diff --git a/src/abg-elf-reader.cc b/src/abg-elf-reader.cc index a7ba4a87..bf590f8f 100644 --- a/src/abg-elf-reader.cc +++ b/src/abg-elf-reader.cc @@ -100,151 +100,6 @@ find_alt_dwarf_debug_info_link(Dwfl_Module *elf_module, return false; } -/// Find alternate debuginfo file of a given "link" under a set of -/// root directories. -/// -/// The link is a string that is read by the function -/// find_alt_dwarf_debug_info_link(). That link is a path that is relative -/// to a given debug info file, e.g, "../../../.dwz/something.debug". -/// It designates the alternate debug info file associated to a given -/// debug info file. -/// -/// This function will thus try to find the .dwz/something.debug file -/// under some given root directories. -/// -/// @param root_dirs the set of root directories to look from. -/// -/// @param alt_file_name a relative path to the alternate debug info -/// file to look for. -/// -/// @param alt_file_path the resulting absolute path to the alternate -/// debuginfo path denoted by @p alt_file_name and found under one of -/// the directories in @p root_dirs. This is set iff the function -/// returns true. -/// -/// @return true iff the function found the alternate debuginfo file. -static bool -find_alt_dwarf_debug_info_path(const vector root_dirs, - const string &alt_file_name, - string &alt_file_path) -{ - if (alt_file_name.empty()) - return false; - - string altfile_name = tools_utils::trim_leading_string(alt_file_name, "../"); - // In case the alt dwarf debug info file is to be found under - // "/usr/lib/debug", look for it under the provided root directories - // instead. - altfile_name = tools_utils::trim_leading_string(altfile_name, - "/usr/lib/debug/"); - - for (vector::const_iterator i = root_dirs.begin(); - i != root_dirs.end(); - ++i) - if (tools_utils::find_file_under_dir(**i, altfile_name, alt_file_path)) - return true; - - return false; -} - -/// Return the alternate debug info associated to a given main debug -/// info file. -/// -/// @param elf_module the elf module to consider. -/// -/// @param debug_root_dirs a set of root debuginfo directories under -/// which too look for the alternate debuginfo file. -/// -/// @param alt_file_name output parameter. This is set to the file -/// path of the alternate debug info file associated to @p elf_module. -/// This is set iff the function returns a non-null result. -/// -/// @param alt_fd the file descriptor used to access the alternate -/// debug info. If this parameter is set by the function, then the -/// caller needs to fclose it, otherwise the file descriptor is going -/// to be leaked. Note however that on recent versions of elfutils -/// where libdw.h contains the function dwarf_getalt(), this parameter -/// is set to 0, so it doesn't need to be fclosed. -/// -/// Note that the alternate debug info file is a DWARF extension as of -/// DWARF 4 ans is decribed at -/// http://www.dwarfstd.org/ShowIssue.php?issue=120604.1. -/// -/// @return the alternate debuginfo, or null. If @p alt_fd is -/// non-zero, then the caller of this function needs to call -/// dwarf_end() on the returned alternate debuginfo pointer, -/// otherwise, it's going to be leaked. -static Dwarf* -find_alt_dwarf_debug_info(Dwfl_Module *elf_module, - const vector debug_root_dirs, - string& alt_file_name, - int& alt_fd) -{ - if (elf_module == 0) - return 0; - - Dwarf* result = 0; - find_alt_dwarf_debug_info_link(elf_module, alt_file_name); - -#ifdef LIBDW_HAS_DWARF_GETALT - // We are on recent versions of elfutils where the function - // dwarf_getalt exists, so let's use it. - Dwarf_Addr bias = 0; - Dwarf* dwarf = dwfl_module_getdwarf(elf_module, &bias); - result = dwarf_getalt(dwarf); - alt_fd = 0; -#else - // We are on an old version of elfutils where the function - // dwarf_getalt doesn't exist yet, so let's open code its - // functionality - char *alt_name = 0; - const char *file_name = 0; - void **user_data = 0; - Dwarf_Addr low_addr = 0; - char *alt_file = 0; - - file_name = dwfl_module_info(elf_module, &user_data, - &low_addr, 0, 0, 0, 0, 0); - - alt_fd = dwfl_standard_find_debuginfo(elf_module, user_data, - file_name, low_addr, - alt_name, file_name, - 0, &alt_file); - - result = dwarf_begin(alt_fd, DWARF_C_READ); -#endif - - if (result == 0) - { - // So we didn't find the alternate debuginfo file from the - // information that is in the debuginfo file associated to - // elf_module. Maybe the alternate debuginfo file is located - // under one of the directories in debug_root_dirs. So let's - // look in there. - string alt_file_path; - if (!find_alt_dwarf_debug_info_path(debug_root_dirs, - alt_file_name, - alt_file_path)) - return result; - - // If we reach this point it means we have found the path to the - // alternate debuginfo file and it's in alt_file_path. So let's - // open it and read it. - alt_fd = open(alt_file_path.c_str(), O_RDONLY); - if (alt_fd == -1) - return result; - result = dwarf_begin(alt_fd, DWARF_C_READ); - -#ifdef LIBDW_HAS_DWARF_GETALT - Dwarf_Addr bias = 0; - Dwarf* dwarf = dwfl_module_getdwarf(elf_module, &bias); - dwarf_setalt(dwarf, result); -#endif - } - - return result; -} - /// Private data of the @ref elf::reader type. struct reader::priv { @@ -258,6 +113,14 @@ struct reader::priv mutable symtab_reader::symtab_sptr symt; // Where split debug info is to be searched for on disk. vector debug_info_root_paths; + // The formatted string version of debug_info_root_paths. The + // format is according to what elfutils expects. For the details of + // what elfutils expects, please read the comments of the function + // dwfl_build_id_find_elf in /usr/include/elfutils/libdwfl.h. + string formated_di_root_paths; + // A pointer to where the string held by formated_di_root_paths is. + // This is fed to elfutils. + char* raw_formated_di_root_paths = nullptr; // Some very useful callback functions that elfutils needs to // perform various tasks. Dwfl_Callbacks offline_callbacks; @@ -311,6 +174,8 @@ struct reader::priv dt_needed.clear(); symt.reset(); debug_info_root_paths = debug_info_roots; + formated_di_root_paths.clear(); + raw_formated_di_root_paths = nullptr; memset(&offline_callbacks, 0, sizeof(offline_callbacks)); dwfl_handle.reset(); elf_module = nullptr; @@ -324,6 +189,31 @@ struct reader::priv alt_ctf_fd = 0; } + /// Initialize the debug info root path. The format of this path is + /// described in /usr/include/elfutils/libdwfl.h in the comment for + /// the function dwfl_build_id_find_elf. + /// + /// The string must start with '-' to disable CRC32 checksum + /// validation. Directories must be separated by the ':' character. + /// The search order depends on if each path is absolute or relative + /// as described by that comment. + /// + /// In any case, let's format the debuginfo search path here for + /// elfutils consumption. + void + initialize_debug_info_root_paths() + { + for (auto path : debug_info_root_paths) + { + if (formated_di_root_paths.empty()) + formated_di_root_paths = "-"; + if (*path) + formated_di_root_paths += string(*path) + string (":"); + } + raw_formated_di_root_paths = + const_cast(formated_di_root_paths.c_str()); + } + /// Setup the necessary plumbing to open the ELF file and find all /// the associated split debug info files. /// @@ -333,10 +223,11 @@ struct reader::priv crack_open_elf_file() { // Initialize the callback functions used by elfutils. + initialize_debug_info_root_paths(); elf_helpers::initialize_dwfl_callbacks(offline_callbacks, - debug_info_root_paths.empty() + formated_di_root_paths.empty() ? nullptr - : debug_info_root_paths.front()); + : &raw_formated_di_root_paths); // Create a handle to the DWARF Front End Library that we'll need. dwfl_handle = elf_helpers::create_new_dwfl_handle(offline_callbacks); @@ -358,25 +249,6 @@ struct reader::priv ABG_ASSERT(elf_handle); } - /// Find the alternate debuginfo file associated to a given elf file. - /// - /// @param elf_module represents the elf file to consider. - /// - /// @param alt_file_name the resulting path to the alternate - /// debuginfo file found. This is set iff the function returns a - /// non-nil value. - Dwarf* - find_alt_dwarf_debug_info(Dwfl_Module* elf_module, - string& alt_file_name, - int& alt_fd) - { - Dwarf *result = 0; - result = elf::find_alt_dwarf_debug_info(elf_module, - debug_info_root_paths, - alt_file_name, alt_fd); - return result; - } - /// Clear the resources related to the alternate DWARF data. void clear_alt_dwarf_debug_info_data() @@ -405,24 +277,10 @@ struct reader::priv if (dwarf_handle) return; - // First let's see if the ELF file that was cracked open does have - // some DWARF debug info embedded. Dwarf_Addr bias = 0; dwarf_handle = dwfl_module_getdwarf(elf_module, &bias); - - // If no debug info was found in the binary itself, then look for - // split debuginfo files under multiple possible debuginfo roots. - for (vector::const_iterator i = debug_info_root_paths.begin(); - dwarf_handle == 0 && i != debug_info_root_paths.end(); - ++i) - { - offline_callbacks.debuginfo_path = *i; - dwarf_handle = dwfl_module_getdwarf(elf_module, &bias); - } - - alt_dwarf_handle = find_alt_dwarf_debug_info(elf_module, - alt_dwarf_path, - alt_dwarf_fd); + alt_dwarf_handle = dwarf_getalt(dwarf_handle); + find_alt_dwarf_debug_info_link(elf_module, alt_dwarf_path); } /// Clear the resources related to the alternate CTF data.