v2-0001-Add-errbacktrace-and-backtrace_function-GUC.patch

From ea79d7d04e940e70fa5b63f1be5b5272d287677c Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 18 Jun 2019 00:36:20 +0200
Subject: [PATCH v2] Add errbacktrace() and backtrace_function GUC

---
 configure                      | 101 ++++++++++++++++++++++++++++-
 configure.in                   |  17 +++++
 src/Makefile.global.in         |   1 +
 src/backend/utils/error/elog.c | 115 +++++++++++++++++++++++++++++++++
 src/backend/utils/misc/guc.c   |  10 +++
 src/include/pg_config.h.in     |   9 +++
 src/include/utils/elog.h       |   3 +
 src/include/utils/guc.h        |   1 +
 8 files changed, 255 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 8d47071e4a..a8394ecfd9 100755
--- a/configure
+++ b/configure
@@ -710,6 +710,7 @@ with_uuid
 with_systemd
 with_selinux
 with_openssl
+with_libunwind
 with_ldap
 with_krb_srvnam
 krb_srvtab
@@ -853,6 +854,7 @@ with_pam
 with_bsd_auth
 with_ldap
 with_bonjour
+with_libunwind
 with_openssl
 with_selinux
 with_systemd
@@ -1557,6 +1559,7 @@ Optional Packages:
   --with-bsd-auth         build with BSD Authentication support
   --with-ldap             build with LDAP support
   --with-bonjour          build with Bonjour support
+  --with-libunwind        build with libunwind support
   --with-openssl          build with OpenSSL support
   --with-selinux          build with SELinux support
   --with-systemd          build with systemd support
@@ -7861,6 +7864,39 @@ fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_bonjour" >&5
 $as_echo "$with_bonjour" >&6; }
 
+#
+# libunwind
+#
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to build with libunwind" >&5
+$as_echo_n "checking whether to build with libunwind... " >&6; }
+
+
+
+# Check whether --with-libunwind was given.
+if test "${with_libunwind+set}" = set; then :
+  withval=$with_libunwind;
+  case $withval in
+    yes)
+
+$as_echo "#define USE_LIBUNWIND 1" >>confdefs.h
+
+      ;;
+    no)
+      :
+      ;;
+    *)
+      as_fn_error $? "no argument expected for --with-libunwind option" "$LINENO" 5
+      ;;
+  esac
+
+else
+  with_libunwind=no
+
+fi
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_libunwind" >&5
+$as_echo "$with_libunwind" >&6; }
 
 #
 # OpenSSL
@@ -12224,6 +12260,67 @@ fi
 
 fi
 
+if test "$with_libunwind" = yes; then
+  # On macOS, the library does not exist, the functionality is built
+  # into the OS.
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing unw_getcontext" >&5
+$as_echo_n "checking for library containing unw_getcontext... " >&6; }
+if ${ac_cv_search_unw_getcontext+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char unw_getcontext ();
+int
+main ()
+{
+return unw_getcontext ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' unwind; do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_search_unw_getcontext=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext
+  if ${ac_cv_search_unw_getcontext+:} false; then :
+  break
+fi
+done
+if ${ac_cv_search_unw_getcontext+:} false; then :
+
+else
+  ac_cv_search_unw_getcontext=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_unw_getcontext" >&5
+$as_echo "$ac_cv_search_unw_getcontext" >&6; }
+ac_res=$ac_cv_search_unw_getcontext
+if test "$ac_res" != no; then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+fi
+
+fi
+
 if test "$with_libxml" = yes ; then
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for xmlSaveToBuffer in -lxml2" >&5
 $as_echo_n "checking for xmlSaveToBuffer in -lxml2... " >&6; }
@@ -12793,7 +12890,7 @@ $as_echo "#define HAVE_STDBOOL_H 1" >>confdefs.h
 fi
 
 
-for ac_header in atomic.h copyfile.h crypt.h fp_class.h getopt.h ieeefp.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/ipc.h sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/sockio.h sys/tas.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h
+for ac_header in atomic.h copyfile.h crypt.h execinfo.h fp_class.h getopt.h ieeefp.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/ipc.h sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/sockio.h sys/tas.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h
 do :
   as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
 ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
@@ -15176,7 +15273,7 @@ fi
 LIBS_including_readline="$LIBS"
 LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
 
-for ac_func in cbrt clock_gettime copyfile fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll posix_fallocate ppoll pstat pthread_is_threaded_np readlink setproctitle setproctitle_fast setsid shm_open strchrnul strsignal symlink sync_file_range uselocale utime utimes wcstombs_l
+for ac_func in backtrace_symbols cbrt clock_gettime copyfile fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll posix_fallocate ppoll pstat pthread_is_threaded_np readlink setproctitle setproctitle_fast setsid shm_open strchrnul strsignal symlink sync_file_range uselocale utime utimes wcstombs_l
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
diff --git a/configure.in b/configure.in
index 74938d4190..1349daf54a 100644
--- a/configure.in
+++ b/configure.in
@@ -831,6 +831,15 @@ PGAC_ARG_BOOL(with, bonjour, no,
               [AC_DEFINE([USE_BONJOUR], 1, [Define to 1 to build with Bonjour support. (--with-bonjour)])])
 AC_MSG_RESULT([$with_bonjour])
 
+#
+# libunwind
+#
+AC_MSG_CHECKING([whether to build with libunwind])
+PGAC_ARG_BOOL(with, libunwind, no,
+              [build with libunwind support],
+              [AC_DEFINE([USE_LIBUNWIND], 1, [Define to 1 to build with libunwind support. (--with-libunwind)])])
+AC_MSG_RESULT([$with_libunwind])
+AC_SUBST(with_libunwind)[]dnl
 
 #
 # OpenSSL
@@ -1223,6 +1232,12 @@ if test "$with_pam" = yes ; then
   AC_CHECK_LIB(pam,    pam_start, [], [AC_MSG_ERROR([library 'pam' is required for PAM])])
 fi
 
+if test "$with_libunwind" = yes; then
+  # On macOS, the library does not exist, the functionality is built
+  # into the OS.
+  AC_SEARCH_LIBS(unw_getcontext, [unwind])
+fi
+
 if test "$with_libxml" = yes ; then
   AC_CHECK_LIB(xml2, xmlSaveToBuffer, [], [AC_MSG_ERROR([library 'xml2' (version >= 2.6.23) is required for XML support])])
 fi
@@ -1298,6 +1313,7 @@ AC_CHECK_HEADERS(m4_normalize([
 	atomic.h
 	copyfile.h
 	crypt.h
+	execinfo.h
 	fp_class.h
 	getopt.h
 	ieeefp.h
@@ -1612,6 +1628,7 @@ LIBS_including_readline="$LIBS"
 LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
 
 AC_CHECK_FUNCS(m4_normalize([
+	backtrace_symbols
 	cbrt
 	clock_gettime
 	copyfile
diff --git a/src/Makefile.global.in b/src/Makefile.global.in
index b9d86acaa9..6e14a4b217 100644
--- a/src/Makefile.global.in
+++ b/src/Makefile.global.in
@@ -190,6 +190,7 @@ with_systemd	= @with_systemd@
 with_gssapi	= @with_gssapi@
 with_krb_srvnam	= @with_krb_srvnam@
 with_ldap	= @with_ldap@
+with_libunwind	= @with_libunwind@
 with_libxml	= @with_libxml@
 with_libxslt	= @with_libxslt@
 with_llvm	= @with_llvm@
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 8b4720ef3a..901287c335 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -62,6 +62,12 @@
 #ifdef HAVE_SYSLOG
 #include <syslog.h>
 #endif
+#ifdef HAVE_EXECINFO_H
+#include <execinfo.h>
+#endif
+#ifdef USE_LIBUNWIND
+#include <libunwind.h>
+#endif
 
 #include "access/transam.h"
 #include "access/xact.h"
@@ -166,6 +172,7 @@ static char formatted_log_time[FORMATTED_TS_LEN];
 	} while (0)
 
 
+static void set_backtrace(ErrorData *edata, int num_skip);
 static const char *err_gettext(const char *str) pg_attribute_format_arg(1);
 static void set_errdata_field(MemoryContextData *cxt, char **ptr, const char *str);
 static void write_console(const char *line, int len);
@@ -424,6 +431,12 @@ errfinish(int dummy,...)
 	 */
 	oldcontext = MemoryContextSwitchTo(ErrorContext);
 
+	if (!edata->backtrace &&
+		edata->funcname &&
+		backtrace_function[0] &&
+		strcmp(backtrace_function, edata->funcname) == 0)
+		set_backtrace(edata, 2);
+
 	/*
 	 * Call any context callback functions.  Errors occurring in callback
 	 * functions will be treated as recursive errors --- this ensures we will
@@ -488,6 +501,8 @@ errfinish(int dummy,...)
 		pfree(edata->hint);
 	if (edata->context)
 		pfree(edata->context);
+	if (edata->backtrace)
+		pfree(edata->backtrace);
 	if (edata->schema_name)
 		pfree(edata->schema_name);
 	if (edata->table_name)
@@ -798,6 +813,85 @@ errmsg(const char *fmt,...)
 	return 0;					/* return value does not matter */
 }
 
+int
+errbacktrace(void)
+{
+	ErrorData   *edata = &errordata[errordata_stack_depth];
+	MemoryContext oldcontext;
+
+	recursion_depth++;
+	CHECK_STACK_DEPTH();
+	oldcontext = MemoryContextSwitchTo(edata->assoc_context);
+
+	set_backtrace(edata, 1);
+
+	MemoryContextSwitchTo(oldcontext);
+	recursion_depth--;
+
+	return 0;
+}
+
+static void
+set_backtrace(ErrorData *edata, int num_skip)
+{
+	StringInfoData errtrace;
+
+	initStringInfo(&errtrace);
+
+#ifdef USE_LIBUNWIND
+	{
+		unw_context_t context;
+		unw_cursor_t cursor;
+		int			n = 0;
+
+		unw_getcontext(&context);
+		unw_init_local(&cursor, &context);
+
+		while (unw_step(&cursor))
+		{
+			unw_word_t ip, off;
+			char symbol[256] = "<unknown>";
+
+			if (n < num_skip - 1)
+			{
+				n++;
+				continue;
+			}
+
+			unw_get_reg(&cursor, UNW_REG_IP, &ip);
+			unw_get_proc_name(&cursor, symbol, sizeof(symbol), &off);
+
+			appendStringInfo(&errtrace,
+							 "#%-2d %s+0x%llx [0x%016llx]\n",
+							 n - 1,
+							 symbol,
+							 (unsigned long long) off,
+							 (unsigned long long) ip);
+
+			n++;
+		}
+	}
+#elif defined(HAVE_EXECINFO_H) && defined(HAVE_BACKTRACE_SYMBOLS)
+	{
+		void	   *buf[100];
+		int			nframes;
+		char	  **strfrms;
+
+		nframes = backtrace(buf, sizeof(buf));
+		strfrms = backtrace_symbols(buf, nframes);
+		if (strfrms == NULL)
+			return;
+
+		for (int i = num_skip; i < nframes; i++)
+			appendStringInfo(&errtrace, "%s\n", strfrms[i]);
+		free(strfrms);
+	}
+#else
+	appendStringInfoString(&errtrace, "backtrace not supported");
+#endif
+
+	edata->backtrace = errtrace.data;
+}
 
 /*
  * errmsg_internal --- add a primary error message text to the current error
@@ -1353,6 +1447,12 @@ elog_finish(int elevel, const char *fmt,...)
 	recursion_depth++;
 	oldcontext = MemoryContextSwitchTo(edata->assoc_context);
 
+	if (!edata->backtrace &&
+		edata->funcname &&
+		backtrace_function[0] &&
+		strcmp(backtrace_function, edata->funcname) == 0)
+		set_backtrace(edata, 2);
+
 	edata->message_id = fmt;
 	EVALUATE_MESSAGE(edata->domain, message, false, false);
 
@@ -1509,6 +1609,8 @@ CopyErrorData(void)
 		newedata->hint = pstrdup(newedata->hint);
 	if (newedata->context)
 		newedata->context = pstrdup(newedata->context);
+	if (newedata->backtrace)
+		newedata->backtrace = pstrdup(newedata->backtrace);
 	if (newedata->schema_name)
 		newedata->schema_name = pstrdup(newedata->schema_name);
 	if (newedata->table_name)
@@ -1547,6 +1649,8 @@ FreeErrorData(ErrorData *edata)
 		pfree(edata->hint);
 	if (edata->context)
 		pfree(edata->context);
+	if (edata->backtrace)
+		pfree(edata->backtrace);
 	if (edata->schema_name)
 		pfree(edata->schema_name);
 	if (edata->table_name)
@@ -1622,6 +1726,8 @@ ThrowErrorData(ErrorData *edata)
 		newedata->hint = pstrdup(edata->hint);
 	if (edata->context)
 		newedata->context = pstrdup(edata->context);
+	if (edata->backtrace)
+		newedata->backtrace = pstrdup(edata->backtrace);
 	/* assume message_id is not available */
 	if (edata->schema_name)
 		newedata->schema_name = pstrdup(edata->schema_name);
@@ -1689,6 +1795,8 @@ ReThrowError(ErrorData *edata)
 		newedata->hint = pstrdup(newedata->hint);
 	if (newedata->context)
 		newedata->context = pstrdup(newedata->context);
+	if (newedata->backtrace)
+		newedata->backtrace = pstrdup(newedata->backtrace);
 	if (newedata->schema_name)
 		newedata->schema_name = pstrdup(newedata->schema_name);
 	if (newedata->table_name)
@@ -2914,6 +3022,13 @@ send_message_to_server_log(ErrorData *edata)
 			append_with_tabs(&buf, edata->context);
 			appendStringInfoChar(&buf, '\n');
 		}
+		if (edata->backtrace)
+		{
+			log_line_prefix(&buf, edata);
+			appendStringInfoString(&buf, _("BACKTRACE:  "));
+			append_with_tabs(&buf, edata->backtrace);
+			appendStringInfoChar(&buf, '\n');
+		}
 		if (Log_error_verbosity >= PGERROR_VERBOSE)
 		{
 			/* assume no newlines in funcname or filename... */
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 1208eb9a68..328e5b6699 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -514,6 +514,7 @@ int			log_temp_files = -1;
 double		log_statement_sample_rate = 1.0;
 double		log_xact_sample_rate = 0;
 int			trace_recovery_messages = LOG;
+char	   *backtrace_function;
 
 int			temp_file_limit = -1;
 
@@ -4213,6 +4214,15 @@ static struct config_string ConfigureNamesString[] =
 		NULL, NULL, NULL
 	},
 
+	{
+		{"backtrace_function", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Log backtrace for errors in this function."),
+		},
+		&backtrace_function,
+		"",
+		NULL, NULL, NULL
+	},
+
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, NULL, NULL, NULL, NULL
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 6cd4cfed0a..6959ce6c61 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -96,6 +96,9 @@
 /* Define to 1 if you have the <atomic.h> header file. */
 #undef HAVE_ATOMIC_H
 
+/* Define to 1 if you have the `backtrace_symbols' function. */
+#undef HAVE_BACKTRACE_SYMBOLS
+
 /* Define to 1 if you have the `BIO_get_data' function. */
 #undef HAVE_BIO_GET_DATA
 
@@ -201,6 +204,9 @@
 /* Define to 1 if you have the <editline/readline.h> header file. */
 #undef HAVE_EDITLINE_READLINE_H
 
+/* Define to 1 if you have the <execinfo.h> header file. */
+#undef HAVE_EXECINFO_H
+
 /* Define to 1 if you have the `fdatasync' function. */
 #undef HAVE_FDATASYNC
 
@@ -922,6 +928,9 @@
 /* Define to 1 to build with LDAP support. (--with-ldap) */
 #undef USE_LDAP
 
+/* Define to 1 to build with libunwind support. (--with-libunwind) */
+#undef USE_LIBUNWIND
+
 /* Define to 1 to build with XML support. (--with-libxml) */
 #undef USE_LIBXML
 
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index dbfd8efd26..b58aee792a 100644
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -189,6 +189,8 @@ extern int	errcontext_msg(const char *fmt,...) pg_attribute_printf(1, 2);
 extern int	errhidestmt(bool hide_stmt);
 extern int	errhidecontext(bool hide_ctx);
 
+extern int	errbacktrace(void);
+
 extern int	errfunction(const char *funcname);
 extern int	errposition(int cursorpos);
 
@@ -362,6 +364,7 @@ typedef struct ErrorData
 	char	   *detail_log;		/* detail error message for server log only */
 	char	   *hint;			/* hint message */
 	char	   *context;		/* context message */
+	char	   *backtrace;		/* backtrace */
 	const char *message_id;		/* primary message's id (original string) */
 	char	   *schema_name;	/* name of schema */
 	char	   *table_name;		/* name of table */
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index e709177c37..032f4f16ab 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -255,6 +255,7 @@ extern int	log_min_duration_statement;
 extern int	log_temp_files;
 extern double log_statement_sample_rate;
 extern double log_xact_sample_rate;
+extern char *backtrace_function;
 
 extern int	temp_file_limit;
 
-- 
2.22.0