cosmopolitan/libc/x/xstrcat.c

65 lines
2.9 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/safemacros.h"
#include "libc/mem/mem.h"
#include "libc/str/str.h"
#include "libc/x/x.h"
/**
* Concatenates strings / chars to newly allocated memory, e.g.
*
* xstrcat("hi", ' ', "there")
*
* Or without the C99 helper macro:
*
* (xstrcat)("hi", ' ', "there", NULL)
*
* This goes twice as fast as the more powerful xasprintf(). It's not
* quadratic like strcat(). It's much slower than high-effort stpcpy(),
* particularly with string literals.
*
* @see gc()
*/
char *(xstrcat)(const char *s, ...) {
char *p, b[2];
va_list va;
size_t i, n, n2, l;
p = NULL;
i = n = 0;
va_start(va, s);
do {
if ((intptr_t)s > 0 && (intptr_t)s <= 255) {
b[0] = (unsigned char)(intptr_t)s;
b[1] = '\0';
s = b;
l = 1;
} else {
l = strlen(s);
}
if ((n2 = i + l + 16) >= n) {
p = xrealloc(p, (n = n2 + (n2 >> 1)));
}
memcpy(p + i, s, l + 1);
i += l;
} while ((s = va_arg(va, const char *)));
va_end(va);
return p;
}