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W32: Remove allocations from the crash handler

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Use OutputDebugStringA() instead of fprintf.

The goal for this code is to inform the person running the debugger
about the exception that caused the debugger to be attached.
This is useful for debugging with gdb, because gdb does not catch Windows
exception information (it just displays "Segmentation fault").

OutputDebugStringA() ensures that the output goes to the debugger,
and the (ab)use of strcpy() with a stack-allocated buffer ensures
that we do not allocate anything while the crash handler is running,
nor to we call CRT functions that can be reasinably expected to allocate
anything.
This commit is contained in:
Руслан Ижбулатов 2021-04-06 11:03:45 +00:00
parent 891e3a0bba
commit 6d9c3e3226
1 changed files with 84 additions and 38 deletions
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122
glib/gwin32.c
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@ -1049,6 +1049,24 @@ static DWORD debugger_spawn_flags = 0;
#include "gwin32-private.c"
static char *
copy_chars (char *buffer,
gsize *buffer_size,
const char *to_copy)
{
gsize copy_count = strlen (to_copy);
if (copy_count <= *buffer_size)
memset (buffer, 0x20, copy_count);
else
memset (buffer, 0x20, *buffer_size);
strncpy_s (buffer, *buffer_size, to_copy, copy_count);
if (*buffer_size >= copy_count)
*buffer_size -= copy_count;
else
*buffer_size = 0;
return &buffer[copy_count];
}
/* Handles exceptions (useful for debugging).
* Issues a DebugBreak() call if the process is being debugged (not really
* useful - if the process is being debugged, this handler won't be invoked
@ -1092,10 +1110,17 @@ g_win32_veh_handler (PEXCEPTION_POINTERS ExceptionInfo)
gsize i;
STARTUPINFOA si;
PROCESS_INFORMATION pi;
#define ITOA_BUFFER_SIZE 100
char itoa_buffer[ITOA_BUFFER_SIZE];
#define DEBUG_STRING_SIZE 1024
gsize dbgs = DEBUG_STRING_SIZE;
char debug_string[DEBUG_STRING_SIZE];
char *dbgp;
if (ExceptionInfo == NULL ||
ExceptionInfo->ExceptionRecord == NULL ||
IsDebuggerPresent ())
IsDebuggerPresent () ||
debugger[0] == 0)
return EXCEPTION_CONTINUE_SEARCH;
er = ExceptionInfo->ExceptionRecord;
@ -1117,43 +1142,6 @@ g_win32_veh_handler (PEXCEPTION_POINTERS ExceptionInfo)
break;
}
fprintf_s (stderr,
"Exception code=0x%lx flags=0x%lx at 0x%p",
er->ExceptionCode,
er->ExceptionFlags,
er->ExceptionAddress);
switch (er->ExceptionCode)
{
case EXCEPTION_ACCESS_VIOLATION:
fprintf_s (stderr,
". Access violation - attempting to %s at address 0x%p\n",
er->ExceptionInformation[0] == 0 ? "read data" :
er->ExceptionInformation[0] == 1 ? "write data" :
er->ExceptionInformation[0] == 8 ? "execute data" :
"do something bad",
(void *) er->ExceptionInformation[1]);
break;
case EXCEPTION_IN_PAGE_ERROR:
fprintf_s (stderr,
". Page access violation - attempting to %s at address 0x%p with status %Ix\n",
er->ExceptionInformation[0] == 0 ? "read from an inaccessible page" :
er->ExceptionInformation[0] == 1 ? "write to an inaccessible page" :
er->ExceptionInformation[0] == 8 ? "execute data in page" :
"do something bad with a page",
(void *) er->ExceptionInformation[1],
er->ExceptionInformation[2]);
break;
default:
fprintf_s (stderr, "\n");
break;
}
fflush (stderr);
if (debugger[0] == 0)
return EXCEPTION_CONTINUE_SEARCH;
memset (&si, 0, sizeof (si));
memset (&pi, 0, sizeof (pi));
si.cb = sizeof (si);
@ -1170,6 +1158,64 @@ g_win32_veh_handler (PEXCEPTION_POINTERS ExceptionInfo)
* event signalling.
*/
WaitForSingleObject (debugger_wakeup_event, 60000);
dbgp = &debug_string[0];
dbgp = copy_chars (dbgp, &dbgs, "Exception code=0x");
itoa_buffer[0] = 0;
_ui64toa_s (er->ExceptionCode, itoa_buffer, ITOA_BUFFER_SIZE, 16);
dbgp = copy_chars (dbgp, &dbgs, itoa_buffer);
dbgp = copy_chars (dbgp, &dbgs, " flags=0x");
itoa_buffer[0] = 0;
_ui64toa_s (er->ExceptionFlags, itoa_buffer, ITOA_BUFFER_SIZE, 16);
dbgp = copy_chars (dbgp, &dbgs, itoa_buffer);
dbgp = copy_chars (dbgp, &dbgs, " at 0x");
itoa_buffer[0] = 0;
_ui64toa_s ((guintptr) er->ExceptionAddress, itoa_buffer, ITOA_BUFFER_SIZE, 16);
dbgp = copy_chars (dbgp, &dbgs, itoa_buffer);
switch (er->ExceptionCode)
{
case EXCEPTION_ACCESS_VIOLATION:
dbgp = copy_chars (dbgp, &dbgs, ". Access violation - attempting to ");
if (er->ExceptionInformation[0] == 0)
dbgp = copy_chars (dbgp, &dbgs, "read data");
else if (er->ExceptionInformation[0] == 1)
dbgp = copy_chars (dbgp, &dbgs, "write data");
else if (er->ExceptionInformation[0] == 8)
dbgp = copy_chars (dbgp, &dbgs, "execute data");
else
dbgp = copy_chars (dbgp, &dbgs, "do something bad");
dbgp = copy_chars (dbgp, &dbgs, " at address 0x");
itoa_buffer[0] = 0;
_ui64toa_s (er->ExceptionInformation[1], itoa_buffer, ITOA_BUFFER_SIZE, 16);
dbgp = copy_chars (dbgp, &dbgs, itoa_buffer);
break;
case EXCEPTION_IN_PAGE_ERROR:
dbgp = copy_chars (dbgp, &dbgs, ". Page access violation - attempting to ");
if (er->ExceptionInformation[0] == 0)
dbgp = copy_chars (dbgp, &dbgs, "read from an inaccessible page");
else if (er->ExceptionInformation[0] == 1)
dbgp = copy_chars (dbgp, &dbgs, "write to an inaccessible page");
else if (er->ExceptionInformation[0] == 8)
dbgp = copy_chars (dbgp, &dbgs, "execute data in page");
else
dbgp = copy_chars (dbgp, &dbgs, "do something bad with a page");
dbgp = copy_chars (dbgp, &dbgs, " at address 0x");
itoa_buffer[0] = 0;
_ui64toa_s (er->ExceptionInformation[1], itoa_buffer, ITOA_BUFFER_SIZE, 16);
dbgp = copy_chars (dbgp, &dbgs, itoa_buffer);
dbgp = copy_chars (dbgp, &dbgs, " with status ");
itoa_buffer[0] = 0;
_ui64toa_s (er->ExceptionInformation[2], itoa_buffer, ITOA_BUFFER_SIZE, 16);
dbgp = copy_chars (dbgp, &dbgs, itoa_buffer);
break;
default:
break;
}
dbgp = copy_chars (dbgp, &dbgs, "\n");
OutputDebugStringA (debug_string);
}
/* Now the debugger is present, and we can try