mirror of
https://github.com/jart/cosmopolitan.git
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77 lines
3 KiB
C
77 lines
3 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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│ 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/calls/strace.internal.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/log/libfatal.internal.h"
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#include "libc/runtime/runtime.h"
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forceinline int Identity(int c) {
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return c;
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}
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forceinline int ToUpper(int c) {
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return 'a' <= c && c <= 'z' ? c - ('a' - 'A') : c;
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}
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forceinline char *GetEnv(const char *s, int xlat(int)) {
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char **p;
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size_t i, j;
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if ((p = environ)) {
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for (i = 0; p[i]; ++i) {
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for (j = 0;; ++j) {
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if (!s[j]) {
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if (p[i][j] == '=') {
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return p[i] + j + 1;
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}
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break;
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}
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if (xlat(s[j]) != xlat(p[i][j])) {
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break;
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}
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}
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}
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}
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return 0;
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}
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/**
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* Returns value of environment variable, or NULL if not found.
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*
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* Environment variables can store empty string on Unix but not Windows.
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*
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* @note should not be used after __cxa_finalize() is called
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*/
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char *getenv(const char *s) {
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char *r;
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if (!s) return 0;
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if (!IsWindows()) {
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r = GetEnv(s, Identity);
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} else {
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r = GetEnv(s, ToUpper);
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}
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#if SYSDEBUG
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if (!(s[0] == 'T' && s[1] == 'Z' && !s[2])) {
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// TODO(jart): memoize TZ or something
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STRACE("getenv(%#s) → %#s", s, r);
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}
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#endif
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return r;
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}
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