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postgres/src/include/utils/guc.h
Tom Lane 3853664265 Introduce GUC_NO_RESET flag. 
Previously, the transaction-property GUCs such as transaction_isolation
could be reset after starting a transaction, because we marked them
as GUC_NO_RESET_ALL but still allowed a targeted RESET.  That leads to
assertion failures or worse, because those properties aren't supposed
to change after we've acquired a transaction snapshot.

There are some NO_RESET_ALL variables for which RESET is okay, so
we can't just redefine the semantics of that flag.  Instead introduce
a separate GUC_NO_RESET flag.  Mark "seed", as well as the transaction
property GUCs, as GUC_NO_RESET.

We have to disallow GUC_ACTION_SAVE as well as straight RESET, because
otherwise a function having a "SET transaction_isolation" clause can
still break things: the end-of-function restore action is equivalent
to a RESET.

No back-patch, as it's conceivable that someone is doing something
this patch will forbid (like resetting one of these GUCs at transaction
start, or "CREATE FUNCTION ... SET transaction_read_only = 1") and not
running into problems with it today.  Given how long we've had this
issue and not noticed, the side effects in non-assert builds can't be
too serious.

Per bug #17385 from Andrew Bille.

Masahiko Sawada

Discussion: https://postgr.es/m/17385-9ee529fb091f0ce5@postgresql.org
2022-09-27 11:47:12 -04:00

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/*--------------------------------------------------------------------
* guc.h
*
* External declarations pertaining to Grand Unified Configuration.
*
* Copyright (c) 2000-2022, PostgreSQL Global Development Group
* Written by Peter Eisentraut <peter_e@gmx.net>.
*
* src/include/utils/guc.h
*--------------------------------------------------------------------
*/
#ifndef GUC_H
#define GUC_H
#include "nodes/parsenodes.h"
#include "tcop/dest.h"
#include "utils/array.h"
/* upper limit for GUC variables measured in kilobytes of memory */
/* note that various places assume the byte size fits in a "long" variable */
#if SIZEOF_SIZE_T > 4 && SIZEOF_LONG > 4
#define MAX_KILOBYTES INT_MAX
#else
#define MAX_KILOBYTES (INT_MAX / 1024)
#endif
/*
* Automatic configuration file name for ALTER SYSTEM.
* This file will be used to store values of configuration parameters
* set by ALTER SYSTEM command.
*/
#define PG_AUTOCONF_FILENAME "postgresql.auto.conf"
/*
* Certain options can only be set at certain times. The rules are
* like this:
*
* INTERNAL options cannot be set by the user at all, but only through
* internal processes ("server_version" is an example). These are GUC
* variables only so they can be shown by SHOW, etc.
*
* POSTMASTER options can only be set when the postmaster starts,
* either from the configuration file or the command line.
*
* SIGHUP options can only be set at postmaster startup or by changing
* the configuration file and sending the HUP signal to the postmaster
* or a backend process. (Notice that the signal receipt will not be
* evaluated immediately. The postmaster and the backend check it at a
* certain point in their main loop. It's safer to wait than to read a
* file asynchronously.)
*
* BACKEND and SU_BACKEND options can only be set at postmaster startup,
* from the configuration file, or by client request in the connection
* startup packet (e.g., from libpq's PGOPTIONS variable). SU_BACKEND
* options can be set from the startup packet only when the user is a
* superuser. Furthermore, an already-started backend will ignore changes
* to such an option in the configuration file. The idea is that these
* options are fixed for a given backend once it's started, but they can
* vary across backends.
*
* SUSET options can be set at postmaster startup, with the SIGHUP
* mechanism, or from the startup packet or SQL if you're a superuser.
*
* USERSET options can be set by anyone any time.
*/
typedef enum
{
PGC_INTERNAL,
PGC_POSTMASTER,
PGC_SIGHUP,
PGC_SU_BACKEND,
PGC_BACKEND,
PGC_SUSET,
PGC_USERSET
} GucContext;
/*
* The following type records the source of the current setting. A
* new setting can only take effect if the previous setting had the
* same or lower level. (E.g, changing the config file doesn't
* override the postmaster command line.) Tracking the source allows us
* to process sources in any convenient order without affecting results.
* Sources <= PGC_S_OVERRIDE will set the default used by RESET, as well
* as the current value.
*
* PGC_S_INTERACTIVE isn't actually a source value, but is the
* dividing line between "interactive" and "non-interactive" sources for
* error reporting purposes.
*
* PGC_S_TEST is used when testing values to be used later. For example,
* ALTER DATABASE/ROLE tests proposed per-database or per-user defaults this
* way, and CREATE FUNCTION tests proposed function SET clauses this way.
* This is an interactive case, but it needs its own source value because
* some assign hooks need to make different validity checks in this case.
* In particular, references to nonexistent database objects generally
* shouldn't throw hard errors in this case, at most NOTICEs, since the
* objects might exist by the time the setting is used for real.
*
* When setting the value of a non-compile-time-constant PGC_INTERNAL option,
* source == PGC_S_DYNAMIC_DEFAULT should typically be used so that the value
* will show as "default" in pg_settings. If there is a specific reason not
* to want that, use source == PGC_S_OVERRIDE.
*
* NB: see GucSource_Names in guc.c if you change this.
*/
typedef enum
{
PGC_S_DEFAULT, /* hard-wired default ("boot_val") */
PGC_S_DYNAMIC_DEFAULT, /* default computed during initialization */
PGC_S_ENV_VAR, /* postmaster environment variable */
PGC_S_FILE, /* postgresql.conf */
PGC_S_ARGV, /* postmaster command line */
PGC_S_GLOBAL, /* global in-database setting */
PGC_S_DATABASE, /* per-database setting */
PGC_S_USER, /* per-user setting */
PGC_S_DATABASE_USER, /* per-user-and-database setting */
PGC_S_CLIENT, /* from client connection request */
PGC_S_OVERRIDE, /* special case to forcibly set default */
PGC_S_INTERACTIVE, /* dividing line for error reporting */
PGC_S_TEST, /* test per-database or per-user setting */
PGC_S_SESSION /* SET command */
} GucSource;
/*
* Parsing the configuration file(s) will return a list of name-value pairs
* with source location info. We also abuse this data structure to carry
* error reports about the config files. An entry reporting an error will
* have errmsg != NULL, and might have NULLs for name, value, and/or filename.
*
* If "ignore" is true, don't attempt to apply the item (it might be an error
* report, or an item we determined to be duplicate). "applied" is set true
* if we successfully applied, or could have applied, the setting.
*/
typedef struct ConfigVariable
{
char *name;
char *value;
char *errmsg;
char *filename;
int sourceline;
bool ignore;
bool applied;
struct ConfigVariable *next;
} ConfigVariable;
extern bool ParseConfigFile(const char *config_file, bool strict,
const char *calling_file, int calling_lineno,
int depth, int elevel,
ConfigVariable **head_p, ConfigVariable **tail_p);
extern bool ParseConfigFp(FILE *fp, const char *config_file,
int depth, int elevel,
ConfigVariable **head_p, ConfigVariable **tail_p);
extern bool ParseConfigDirectory(const char *includedir,
const char *calling_file, int calling_lineno,
int depth, int elevel,
ConfigVariable **head_p,
ConfigVariable **tail_p);
extern void FreeConfigVariables(ConfigVariable *list);
extern char *DeescapeQuotedString(const char *s);
/*
* The possible values of an enum variable are specified by an array of
* name-value pairs. The "hidden" flag means the value is accepted but
* won't be displayed when guc.c is asked for a list of acceptable values.
*/
struct config_enum_entry
{
const char *name;
int val;
bool hidden;
};
/*
* Signatures for per-variable check/assign/show hook functions
*/
typedef bool (*GucBoolCheckHook) (bool *newval, void **extra, GucSource source);
typedef bool (*GucIntCheckHook) (int *newval, void **extra, GucSource source);
typedef bool (*GucRealCheckHook) (double *newval, void **extra, GucSource source);
typedef bool (*GucStringCheckHook) (char **newval, void **extra, GucSource source);
typedef bool (*GucEnumCheckHook) (int *newval, void **extra, GucSource source);
typedef void (*GucBoolAssignHook) (bool newval, void *extra);
typedef void (*GucIntAssignHook) (int newval, void *extra);
typedef void (*GucRealAssignHook) (double newval, void *extra);
typedef void (*GucStringAssignHook) (const char *newval, void *extra);
typedef void (*GucEnumAssignHook) (int newval, void *extra);
typedef const char *(*GucShowHook) (void);
/*
* Miscellaneous
*/
typedef enum
{
/* Types of set_config_option actions */
GUC_ACTION_SET, /* regular SET command */
GUC_ACTION_LOCAL, /* SET LOCAL command */
GUC_ACTION_SAVE /* function SET option, or temp assignment */
} GucAction;
#define GUC_QUALIFIER_SEPARATOR '.'
/*
* bit values in "flags" of a GUC variable
*/
#define GUC_LIST_INPUT 0x0001 /* input can be list format */
#define GUC_LIST_QUOTE 0x0002 /* double-quote list elements */
#define GUC_NO_SHOW_ALL 0x0004 /* exclude from SHOW ALL */
#define GUC_NO_RESET 0x400000 /* disallow RESET and SAVE */
#define GUC_NO_RESET_ALL 0x0008 /* exclude from RESET ALL */
#define GUC_REPORT 0x0010 /* auto-report changes to client */
#define GUC_NOT_IN_SAMPLE 0x0020 /* not in postgresql.conf.sample */
#define GUC_DISALLOW_IN_FILE 0x0040 /* can't set in postgresql.conf */
#define GUC_CUSTOM_PLACEHOLDER 0x0080 /* placeholder for custom variable */
#define GUC_SUPERUSER_ONLY 0x0100 /* show only to superusers */
#define GUC_IS_NAME 0x0200 /* limit string to NAMEDATALEN-1 */
#define GUC_NOT_WHILE_SEC_REST 0x0400 /* can't set if security restricted */
#define GUC_DISALLOW_IN_AUTO_FILE 0x0800 /* can't set in
* PG_AUTOCONF_FILENAME */
#define GUC_UNIT_KB 0x1000 /* value is in kilobytes */
#define GUC_UNIT_BLOCKS 0x2000 /* value is in blocks */
#define GUC_UNIT_XBLOCKS 0x3000 /* value is in xlog blocks */
#define GUC_UNIT_MB 0x4000 /* value is in megabytes */
#define GUC_UNIT_BYTE 0x5000 /* value is in bytes */
#define GUC_UNIT_MEMORY 0xF000 /* mask for size-related units */
#define GUC_UNIT_MS 0x10000 /* value is in milliseconds */
#define GUC_UNIT_S 0x20000 /* value is in seconds */
#define GUC_UNIT_MIN 0x30000 /* value is in minutes */
#define GUC_UNIT_TIME 0xF0000 /* mask for time-related units */
#define GUC_EXPLAIN 0x100000 /* include in explain */
/*
* GUC_RUNTIME_COMPUTED is intended for runtime-computed GUCs that are only
* available via 'postgres -C' if the server is not running.
*/
#define GUC_RUNTIME_COMPUTED 0x200000
#define GUC_UNIT (GUC_UNIT_MEMORY | GUC_UNIT_TIME)
/* GUC vars that are actually defined in guc_tables.c, rather than elsewhere */
extern PGDLLIMPORT bool Debug_print_plan;
extern PGDLLIMPORT bool Debug_print_parse;
extern PGDLLIMPORT bool Debug_print_rewritten;
extern PGDLLIMPORT bool Debug_pretty_print;
extern PGDLLIMPORT bool log_parser_stats;
extern PGDLLIMPORT bool log_planner_stats;
extern PGDLLIMPORT bool log_executor_stats;
extern PGDLLIMPORT bool log_statement_stats;
extern PGDLLIMPORT bool log_btree_build_stats;
extern PGDLLIMPORT bool check_function_bodies;
extern PGDLLIMPORT bool session_auth_is_superuser;
extern PGDLLIMPORT bool log_duration;
extern PGDLLIMPORT int log_parameter_max_length;
extern PGDLLIMPORT int log_parameter_max_length_on_error;
extern PGDLLIMPORT int log_min_error_statement;
extern PGDLLIMPORT int log_min_messages;
extern PGDLLIMPORT int client_min_messages;
extern PGDLLIMPORT int log_min_duration_sample;
extern PGDLLIMPORT int log_min_duration_statement;
extern PGDLLIMPORT int log_temp_files;
extern PGDLLIMPORT double log_statement_sample_rate;
extern PGDLLIMPORT double log_xact_sample_rate;
extern PGDLLIMPORT char *backtrace_functions;
extern PGDLLIMPORT int temp_file_limit;
extern PGDLLIMPORT int num_temp_buffers;
extern PGDLLIMPORT char *cluster_name;
extern PGDLLIMPORT char *ConfigFileName;
extern PGDLLIMPORT char *HbaFileName;
extern PGDLLIMPORT char *IdentFileName;
extern PGDLLIMPORT char *external_pid_file;
extern PGDLLIMPORT char *application_name;
extern PGDLLIMPORT int tcp_keepalives_idle;
extern PGDLLIMPORT int tcp_keepalives_interval;
extern PGDLLIMPORT int tcp_keepalives_count;
extern PGDLLIMPORT int tcp_user_timeout;
#ifdef TRACE_SORT
extern PGDLLIMPORT bool trace_sort;
#endif
/*
* Functions exported by guc.c
*/
extern void SetConfigOption(const char *name, const char *value,
GucContext context, GucSource source);
extern void DefineCustomBoolVariable(const char *name,
const char *short_desc,
const char *long_desc,
bool *valueAddr,
bool bootValue,
GucContext context,
int flags,
GucBoolCheckHook check_hook,
GucBoolAssignHook assign_hook,
GucShowHook show_hook) pg_attribute_nonnull(1, 4);
extern void DefineCustomIntVariable(const char *name,
const char *short_desc,
const char *long_desc,
int *valueAddr,
int bootValue,
int minValue,
int maxValue,
GucContext context,
int flags,
GucIntCheckHook check_hook,
GucIntAssignHook assign_hook,
GucShowHook show_hook) pg_attribute_nonnull(1, 4);
extern void DefineCustomRealVariable(const char *name,
const char *short_desc,
const char *long_desc,
double *valueAddr,
double bootValue,
double minValue,
double maxValue,
GucContext context,
int flags,
GucRealCheckHook check_hook,
GucRealAssignHook assign_hook,
GucShowHook show_hook) pg_attribute_nonnull(1, 4);
extern void DefineCustomStringVariable(const char *name,
const char *short_desc,
const char *long_desc,
char **valueAddr,
const char *bootValue,
GucContext context,
int flags,
GucStringCheckHook check_hook,
GucStringAssignHook assign_hook,
GucShowHook show_hook) pg_attribute_nonnull(1, 4);
extern void DefineCustomEnumVariable(const char *name,
const char *short_desc,
const char *long_desc,
int *valueAddr,
int bootValue,
const struct config_enum_entry *options,
GucContext context,
int flags,
GucEnumCheckHook check_hook,
GucEnumAssignHook assign_hook,
GucShowHook show_hook) pg_attribute_nonnull(1, 4);
extern void MarkGUCPrefixReserved(const char *className);
/* old name for MarkGUCPrefixReserved, for backwards compatibility: */
#define EmitWarningsOnPlaceholders(className) MarkGUCPrefixReserved(className)
extern const char *GetConfigOption(const char *name, bool missing_ok,
bool restrict_privileged);
extern const char *GetConfigOptionResetString(const char *name);
extern int GetConfigOptionFlags(const char *name, bool missing_ok);
extern void ProcessConfigFile(GucContext context);
extern char *convert_GUC_name_for_parameter_acl(const char *name);
extern bool check_GUC_name_for_parameter_acl(const char *name);
extern void InitializeGUCOptions(void);
extern bool SelectConfigFiles(const char *userDoption, const char *progname);
extern void ResetAllOptions(void);
extern void AtStart_GUC(void);
extern int NewGUCNestLevel(void);
extern void AtEOXact_GUC(bool isCommit, int nestLevel);
extern void BeginReportingGUCOptions(void);
extern void ReportChangedGUCOptions(void);
extern void ParseLongOption(const char *string, char **name, char **value);
extern const char *get_config_unit_name(int flags);
extern bool parse_int(const char *value, int *result, int flags,
const char **hintmsg);
extern bool parse_real(const char *value, double *result, int flags,
const char **hintmsg);
extern int set_config_option(const char *name, const char *value,
GucContext context, GucSource source,
GucAction action, bool changeVal, int elevel,
bool is_reload);
extern int set_config_option_ext(const char *name, const char *value,
GucContext context, GucSource source,
Oid srole,
GucAction action, bool changeVal, int elevel,
bool is_reload);
extern void AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt);
extern char *GetConfigOptionByName(const char *name, const char **varname,
bool missing_ok);
extern int GetNumConfigOptions(void);
extern void ProcessGUCArray(ArrayType *array,
GucContext context, GucSource source, GucAction action);
extern ArrayType *GUCArrayAdd(ArrayType *array, const char *name, const char *value);
extern ArrayType *GUCArrayDelete(ArrayType *array, const char *name);
extern ArrayType *GUCArrayReset(ArrayType *array);
extern void *guc_malloc(int elevel, size_t size);
extern pg_nodiscard void *guc_realloc(int elevel, void *old, size_t size);
extern char *guc_strdup(int elevel, const char *src);
#ifdef EXEC_BACKEND
extern void write_nondefault_variables(GucContext context);
extern void read_nondefault_variables(void);
#endif
/* GUC serialization */
extern Size EstimateGUCStateSpace(void);
extern void SerializeGUCState(Size maxsize, char *start_address);
extern void RestoreGUCState(void *gucstate);
/* Functions exported by guc_funcs.c */
extern void ExecSetVariableStmt(VariableSetStmt *stmt, bool isTopLevel);
extern char *ExtractSetVariableArgs(VariableSetStmt *stmt);
extern void SetPGVariable(const char *name, List *args, bool is_local);
extern void GetPGVariable(const char *name, DestReceiver *dest);
extern TupleDesc GetPGVariableResultDesc(const char *name);
/* Support for messages reported from GUC check hooks */
extern PGDLLIMPORT char *GUC_check_errmsg_string;
extern PGDLLIMPORT char *GUC_check_errdetail_string;
extern PGDLLIMPORT char *GUC_check_errhint_string;
extern void GUC_check_errcode(int sqlerrcode);
#define GUC_check_errmsg \
pre_format_elog_string(errno, TEXTDOMAIN), \
GUC_check_errmsg_string = format_elog_string
#define GUC_check_errdetail \
pre_format_elog_string(errno, TEXTDOMAIN), \
GUC_check_errdetail_string = format_elog_string
#define GUC_check_errhint \
pre_format_elog_string(errno, TEXTDOMAIN), \
GUC_check_errhint_string = format_elog_string
#endif /* GUC_H */
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