Support include directives in postgresql.conf.

Patch by Joachim Wieland, somewhat reworked for clarity and portability.

doc/src/sgml/config.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.48 2006/03/03 22:02:07 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.49 2006/03/04 22:19:31 tgl Exp $
 -->
 <chapter Id="runtime-config">
   <title>Server Configuration</title>
@@ -47,7 +47,24 @@ search_path = '"$user", public'
     anywhere.  Parameter values that are not simple identifiers or
     numbers must be single-quoted.  To embed a single quote in a parameter
     value, write either two quotes (preferred) or backslash-quote.
-  </para>
+   </para>
+
+   <para>
+    <indexterm>
+     <primary><literal>include</></primary>
+     <secondary>in configuration file</secondary>
+    </indexterm>
+    In addition to parameter settings, the <filename>postgresql.conf</>
+    file can contain <firstterm>include directives</>, which specify
+    another file to read and process as if it were inserted into the
+    configuration file at this point.  Include directives simply look like
+<programlisting>
+include 'filename'
+</programlisting>
+    If the filename is not an absolute path, it is taken as relative to
+    the directory containing the referencing configuration file.
+    Inclusions can be nested.
+   </para>
 
    <para>
     <indexterm>

src/backend/utils/misc/guc-file.l

@@ -4,26 +4,25 @@
  *
  * Copyright (c) 2000-2005, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/backend/utils/misc/guc-file.l,v 1.34 2006/01/02 19:55:25 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/misc/guc-file.l,v 1.35 2006/03/04 22:19:31 tgl Exp $
  */
 
 %{
 
 #include "postgres.h"
 
-#include <unistd.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)))
 
-static unsigned ConfigFileLineno;
-
 enum {
 	GUC_ID = 1,
 	GUC_STRING = 2,
@@ -36,9 +35,25 @@ enum {
 	GUC_ERROR = 100
 };
 
-/* prototype, so compiler is happy with our high warnings setting */
+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
@@ -85,38 +100,9 @@ STRING          \'([^'\\\n]|\\.|\'\')*\'
 %%
 
 
-struct name_value_pair
-{
-	char       *name;
-	char       *value;
-	struct name_value_pair *next;
-};
-
-
-/*
- * Free a list of name/value pairs, including the names and the values
- */
-static void
-free_name_value_list(struct name_value_pair * list)
-{
-	struct name_value_pair *item;
-
-	item = list;
-	while (item)
-	{
-		struct name_value_pair *save;
-
-		save = item->next;
-		pfree(item->name);
-		pfree(item->value);
-		pfree(item);
-		item = save;
-	}
-}
-
 
 /*
- * Official function to read and process the configuration file. The
+ * 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.
@@ -126,10 +112,7 @@ void
 ProcessConfigFile(GucContext context)
 {
 	int			elevel;
-	int			token;
-	char	   *opt_name, *opt_value;
 	struct name_value_pair *item, *head, *tail;
-	FILE	   *fp;
 
 	Assert(context == PGC_POSTMASTER || context == PGC_SIGHUP);
 
@@ -144,27 +127,124 @@ ProcessConfigFile(GucContext context)
 	else
 		elevel = ERROR;
 
-	fp = AllocateFile(ConfigFileName, "r");
+	head = tail = NULL;
+
+	if (!ParseConfigFile(ConfigFileName, NULL,
+						 0, context, elevel,
+						 &head, &tail))
+		goto cleanup_list;
+
+	/* Check if all options are valid */
+	for (item = head; item; item = item->next)
+	{
+		if (!set_config_option(item->name, item->value, context,
+							   PGC_S_FILE, false, false))
+			goto cleanup_list;
+	}
+
+	/* 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, false, true);
+	}
+
+ cleanup_list:
+	free_name_value_list(head);
+}
+
+
+/*
+ * 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
+ *	calling_file: absolute path of file containing the "include" directive,
+ *		or NULL at outer level (config_file must be absolute at outer level)
+ *	depth: recursion depth (used only to prevent infinite recursion)
+ *	context: GucContext passed to ProcessConfigFile()
+ *	elevel: error logging level determined by ProcessConfigFile()
+ * Output parameters:
+ *	head_p, tail_p: head and tail of linked list of name/value pairs
+ *
+ * *head_p and *tail_p must be initialized to NULL before calling the outer
+ * recursion level.  On exit, they contain a list of name-value pairs read
+ * from the input file(s).
+ *
+ * Returns TRUE if successful, FALSE if an error occurred.  The error has
+ * already been ereport'd, it is only necessary for the caller to clean up
+ * its own state and release the name/value pairs list.
+ *
+ * Note: if elevel >= ERROR then an error will not return control to the
+ * caller, and internal state such as open files will not be cleaned up.
+ * This case occurs only during postmaster or standalone-backend startup,
+ * where an error will lead to immediate process exit anyway; so there is
+ * no point in contorting the code so it can clean up nicely.
+ */
+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)
+{
+	bool		OK = true;
+	char		abs_path[MAXPGPATH];
+	FILE	   *fp;
+	YY_BUFFER_STATE lex_buffer;
+	int			token;
+
+	/*
+	 * Reject too-deep include nesting depth.  This is just a safety check
+	 * to avoid dumping core due to stack overflow if an include file loops
+	 * back to itself.  The maximum nesting depth is pretty arbitrary.
+	 */
+	if (depth > 10)
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				 errmsg("could not open configuration file \"%s\": maximum nesting depth exceeded",
+						config_file)));
+		return false;
+	}
+
+	/*
+	 * If config_file is a relative path, convert to absolute.  We consider
+	 * it to be relative to the directory holding the calling file.
+	 */
+	if (!is_absolute_path(config_file))
+	{
+		Assert(calling_file != NULL);
+		StrNCpy(abs_path, calling_file, MAXPGPATH);
+		get_parent_directory(abs_path);
+		join_path_components(abs_path, abs_path, config_file);
+		canonicalize_path(abs_path);
+		config_file = abs_path;
+	}
+
+	fp = AllocateFile(config_file, "r");
 	if (!fp)
 	{
 		ereport(elevel,
 				(errcode_for_file_access(),
 				 errmsg("could not open configuration file \"%s\": %m",
-						ConfigFileName)));
-		return;
+						config_file)));
+		return false;
 	}
 
 	/*
 	 * Parse
 	 */
-	yyrestart(fp);
-	head = tail = NULL;
-	opt_name = opt_value = NULL;
+	lex_buffer = yy_create_buffer(fp, YY_BUF_SIZE);
+	yy_switch_to_buffer(lex_buffer);
+
 	ConfigFileLineno = 1;
 
 	/* This loop iterates once per logical line */
 	while ((token = yylex()))
 	{
+		char	   *opt_name, *opt_value;
+
 		if (token == GUC_EOL)	/* empty or comment line */
 			continue;
 
@@ -195,8 +275,30 @@ ProcessConfigFile(GucContext context)
 		if (token != GUC_EOL && token != 0)
 			goto parse_error;
 
-		/* OK, save the option name and value */
-		if (strcmp(opt_name, "custom_variable_classes") == 0)
+		/* OK, process the option name and value */
+		if (pg_strcasecmp(opt_name, "include") == 0)
+		{
+			/*
+			 * An include directive isn't a variable and should be processed
+			 * immediately.
+			 */
+			unsigned int save_ConfigFileLineno = ConfigFileLineno;
+
+			if (!ParseConfigFile(opt_value, config_file,
+								 depth + 1, context, elevel,
+								 head_p, tail_p))
+			{
+				pfree(opt_name);
+				pfree(opt_value);
+				OK = false;
+				goto cleanup_exit;
+			}
+			yy_switch_to_buffer(lex_buffer);
+			ConfigFileLineno = save_ConfigFileLineno;
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else if (pg_strcasecmp(opt_name, "custom_variable_classes") == 0)
 		{
 			/*
 			 * This variable must be processed first as it controls
@@ -207,7 +309,8 @@ ProcessConfigFile(GucContext context)
 			{
 				pfree(opt_name);
 				pfree(opt_value);
-				FreeFile(fp);
+				/* we assume error message was logged already */
+				OK = false;
 				goto cleanup_exit;
 			}
 			pfree(opt_name);
@@ -216,15 +319,17 @@ ProcessConfigFile(GucContext context)
 		else
 		{
 			/* append to list */
+			struct name_value_pair *item;
+
 			item = palloc(sizeof *item);
 			item->name = opt_name;
 			item->value = opt_value;
 			item->next = NULL;
-			if (!head)
-				head = item;
+			if (*head_p == NULL)
+				*head_p = item;
 			else
-				tail->next = item;
-			tail = item;
+				(*tail_p)->next = item;
+			*tail_p = item;
 		}
 
 		/* break out of loop if read EOF, else loop for next line */
@@ -232,45 +337,49 @@ ProcessConfigFile(GucContext context)
 			break;
 	}
 
-	FreeFile(fp);
-
-	/*
-	 * Check if all options are valid
-	 */
-	for(item = head; item; item=item->next)
-	{
-		if (!set_config_option(item->name, item->value, context,
-							   PGC_S_FILE, false, false))
-			goto cleanup_exit;
-	}
-
-	/* If we got here all the options parsed okay, so apply them. */
-	for(item = head; item; item=item->next)
-	{
-		set_config_option(item->name, item->value, context,
-						  PGC_S_FILE, false, true);
-	}
-
- cleanup_exit:
-	free_name_value_list(head);
-	return;
+	/* successful completion of parsing */
+	goto cleanup_exit;
 
  parse_error:
-	FreeFile(fp);
-	free_name_value_list(head);
 	if (token == GUC_EOL || token == 0)
 		ereport(elevel,
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("syntax error in file \"%s\" line %u, near end of line",
-						ConfigFileName, ConfigFileLineno - 1)));
+						config_file, ConfigFileLineno - 1)));
 	else
 		ereport(elevel,
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("syntax error in file \"%s\" line %u, near token \"%s\"", 
-						ConfigFileName, ConfigFileLineno, yytext)));
+						config_file, ConfigFileLineno, yytext)));
+	OK = false;
+
+cleanup_exit:
+	yy_delete_buffer(lex_buffer);
+	FreeFile(fp);
+	return OK;
 }
 
 
+/*
+ * Free a list of name/value pairs, including the names and the values
+ */
+static void
+free_name_value_list(struct name_value_pair *list)
+{
+	struct name_value_pair *item;
+
+	item = list;
+	while (item)
+	{
+		struct name_value_pair *next = item->next;
+
+		pfree(item->name);
+		pfree(item->value);
+		pfree(item);
+		item = next;
+	}
+}
+
 
 /*
  *		scanstr