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// Copyright (c) 2010 Google Inc. 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// 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.
// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
// This file implements the google_breakpad::StabsReader class.
// See stabs_reader.h.
#include <a.out.h>
#include <stab.h>
#include <cstring>
#include <cassert>
#include "common/linux/stabs_reader.h"
namespace google_breakpad {
StabsReader::StabsReader(const uint8_t *stab, size_t stab_size,
const uint8_t *stabstr, size_t stabstr_size,
StabsHandler *handler) :
stabstr_(stabstr),
stabstr_size_(stabstr_size),
handler_(handler),
string_offset_(0),
next_cu_string_offset_(0),
symbol_(NULL),
current_source_file_(NULL) {
symbols_ = reinterpret_cast<const struct nlist *>(stab);
symbols_end_ = symbols_ + (stab_size / sizeof (*symbols_));
}
const char *StabsReader::SymbolString() {
ptrdiff_t offset = string_offset_ + symbol_->n_un.n_strx;
if (offset < 0 || (size_t) offset >= stabstr_size_) {
handler_->Warning("symbol %d: name offset outside the string section\n",
symbol_ - symbols_);
// Return our null string, to keep our promise about all names being
// taken from the string section.
offset = 0;
}
return reinterpret_cast<const char *>(stabstr_ + offset);
}
bool StabsReader::Process() {
symbol_ = symbols_;
while (symbol_ < symbols_end_) {
if (symbol_->n_type == N_SO) {
if (! ProcessCompilationUnit())
return false;
} else if (symbol_->n_type == N_UNDF) {
// At the head of each compilation unit's entries there is an
// N_UNDF stab giving the number of symbols in the compilation
// unit, and the number of bytes that compilation unit's strings
// take up in the .stabstr section. Each CU's strings are
// separate; the n_strx values are offsets within the current
// CU's portion of the .stabstr section.
//
// As an optimization, the GNU linker combines all the
// compilation units into one, with a single N_UNDF at the
// beginning. However, other linkers, like Gold, do not perform
// this optimization.
string_offset_ = next_cu_string_offset_;
next_cu_string_offset_ = SymbolValue();
symbol_++;
} else
symbol_++;
}
return true;
}
bool StabsReader::ProcessCompilationUnit() {
assert(symbol_ < symbols_end_ && symbol_->n_type == N_SO);
// There may be an N_SO entry whose name ends with a slash,
// indicating the directory in which the compilation occurred.
// The build directory defaults to NULL.
const char *build_directory = NULL;
{
const char *name = SymbolString();
if (name[0] && name[strlen(name) - 1] == '/') {
build_directory = name;
symbol_++;
}
}
// We expect to see an N_SO entry with a filename next, indicating
// the start of the compilation unit.
{
if (symbol_ >= symbols_end_ || symbol_->n_type != N_SO)
return true;
const char *name = SymbolString();
if (name[0] == '\0') {
// This seems to be a stray end-of-compilation-unit marker;
// consume it, but don't report the end, since we didn't see a
// beginning.
symbol_++;
return true;
}
current_source_file_ = name;
}
if (! handler_->StartCompilationUnit(current_source_file_,
SymbolValue(),
build_directory))
return false;
symbol_++;
// The STABS documentation says that some compilers may emit
// additional N_SO entries with names immediately following the
// first, and that they should be ignored. However, the original
// Breakpad STABS reader doesn't ignore them, so we won't either.
// Process the body of the compilation unit, up to the next N_SO.
while (symbol_ < symbols_end_ && symbol_->n_type != N_SO) {
if (symbol_->n_type == N_FUN) {
if (! ProcessFunction())
return false;
} else
// Ignore anything else.
symbol_++;
}
// An N_SO with an empty name indicates the end of the compilation
// unit. Default to zero.
uint64_t ending_address = 0;
if (symbol_ < symbols_end_) {
assert(symbol_->n_type == N_SO);
const char *name = SymbolString();
if (name[0] == '\0') {
ending_address = SymbolValue();
symbol_++;
}
}
if (! handler_->EndCompilationUnit(ending_address))
return false;
return true;
}
bool StabsReader::ProcessFunction() {
assert(symbol_ < symbols_end_ && symbol_->n_type == N_FUN);
uint64_t function_address = SymbolValue();
// The STABS string for an N_FUN entry is the name of the function,
// followed by a colon, followed by type information for the
// function. We want to pass the name alone to StartFunction.
const char *stab_string = SymbolString();
const char *name_end = strchr(stab_string, ':');
if (! name_end)
name_end = stab_string + strlen(stab_string);
std::string name(stab_string, name_end - stab_string);
if (! handler_->StartFunction(name, function_address))
return false;
symbol_++;
while (symbol_ < symbols_end_) {
if (symbol_->n_type == N_SO || symbol_->n_type == N_FUN)
break;
else if (symbol_->n_type == N_SLINE) {
// The value of an N_SLINE entry is the offset of the line from
// the function's start address.
uint64_t line_address = function_address + SymbolValue();
// The n_desc of a N_SLINE entry is the line number. It's a
// signed 16-bit field; line numbers from 32768 to 65535 are
// stored as n-65536.
uint16_t line_number = symbol_->n_desc;
if (! handler_->Line(line_address, current_source_file_, line_number))
return false;
symbol_++;
} else if (symbol_->n_type == N_SOL) {
current_source_file_ = SymbolString();
symbol_++;
} else
// Ignore anything else.
symbol_++;
}
// If there is a subsequent N_SO or N_FUN entry, its address is our
// end address.
uint64_t ending_address = 0;
if (symbol_ < symbols_end_) {
assert(symbol_->n_type == N_SO || symbol_->n_type == N_FUN);
ending_address = SymbolValue();
// Note: we do not increment symbol_ here, since we haven't consumed it.
}
if (! handler_->EndFunction(ending_address))
return false;
return true;
}
} // namespace google_breakpad
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