include_if_exists facility for config file.

This works the same as include, except that an error is not thrown
if the file is missing. Instead the fact that it's missing is
logged.

Greg Smith, reviewed by Euler Taveira de Oliveira.

2 files changed, 34 insertions, 9 deletions

diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
index a094c7a2d2d..5fe5d14544c 100644
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/backend/utils/misc/guc-file.l
@@ -129,7 +129,7 @@ ProcessConfigFile(GucContext context)
 	/* Parse the file into a list of option names and values */
 	head = tail = NULL;
 
-	if (!ParseConfigFile(ConfigFileName, NULL, 0, elevel, &head, &tail))
+	if (!ParseConfigFile(ConfigFileName, NULL, true, 0, elevel, &head, &tail))
 	{
 		/* Syntax error(s) detected in the file, so bail out */
 		error = true;
@@ -363,7 +363,7 @@ ProcessConfigFile(GucContext context)
  * and absolute-ifying the path name if necessary.
  */
 bool
-ParseConfigFile(const char *config_file, const char *calling_file,
+ParseConfigFile(const char *config_file, const char *calling_file, bool strict,
 				int depth, int elevel,
 				ConfigVariable **head_p,
 				ConfigVariable **tail_p)
@@ -414,11 +414,19 @@ ParseConfigFile(const char *config_file, const char *calling_file,
 	fp = AllocateFile(config_file, "r");
 	if (!fp)
 	{
-		ereport(elevel,
-				(errcode_for_file_access(),
-				 errmsg("could not open configuration file \"%s\": %m",
+		if (strict)
+		{
+			ereport(elevel,
+					(errcode_for_file_access(),
+					 errmsg("could not open configuration file \"%s\": %m",
+							config_file)));
+			return false;
+		}
+
+		ereport(LOG, 
+				(errmsg("skipping missing configuration file \"%s\"", 
 						config_file)));
-		return false;
+		return OK;
 	}
 
 	OK = ParseConfigFp(fp, config_file, depth, elevel, head_p, tail_p);
@@ -512,7 +520,24 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 		}
 
 		/* OK, process the option name and value */
-		if (guc_name_compare(opt_name, "include") == 0)
+		if (guc_name_compare(opt_name, "include_if_exists") == 0)
+		{
+			/*
+			 * An include_if_exists directive isn't a variable and should be
+			 * processed immediately.
+			 */
+			unsigned int save_ConfigFileLineno = ConfigFileLineno;
+
+			if (!ParseConfigFile(opt_value, config_file, false,
+								 depth + 1, elevel,
+								 head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			ConfigFileLineno = save_ConfigFileLineno;
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else if (guc_name_compare(opt_name, "include") == 0)
 		{
 			/*
 			 * An include directive isn't a variable and should be processed
@@ -520,7 +545,7 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 			 */
 			unsigned int save_ConfigFileLineno = ConfigFileLineno;
 
-			if (!ParseConfigFile(opt_value, config_file,
+			if (!ParseConfigFile(opt_value, config_file, true,
 								 depth + 1, elevel,
 								 head_p, tail_p))
 				OK = false;
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 8e3057a0140..52109e533c9 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -111,7 +111,7 @@ typedef struct ConfigVariable
 } ConfigVariable;
 
 extern bool ParseConfigFile(const char *config_file, const char *calling_file,
-				int depth, int elevel,
+				bool strict, int depth, int elevel,
 				ConfigVariable **head_p, ConfigVariable **tail_p);
 extern bool ParseConfigFp(FILE *fp, const char *config_file,
 			  int depth, int elevel,