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// GNU D Compiler routines for stack backtrace support.
// Copyright (C) 2013-2023 Free Software Foundation, Inc.
// GCC is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3, or (at your option) any later
// version.
// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
// for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
module gcc.backtrace;
import gcc.libbacktrace;
// Max size per line of the traceback.
private enum MAX_BUFSIZE = 1536;
static if (BACKTRACE_SUPPORTED && !BACKTRACE_USES_MALLOC)
{
import core.stdc.stdint, core.stdc.string, core.stdc.stdio;
private enum MAXFRAMES = 128;
extern(C) int simpleCallback(void* data, uintptr_t pc)
{
auto context = cast(LibBacktrace)data;
if (context.numPCs == MAXFRAMES)
return 1;
context.pcs[context.numPCs++] = pc;
return 0;
}
/*
* Used for backtrace_create_state and backtrace_simple
*/
extern(C) void simpleErrorCallback(void* data, const(char)* msg, int errnum) @nogc
{
if (data) // context is not available in backtrace_create_state
{
auto context = cast(LibBacktrace)data;
strncpy(context.errorBuf.ptr, msg, context.errorBuf.length - 1);
context.error = errnum;
}
}
/*
* Used for backtrace_pcinfo
*/
extern(C) int pcinfoCallback(void* data, uintptr_t pc, const(char)* filename,
int lineno, const(char)* func)
{
auto context = cast(SymbolCallbackInfo*)data;
// Try to get the function name via backtrace_syminfo
if (func is null)
{
SymbolCallbackInfo2 info;
info.base = context;
info.filename = filename;
info.lineno = lineno;
if (backtrace_syminfo(context.state, pc, &syminfoCallback2, null, &info) != 0)
{
return context.retval;
}
}
auto sym = SymbolOrError(0, SymbolInfo(func, filename, lineno, cast(void*)pc));
context.retval = context.applyCB(context.num, sym);
context.num++;
return context.retval;
}
/*
* Used for backtrace_pcinfo and backtrace_syminfo
*/
extern(C) void pcinfoErrorCallback(void* data, const(char)* msg, int errnum)
{
auto context = cast(SymbolCallbackInfo*)data;
if (errnum == -1)
{
context.noInfo = true;
return;
}
SymbolOrError symError;
symError.errnum = errnum;
symError.msg = msg;
size_t i = 0;
context.retval = context.applyCB(i, symError);
}
/*
* Used for backtrace_syminfo (in opApply)
*/
extern(C) void syminfoCallback(void* data, uintptr_t pc,
const(char)* symname, uintptr_t symval)
{
auto context = cast(SymbolCallbackInfo*)data;
auto sym = SymbolOrError(0, SymbolInfo(symname, null, 0, cast(void*)pc));
context.retval = context.applyCB(context.num, sym);
context.num++;
}
/*
* This callback is used if backtrace_syminfo is called from the pcinfoCallback
* callback. It merges it's information with the information from pcinfoCallback.
*/
extern(C) void syminfoCallback2(void* data, uintptr_t pc,
const(char)* symname, uintptr_t symval)
{
auto context = cast(SymbolCallbackInfo2*)data;
auto sym = SymbolOrError(0, SymbolInfo(symname, context.filename, context.lineno,
cast(void*)pc));
context.base.retval = context.base.applyCB(context.base.num, sym);
context.base.num++;
}
/*
* The callback type used with the opApply overload which returns a SymbolOrError
*/
private alias int delegate(ref size_t, ref SymbolOrError) ApplyCallback;
/*
* Passed to syminfoCallback, pcinfoCallback and pcinfoErrorCallback
*/
struct SymbolCallbackInfo
{
bool noInfo = false; // True if debug info / symbol table is not available
size_t num = 0; // Counter for opApply
int retval; // Value returned by applyCB
backtrace_state* state;
// info.fileName / funcName / errmsg may become invalid after this delegate returned
ApplyCallback applyCB;
void reset()
{
noInfo = false;
num = 0;
}
}
/*
* Passed to the syminfoCallback2 callback. That function merges it's
* funcName with this information and updates base as all other callbacks do.
*/
struct SymbolCallbackInfo2
{
SymbolCallbackInfo* base;
const(char)* filename;
int lineno;
}
/*
* Contains a valid symbol or an error message if errnum is != 0.
*/
struct SymbolOrError
{
int errnum; // == 0: No error
union
{
SymbolInfo symbol;
const(char)* msg;
}
}
// FIXME: state is never freed as libbacktrace doesn't provide a free function...
public class LibBacktrace : Throwable.TraceInfo
{
static void initLibBacktrace() @nogc
{
if (!initialized)
{
state = backtrace_create_state(null, false, &simpleErrorCallback, null);
initialized = true;
}
}
this(int firstFrame) @nogc
{
_firstFrame = firstFrame;
initLibBacktrace();
if (state)
{
backtrace_simple(state, _firstFrame, &simpleCallback,
&simpleErrorCallback, cast(void*)this);
}
}
override int opApply(scope int delegate(ref const(char[])) dg) const
{
return opApply(
(ref size_t, ref const(char[]) buf)
{
return dg(buf);
}
);
}
override int opApply(scope int delegate(ref size_t, ref const(char[])) dg) const
{
return opApply(
(ref size_t i, ref SymbolOrError sym)
{
char[MAX_BUFSIZE] buffer = void;
char[] msg;
if (sym.errnum != 0)
{
auto retval = snprintf(buffer.ptr, buffer.length,
"libbacktrace error: '%s' errno: %d", sym.msg, sym.errnum);
if (retval >= buffer.length)
retval = buffer.length - 1; // Ignore zero terminator
if (retval > 0)
msg = buffer[0 .. retval];
return dg(i, msg);
}
else
{
msg = formatLine(sym.symbol, buffer);
int ret = dg(i, msg);
if (!ret && sym.symbol.funcName && strcmp(sym.symbol.funcName, "_Dmain") == 0)
return 1;
return ret;
}
}
);
}
int opApply(scope ApplyCallback dg) const
{
initLibBacktrace();
// If backtrace_simple produced an error report it and exit
if (!state || error != 0)
{
size_t pos = 0;
SymbolOrError symError;
if (!state)
{
symError.msg = "libbacktrace failed to initialize\0";
symError.errnum = 1;
}
else
{
symError.errnum = error;
symError.msg = errorBuf.ptr;
}
return dg(pos, symError);
}
SymbolCallbackInfo cinfo;
cinfo.applyCB = dg;
cinfo.state = cast(backtrace_state*)state;
// Try using debug info first
foreach (i, pc; pcs[0 .. numPCs])
{
// FIXME: We may violate const guarantees here...
if (backtrace_pcinfo(cast(backtrace_state*)state, pc, &pcinfoCallback,
&pcinfoErrorCallback, &cinfo) != 0)
{
break; // User delegate requested abort or no debug info at all
}
}
// If no error or other error which has already been reported via callback
if (!cinfo.noInfo)
return cinfo.retval;
// Try using symbol table
cinfo.reset();
foreach (pc; pcs[0 .. numPCs])
{
if (backtrace_syminfo(cast(backtrace_state*)state, pc, &syminfoCallback,
&pcinfoErrorCallback, &cinfo) == 0)
{
break;
}
}
if (!cinfo.noInfo)
return cinfo.retval;
// No symbol table
foreach (i, pc; pcs[0 .. numPCs])
{
auto sym = SymbolOrError(0, SymbolInfo(null, null, 0, cast(void*)pc));
if (auto ret = dg(i, sym) != 0)
return ret;
}
return 0;
}
override string toString() const
{
string buf;
foreach (i, const(char[]) line; this)
buf ~= i ? "\n" ~ line : line;
return buf;
}
private:
static backtrace_state* state = null;
static bool initialized = false;
size_t numPCs = 0;
uintptr_t[MAXFRAMES] pcs;
int error = 0;
int _firstFrame = 0;
char[128] errorBuf = "\0";
}
}
else
{
/*
* Our fallback backtrace implementation using libgcc's unwind
* and backtrace support. In theory libbacktrace should be available
* everywhere where this code works. We keep it anyway till libbacktrace
* is well-tested.
*/
public class UnwindBacktrace : Throwable.TraceInfo
{
this(int firstFrame) @nogc
{
_firstFrame = firstFrame;
_callstack = getBacktrace();
_framelist = getBacktraceSymbols(_callstack);
}
override int opApply(scope int delegate(ref const(char[])) dg) const
{
return opApply(
(ref size_t, ref const(char[]) buf)
{
return dg(buf);
}
);
}
override int opApply(scope int delegate(ref size_t, ref const(char[])) dg) const
{
char[MAX_BUFSIZE] buffer = void;
int ret = 0;
for (int i = _firstFrame; i < _framelist.entries; ++i)
{
auto pos = cast(size_t)(i - _firstFrame);
auto msg = formatLine(_framelist.symbols[i], buffer);
ret = dg(pos, msg);
if (ret)
break;
}
return ret;
}
override string toString() const
{
string buf;
foreach (i, line; this)
buf ~= i ? "\n" ~ line : line;
return buf;
}
private:
BTSymbolData _framelist;
UnwindBacktraceData _callstack;
int _firstFrame = 0;
}
// Implementation details
private:
import gcc.unwind;
version (linux)
import core.sys.linux.dlfcn;
else version (OSX)
import core.sys.darwin.dlfcn;
else version (FreeBSD)
import core.sys.freebsd.dlfcn;
else version (NetBSD)
import core.sys.netbsd.dlfcn;
else version (OpenBSD)
import core.sys.openbsd.dlfcn;
else version (Solaris)
import core.sys.solaris.dlfcn;
else version (Posix)
import core.sys.posix.dlfcn;
private enum MAXFRAMES = 128;
struct UnwindBacktraceData
{
void*[MAXFRAMES] callstack;
int numframes = 0;
}
struct BTSymbolData
{
size_t entries;
SymbolInfo[MAXFRAMES] symbols;
}
static extern (C) _Unwind_Reason_Code unwindCB(_Unwind_Context *ctx, void *d)
{
UnwindBacktraceData* bt = cast(UnwindBacktraceData*)d;
if (bt.numframes >= MAXFRAMES)
return _URC_NO_REASON;
bt.callstack[bt.numframes] = cast(void*)_Unwind_GetIP(ctx);
bt.numframes++;
return _URC_NO_REASON;
}
UnwindBacktraceData getBacktrace() @nogc
{
UnwindBacktraceData stackframe;
_Unwind_Backtrace(&unwindCB, &stackframe);
return stackframe;
}
BTSymbolData getBacktraceSymbols(UnwindBacktraceData data) @nogc
{
BTSymbolData symData;
for (auto i = 0; i < data.numframes; i++)
{
static if ( __traits(compiles, Dl_info))
{
Dl_info funcInfo;
if (data.callstack[i] !is null && dladdr(data.callstack[i], &funcInfo) != 0)
{
symData.symbols[symData.entries].funcName = funcInfo.dli_sname;
symData.symbols[symData.entries].address = data.callstack[i];
symData.entries++;
}
else
{
symData.symbols[symData.entries].address = data.callstack[i];
symData.entries++;
}
}
else
{
symData.symbols[symData.entries].address = data.callstack[i];
symData.entries++;
}
}
return symData;
}
}
/*
* Struct representing a symbol (function) in the backtrace
*/
struct SymbolInfo
{
const(char)* funcName, fileName;
size_t line;
const(void)* address;
}
/*
* Format one output line for symbol sym.
* Returns a slice of buffer.
*/
char[] formatLine(const SymbolInfo sym, return ref char[MAX_BUFSIZE] buffer)
{
import core.demangle, core.stdc.config;
import core.stdc.stdio : snprintf, printf;
import core.stdc.string : strlen;
size_t bufferLength = 0;
void appendToBuffer(Args...)(const(char)* format, Args args)
{
const count = snprintf(buffer.ptr + bufferLength,
buffer.length - bufferLength,
format, args);
assert(count >= 0);
bufferLength += count;
if (bufferLength >= buffer.length)
bufferLength = buffer.length - 1;
}
if (sym.fileName is null)
appendToBuffer("??:? ");
else
appendToBuffer("%s:%d ", sym.fileName, sym.line);
if (sym.funcName is null)
appendToBuffer("???");
else
{
char[1024] symbol = void;
auto demangled = demangle(sym.funcName[0 .. strlen(sym.funcName)], symbol);
if (demangled.length > 0)
appendToBuffer("%.*s ", cast(int) demangled.length, demangled.ptr);
}
version (D_LP64)
appendToBuffer("[0x%llx]", cast(size_t)sym.address);
else
appendToBuffer("[0x%x]", cast(size_t)sym.address);
return buffer[0 .. bufferLength];
}
unittest
{
char[MAX_BUFSIZE] sbuf = '\0';
char[] result;
string longString;
for (size_t i = 0; i < 60; i++)
longString ~= "abcdefghij";
longString ~= '\0';
auto symbol = SymbolInfo(null, null, 0, null);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo(longString.ptr, null, 0, null);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo("func", "test.d", 0, null);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo("func", longString.ptr, 0, null);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo(longString.ptr, "test.d", 0, null);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo(longString.ptr, longString.ptr, 0, null);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo("func", "test.d", 1000, null);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo(null, (longString[0..500] ~ '\0').ptr, 100000000, null);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo("func", "test.d", 0, cast(void*)0x100000);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo("func", null, 0, cast(void*)0x100000);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo(null, "test.d", 0, cast(void*)0x100000);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
symbol = SymbolInfo(longString.ptr, "test.d", 0, cast(void*)0x100000);
result = formatLine(symbol, sbuf);
assert(result.length < MAX_BUFSIZE && result.ptr[result.length] == '\0' && sbuf[$-1] == '\0');
}