src/backend/port/win32/crashdump.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * crashdump.c
   4  *                 Automatic crash dump creation for PostgreSQL on Windows
   5  *
   6  * The crashdump feature traps unhandled win32 exceptions produced by the
   7  * backend, and tries to produce a Windows MiniDump crash
   8  * dump for later debugging and analysis. The machine performing the dump
   9  * doesn't need any special debugging tools; the user only needs to send
  10  * the dump to somebody who has the same version of PostgreSQL and has debugging
  11  * tools.
  12  *
  13  * crashdump module originally by Craig Ringer <ringerc@ringerc.id.au>
  14  *
  15  * LIMITATIONS
  16  * ===========
  17  * This *won't* work in hard OOM situations or stack overflows.
  18  *
  19  * For those, it'd be necessary to take a much more complicated approach where
  20  * the handler switches to a new stack (if it can) and forks a helper process
  21  * to debug it self.
  22  *
  23  * POSSIBLE FUTURE WORK
  24  * ====================
  25  * For bonus points, the crash dump format permits embedding of user-supplied
  26  * data. If there's anything else that should always be supplied with a crash
  27  * dump (postgresql.conf? Last few lines of a log file?), it could potentially
  28  * be added, though at the cost of a greater chance of the crash dump failing.
  29  *
  30  *
  31  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
  32  *
  33  * IDENTIFICATION
  34  *        src/backend/port/win32/crashdump.c
  35  *
  36  *-------------------------------------------------------------------------
  37  */
  38
  39 #include "postgres.h"
  40
  41 /*
  42  * Some versions of the MS SDK contain "typedef enum { ... } ;" which the MS
  43  * compiler quite sanely complains about. Well done, Microsoft.
  44  * This pragma disables the warning just while we include the header.
  45  * The pragma is known to work with all (as at the time of writing) supported
  46  * versions of MSVC.
  47  */
  48 #ifdef _MSC_VER
  49 #pragma warning(push)
  50 #pragma warning(disable : 4091)
  51 #endif
  52 #include <dbghelp.h>
  53 #ifdef _MSC_VER
  54 #pragma warning(pop)
  55 #endif
  56
  57 /*
  58  * Much of the following code is based on CodeProject and MSDN examples,
  59  * particularly
  60  * http://www.codeproject.com/KB/debug/postmortemdebug_standalone1.aspx
  61  *
  62  * Useful MSDN articles:
  63  *
  64  * http://msdn.microsoft.com/en-us/library/ff805116(v=VS.85).aspx
  65  * http://msdn.microsoft.com/en-us/library/ms679294(VS.85).aspx
  66  *
  67  * Other useful articles on working with minidumps:
  68  * http://www.debuginfo.com/articles/effminidumps.html
  69  */
  70
  71 typedef BOOL (WINAPI * MINIDUMPWRITEDUMP) (HANDLE hProcess, DWORD dwPid, HANDLE hFile, MINIDUMP_TYPE DumpType,
  72                                                                                    CONST PMINIDUMP_EXCEPTION_INFORMATION ExceptionParam,
  73                                                                                    CONST PMINIDUMP_USER_STREAM_INFORMATION UserStreamParam,
  74                                                                                    CONST PMINIDUMP_CALLBACK_INFORMATION CallbackParam
  75 );
  76
  77
  78 /*
  79  * This function is the exception handler passed to SetUnhandledExceptionFilter.
  80  * It's invoked only if there's an unhandled exception. The handler will use
  81  * dbghelp.dll to generate a crash dump, then resume the normal unhandled
  82  * exception process, which will generally exit with an error message from
  83  * the runtime.
  84  *
  85  * This function is run under the unhandled exception handler, effectively
  86  * in a crash context, so it should be careful with memory and avoid using
  87  * any PostgreSQL functions.
  88  */
  89 static LONG WINAPI
  90 crashDumpHandler(struct _EXCEPTION_POINTERS *pExceptionInfo)
  91 {
  92         /*
  93          * We only write crash dumps if the "crashdumps" directory within the
  94          * postgres data directory exists.
  95          */
  96         DWORD           attribs = GetFileAttributesA("crashdumps");
  97
  98         if (attribs != INVALID_FILE_ATTRIBUTES && (attribs & FILE_ATTRIBUTE_DIRECTORY))
  99         {
 100                 /* 'crashdumps' exists and is a directory. Try to write a dump' */
 101                 HMODULE         hDll = NULL;
 102                 MINIDUMPWRITEDUMP pDump = NULL;
 103                 MINIDUMP_TYPE dumpType;
 104                 char            dumpPath[_MAX_PATH];
 105                 HANDLE          selfProcHandle = GetCurrentProcess();
 106                 DWORD           selfPid = GetProcessId(selfProcHandle);
 107                 HANDLE          dumpFile;
 108                 DWORD           systemTicks;
 109                 struct _MINIDUMP_EXCEPTION_INFORMATION ExInfo;
 110
 111                 ExInfo.ThreadId = GetCurrentThreadId();
 112                 ExInfo.ExceptionPointers = pExceptionInfo;
 113                 ExInfo.ClientPointers = FALSE;
 114
 115                 /* Load the dbghelp.dll library and functions */
 116                 hDll = LoadLibrary("dbghelp.dll");
 117                 if (hDll == NULL)
 118                 {
 119                         write_stderr("could not load dbghelp.dll, cannot write crash dump\n");
 120                         return EXCEPTION_CONTINUE_SEARCH;
 121                 }
 122
 123                 pDump = (MINIDUMPWRITEDUMP) (pg_funcptr_t) GetProcAddress(hDll, "MiniDumpWriteDump");
 124
 125                 if (pDump == NULL)
 126                 {
 127                         write_stderr("could not load required functions in dbghelp.dll, cannot write crash dump\n");
 128                         return EXCEPTION_CONTINUE_SEARCH;
 129                 }
 130
 131                 /*
 132                  * Dump as much as we can, except shared memory, code segments, and
 133                  * memory mapped files. Exactly what we can dump depends on the
 134                  * version of dbghelp.dll, see:
 135                  * http://msdn.microsoft.com/en-us/library/ms680519(v=VS.85).aspx
 136                  */
 137                 dumpType = MiniDumpNormal | MiniDumpWithHandleData |
 138                         MiniDumpWithDataSegs;
 139
 140                 if (GetProcAddress(hDll, "EnumDirTree") != NULL)
 141                 {
 142                         /* If this function exists, we have version 5.2 or newer */
 143                         dumpType |= MiniDumpWithIndirectlyReferencedMemory |
 144                                 MiniDumpWithPrivateReadWriteMemory;
 145                 }
 146
 147                 systemTicks = GetTickCount();
 148                 snprintf(dumpPath, _MAX_PATH,
 149                                  "crashdumps\\postgres-pid%0i-%0i.mdmp",
 150                                  (int) selfPid, (int) systemTicks);
 151                 dumpPath[_MAX_PATH - 1] = '\0';
 152
 153                 dumpFile = CreateFile(dumpPath, GENERIC_WRITE, FILE_SHARE_WRITE,
 154                                                           NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL,
 155                                                           NULL);
 156                 if (dumpFile == INVALID_HANDLE_VALUE)
 157                 {
 158                         write_stderr("could not open crash dump file \"%s\" for writing: error code %lu\n",
 159                                                  dumpPath, GetLastError());
 160                         return EXCEPTION_CONTINUE_SEARCH;
 161                 }
 162
 163                 if ((*pDump) (selfProcHandle, selfPid, dumpFile, dumpType, &ExInfo,
 164                                           NULL, NULL))
 165                         write_stderr("wrote crash dump to file \"%s\"\n", dumpPath);
 166                 else
 167                         write_stderr("could not write crash dump to file \"%s\": error code %lu\n",
 168                                                  dumpPath, GetLastError());
 169
 170                 CloseHandle(dumpFile);
 171         }
 172
 173         return EXCEPTION_CONTINUE_SEARCH;
 174 }
 175
 176
 177 void
 178 pgwin32_install_crashdump_handler(void)
 179 {
 180         SetUnhandledExceptionFilter(crashDumpHandler);
 181 }