guc-file.l

postgresql8.3.4源码,开源数据库

/* -*-pgsql-c-*- */
/*
 * Scanner for the configuration file
 *
 * Copyright (c) 2000-2008, PostgreSQL Global Development Group
 *
 * $PostgreSQL: pgsql/src/backend/utils/misc/guc-file.l,v 1.53 2008/01/01 19:45:54 momjian Exp $
 */

%{

#include "postgres.h"

#include <ctype.h>
#include <unistd.h>

#include "miscadmin.h"
#include "storage/fd.h"
#include "utils/guc.h"


/* Avoid exit() on fatal scanner errors (a bit ugly -- see yy_fatal_error) */
#undef fprintf
#define fprintf(file, fmt, msg)  ereport(ERROR, (errmsg_internal("%s", msg)))

enum {
	GUC_ID = 1,
	GUC_STRING = 2,
	GUC_INTEGER = 3,
	GUC_REAL = 4,
	GUC_EQUALS = 5,
	GUC_UNQUOTED_STRING = 6,
	GUC_QUALIFIED_ID = 7,
	GUC_EOL = 99,
	GUC_ERROR = 100
};

struct name_value_pair
{
	char       *name;
	char       *value;
	struct name_value_pair *next;
};

static unsigned int ConfigFileLineno;

/* flex fails to supply a prototype for yylex, so provide one */
int GUC_yylex(void);

static bool ParseConfigFile(const char *config_file, const char *calling_file,
							int depth, GucContext context, int elevel,
							struct name_value_pair **head_p,
							struct name_value_pair **tail_p);
static void free_name_value_list(struct name_value_pair * list);
static char *GUC_scanstr(const char *s);

%}

%option 8bit
%option never-interactive
%option nodefault
%option nounput
%option noyywrap
%option prefix="GUC_yy"


SIGN            ("-"|"+")
DIGIT           [0-9]
HEXDIGIT        [0-9a-fA-F]

UNIT_LETTER     [a-zA-Z]

INTEGER         {SIGN}?({DIGIT}+|0x{HEXDIGIT}+){UNIT_LETTER}*

EXPONENT        [Ee]{SIGN}?{DIGIT}+
REAL            {SIGN}?{DIGIT}*"."{DIGIT}*{EXPONENT}?

LETTER          [A-Za-z_\200-\377]
LETTER_OR_DIGIT [A-Za-z_0-9\200-\377]

ID              {LETTER}{LETTER_OR_DIGIT}*
QUALIFIED_ID    {ID}"."{ID}

UNQUOTED_STRING {LETTER}({LETTER_OR_DIGIT}|[-._:/])*
STRING          \'([^'\\\n]|\\.|\'\')*\'

%%

\n              ConfigFileLineno++; return GUC_EOL;
[ \t\r]+        /* eat whitespace */
#.*             /* eat comment (.* matches anything until newline) */

{ID}            return GUC_ID;
{QUALIFIED_ID}  return GUC_QUALIFIED_ID;
{STRING}        return GUC_STRING;
{UNQUOTED_STRING} return GUC_UNQUOTED_STRING;
{INTEGER}       return GUC_INTEGER;
{REAL}          return GUC_REAL;
=               return GUC_EQUALS;

.               return GUC_ERROR;

%%



/*
 * Exported function to read and process the configuration file. The
 * parameter indicates in what context the file is being read --- either
 * postmaster startup (including standalone-backend startup) or SIGHUP.
 * All options mentioned in the configuration file are set to new values.
 * If an error occurs, no values will be changed.
 */
void
ProcessConfigFile(GucContext context)
{
	int			elevel;
	struct name_value_pair *item, *head, *tail;
	char	   *cvc = NULL;
	struct config_string *cvc_struct;
	const char *envvar;
	int			i;

	Assert(context == PGC_POSTMASTER || context == PGC_SIGHUP);

	if (context == PGC_SIGHUP)
	{
		/*
		 * To avoid cluttering the log, only the postmaster bleats loudly
		 * about problems with the config file.
		 */
		elevel = IsUnderPostmaster ? DEBUG2 : LOG;
	}
	else
		elevel = ERROR;

	/* Parse the file into a list of option names and values */
	head = tail = NULL;

	if (!ParseConfigFile(ConfigFileName, NULL,
						 0, context, elevel,
						 &head, &tail))
		goto cleanup_list;

	/*
	 * We need the proposed new value of custom_variable_classes to check
	 * custom variables with.  ParseConfigFile ensured that if it's in
	 * the file, it's first in the list.  But first check to see if we
	 * have an active value from the command line, which should override
	 * the file in any case.  (Since there's no relevant env var, the
	 * only possible nondefault sources are the file and ARGV.)
	 */
	cvc_struct = (struct config_string *)
		find_option("custom_variable_classes", false, elevel);
	if (cvc_struct && cvc_struct->gen.reset_source > PGC_S_FILE)
	{
		cvc = guc_strdup(elevel, cvc_struct->reset_val);
		if (cvc == NULL)
			goto cleanup_list;
	}
	else if (head != NULL &&
			 guc_name_compare(head->name, "custom_variable_classes") == 0)
	{
		/*
		 * Need to canonicalize the value via the assign hook.  Casting away
		 * const is a bit ugly, but we know the result is malloc'd.
		 */
		cvc = (char *) assign_custom_variable_classes(head->value,
													  false, PGC_S_FILE);
		if (cvc == NULL)
		{
			ereport(elevel,
					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
					 errmsg("invalid value for parameter \"%s\": \"%s\"",
							head->name, head->value)));
			goto cleanup_list;
		}
	}

	/*
	 * Mark all extant GUC variables as not present in the config file.
	 * We need this so that we can tell below which ones have been removed
	 * from the file since we last processed it.
	 */
	for (i = 0; i < num_guc_variables; i++)
	{
		struct config_generic *gconf = guc_variables[i];

		gconf->status &= ~GUC_IS_IN_FILE;
	}

	/*
	 * Check if all options are valid.  As a side-effect, the GUC_IS_IN_FILE
	 * flag is set on each GUC variable mentioned in the list.
	 */
	for (item = head; item; item = item->next)
	{
		char *sep = strchr(item->name, GUC_QUALIFIER_SEPARATOR);

		if (sep)
		{
			/*
			 * We have to consider three cases for custom variables:
			 *
			 * 1. The class name is not valid according to the (new) setting
			 * of custom_variable_classes.  If so, reject.  We don't care
			 * which side is at fault.
			 */
			if (!is_custom_class(item->name, sep - item->name, cvc))
			{
				ereport(elevel,
						(errcode(ERRCODE_UNDEFINED_OBJECT),
						 errmsg("unrecognized configuration parameter \"%s\"",
								item->name)));
				goto cleanup_list;
			}
			/*
			 * 2. There is no GUC entry.  If we called set_config_option then
			 * it would make a placeholder, which we don't want to do yet,
			 * since we could still fail further down the list.  Do nothing
			 * (assuming that making the placeholder will succeed later).
			 */
			if (find_option(item->name, false, elevel) == NULL)
				continue;
			/*
			 * 3. There is already a GUC entry (either real or placeholder) for
			 * the variable.  In this case we should let set_config_option
			 * check it, since the assignment could well fail if it's a real
			 * entry.
			 */
		}

		if (!set_config_option(item->name, item->value, context,
							   PGC_S_FILE, GUC_ACTION_SET, false))
			goto cleanup_list;
	}

	/*
	 * Check for variables having been removed from the config file, and
	 * revert their reset values (and perhaps also effective values) to the
	 * boot-time defaults.  If such a variable can't be changed after startup,
	 * just throw a warning and continue.  (This is analogous to the fact that
	 * set_config_option only throws a warning for a new but different value.
	 * If we wanted to make it a hard error, we'd need an extra pass over the
	 * list so that we could throw the error before starting to apply
	 * changes.)
	 */
	for (i = 0; i < num_guc_variables; i++)
	{
		struct config_generic *gconf = guc_variables[i];
		GucStack   *stack;

		if (gconf->reset_source != PGC_S_FILE ||
			(gconf->status & GUC_IS_IN_FILE))
			continue;
		if (gconf->context < PGC_SIGHUP)
		{
			ereport(elevel,
					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
					 errmsg("parameter \"%s\" cannot be changed after server start; configuration file change ignored",
							gconf->name)));
			continue;
		}

		/*
		 * Reset any "file" sources to "default", else set_config_option
		 * will not override those settings.
		 */
		if (gconf->reset_source == PGC_S_FILE)
			gconf->reset_source = PGC_S_DEFAULT;
		if (gconf->source == PGC_S_FILE)
			gconf->source = PGC_S_DEFAULT;
		for (stack = gconf->stack; stack; stack = stack->prev)
		{
			if (stack->source == PGC_S_FILE)
				stack->source = PGC_S_DEFAULT;
		}

		/* Now we can re-apply the wired-in default */
		set_config_option(gconf->name, NULL, context, PGC_S_DEFAULT,
						  GUC_ACTION_SET, true);
	}

	/*
	 * Restore any variables determined by environment variables.  This
	 * is a no-op except in the case where one of these had been in the
	 * config file and is now removed.  PGC_S_ENV_VAR will override the
	 * wired-in default we just applied, but cannot override any other source.
	 *
	 * Keep this list in sync with InitializeGUCOptions()!
	 * PGPORT can be ignored, because it cannot be changed without restart.
	 * We assume rlimit hasn't changed, either.
	 */
	envvar = getenv("PGDATESTYLE");
	if (envvar != NULL)
		set_config_option("datestyle", envvar, PGC_POSTMASTER,
						  PGC_S_ENV_VAR, GUC_ACTION_SET, true);

	envvar = getenv("PGCLIENTENCODING");
	if (envvar != NULL)
		set_config_option("client_encoding", envvar, PGC_POSTMASTER,
						  PGC_S_ENV_VAR, GUC_ACTION_SET, true);


	/* If we got here all the options checked out okay, so apply them. */
	for (item = head; item; item = item->next)
	{
		set_config_option(item->name, item->value, context,
						  PGC_S_FILE, GUC_ACTION_SET, true);
	}

 cleanup_list:
	free_name_value_list(head);
	if (cvc)
		free(cvc);
}


/*
 * Read and parse a single configuration file.  This function recurses
 * to handle "include" directives.
 *
 * Input parameters:
 *	config_file: absolute or relative path of file to read