70 lines
3.2 KiB
C
70 lines
3.2 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/dce.h"
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#include "libc/runtime/runtime.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/auxv.h"
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/**
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* Returns auxiliary value, or zero if kernel didn't provide it.
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*
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* This function is typically regarded as a libc implementation detail;
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* thus, the source code is the documentation.
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*
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* @see libc/sysv/consts.sh
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* @see System Five Application Binary Interface § 3.4.3
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* @asyncsignalsafe
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*/
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unsigned long getauxval(unsigned long at) {
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unsigned long res = 0;
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if (at != -1) {
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if (!IsWindows()) {
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if (!g_auxv) return 0;
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if (IsXnu()) {
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if (at) {
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const char *name =
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at == AT_EXECFN ? "executable_path" : (const char *)at;
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const char **auxv = (const char **)g_auxv;
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unsigned namelen = strlen(name);
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for (int i = 0; auxv[i]; ++i) {
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if (strncmp(auxv[i], name, namelen) == 0 &&
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auxv[i][namelen] == '=') {
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res = (intptr_t)&auxv[i][namelen + 1];
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break;
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}
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}
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}
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} else {
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for (const unsigned long *ap = g_auxv; *ap; ap += 2) {
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if (ap[0] == at) {
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res = ap[1];
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break;
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}
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}
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}
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} else {
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/* TODO(jart): GetProcessImageFileName */
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}
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if (res == 0 && at == AT_EXECFN) {
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res = (uintptr_t)program_invocation_name;
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}
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}
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return res;
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}
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