55 lines
2.9 KiB
C
55 lines
2.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/bits/safemacros.h"
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#include "libc/dce.h"
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#include "libc/fmt/fmt.h"
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#include "libc/limits.h"
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#include "libc/runtime/runtime.h"
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struct SprintfStr {
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char *p;
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size_t i;
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size_t n;
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};
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static int vsnprintfputchar(unsigned char c, struct SprintfStr *str) {
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if (str->i < str->n) str->p[str->i] = c;
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str->i++;
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return 0;
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}
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/**
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* Formats string to buffer w/ preexisting vararg state.
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*
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* @param buf stores output and a NUL-terminator is always written,
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* provided buf!=NULL && size!=0
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* @param size is byte capacity buf
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* @return number of bytes written, excluding the NUL terminator; or,
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* if the output buffer wasn't passed, or was too short, then the
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* number of characters that *would* have been written is returned
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* @see palandprintf() and printf() for detailed documentation
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*/
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int(vsnprintf)(char *buf, size_t size, const char *fmt, va_list va) {
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struct SprintfStr str = {buf, 0, size};
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palandprintf(vsnprintfputchar, &str, fmt, va);
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if (str.n) str.p[min(str.i, str.n - 1)] = '\0';
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return str.i;
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}
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