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/* vim: set expandtab tabstop=4 softtabstop=4 shiftwidth=4: */
/*
* Copyright © 2016 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#define _GNU_SOURCE
#include <dlfcn.h>
#include <link.h>
#include <stddef.h>
#include <string.h>
#include "build-id.h"
#ifndef NT_GNU_BUILD_ID
#define NT_GNU_BUILD_ID 3
#endif
#ifndef ElfW
#define ElfW(type) Elf_##type
#endif
#define ALIGN(val, align) (((val) + (align) - 1) & ~((align) - 1))
struct build_id_note {
ElfW(Nhdr) nhdr;
char name[4];
uint8_t build_id[0];
};
enum tag { BY_NAME, BY_SYMBOL };
struct callback_data {
union {
const char *name;
/* Base address of shared object, taken from Dl_info::dli_fbase */
const void *dli_fbase;
};
enum tag tag;
struct build_id_note *note;
};
static int
build_id_find_nhdr_callback(struct dl_phdr_info *info, size_t size, void *data_)
{
struct callback_data *data = data_;
if (data->tag == BY_NAME)
if (!info->dlpi_name || strcmp(info->dlpi_name, data->name) != 0)
return 0;
if (data->tag == BY_SYMBOL) {
/* Calculate address where shared object is mapped into the process space.
* (Using the base address and the virtual address of the first LOAD segment)
*/
void *map_start = NULL;
for (unsigned i = 0; i < info->dlpi_phnum; i++) {
if (info->dlpi_phdr[i].p_type == PT_LOAD) {
map_start = (void *)(info->dlpi_addr + info->dlpi_phdr[i].p_vaddr);
break;
}
}
if (map_start != data->dli_fbase)
return 0;
}
for (unsigned i = 0; i < info->dlpi_phnum; i++) {
if (info->dlpi_phdr[i].p_type != PT_NOTE)
continue;
struct build_id_note *note = (void *)(info->dlpi_addr +
info->dlpi_phdr[i].p_vaddr);
ptrdiff_t len = info->dlpi_phdr[i].p_filesz;
while (len >= sizeof(struct build_id_note)) {
if (note->nhdr.n_type == NT_GNU_BUILD_ID &&
note->nhdr.n_descsz != 0 &&
note->nhdr.n_namesz == 4 &&
memcmp(note->name, "GNU", 4) == 0) {
data->note = note;
return 1;
}
size_t offset = sizeof(ElfW(Nhdr)) +
ALIGN(note->nhdr.n_namesz, 4) +
ALIGN(note->nhdr.n_descsz, 4);
note = (struct build_id_note *)((char *)note + offset);
len -= offset;
}
}
return 0;
}
const struct build_id_note *
build_id_find_nhdr_by_name(const char *name)
{
struct callback_data data = {
.tag = BY_NAME,
.name = name,
.note = NULL,
};
if (!dl_iterate_phdr(build_id_find_nhdr_callback, &data))
return NULL;
return data.note;
}
const struct build_id_note *
build_id_find_nhdr_by_symbol(const void *symbol)
{
Dl_info info;
if (!dladdr(symbol, &info))
return NULL;
if (!info.dli_fbase)
return NULL;
struct callback_data data = {
.tag = BY_SYMBOL,
.dli_fbase = info.dli_fbase,
.note = NULL,
};
if (!dl_iterate_phdr(build_id_find_nhdr_callback, &data))
return NULL;
return data.note;
}
ElfW(Word)
build_id_length(const struct build_id_note *note)
{
return note->nhdr.n_descsz;
}
const uint8_t *
build_id_data(const struct build_id_note *note)
{
return note->build_id;
}
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