mirror of
https://github.com/jart/cosmopolitan.git
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72 lines
3 KiB
C
72 lines
3 KiB
C
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/*-*- 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 2021 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/dce.h"
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#include "libc/macros.internal.h"
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#include "libc/mem/mem.h"
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#include "libc/stdio/append.internal.h"
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#include "libc/str/str.h"
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#define W sizeof(size_t)
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/**
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* Resets length of append buffer, e.g.
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*
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* char *b = 0;
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* appends(&b, "hello");
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* appendr(&b, 1);
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* assert(!strcmp(b, "h"));
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* appendr(&b, 0);
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* assert(!strcmp(b, ""));
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* free(b);
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*
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* If `i` is greater than the current length then the extra bytes are
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* filled with NUL characters.
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*
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* The resulting buffer is guarranteed to be NUL-terminated, i.e.
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* `!b[appendz(b).i]` will be the case.
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*
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* @return `i` or -1 if `ENOMEM`
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* @see appendz(b).i to get buffer length
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*/
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ssize_t appendr(char **b, size_t i) {
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char *p;
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struct appendz z;
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assert(b);
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z = appendz((p = *b));
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z.n = ROUNDUP(i + 1, 8) + W;
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if ((p = realloc(p, z.n))) {
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z.n = malloc_usable_size(p);
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assert(!(z.n & (W - 1)));
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*b = p;
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} else {
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return -1;
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}
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if (i > z.i) {
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memset(p, z.i, i - z.i);
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}
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z.i = i;
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p[z.i] = 0;
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if (!IsTiny() && W == 8) {
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z.i |= (size_t)APPEND_COOKIE << 48;
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}
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*(size_t *)(p + z.n - W) = z.i;
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return i;
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}
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