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/*
* Copyright (C) 2006 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 <elf.h>
#include <string.h>
#include <sys/auxv.h>
#include <sys/types.h>
#include <link.h>
/* ld provides this to us in the default link script */
extern "C" void* __executable_start;
int dl_iterate_phdr(int (*cb)(struct dl_phdr_info* info, size_t size, void* data), void* data) {
ElfW(Ehdr)* ehdr = reinterpret_cast<ElfW(Ehdr)*>(&__executable_start);
if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) {
return -1;
}
// Dynamic binaries get their dl_iterate_phdr from the dynamic linker, but
// static binaries get this. We don't have a list of shared objects to
// iterate over, since there's really only a single monolithic blob of
// code/data, plus optionally a VDSO.
struct dl_phdr_info exe_info;
exe_info.dlpi_addr = 0;
exe_info.dlpi_name = NULL;
exe_info.dlpi_phdr = reinterpret_cast<ElfW(Phdr)*>(reinterpret_cast<uintptr_t>(ehdr) + ehdr->e_phoff);
exe_info.dlpi_phnum = ehdr->e_phnum;
#if defined(AT_SYSINFO_EHDR)
// Try the executable first.
int rc = cb(&exe_info, sizeof(exe_info), data);
if (rc != 0) {
return rc;
}
// Try the VDSO if that didn't work.
ElfW(Ehdr)* ehdr_vdso = reinterpret_cast<ElfW(Ehdr)*>(getauxval(AT_SYSINFO_EHDR));
if (ehdr_vdso == nullptr) {
// There is no VDSO, so there's nowhere left to look.
return rc;
}
struct dl_phdr_info vdso_info;
vdso_info.dlpi_addr = 0;
vdso_info.dlpi_name = NULL;
vdso_info.dlpi_phdr = reinterpret_cast<ElfW(Phdr)*>(reinterpret_cast<char*>(ehdr_vdso) + ehdr_vdso->e_phoff);
vdso_info.dlpi_phnum = ehdr_vdso->e_phnum;
for (size_t i = 0; i < vdso_info.dlpi_phnum; ++i) {
if (vdso_info.dlpi_phdr[i].p_type == PT_LOAD) {
vdso_info.dlpi_addr = (ElfW(Addr)) ehdr_vdso - vdso_info.dlpi_phdr[i].p_vaddr;
break;
}
}
return cb(&vdso_info, sizeof(vdso_info), data);
#else
// There's only the executable to try.
return cb(&exe_info, sizeof(exe_info), data);
#endif
}
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