From 71a8a4f6e36547bb060dbcc961ea9b57420f7190 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Fri, 8 Nov 2019 15:44:20 -0300 Subject: [PATCH] Add backtrace support for error reporting MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add some support for automatically showing backtraces in certain error situations in the server. Backtraces are shown on assertion failure; also, a new setting backtrace_functions can be set to a list of C function names, and all ereport()s and elog()s from the mentioned functions will have backtraces generated. Finally, the function errbacktrace() can be manually added to an ereport() call to generate a backtrace for that call. Authors: Peter Eisentraut, Álvaro Herrera Discussion: https://postgr.es/m//5f48cb47-bf1e-05b6-7aae-3bf2cd01586d@2ndquadrant.com Discussion: https://postgr.es/m/CAMsr+YGL+yfWE=JvbUbnpWtrRZNey7hJ07+zT4bYJdVp4Szdrg@mail.gmail.com --- configure | 61 +++++++++++++++- configure.in | 4 ++ doc/src/sgml/config.sgml | 26 +++++++ src/backend/utils/error/assert.c | 13 ++++ src/backend/utils/error/elog.c | 117 +++++++++++++++++++++++++++++++ src/backend/utils/misc/guc.c | 85 ++++++++++++++++++++++ src/include/pg_config.h.in | 6 ++ src/include/utils/elog.h | 3 + src/include/utils/guc.h | 2 + 9 files changed, 315 insertions(+), 2 deletions(-) diff --git a/configure b/configure index 7312bd7a7a..d6ce394525 100755 --- a/configure +++ b/configure @@ -11607,6 +11607,63 @@ if test "$ac_res" != no; then : fi +# *BSD: +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing backtrace_symbols" >&5 +$as_echo_n "checking for library containing backtrace_symbols... " >&6; } +if ${ac_cv_search_backtrace_symbols+:} false; then : + $as_echo_n "(cached) " >&6 +else + ac_func_search_save_LIBS=$LIBS +cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ + +/* Override any GCC internal prototype to avoid an error. + Use char because int might match the return type of a GCC + builtin and then its argument prototype would still apply. */ +#ifdef __cplusplus +extern "C" +#endif +char backtrace_symbols (); +int +main () +{ +return backtrace_symbols (); + ; + return 0; +} +_ACEOF +for ac_lib in '' execinfo; do + if test -z "$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_backtrace_symbols=$ac_res +fi +rm -f core conftest.err conftest.$ac_objext \ + conftest$ac_exeext + if ${ac_cv_search_backtrace_symbols+:} false; then : + break +fi +done +if ${ac_cv_search_backtrace_symbols+:} false; then : + +else + ac_cv_search_backtrace_symbols=no +fi +rm conftest.$ac_ext +LIBS=$ac_func_search_save_LIBS +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_backtrace_symbols" >&5 +$as_echo "$ac_cv_search_backtrace_symbols" >&6; } +ac_res=$ac_cv_search_backtrace_symbols +if test "$ac_res" != no; then : + test "$ac_res" = "none required" || LIBS="$ac_res $LIBS" + +fi + if test "$with_readline" = yes; then @@ -12705,7 +12762,7 @@ $as_echo "#define HAVE_STDBOOL_H 1" >>confdefs.h fi -for ac_header in atomic.h copyfile.h fp_class.h getopt.h ieeefp.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/ipc.h sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/sockio.h sys/tas.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h +for ac_header in atomic.h copyfile.h execinfo.h fp_class.h getopt.h ieeefp.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/ipc.h sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/sockio.h sys/tas.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h do : as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh` ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default" @@ -14935,7 +14992,7 @@ fi LIBS_including_readline="$LIBS" LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'` -for ac_func in cbrt clock_gettime copyfile fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memset_s memmove poll posix_fallocate ppoll pstat pthread_is_threaded_np readlink setproctitle setproctitle_fast setsid shm_open strchrnul strsignal symlink sync_file_range uselocale utime utimes wcstombs_l +for ac_func in backtrace_symbols cbrt clock_gettime copyfile fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memset_s memmove poll posix_fallocate ppoll pstat pthread_is_threaded_np readlink setproctitle setproctitle_fast setsid shm_open strchrnul strsignal symlink sync_file_range uselocale utime utimes wcstombs_l do : as_ac_var=`$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 ea83d921cb..5bd31a876e 100644 --- a/configure.in +++ b/configure.in @@ -1133,6 +1133,8 @@ AC_SEARCH_LIBS(sched_yield, rt) AC_SEARCH_LIBS(gethostbyname_r, nsl) # Cygwin: AC_SEARCH_LIBS(shmget, cygipc) +# *BSD: +AC_SEARCH_LIBS(backtrace_symbols, execinfo) if test "$with_readline" = yes; then PGAC_CHECK_READLINE @@ -1275,6 +1277,7 @@ AC_HEADER_STDBOOL AC_CHECK_HEADERS(m4_normalize([ atomic.h copyfile.h + execinfo.h fp_class.h getopt.h ieeefp.h @@ -1608,6 +1611,7 @@ LIBS_including_readline="$LIBS" LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'` AC_CHECK_FUNCS(m4_normalize([ + backtrace_symbols cbrt clock_gettime copyfile diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 46bc31de4c..a0e1925a19 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -9489,6 +9489,32 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir' + + backtrace_functions (string) + + backtrace_functions configuration parameter + + + + + This parameter contains a comma-separated list of C function names. + If an error is raised and the name of the internal C function where + the error happens matches a value in the list, then a backtrace is + written to the server log together with the error message. This can + be used to debug specific areas of the source code. + + + + Backtrace support is not available on all platforms, and the quality + of the backtraces depends on compilation options. + + + + This parameter can only be set by superusers. + + + + ignore_system_indexes (boolean) diff --git a/src/backend/utils/error/assert.c b/src/backend/utils/error/assert.c index 2050b4355d..1069bbee81 100644 --- a/src/backend/utils/error/assert.c +++ b/src/backend/utils/error/assert.c @@ -18,6 +18,9 @@ #include "postgres.h" #include +#ifdef HAVE_EXECINFO_H +#include +#endif /* * ExceptionalCondition - Handles the failure of an Assert() @@ -42,6 +45,16 @@ ExceptionalCondition(const char *conditionName, /* Usually this shouldn't be needed, but make sure the msg went out */ fflush(stderr); +#ifdef HAVE_BACKTRACE_SYMBOLS + { + void *buf[100]; + int nframes; + + nframes = backtrace(buf, lengthof(buf)); + backtrace_symbols_fd(buf, nframes, fileno(stderr)); + } +#endif + #ifdef SLEEP_ON_ASSERT /* diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c index 8b4720ef3a..9ef4bc2472 100644 --- a/src/backend/utils/error/elog.c +++ b/src/backend/utils/error/elog.c @@ -62,6 +62,9 @@ #ifdef HAVE_SYSLOG #include #endif +#ifdef HAVE_EXECINFO_H +#include +#endif #include "access/transam.h" #include "access/xact.h" @@ -167,6 +170,7 @@ static char formatted_log_time[FORMATTED_TS_LEN]; static const char *err_gettext(const char *str) pg_attribute_format_arg(1); +static pg_noinline void set_backtrace(ErrorData *edata, int num_skip); static void set_errdata_field(MemoryContextData *cxt, char **ptr, const char *str); static void write_console(const char *line, int len); static void setup_formatted_log_time(void); @@ -398,6 +402,32 @@ errstart(int elevel, const char *filename, int lineno, return true; } +/* + * Checks whether the given funcname matches backtrace_functions; see + * check_backtrace_functions. + */ +static bool +matches_backtrace_functions(const char *funcname) +{ + char *p; + + if (!backtrace_symbol_list || funcname == NULL || funcname[0] == '\0') + return false; + + p = backtrace_symbol_list; + for (;;) + { + if (*p == '\0') /* end of backtrace_symbol_list */ + break; + + if (strcmp(funcname, p) == 0) + return true; + p += strlen(p) + 1; + } + + return false; +} + /* * errfinish --- end an error-reporting cycle * @@ -424,6 +454,12 @@ errfinish(int dummy,...) */ oldcontext = MemoryContextSwitchTo(ErrorContext); + if (!edata->backtrace && + edata->funcname && + backtrace_functions && + matches_backtrace_functions(edata->funcname)) + 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 +524,8 @@ 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 +836,65 @@ errmsg(const char *fmt,...) return 0; /* return value does not matter */ } +/* + * Add a backtrace to the containing ereport() call. This is intended to be + * added temporarily during debugging. + */ +int +errbacktrace(void) +{ + ErrorData *edata = &errordata[errordata_stack_depth]; + MemoryContext oldcontext; + + Assert(false); + + recursion_depth++; + CHECK_STACK_DEPTH(); + oldcontext = MemoryContextSwitchTo(edata->assoc_context); + + set_backtrace(edata, 1); + + MemoryContextSwitchTo(oldcontext); + recursion_depth--; + + return 0; +} + +/* + * Compute backtrace data and add it to the supplied ErrorData. num_skip + * specifies how many inner frames to skip. Use this to avoid showing the + * internal backtrace support functions in the backtrace. This requires that + * this and related functions are not inlined. + */ +static void +set_backtrace(ErrorData *edata, int num_skip) +{ + StringInfoData errtrace; + + initStringInfo(&errtrace); + +#ifdef HAVE_BACKTRACE_SYMBOLS + { + void *buf[100]; + int nframes; + char **strfrms; + + nframes = backtrace(buf, lengthof(buf)); + strfrms = backtrace_symbols(buf, nframes); + if (strfrms == NULL) + return; + + for (int i = num_skip; i < nframes; i++) + appendStringInfo(&errtrace, "\n%s", strfrms[i]); + free(strfrms); + } +#else + appendStringInfoString(&errtrace, + "backtrace generation is not supported by this installation"); +#endif + + edata->backtrace = errtrace.data; +} /* * errmsg_internal --- add a primary error message text to the current error @@ -1353,6 +1450,11 @@ elog_finish(int elevel, const char *fmt,...) recursion_depth++; oldcontext = MemoryContextSwitchTo(edata->assoc_context); + if (!edata->backtrace && + edata->funcname && + matches_backtrace_functions(edata->funcname)) + set_backtrace(edata, 2); + edata->message_id = fmt; EVALUATE_MESSAGE(edata->domain, message, false, false); @@ -1509,6 +1611,8 @@ 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 +1651,8 @@ 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 +1728,8 @@ 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 +1797,8 @@ 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 +3024,13 @@ 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 e84c8cc4cf..994bf37477 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -201,6 +201,8 @@ static bool check_cluster_name(char **newval, void **extra, GucSource source); static const char *show_unix_socket_permissions(void); static const char *show_log_file_mode(void); static const char *show_data_directory_mode(void); +static bool check_backtrace_functions(char **newval, void **extra, GucSource source); +static void assign_backtrace_functions(const char *newval, void *extra); static bool check_recovery_target_timeline(char **newval, void **extra, GucSource source); static void assign_recovery_target_timeline(const char *newval, void *extra); static bool check_recovery_target(char **newval, void **extra, GucSource source); @@ -515,6 +517,8 @@ 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_functions; +char *backtrace_symbol_list; int temp_file_limit = -1; @@ -4224,6 +4228,17 @@ static struct config_string ConfigureNamesString[] = NULL, NULL, NULL }, + { + {"backtrace_functions", PGC_SUSET, DEVELOPER_OPTIONS, + gettext_noop("Log backtrace for errors in these functions."), + NULL, + GUC_NOT_IN_SAMPLE + }, + &backtrace_functions, + "", + check_backtrace_functions, assign_backtrace_functions, NULL + }, + /* End-of-list marker */ { {NULL, 0, 0, NULL, NULL}, NULL, NULL, NULL, NULL, NULL @@ -11487,6 +11502,76 @@ show_data_directory_mode(void) return buf; } +/* + * We split the input string, where commas separate function names + * and certain whitespace chars are ignored, into a \0-separated (and + * \0\0-terminated) list of function names. This formulation allows + * easy scanning when an error is thrown while avoiding the use of + * non-reentrant strtok(), as well as keeping the output data in a + * single palloc() chunk. + */ +static bool +check_backtrace_functions(char **newval, void **extra, GucSource source) +{ + int newvallen = strlen(*newval); + char *someval; + int validlen; + int i; + int j; + + /* + * Allow characters that can be C identifiers and commas as separators, as + * well as some whitespace for readability. + */ + validlen = strspn(*newval, + "0123456789_" + "abcdefghijklmnopqrstuvwxyz" + "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + ", \n\t"); + if (validlen != newvallen) + { + GUC_check_errdetail("invalid character"); + return false; + } + + if (*newval[0] == '\0') + { + *extra = NULL; + return true; + } + + /* + * Allocate space for the output and create the copy. We could discount + * whitespace chars to save some memory, but it doesn't seem worth the + * trouble. + */ + someval = guc_malloc(ERROR, newvallen + 1 + 1); + for (i = 0, j = 0; i < newvallen; i++) + { + if ((*newval)[i] == ',') + someval[j++] = '\0'; /* next item */ + else if ((*newval)[i] == ' ' || + (*newval)[i] == '\n' || + (*newval)[i] == '\t') + ; /* ignore these */ + else + someval[j++] = (*newval)[i]; /* copy anything else */ + } + + /* two \0s end the setting */ + someval[j] = '\0'; + someval[j + 1] = '\0'; + + *extra = someval; + return true; +} + +static void +assign_backtrace_functions(const char *newval, void *extra) +{ + backtrace_symbol_list = (char *) extra; +} + static bool check_recovery_target_timeline(char **newval, void **extra, GucSource source) { diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in index 2bf506033d..a56161cf28 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 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 @@ -198,6 +201,9 @@ /* Define to 1 if you have the `explicit_bzero' function. */ #undef HAVE_EXPLICIT_BZERO +/* Define to 1 if you have the header file. */ +#undef HAVE_EXECINFO_H + /* Define to 1 if you have the `fdatasync' function. */ #undef HAVE_FDATASYNC diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h index 47412a831f..9ab4b5470b 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); @@ -392,6 +394,7 @@ 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 9aa3d02596..50098e63fe 100644 --- a/src/include/utils/guc.h +++ b/src/include/utils/guc.h @@ -256,6 +256,8 @@ 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_functions; +extern char *backtrace_symbol_list; extern int temp_file_limit;