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/* $OpenBSD: init.c,v 1.4 2016/05/07 19:05:22 guenther Exp $ */
/*
* Copyright (c) 2014,2015 Philip Guenther <guenther@openbsd.org>
*
* Permission to use, copy, modify, and 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.
*
* 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.
*/
#define _DYN_LOADER
#include <sys/types.h>
#include <sys/exec_elf.h>
#include <sys/syscall.h>
#ifndef PIC
#include <sys/mman.h>
#endif
#include <tib.h>
#include <limits.h> /* NAME_MAX */
#include <stdlib.h> /* atexit */
#include <string.h>
#include <unistd.h>
/* XXX should be in an include file shared with csu */
char ***_csu_finish(char **_argv, char **_envp, void (*_cleanup)(void));
/* provide definition for this */
int _pagesize = 0;
/*
* In dynamicly linked binaries environ and __progname are overriden by
* the definitions in ld.so.
*/
char **environ __attribute__((weak)) = NULL;
char *__progname __attribute__((weak)) = NULL;
#ifndef PIC
static inline void early_static_init(char **_argv, char **_envp);
static inline void setup_static_tib(Elf_Phdr *_phdr, int _phnum);
#endif /* PIC */
/*
* extract useful bits from the auxiliary vector and either
* a) register ld.so's cleanup in dynamic links, or
* b) init __progname, environ, and the TIB in static links.
*/
char ***
_csu_finish(char **argv, char **envp, void (*cleanup)(void))
{
AuxInfo *aux;
#ifndef PIC
Elf_Phdr *phdr = NULL;
int phnum = 0;
/* static libc in a static link? */
if (cleanup == NULL)
early_static_init(argv, envp);
#endif /* !PIC */
/* Extract useful bits from the auxiliary vector */
while (*envp++ != NULL)
;
for (aux = (void *)envp; aux->au_id != AUX_null; aux++) {
switch (aux->au_id) {
case AUX_pagesz:
_pagesize = aux->au_v;
break;
#ifndef PIC
case AUX_phdr:
phdr = (void *)aux->au_v;
break;
case AUX_phnum:
phnum = aux->au_v;
break;
#endif /* !PIC */
}
}
#ifndef PIC
/* static libc in a static link? */
if (cleanup == NULL)
setup_static_tib(phdr, phnum);
#endif /* !PIC */
if (cleanup != NULL)
atexit(cleanup);
return &environ;
}
#ifndef PIC
/*
* static libc in a static link? Then disable kbind and set up
* __progname and environ
*/
static inline void
early_static_init(char **argv, char **envp)
{
static char progname_storage[NAME_MAX+1];
/* disable kbind */
syscall(SYS_kbind, (void *)NULL, (size_t)0, (long long)0);
environ = envp;
/* set up __progname */
if (*argv != NULL) { /* NULL ptr if argc = 0 */
const char *p = strrchr(*argv, '/');
if (p == NULL)
p = *argv;
else
p++;
strlcpy(progname_storage, p, sizeof(progname_storage));
}
__progname = progname_storage;
}
/*
* static TLS handling
*/
#define ELF_ROUND(x,malign) (((x) + (malign)-1) & ~((malign)-1))
/* for static binaries, the location and size of the TLS image */
static void *static_tls;
static size_t static_tls_fsize;
size_t _static_tls_size = 0;
static inline void
setup_static_tib(Elf_Phdr *phdr, int phnum)
{
struct tib *tib;
char *base;
int i;
if (phdr != NULL) {
for (i = 0; i < phnum; i++) {
if (phdr[i].p_type != PT_TLS)
continue;
if (phdr[i].p_memsz == 0)
break;
if (phdr[i].p_memsz < phdr[i].p_filesz)
break; /* invalid */
#if TLS_VARIANT == 1
_static_tls_size = phdr[i].p_memsz;
#elif TLS_VARIANT == 2
/*
* variant 2 places the data before the TIB
* so we need to round up to the alignment
*/
_static_tls_size = ELF_ROUND(phdr[i].p_memsz,
phdr[i].p_align);
#endif
if (phdr[i].p_vaddr != 0 && phdr[i].p_filesz != 0) {
static_tls = (void *)phdr[i].p_vaddr;
static_tls_fsize = phdr[i].p_filesz;
}
break;
}
}
/*
* We call getpagesize() here instead of using _pagesize because
* there's no aux-vector in non-PIE static links, so _pagesize
* might not be set yet. If so getpagesize() will get the value.
*/
base = mmap(NULL, ELF_ROUND(_static_tls_size + sizeof *tib,
getpagesize()), PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
# if TLS_VARIANT == 1
tib = (struct tib *)base;
# elif TLS_VARIANT == 2
tib = (struct tib *)(base + _static_tls_size);
# endif
_static_tls_init(base);
TIB_INIT(tib, NULL, NULL);
tib->tib_tid = getthrid();
TCB_SET(TIB_TO_TCB(tib));
#if ! TCB_HAVE_MD_GET
_libc_single_tcb = TIB_TO_TCB(tib);
#endif
}
void
_static_tls_init(char *base)
{
if (_static_tls_size) {
#if TLS_VARIANT == 1
base += sizeof(struct tib);
#endif
if (static_tls != NULL)
memcpy(base, static_tls, static_tls_fsize);
memset(base + static_tls_fsize, 0,
_static_tls_size - static_tls_fsize);
}
}
#endif /* !PIC */
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