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am 2c5153b0: libc: add getauxval()

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* commit '2c5153b043b44e9935a334ae9b2d5a4bc5258b40':
  libc: add getauxval()
This commit is contained in:
Nick Kralevich 2013-01-11 16:59:57 -08:00 committed by Android Git Automerger
commit fdd6dfa863
9 changed files with 214 additions and 28 deletions
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1
libc/Android.mk
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@ -275,6 +275,7 @@ libc_bionic_src_files := \
bionic/dirent.cpp \
bionic/eventfd.cpp \
bionic/__fgets_chk.cpp \
bionic/getauxval.cpp \
bionic/getcwd.cpp \
bionic/libgen.cpp \
bionic/__memcpy_chk.cpp \

48
libc/bionic/getauxval.cpp Normal file
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@ -0,0 +1,48 @@
/*
* Copyright (C) 2013 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <stddef.h>
#include <sys/cdefs.h>
#include <sys/auxv.h>
#include <private/bionic_auxv.h>
#include <elf.h>
__LIBC_HIDDEN__
Elf32_auxv_t* __libc_auxv = NULL;
extern "C" unsigned long int getauxval(unsigned long int type) {
Elf32_auxv_t* v;
for (v = __libc_auxv; v->a_type != AT_NULL; v++) {
if (v->a_type == type) {
return v->a_un.a_val;
}
}
return 0;
}

10
libc/bionic/libc_init_common.c
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@ -38,6 +38,7 @@
#include <bionic_tls.h>
#include <errno.h>
#include <private/bionic_auxv.h>
extern unsigned __get_sp(void);
extern pid_t gettid(void);
@ -95,6 +96,15 @@ void __libc_init_common(uintptr_t* elf_data) {
__progname = argv[0] ? argv[0] : "<unknown>";
environ = envp;
// The auxiliary vector is at the end of the environment block
while(*envp != NULL) {
envp++;
}
/* The end of the environment block is marked by two NULL pointers */
envp++;
__libc_auxv = (Elf32_auxv_t*) envp;
__system_properties_init(); // Requires 'environ'.
}

34
libc/bionic/libc_init_static.c
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@ -49,6 +49,7 @@
#include <bionic_tls.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/auxv.h>
// Returns the address of the page containing address 'x'.
#define PAGE_START(x) ((x) & PAGE_MASK)
@ -65,27 +66,13 @@ static void call_array(void(**list)())
}
}
/*
* Find the value of the AT_* variable passed to us by the kernel.
*/
static unsigned find_aux(unsigned *vecs, unsigned type) {
while (vecs[0]) {
if (vecs[0] == type) {
return vecs[1];
}
vecs += 2;
}
return 0; // should never happen
}
static void apply_gnu_relro(unsigned *vecs) {
static void apply_gnu_relro() {
Elf32_Phdr *phdr_start;
unsigned phdr_ct;
unsigned long int phdr_ct;
Elf32_Phdr *phdr;
phdr_start = (Elf32_Phdr *) find_aux(vecs, AT_PHDR);
phdr_ct = find_aux(vecs, AT_PHNUM);
phdr_start = (Elf32_Phdr *) getauxval(AT_PHDR);
phdr_ct = getauxval(AT_PHNUM);
for (phdr = phdr_start; phdr < (phdr_start + phdr_ct); phdr++) {
if (phdr->p_type != PT_GNU_RELRO)
@ -108,7 +95,6 @@ __noreturn void __libc_init(uintptr_t *elfdata,
{
int argc;
char **argv, **envp;
unsigned *vecs;
__libc_init_tls(NULL);
@ -129,14 +115,6 @@ __noreturn void __libc_init(uintptr_t *elfdata,
argv = (char**)(elfdata + 1);
envp = argv + argc + 1;
// The auxiliary vector is at the end of the environment block
vecs = (unsigned *) envp;
while (vecs[0] != 0) {
vecs++;
}
/* The end of the environment block is marked by two NULL pointers */
vecs++;
/* The executable may have its own destructors listed in its .fini_array
* so we need to ensure that these are called when the program exits
* normally.
@ -144,6 +122,6 @@ __noreturn void __libc_init(uintptr_t *elfdata,
if (structors->fini_array)
__cxa_atexit(__libc_fini,structors->fini_array,NULL);
apply_gnu_relro(vecs);
apply_gnu_relro();
exit(slingshot(argc, argv, envp));
}

15
libc/include/elf.h
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@ -28,8 +28,23 @@
#ifndef _ELF_H
#define _ELF_H
#include <stdint.h>
#include <linux/auxvec.h>
#include <sys/exec_elf.h>
typedef struct {
uint32_t a_type;
union {
uint32_t a_val;
} a_un;
} Elf32_auxv_t;
typedef struct {
uint64_t a_type;
union {
uint64_t a_val;
} a_un;
} Elf64_auxv_t;
#endif /* _ELF_H */

39
libc/include/sys/auxv.h Normal file
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@ -0,0 +1,39 @@
/*
* Copyright (C) 2013 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _SYS_AUXV_H_
#define _SYS_AUXV_H_
#include <linux/auxvec.h>
__BEGIN_DECLS
unsigned long int getauxval(unsigned long int type);
__END_DECLS
#endif /* _SYS_AUXV_H_ */

39
libc/private/bionic_auxv.h Normal file
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@ -0,0 +1,39 @@
/*
* Copyright (C) 2013 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _SYS_AUXV_H_
#define _SYS_AUXV_H_
#include <elf.h>
__BEGIN_DECLS
extern Elf32_auxv_t* __libc_auxv;
__END_DECLS
#endif /* _SYS_AUXV_H_ */

1
tests/Android.mk
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@ -55,6 +55,7 @@ test_c_flags = \
test_src_files = \
dirent_test.cpp \
fenv_test.cpp \
getauxval_test.cpp \
getcwd_test.cpp \
libgen_test.cpp \
pthread_test.cpp \

55
tests/getauxval_test.cpp Normal file
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@ -0,0 +1,55 @@
/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <sys/cdefs.h>
#include <features.h>
#include <gtest/gtest.h>
// getauxval() was only added as of glibc version 2.16.
// See: http://lwn.net/Articles/519085/
// Don't try to compile this code on older glibc versions.
#if defined(__BIONIC__)
#define GETAUXVAL_CAN_COMPILE 1
#elif defined(__GLIBC_PREREQ)
#if __GLIBC_PREREQ(2, 16)
#define GETAUXVAL_CAN_COMPILE 1
#endif
#endif
#if defined(GETAUXVAL_CAN_COMPILE)
#include <sys/auxv.h>
TEST(getauxval, expected_values) {
ASSERT_EQ((unsigned long int) 0, getauxval(AT_SECURE));
ASSERT_EQ(getuid(), getauxval(AT_UID));
ASSERT_EQ(geteuid(), getauxval(AT_EUID));
ASSERT_EQ(getgid(), getauxval(AT_GID));
ASSERT_EQ(getegid(), getauxval(AT_EGID));
ASSERT_EQ((unsigned long int) getpagesize(), getauxval(AT_PAGESZ));
ASSERT_NE((unsigned long int) 0, getauxval(AT_PHDR));
ASSERT_NE((unsigned long int) 0, getauxval(AT_PHNUM));
ASSERT_NE((unsigned long int) 0, getauxval(AT_ENTRY));
ASSERT_NE((unsigned long int) 0, getauxval(AT_PAGESZ));
}
TEST(getauxval, unexpected_values) {
ASSERT_EQ((unsigned long int) 0, getauxval(0xdeadbeef));
}
#endif /* GETAUXVAL_CAN_COMPILE */