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Update dladdr path to not use dli_fname as it's unreliable in the case of a non-standard argv[0]

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This commit is contained in:
Jeremy 2024-05-02 10:47:31 -05:00
parent beb5506233
commit b125248b32
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GPG Key ID: 3E11861CB34E158C
1 changed files with 25 additions and 19 deletions
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42
src/binary/object.hpp
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@ -13,9 +13,7 @@
#if IS_LINUX || IS_APPLE
#include <unistd.h>
#include <dlfcn.h>
#ifdef CPPTRACE_HAS_DL_FIND_OBJECT
#include <link.h>
#endif
#elif IS_WINDOWS
#include <windows.h>
#endif
@ -23,6 +21,21 @@
namespace cpptrace {
namespace detail {
#if IS_LINUX || IS_APPLE
inline std::string resolve_l_name(const char* l_name) {
if(l_name != nullptr && l_name[0] != 0) {
return l_name;
} else {
// empty l_name, this means it's the currently running executable
// TODO: Caching and proper handling
char buffer[CPPTRACE_PATH_MAX + 1]{};
auto res = readlink("/proc/self/exe", buffer, CPPTRACE_PATH_MAX);
if(res == -1) {
return ""; // TODO
} else {
return buffer;
}
}
}
#ifdef CPPTRACE_HAS_DL_FIND_OBJECT
inline object_frame get_frame_object_info(frame_ptr address) {
// Use _dl_find_object when we can, it's orders of magnitude faster
@ -31,19 +44,7 @@ namespace detail {
frame.object_address = 0;
dl_find_object result;
if(_dl_find_object(reinterpret_cast<void*>(address), &result) == 0) { // thread safe
if(result.dlfo_link_map->l_name != nullptr && result.dlfo_link_map->l_name[0] != 0) {
frame.object_path = result.dlfo_link_map->l_name;
} else {
// empty l_name, this means it's the currently running executable
// TODO: Caching and proper handling
char buffer[CPPTRACE_PATH_MAX + 1]{};
auto res = readlink("/proc/self/exe", buffer, CPPTRACE_PATH_MAX);
if(res == -1) {
// error handling?
} else {
frame.object_path = buffer;
}
}
frame.object_path = resolve_l_name(result.dlfo_link_map->l_name);
frame.object_address = address - to_frame_ptr(result.dlfo_link_map->l_addr);
}
return frame;
@ -52,13 +53,18 @@ namespace detail {
// dladdr queries are needed to get pre-ASLR addresses and targets to run addr2line on
inline object_frame get_frame_object_info(frame_ptr address) {
// reference: https://github.com/bminor/glibc/blob/master/debug/backtracesyms.c
// https://github.com/bminor/glibc/blob/91695ee4598b39d181ab8df579b888a8863c4cab/elf/dl-addr.c#L26
Dl_info info;
link_map* link_map_info;
object_frame frame;
frame.raw_address = address;
frame.object_address = 0;
if(dladdr(reinterpret_cast<void*>(address), &info)) { // thread safe
frame.object_path = info.dli_fname;
auto base = get_module_image_base(info.dli_fname);
if(
// thread safe
dladdr1(reinterpret_cast<void*>(address), &info, reinterpret_cast<void**>(&link_map_info), RTLD_DL_LINKMAP)
) {
frame.object_path = resolve_l_name(link_map_info->l_name);
auto base = get_module_image_base(frame.object_path);
if(base.has_value()) {
frame.object_address = address
- reinterpret_cast<std::uintptr_t>(info.dli_fbase)