cosmopolitan/libc/calls/hefty/sortenvp.c

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/*-*- 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
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Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted, provided that the
above copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
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*/
#include "libc/alg/alg.h"
#include "libc/alg/arraylist.internal.h"
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#include "libc/calls/hefty/ntspawn.h"
#include "libc/dce.h"
#include "libc/str/str.h"
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static int CompareStrings(const char *l, const char *r) {
size_t i = 0;
while (l[i] == r[i] && r[i]) ++i;
return (l[i] & 0xff) - (r[i] & 0xff);
}
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static void SortStrings(char **a, size_t n) {
char *t;
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size_t i, j;
for (i = 1; i < n; ++i) {
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for (t = a[i], j = i; j > 0 && CompareStrings(t, a[j - 1]) < 0; --j) {
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a[j] = a[j - 1];
}
a[j] = t;
}
}
/**
* Copies environment variable pointers and sorts them.
*
* This is useful for (a) binary searching; and (b) keeping the NT
* Executive happy, which wants strings to be ordered by UNICODE
* codepoint identifiers. That's basically what uint8_t comparisons on
* UTF8-encoded data gives us.
*
* @param envp is a NULL-terminated string array
* @return newly allocated sorted copy of envp pointer array
*/
hidden textwindows nodiscard char **sortenvp(char *const envp[]) {
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char **copy;
size_t n, size;
n = 0;
while (envp[n]) n++;
size = (n + 1) * sizeof(char *);
if ((copy = malloc(size))) {
memcpy(copy, envp, size);
SortStrings(copy, n);
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}
return copy;
}