = 0; /* for decimal, octal, hexadecimal cases */
if ((*cp != '\\' && *cp != '^') || !cp[1]) {
/* simple character, or nothing left for \ or ^ to escape */
cval = *cp++;
} else if (*cp == '^') { /* expand control-character syntax */
cval = (*++cp & 0x1f);
++cp;
/* remaining cases are all for backslash and we know cp[1] is not \0 */
} else if (index(dec, cp[1])) {
++cp; /* move past backslash to first digit */
do {
cval = (cval * 10) + (*cp - '0');
} while (*++cp && index(dec, *cp) && ++dcount < 3);
} else if ((cp[1] == 'o' || cp[1] == 'O') &&
cp[2] && index(oct, cp[2])) {
cp += 2; /* move past backslash and 'O' */
do {
cval = (cval * 8) + (*cp - '0');
} while (*++cp && index(oct, *cp) && ++dcount < 3);
} else if ((cp[1] == 'x' || cp[1] == 'X') &&
cp[2] && (dp = index(hex, cp[2])) != 0) {
cp += 2; /* move past backslash and 'X' */
do {
cval = (cval * 16) + ((int)(dp - hex) / 2);
} while (*++cp && (dp = index(hex, *cp)) != 0 && ++dcount < 2);
} else { /* C-style character escapes */
switch (*++cp) {
case '\\': cval = '\\'; break;
case 'n': cval = '\n'; break;
@@ -795,16 +813,12 @@ char *tp;
case 'r': cval = '\r'; break;
default: cval = *cp;
}
cp++;
} else if (*cp == '^' && cp[1]) { /* expand control-character syntax */
cval = (*++cp & 0x1f);
cp++;
} else
cval = *cp++;
++cp;
}
if (meta)
cval |= 0x80;
*tp++ = cval;
*tp++ = (char)cval;
}
*tp = '\0';
}