/**
* =========================================================================
* File : debug.h
* Project : 0 A.D.
* Description : platform-independent debug support code.
* =========================================================================
*/
// license: GPL; see lib/license.txt
#ifndef INCLUDED_DEBUG
#define INCLUDED_DEBUG
#if OS_WIN
#include "lib/sysdep/win/wdbg.h"
#else
#include "lib/sysdep/unix/udbg.h"
#endif
/**
overview
--------
this module provides platform-independent debug facilities, useful for
diagnosing and reporting program errors.
- a symbol engine provides access to compiler-generated debug information and
can also give a stack trace including local variables;
- the breakpoint API enables stopping when a given address is
executed, read or written to (as specified);
- a hook into the system's memory allocator can optionally check for and
report heap corruption;
- our more powerful assert() replacement gives a stack trace so
that the underlying problem becomes apparent;
- the output routines make for platform-independent logging and
crashlogs with "last-known activity" reporting.
usage
-----
please see the detailed comments below on how to use the individual features.
much of this is only helpful if you explicity ask for it!
rationale
---------
much of this functionality already exists within the VC7 IDE/debugger.
motivation for this code is as follows:
- we want a consistent interface for all platforms;
- limitations(*) in the VC variants should be fixed;
- make debugging as easy as possible.
* mostly pertaining to Release mode - e.g. symbols cannot be resolved
even if debug information is present and assert dialogs are useless.
**/
//-----------------------------------------------------------------------------
// debug memory allocator
//-----------------------------------------------------------------------------
/**
* check heap integrity (independently of mmgr).
* errors are reported by the CRT or via debug_display_error.
**/
extern void debug_heap_check(void);
enum DebugHeapChecks
{
/**
* no automatic checks. (default)
**/
DEBUG_HEAP_NONE = 0,
/**
* basic automatic checks when deallocating.
**/
DEBUG_HEAP_NORMAL = 1,
/**
* all automatic checks on every memory API call. this is really
* slow (x100), but reports errors closer to where they occurred.
**/
DEBUG_HEAP_ALL = 2
};
/**
* call at any time; from then on, the specified checks will be performed.
* if not called, the default is DEBUG_HEAP_NONE, i.e. do nothing.
**/
extern void debug_heap_enable(DebugHeapChecks what);
//-----------------------------------------------------------------------------
// output
//-----------------------------------------------------------------------------
enum DebugLevel
{
DEBUG_LEVEL_NONE = 0,
DEBUG_LEVEL_BRIEF = 2,
DEBUG_LEVEL_DETAILED = 5,
DEBUG_LEVEL_FULL = 9,
};
#define DEBUG_PRINTF_BRIEF if(debug_level >= DEBUG_LEVEL_BRIEF) debug_printf
#define DEBUG_PRINTF_DETAILED if(debug_level >= DEBUG_LEVEL_DETAILED) debug_printf
#define DEBUG_PRINTF_FULL if(debug_level >= DEBUG_LEVEL_FULL ) debug_printf
/**
* write a formatted string to the debug channel, subject to filtering
* (see below). implemented via debug_puts - see performance note there.
*
* @param format string and varargs; see printf.
**/
extern void debug_printf(const char* fmt, ...);
/// note: this merely converts to a MBS and calls debug_printf.
extern void debug_wprintf(const wchar_t* fmt, ...);
/**
* translates and displays the given strings in a dialog.
* this is typically only used when debug_display_error has failed or
* is unavailable because that function is much more capable.
* implemented via sys_display_msgw; see documentation there.
**/
extern void debug_display_msgw(const wchar_t* caption, const wchar_t* msg);
/// flags to customize debug_display_error behavior
enum DebugDisplayErrorFlags
{
/**
* disallow the Continue button. used e.g. if an exception is fatal.
**/
DE_NO_CONTINUE = 1,
/**
* enable the Suppress button. set automatically by debug_display_error if
* it receives a non-NULL suppress pointer. a flag is necessary because
* the sys_display_error interface doesn't get that pointer.
* rationale for automatic setting: this may prevent someone from
* forgetting to specify it, and disabling Suppress despite having
* passed a non-NULL pointer doesn't make much sense.
**/
DE_ALLOW_SUPPRESS = 2,
/**
* do not trigger a breakpoint inside debug_display_error; caller
* will take care of this if ER_BREAK is returned. this is so that the
* debugger can jump directly into the offending function.
**/
DE_MANUAL_BREAK = 4
};
/**
* value for suppress flag once set by debug_display_error.
* rationale: this value is fairly distinctive and helps when
* debugging the symbol engine.
* initial value is 0 rather that another constant; this avoids
* allocating .rdata space.
**/
const u8 DEBUG_SUPPRESS = 0xAB;
/**
* choices offered by the shared error dialog
**/
enum ErrorReaction
{
/**
* ignore, continue as if nothing happened.
* note: value doesn't start at 0 because that is interpreted as a
* DialogBoxParam failure.
**/
ER_CONTINUE = 1,
/**
* trigger breakpoint, i.e. enter debugger.
* only returned if DE_MANUAL_BREAK was passed; otherwise,
* debug_display_error will trigger a breakpoint itself.
**/
ER_BREAK,
/**
* ignore and do not report again.
* note: non-persistent; only applicable during this program run.
* acted on by debug_display_error; never returned to caller.
**/
ER_SUPPRESS,
/**
* exit the program immediately.
* acted on by debug_display_error; never returned to caller.
**/
ER_EXIT,
/**
* special return value for the display_error app hook stub to indicate
* that it has done nothing and that the normal sys_display_error
* implementation should be called instead.
* acted on by debug_display_error; never returned to caller.
**/
ER_NOT_IMPLEMENTED
};
/**
* display an error dialog with a message and stack trace.
*
* @param description text to show.
* @param flags: see DebugDisplayErrorFlags.
* @param context, skip: see debug_dump_stack.
* @param file, line, func: location of the error (typically passed as
* __FILE__, __LINE__, __func__ from a macro)
* @param suppress pointer to a caller-allocated flag that can be used to
* suppress this error. if NULL, this functionality is skipped and the
* "Suppress" dialog button will be disabled.
* note: this flag is read and written exclusively here; caller only
* provides the storage. values: see DEBUG_SUPPRESS above.
* @return ErrorReaction (user's choice: continue running or stop?)
**/
extern ErrorReaction debug_display_error(const wchar_t* description,
uint flags, uint skip, void* context,
const char* file, int line, const char* func,
u8* suppress);
/**
* convenience version, in case the advanced parameters aren't needed.
* macro instead of providing overload/default values for C compatibility.
**/
#define DISPLAY_ERROR(text) debug_display_error(text, 0, 0,0, __FILE__,__LINE__,__func__, 0)
//
// filtering
//
/**
* debug output is very useful, but "too much of a good thing can kill you".
* we don't want to require different LOGn() macros that are enabled
* depending on "debug level", because changing that entails lengthy
* compiles and it's too coarse-grained. instead, we require all
* strings to start with "tag_string|" (exact case and no quotes;
* the alphanumeric-only <tag_string> identifies output type).
* they are then subject to filtering: only if the tag has been
* "added" via debug_filter_add is the appendant string displayed.
*
* this approach is easiest to implement and is fine because we control
* all logging code. LIMODS falls from consideration since it's not
* portable and too complex.
*
* notes:
* - filter changes only affect subsequent debug_*printf calls;
* output that didn't pass the filter is permanently discarded.
* - strings not starting with a tag are always displayed.
* - debug_filter_* can be called at any time and from the debugger.
* in future, allow output with the given tag to proceed.
* no effect if already added.
**/
extern void debug_filter_add(const char* tag);
/**
* in future, discard output with the given tag.
* no effect if not currently added.
**/
extern void debug_filter_remove(const char* tag);
/**
* clear all filter state; equivalent to debug_filter_remove for
* each tag that was debug_filter_add-ed.
**/
extern void debug_filter_clear();
/**
* indicate if the given text would be printed.
* useful for a series of debug_printfs - avoids needing to add a tag to
* each of their format strings.
**/
extern bool debug_filter_allows(const char* text);
/**
* write to memory buffer (fast)
* used for "last activity" reporting in the crashlog.
*
* @param format string and varags; see printf.
**/
extern void debug_wprintf_mem(const wchar_t* fmt, ...);
/**
* write an error description and all logs into crashlog.txt
* (in unicode format).
*
* @param text description of the error (including stack trace);
* typically generated by debug_error_message_build.
*
* @return LibError; ERR::REENTERED if reentered via recursion or
* multithreading (not allowed since an infinite loop may result).
**/
extern LibError debug_write_crashlog(const wchar_t* text);
//-----------------------------------------------------------------------------
// debug_assert
//-----------------------------------------------------------------------------
/**
* make sure the expression <expr> evaluates to non-zero. used to validate
* invariants in the program during development and thus gives a
* very helpful warning if something isn't going as expected.
* sprinkle these liberally throughout your code!
*
* recommended use is debug_assert(expression && "descriptive string") -
* the string can pass more information about the problem on to whomever
* is seeing the error.
*
* rationale: we call this "debug_assert" instead of "assert" for the
* following reasons:
* - consistency (everything here is prefixed with debug_) and
* - to avoid inadvertent use of the much less helpful built-in CRT assert.
* if we were to override assert, it would be difficult to tell whether
* user source has included <assert.h> (possibly indirectly via other
* headers) and thereby stomped on our definition.
**/
#define debug_assert(expr) \
STMT(\
static u8 suppress__;\
if(!(expr))\
{\
switch(debug_assert_failed(#expr, &suppress__, __FILE__, __LINE__, __func__))\
{\
case ER_BREAK:\
debug_break();\
break;\
default:\
break;\
}\
}\
)
/**
* show a dialog to make sure unexpected states in the program are noticed.
* this is less error-prone than "debug_assert(0 && "text");" and avoids
* "conditional expression is constant" warnings. we'd really like to
* completely eliminate the problem; replacing 0 literals with extern
* volatile variables fools VC7 but isn't guaranteed to be free of overhead.
* we therefore just squelch the warning (unfortunately non-portable).
* this duplicates the code from debug_assert to avoid compiler warnings about
* constant conditions.
**/
#define debug_warn(expr) \
STMT(\
static u8 suppress__;\
switch(debug_assert_failed(expr, &suppress__, __FILE__, __LINE__, __func__))\
{\
case ER_BREAK:\
debug_break();\
break;\
default:\
break;\
}\
)
/**
* if (LibError)err indicates an function failed, display the error dialog.
* used by CHECK_ERR et al., which wrap function calls and automatically
* warn user and return to caller.
**/
#define DEBUG_WARN_ERR(err)\
STMT(\
static u8 suppress__;\
switch(debug_warn_err(err, &suppress__, __FILE__, __LINE__, __func__))\
{\
case ER_BREAK:\
debug_break();\
break;\
default:\
break;\
}\
)
/**
* called when a debug_assert fails;
* notifies the user via debug_display_error.
*
* @param assert_expr the expression that failed; typically passed as
* #expr in the assert macro.
* @param suppress see debug_display_error.
* @param file, line source file name and line number of the spot that failed
* @param func name of the function containing it
* @return ErrorReaction (user's choice: continue running or stop?)
**/
extern ErrorReaction debug_assert_failed(const char* assert_expr,
u8* suppress,
const char* file, int line, const char* func);
/**
* called when a DEBUG_WARN_ERR indicates an error occurred;
* notifies the user via debug_display_error.
*
* @param err LibError value indicating the error that occurred
* @param suppress see debug_display_error.
* @param file, line source file name and line number of the spot that failed
* @param func name of the function containing it
* @return ErrorReaction (user's choice: continue running or stop?)
**/
extern ErrorReaction debug_warn_err(LibError err,
u8* suppress,
const char* file, int line, const char* func);
/**
* suppress (prevent from showing) the next error dialog for a
* specific LibError.
*
* rationale: for edge cases in some functions, warnings are raised in
* addition to returning an error code. self-tests deliberately trigger
* these cases and check for the latter but shouldn't cause the former.
* we therefore need to squelch them.
*
* @param err the LibError to skip. if the next error to be raised matches
* this, it is skipped. otherwise, we raise a warning to help catch
* erroneous usage. either way, the skip request is reset afterwards.
*
* note: this is thread-safe, but to prevent confusion, only one
* concurrent skip request is allowed.
*/
extern void debug_skip_next_err(LibError err);
/**
* same as debug_skip_next_err, but for asserts.
* note that this is implemented in terms of it, so only one assert or
* error skip request may be active at a time.
*/
extern void debug_skip_assert();
//-----------------------------------------------------------------------------
// breakpoints
//-----------------------------------------------------------------------------
/**
* trigger a breakpoint when reached/"called".
* defined as a macro by the platform-specific header above; this allows
* breaking directly into the target function, instead of one frame
* below it as with a conventional call-based implementation.
**/
//#define debug_break() // not defined here; see above
/**
* sometimes mmgr's 'fences' (making sure padding before and after the
* allocation remains intact) aren't enough to catch hard-to-find
* memory corruption bugs. another tool is to trigger a debug exception
* when the later to be corrupted variable is accessed; the problem should
* then become apparent.
* the VC++ IDE provides such 'breakpoints', but can only detect write access.
* additionally, it can't resolve symbols in Release mode (where this would
* be most useful), so we provide a breakpoint API.
* (values chosen to match IA-32 bit defs, so compiler can optimize.
* this isn't required; it'll work regardless.)
**/
enum DbgBreakType
{
DBG_BREAK_CODE = 0, /// execute
DBG_BREAK_DATA_WRITE = 1, /// write
DBG_BREAK_DATA = 3 /// read or write
};
/**
* arrange for a debug exception to be raised when the
* indicated memory is accessed.
*
* @param addr memory address
* for simplicity, the length (range of bytes to be checked) is derived
* from addr's alignment, and is typically 1 machine word.
* @param type the type of access to watch for (see DbgBreakType)
* @return LibError; ERR::LIMIT if no more breakpoints are available
* (they are a limited resource - only 4 on IA-32).
**/
extern LibError debug_set_break(void* addr, DbgBreakType type);
/**
* remove all breakpoints that were set by debug_set_break.
* important, since these are a limited resource.
**/
extern LibError debug_remove_all_breaks();
//-----------------------------------------------------------------------------
// symbol access
//-----------------------------------------------------------------------------
namespace ERR
{
const LibError SYM_NO_STACK_FRAMES_FOUND = -100400;
const LibError SYM_UNRETRIEVABLE_STATIC = -100401;
const LibError SYM_UNRETRIEVABLE_REG = -100402;
const LibError SYM_TYPE_INFO_UNAVAILABLE = -100403;
const LibError SYM_INTERNAL_ERROR = -100404;
const LibError SYM_UNSUPPORTED = -100405;
const LibError SYM_CHILD_NOT_FOUND = -100406;
// this limit is to prevent infinite recursion.
const LibError SYM_NESTING_LIMIT = -100407;
// this limit is to prevent large symbols (e.g. arrays or linked lists)
// from taking up all available output space.
const LibError SYM_SINGLE_SYMBOL_LIMIT = -100408;
}
namespace INFO
{
// one of the dump_sym* functions decided not to output anything at
// all (e.g. for member functions in UDTs - we don't want those).
// therefore, skip any post-symbol formatting (e.g. ) as well.
const LibError SYM_SUPPRESS_OUTPUT = +100809;
}
/**
* maximum number of characters (including trailing \0) written to
* user's buffers by debug_resolve_symbol.
**/
const size_t DBG_SYMBOL_LEN = 1000;
const size_t DBG_FILE_LEN = 100;
/**
* read and return symbol information for the given address.
*
* NOTE: the PDB implementation is rather slow (~500us).
*
* @param ptr_of_interest address of symbol (e.g. function, variable)
* @param sym_name optional out; size >= DBG_SYMBOL_LEN chars;
* receives symbol name returned via debug info.
* @param file optional out; size >= DBG_FILE_LEN chars; receives
* base name only (no path; see rationale in wdbg_sym) of
* source file containing the symbol.
* @param line optional out; receives source file line number of symbol.
*
* note: all of the output parameters are optional; we pass back as much
* information as is available and desired.
* @return LibError; INFO::OK iff any information was successfully
* retrieved and stored.
**/
extern LibError debug_resolve_symbol(void* ptr_of_interest, char* sym_name, char* file, int* line);
/**
* write a complete stack trace (including values of local variables) into
* the specified buffer.
*
* @param buf target buffer
* @param max_chars of buffer (should be several thousand)
* @param skip number of stack frames (i.e. functions on call stack) to skip.
* this prevents error-reporting functions like debug_assert_failed from
* cluttering up the trace.
* @param context platform-specific representation of execution state
* (e.g. Win32 CONTEXT). if not NULL, tracing starts there; this is useful
* for exceptions. otherwise, tracing starts from the current call stack.
* @return LibError; ERR::REENTERED if reentered via recursion or
* multithreading (not allowed since static data is used).
**/
extern LibError debug_dump_stack(wchar_t* buf, size_t max_chars, uint skip, void* context);
extern const char* debug_get_symbol_string(void* symbol, const char* name, const char* file, int line);
//-----------------------------------------------------------------------------
// helper functions (used by implementation)
//-----------------------------------------------------------------------------
/**
* [system-dependent] write a string to the debug channel.
* this can be quite slow (~1 ms)! On Windows, it uses OutputDebugString
* (entails context switch), otherwise stdout+fflush (waits for IO).
**/
extern void debug_puts(const char* text);
/**
* return address of the Nth function on the call stack.
*
* used by mmgr to determine what function requested each allocation;
* this is fast enough to allow that.
*
* @param skip number of stack frames (i.e. functions on call stack) to skip.
* @param context platform-specific representation of execution state
* (e.g. Win32 CONTEXT). if not NULL, tracing starts there; this is useful
* for exceptions. otherwise, tracing starts from the current call stack.
* @return address of Nth function
**/
extern void* debug_get_nth_caller(uint skip, void* context);
/**
* check if a pointer appears to be totally invalid.
*
* this check is not authoritative (the pointer may be "valid" but incorrect)
* but can be used to filter out obviously wrong values in a portable manner.
*
* @param p pointer
* @return 1 if totally bogus, otherwise 0.
**/
extern int debug_is_pointer_bogus(const void* p);
/// does the given pointer appear to point to code?
extern bool debug_is_code_ptr(void* p);
/// does the given pointer appear to point to the stack?
extern bool debug_is_stack_ptr(void* p);
/**
* set the current thread's name; it will be returned by subsequent calls to
* debug_get_thread_name.
*
* if supported on this platform, the debugger is notified of the new name;
* it will be displayed there instead of just the handle.
*
* @param name identifier string for thread. MUST remain valid throughout
* the entire program; best to pass a string literal. allocating a copy
* would be quite a bit more work due to cleanup issues.
**/
extern void debug_set_thread_name(const char* name);
/**
* return current thread's name.
*
* @return thread name, or NULL if one hasn't been assigned yet
* via debug_set_thread_name.
**/
extern const char* debug_get_thread_name();
/**
* holds memory for an error message.
**/
struct ErrorMessageMem
{
// rationale:
// - error messages with stack traces require a good deal of memory
// (dozens of KB). static buffers of that size are undesirable.
// - the heap may be corrupted, so don't use malloc. allocator.h's
// page_aligned_malloc (implemented via mmap) should be safe.
// - alloca is a bit iffy (the stack may be maxed out), non-portable and
// complicates the code because it can't be allocated by a subroutine.
// - this method is probably slow, but error messages aren't built often.
// if necessary, first try malloc and use mmap if that fails.
void* pa_mem;
};
/**
* free memory from the error message.
*
* @param ErrorMessageMem*
**/
extern void debug_error_message_free(ErrorMessageMem* emm);
/**
* build a string describing the given error.
*
* this is a helper function used by debug_dump_stack and is made available
* so that the self-test doesn't have to display the error dialog.
*
* @param description: general description of the problem.
* @param fn_only filename (no path) of source file that triggered the error.
* @param line, func: exact position of the error.
* @param skip, context: see debug_dump_stack.
* @param emm memory for the error message. caller should allocate
* stack memory and set alloc_buf*; if not, there will be no
* fallback in case heap alloc fails. should be freed via
* debug_error_message_free when no longer needed.
**/
extern const wchar_t* debug_error_message_build(
const wchar_t* description,
const char* fn_only, int line, const char* func,
uint skip, void* context,
ErrorMessageMem* emm);
/**
* call at exit to avoid some leaks.
* not strictly necessary.
**/
extern void debug_shutdown();
#endif // #ifndef INCLUDED_DEBUG