cosmopolitan/libc/escape/escapec.c

69 lines
3.3 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/escape/escape.h"
#include "libc/limits.h"
#include "libc/sysv/errfuns.h"
/**
* Escapes memory for inclusion in C string literals (or Python, etc.)
*
* The outer quotation marks are *not* added.
*
* @param buf is the output area, which can't overlap and, no matter
* what, a NUL-terminator will always be placed in the buffer at
* an appropriate place, provided buf!=NULL && size!=0
* @param size is the byte-length of the output area
* @param s is the data, which may have NUL characters
* @param l is the byte-length of s or -1 if s is NUL-terminated
* @return number of characters written, excluding NUL terminator; or,
* if the output buffer wasn't passed, or was too short, then the
* number of characters that *would* have been written is returned;
* since that's how the snprintf() API works; or -1 on overflow
* @see xaescapec() for an easier api
*/
int escapec(char *buf, unsigned size, const char *s, unsigned l) {
if (l >= INT_MAX) return eoverflow();
unsigned i, j = 0;
for (i = 0; i < l; ++i) {
unsigned t = cescapec(s[i]);
if (t) {
while (t) {
if (j < size) {
buf[j] = (unsigned char)t;
t >>= 8;
}
j++;
}
} else {
if (l == -1) {
break;
}
}
}
if (buf && size) {
if (j < size) {
buf[j] = '\0';
} else {
buf[size - 1] = '\0';
}
}
return j;
}