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/*-------------------------------------------------------------------------
*
* crashdump.c
* Automatic crash dump creation for PostgreSQL on Windows
*
* The crashdump feature traps unhandled win32 exceptions produced by the
* backend, and tries to produce a Windows MiniDump crash
* dump for later debugging and analysis. The machine performing the dump
* doesn't need any special debugging tools; the user only needs to send
* the dump to somebody who has the same version of PostgreSQL and has debugging
* tools.
*
* crashdump module originally by Craig Ringer <ringerc@ringerc.id.au>
*
* LIMITATIONS
* ===========
* This *won't* work in hard OOM situations or stack overflows.
*
* For those, it'd be necessary to take a much more complicated approach where
* the handler switches to a new stack (if it can) and forks a helper process
* to debug it self.
*
* POSSIBLE FUTURE WORK
* ====================
* For bonus points, the crash dump format permits embedding of user-supplied
* data. If there's anything else that should always be supplied with a crash
* dump (postgresql.conf? Last few lines of a log file?), it could potentially
* be added, though at the cost of a greater chance of the crash dump failing.
*
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/backend/port/win32/crashdump.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#define WIN32_LEAN_AND_MEAN
/*
* Some versions of the MS SDK contain "typedef enum { ... } ;" which the MS
* compiler quite sanely complains about. Well done, Microsoft.
* This pragma disables the warning just while we include the header.
* The pragma is known to work with all (as at the time of writing) supported
* versions of MSVC.
*/
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4091)
#endif
#include <dbghelp.h>
#ifdef _MSC_VER
#pragma warning(pop)
#endif
/*
* Much of the following code is based on CodeProject and MSDN examples,
* particularly
* http://www.codeproject.com/KB/debug/postmortemdebug_standalone1.aspx
*
* Useful MSDN articles:
*
* http://msdn.microsoft.com/en-us/library/ff805116(v=VS.85).aspx
* http://msdn.microsoft.com/en-us/library/ms679294(VS.85).aspx
*
* Other useful articles on working with minidumps:
* http://www.debuginfo.com/articles/effminidumps.html
*/
typedef BOOL (WINAPI * MINIDUMPWRITEDUMP) (HANDLE hProcess, DWORD dwPid, HANDLE hFile, MINIDUMP_TYPE DumpType,
CONST PMINIDUMP_EXCEPTION_INFORMATION ExceptionParam,
CONST PMINIDUMP_USER_STREAM_INFORMATION UserStreamParam,
CONST PMINIDUMP_CALLBACK_INFORMATION CallbackParam
);
/*
* This function is the exception handler passed to SetUnhandledExceptionFilter.
* It's invoked only if there's an unhandled exception. The handler will use
* dbghelp.dll to generate a crash dump, then resume the normal unhandled
* exception process, which will generally exit with an error message from
* the runtime.
*
* This function is run under the unhandled exception handler, effectively
* in a crash context, so it should be careful with memory and avoid using
* any PostgreSQL functions.
*/
static LONG WINAPI
crashDumpHandler(struct _EXCEPTION_POINTERS *pExceptionInfo)
{
/*
* We only write crash dumps if the "crashdumps" directory within the
* postgres data directory exists.
*/
DWORD attribs = GetFileAttributesA("crashdumps");
if (attribs != INVALID_FILE_ATTRIBUTES && (attribs & FILE_ATTRIBUTE_DIRECTORY))
{
/* 'crashdumps' exists and is a directory. Try to write a dump' */
HMODULE hDll = NULL;
MINIDUMPWRITEDUMP pDump = NULL;
MINIDUMP_TYPE dumpType;
char dumpPath[_MAX_PATH];
HANDLE selfProcHandle = GetCurrentProcess();
DWORD selfPid = GetProcessId(selfProcHandle);
HANDLE dumpFile;
DWORD systemTicks;
struct _MINIDUMP_EXCEPTION_INFORMATION ExInfo;
ExInfo.ThreadId = GetCurrentThreadId();
ExInfo.ExceptionPointers = pExceptionInfo;
ExInfo.ClientPointers = FALSE;
/* Load the dbghelp.dll library and functions */
hDll = LoadLibrary("dbghelp.dll");
if (hDll == NULL)
{
write_stderr("could not load dbghelp.dll, cannot write crash dump\n");
return EXCEPTION_CONTINUE_SEARCH;
}
pDump = (MINIDUMPWRITEDUMP) (pg_funcptr_t) GetProcAddress(hDll, "MiniDumpWriteDump");
if (pDump == NULL)
{
write_stderr("could not load required functions in dbghelp.dll, cannot write crash dump\n");
return EXCEPTION_CONTINUE_SEARCH;
}
/*
* Dump as much as we can, except shared memory, code segments, and
* memory mapped files. Exactly what we can dump depends on the
* version of dbghelp.dll, see:
* http://msdn.microsoft.com/en-us/library/ms680519(v=VS.85).aspx
*/
dumpType = MiniDumpNormal | MiniDumpWithHandleData |
MiniDumpWithDataSegs;
if (GetProcAddress(hDll, "EnumDirTree") != NULL)
{
/* If this function exists, we have version 5.2 or newer */
dumpType |= MiniDumpWithIndirectlyReferencedMemory |
MiniDumpWithPrivateReadWriteMemory;
}
systemTicks = GetTickCount();
snprintf(dumpPath, _MAX_PATH,
"crashdumps\\postgres-pid%0i-%0i.mdmp",
(int) selfPid, (int) systemTicks);
dumpPath[_MAX_PATH - 1] = '\0';
dumpFile = CreateFile(dumpPath, GENERIC_WRITE, FILE_SHARE_WRITE,
NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL,
NULL);
if (dumpFile == INVALID_HANDLE_VALUE)
{
write_stderr("could not open crash dump file \"%s\" for writing: error code %lu\n",
dumpPath, GetLastError());
return EXCEPTION_CONTINUE_SEARCH;
}
if ((*pDump) (selfProcHandle, selfPid, dumpFile, dumpType, &ExInfo,
NULL, NULL))
write_stderr("wrote crash dump to file \"%s\"\n", dumpPath);
else
write_stderr("could not write crash dump to file \"%s\": error code %lu\n",
dumpPath, GetLastError());
CloseHandle(dumpFile);
}
return EXCEPTION_CONTINUE_SEARCH;
}
void
pgwin32_install_crashdump_handler(void)
{
SetUnhandledExceptionFilter(crashDumpHandler);
}
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