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Make configuration parameters fall back to their default values when they are removed from the configuration file. Joachim Wieland
478 lines
11 KiB
Plaintext
478 lines
11 KiB
Plaintext
/* -*-pgsql-c-*- */
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/*
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* Scanner for the configuration file
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*
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* Copyright (c) 2000-2007, PostgreSQL Global Development Group
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*
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* $PostgreSQL: pgsql/src/backend/utils/misc/guc-file.l,v 1.49 2007/03/13 14:32:25 petere Exp $
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*/
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%{
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#include "postgres.h"
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#include <ctype.h>
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#include <unistd.h>
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#include "miscadmin.h"
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#include "storage/fd.h"
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#include "utils/guc.h"
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/* Avoid exit() on fatal scanner errors (a bit ugly -- see yy_fatal_error) */
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#undef fprintf
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#define fprintf(file, fmt, msg) ereport(ERROR, (errmsg_internal("%s", msg)))
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enum {
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GUC_ID = 1,
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GUC_STRING = 2,
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GUC_INTEGER = 3,
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GUC_REAL = 4,
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GUC_EQUALS = 5,
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GUC_UNQUOTED_STRING = 6,
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GUC_QUALIFIED_ID = 7,
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GUC_EOL = 99,
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GUC_ERROR = 100
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};
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struct name_value_pair
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{
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char *name;
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char *value;
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struct name_value_pair *next;
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};
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static unsigned int ConfigFileLineno;
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/* flex fails to supply a prototype for yylex, so provide one */
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int GUC_yylex(void);
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static bool ParseConfigFile(const char *config_file, const char *calling_file,
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int depth, GucContext context, int elevel,
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struct name_value_pair **head_p,
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struct name_value_pair **tail_p);
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static void free_name_value_list(struct name_value_pair * list);
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static char *GUC_scanstr(const char *s);
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%}
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%option 8bit
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%option never-interactive
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%option nodefault
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%option nounput
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%option noyywrap
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%option prefix="GUC_yy"
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SIGN ("-"|"+")
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DIGIT [0-9]
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HEXDIGIT [0-9a-fA-F]
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UNIT_LETTER [a-zA-Z]
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INTEGER {SIGN}?({DIGIT}+|0x{HEXDIGIT}+){UNIT_LETTER}*
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EXPONENT [Ee]{SIGN}?{DIGIT}+
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REAL {SIGN}?{DIGIT}*"."{DIGIT}*{EXPONENT}?
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LETTER [A-Za-z_\200-\377]
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LETTER_OR_DIGIT [A-Za-z_0-9\200-\377]
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ID {LETTER}{LETTER_OR_DIGIT}*
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QUALIFIED_ID {ID}"."{ID}
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UNQUOTED_STRING {LETTER}({LETTER_OR_DIGIT}|[-._:/])*
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STRING \'([^'\\\n]|\\.|\'\')*\'
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%%
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\n ConfigFileLineno++; return GUC_EOL;
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[ \t\r]+ /* eat whitespace */
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#.* /* eat comment (.* matches anything until newline) */
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{ID} return GUC_ID;
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{QUALIFIED_ID} return GUC_QUALIFIED_ID;
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{STRING} return GUC_STRING;
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{UNQUOTED_STRING} return GUC_UNQUOTED_STRING;
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{INTEGER} return GUC_INTEGER;
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{REAL} return GUC_REAL;
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= return GUC_EQUALS;
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. return GUC_ERROR;
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%%
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/*
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* Exported function to read and process the configuration file. The
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* parameter indicates in what context the file is being read --- either
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* postmaster startup (including standalone-backend startup) or SIGHUP.
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* All options mentioned in the configuration file are set to new values.
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* If an error occurs, no values will be changed.
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*/
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void
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ProcessConfigFile(GucContext context)
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{
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int elevel;
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struct name_value_pair *item, *head, *tail;
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Assert(context == PGC_POSTMASTER || context == PGC_SIGHUP);
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if (context == PGC_SIGHUP)
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{
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/*
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* To avoid cluttering the log, only the postmaster bleats loudly
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* about problems with the config file.
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*/
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elevel = IsUnderPostmaster ? DEBUG2 : LOG;
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}
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else
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elevel = ERROR;
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head = tail = NULL;
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if (!ParseConfigFile(ConfigFileName, NULL,
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0, context, elevel,
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&head, &tail))
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goto cleanup_list;
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/* Check if all options are valid */
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for (item = head; item; item = item->next)
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{
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if (!set_config_option(item->name, item->value, context,
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PGC_S_FILE, false, false))
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goto cleanup_list;
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}
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/* If we got here all the options checked out okay, so apply them. */
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for (item = head; item; item = item->next)
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{
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set_config_option(item->name, item->value, context,
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PGC_S_FILE, false, true);
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}
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cleanup_list:
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free_name_value_list(head);
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}
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/*
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* Read and parse a single configuration file. This function recurses
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* to handle "include" directives.
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*
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* Input parameters:
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* config_file: absolute or relative path of file to read
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* calling_file: absolute path of file containing the "include" directive,
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* or NULL at outer level (config_file must be absolute at outer level)
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* depth: recursion depth (used only to prevent infinite recursion)
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* context: GucContext passed to ProcessConfigFile()
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* elevel: error logging level determined by ProcessConfigFile()
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* Output parameters:
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* head_p, tail_p: head and tail of linked list of name/value pairs
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*
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* *head_p and *tail_p must be initialized to NULL before calling the outer
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* recursion level. On exit, they contain a list of name-value pairs read
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* from the input file(s).
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*
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* Returns TRUE if successful, FALSE if an error occurred. The error has
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* already been ereport'd, it is only necessary for the caller to clean up
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* its own state and release the name/value pairs list.
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*
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* Note: if elevel >= ERROR then an error will not return control to the
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* caller, and internal state such as open files will not be cleaned up.
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* This case occurs only during postmaster or standalone-backend startup,
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* where an error will lead to immediate process exit anyway; so there is
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* no point in contorting the code so it can clean up nicely.
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*/
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static bool
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ParseConfigFile(const char *config_file, const char *calling_file,
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int depth, GucContext context, int elevel,
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struct name_value_pair **head_p,
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struct name_value_pair **tail_p)
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{
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bool OK = true;
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char abs_path[MAXPGPATH];
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FILE *fp;
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YY_BUFFER_STATE lex_buffer;
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int token;
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/*
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* Reject too-deep include nesting depth. This is just a safety check
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* to avoid dumping core due to stack overflow if an include file loops
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* back to itself. The maximum nesting depth is pretty arbitrary.
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*/
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if (depth > 10)
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{
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ereport(elevel,
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(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
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errmsg("could not open configuration file \"%s\": maximum nesting depth exceeded",
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config_file)));
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return false;
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}
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/*
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* If config_file is a relative path, convert to absolute. We consider
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* it to be relative to the directory holding the calling file.
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*/
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if (!is_absolute_path(config_file))
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{
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Assert(calling_file != NULL);
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strlcpy(abs_path, calling_file, sizeof(abs_path));
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get_parent_directory(abs_path);
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join_path_components(abs_path, abs_path, config_file);
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canonicalize_path(abs_path);
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config_file = abs_path;
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}
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fp = AllocateFile(config_file, "r");
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if (!fp)
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{
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ereport(elevel,
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(errcode_for_file_access(),
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errmsg("could not open configuration file \"%s\": %m",
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config_file)));
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return false;
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}
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/*
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* Parse
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*/
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lex_buffer = yy_create_buffer(fp, YY_BUF_SIZE);
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yy_switch_to_buffer(lex_buffer);
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ConfigFileLineno = 1;
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/* This loop iterates once per logical line */
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while ((token = yylex()))
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{
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char *opt_name, *opt_value;
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if (token == GUC_EOL) /* empty or comment line */
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continue;
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/* first token on line is option name */
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if (token != GUC_ID && token != GUC_QUALIFIED_ID)
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goto parse_error;
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opt_name = pstrdup(yytext);
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/* next we have an optional equal sign; discard if present */
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token = yylex();
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if (token == GUC_EQUALS)
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token = yylex();
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/* now we must have the option value */
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if (token != GUC_ID &&
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token != GUC_STRING &&
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token != GUC_INTEGER &&
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token != GUC_REAL &&
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token != GUC_UNQUOTED_STRING)
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goto parse_error;
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if (token == GUC_STRING) /* strip quotes and escapes */
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opt_value = GUC_scanstr(yytext);
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else
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opt_value = pstrdup(yytext);
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/* now we'd like an end of line, or possibly EOF */
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token = yylex();
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if (token != GUC_EOL && token != 0)
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goto parse_error;
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/* OK, process the option name and value */
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if (pg_strcasecmp(opt_name, "include") == 0)
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{
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/*
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* An include directive isn't a variable and should be processed
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* immediately.
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*/
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unsigned int save_ConfigFileLineno = ConfigFileLineno;
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if (!ParseConfigFile(opt_value, config_file,
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depth + 1, context, elevel,
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head_p, tail_p))
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{
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pfree(opt_name);
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pfree(opt_value);
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OK = false;
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goto cleanup_exit;
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}
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yy_switch_to_buffer(lex_buffer);
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ConfigFileLineno = save_ConfigFileLineno;
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pfree(opt_name);
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pfree(opt_value);
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}
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else if (pg_strcasecmp(opt_name, "custom_variable_classes") == 0)
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{
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/*
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* This variable must be processed first as it controls
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* the validity of other variables; so apply immediately.
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*/
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if (!set_config_option(opt_name, opt_value, context,
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PGC_S_FILE, false, true))
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{
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pfree(opt_name);
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pfree(opt_value);
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/* we assume error message was logged already */
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OK = false;
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goto cleanup_exit;
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}
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pfree(opt_name);
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pfree(opt_value);
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}
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else
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{
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/* append to list */
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struct name_value_pair *item;
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item = palloc(sizeof *item);
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item->name = opt_name;
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item->value = opt_value;
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item->next = NULL;
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if (*head_p == NULL)
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*head_p = item;
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else
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(*tail_p)->next = item;
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*tail_p = item;
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}
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/* break out of loop if read EOF, else loop for next line */
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if (token == 0)
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break;
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}
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/* successful completion of parsing */
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goto cleanup_exit;
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parse_error:
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if (token == GUC_EOL || token == 0)
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ereport(elevel,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("syntax error in file \"%s\" line %u, near end of line",
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config_file, ConfigFileLineno - 1)));
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else
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ereport(elevel,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("syntax error in file \"%s\" line %u, near token \"%s\"",
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config_file, ConfigFileLineno, yytext)));
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OK = false;
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cleanup_exit:
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yy_delete_buffer(lex_buffer);
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FreeFile(fp);
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return OK;
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}
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/*
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* Free a list of name/value pairs, including the names and the values
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*/
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static void
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free_name_value_list(struct name_value_pair *list)
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{
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struct name_value_pair *item;
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item = list;
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while (item)
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{
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struct name_value_pair *next = item->next;
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pfree(item->name);
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pfree(item->value);
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pfree(item);
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item = next;
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}
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}
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/*
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* scanstr
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*
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* Strip the quotes surrounding the given string, and collapse any embedded
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* '' sequences and backslash escapes.
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*
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* the string returned is palloc'd and should eventually be pfree'd by the
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* caller.
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*/
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static char *
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GUC_scanstr(const char *s)
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{
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char *newStr;
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int len,
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i,
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j;
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Assert(s != NULL && s[0] == '\'');
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len = strlen(s);
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Assert(len >= 2);
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Assert(s[len-1] == '\'');
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/* Skip the leading quote; we'll handle the trailing quote below */
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s++, len--;
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/* Since len still includes trailing quote, this is enough space */
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newStr = palloc(len);
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for (i = 0, j = 0; i < len; i++)
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{
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if (s[i] == '\\')
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{
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i++;
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switch (s[i])
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{
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case 'b':
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newStr[j] = '\b';
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break;
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case 'f':
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newStr[j] = '\f';
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break;
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case 'n':
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newStr[j] = '\n';
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break;
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case 'r':
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newStr[j] = '\r';
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break;
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case 't':
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newStr[j] = '\t';
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break;
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case '0':
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case '1':
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case '2':
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case '3':
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case '4':
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case '5':
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case '6':
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case '7':
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{
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int k;
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long octVal = 0;
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for (k = 0;
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s[i + k] >= '0' && s[i + k] <= '7' && k < 3;
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k++)
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octVal = (octVal << 3) + (s[i + k] - '0');
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i += k - 1;
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newStr[j] = ((char) octVal);
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}
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break;
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default:
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newStr[j] = s[i];
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break;
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} /* switch */
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}
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else if (s[i] == '\'' && s[i+1] == '\'')
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{
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/* doubled quote becomes just one quote */
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newStr[j] = s[++i];
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}
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else
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newStr[j] = s[i];
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j++;
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}
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/* We copied the ending quote to newStr, so replace with \0 */
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Assert(j > 0 && j <= len);
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newStr[--j] = '\0';
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return newStr;
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}
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