Fix CRC check handling in get_controlfile

The previous patch broke this by returning NULL for a failed CRC check,
which pg_controldata would then try to read.  Fix by returning the
result of the CRC check in a separate argument.

Michael Paquier and myself

Author: petere

src/backend/utils/misc/pg_controldata.c

@@ -34,6 +34,7 @@ pg_control_system(PG_FUNCTION_ARGS)
 	TupleDesc	tupdesc;
 	HeapTuple	htup;
 	ControlFileData *ControlFile;
+	bool		crc_ok;
 
 	/*
 	 * Construct a tuple descriptor for the result row.  This must match this
@@ -51,8 +52,8 @@ pg_control_system(PG_FUNCTION_ARGS)
 	tupdesc = BlessTupleDesc(tupdesc);
 
 	/* read the control file */
-	ControlFile = get_controlfile(DataDir, NULL);
-	if (!ControlFile)
+	ControlFile = get_controlfile(DataDir, NULL, &crc_ok);
+	if (!crc_ok)
 		ereport(ERROR,
 				(errmsg("calculated CRC checksum does not match value stored in file")));
 
@@ -83,6 +84,7 @@ pg_control_checkpoint(PG_FUNCTION_ARGS)
 	ControlFileData *ControlFile;
 	XLogSegNo	segno;
 	char		xlogfilename[MAXFNAMELEN];
+	bool		crc_ok;
 
 	/*
 	 * Construct a tuple descriptor for the result row.  This must match this
@@ -130,8 +132,8 @@ pg_control_checkpoint(PG_FUNCTION_ARGS)
 	tupdesc = BlessTupleDesc(tupdesc);
 
 	/* Read the control file. */
-	ControlFile = get_controlfile(DataDir, NULL);
-	if (!ControlFile)
+	ControlFile = get_controlfile(DataDir, NULL, &crc_ok);
+	if (!crc_ok)
 		ereport(ERROR,
 				(errmsg("calculated CRC checksum does not match value stored in file")));
 
@@ -216,6 +218,7 @@ pg_control_recovery(PG_FUNCTION_ARGS)
 	TupleDesc	tupdesc;
 	HeapTuple	htup;
 	ControlFileData *ControlFile;
+	bool		crc_ok;
 
 	/*
 	 * Construct a tuple descriptor for the result row.  This must match this
@@ -235,8 +238,8 @@ pg_control_recovery(PG_FUNCTION_ARGS)
 	tupdesc = BlessTupleDesc(tupdesc);
 
 	/* read the control file */
-	ControlFile = get_controlfile(DataDir, NULL);
-	if (!ControlFile)
+	ControlFile = get_controlfile(DataDir, NULL, &crc_ok);
+	if (!crc_ok)
 		ereport(ERROR,
 				(errmsg("calculated CRC checksum does not match value stored in file")));
 
@@ -268,6 +271,7 @@ pg_control_init(PG_FUNCTION_ARGS)
 	TupleDesc	tupdesc;
 	HeapTuple	htup;
 	ControlFileData *ControlFile;
+	bool		crc_ok;
 
 	/*
 	 * Construct a tuple descriptor for the result row.  This must match this
@@ -303,8 +307,8 @@ pg_control_init(PG_FUNCTION_ARGS)
 	tupdesc = BlessTupleDesc(tupdesc);
 
 	/* read the control file */
-	ControlFile = get_controlfile(DataDir, NULL);
-	if (!ControlFile)
+	ControlFile = get_controlfile(DataDir, NULL, &crc_ok);
+	if (!crc_ok)
 		ereport(ERROR,
 				(errmsg("calculated CRC checksum does not match value stored in file")));
 

src/bin/pg_controldata/pg_controldata.c

@@ -86,6 +86,7 @@ int
 main(int argc, char *argv[])
 {
 	ControlFileData *ControlFile;
+	bool		crc_ok;
 	char	   *DataDir = NULL;
 	time_t		time_tmp;
 	char		pgctime_str[128];
@@ -155,8 +156,8 @@ main(int argc, char *argv[])
 	}
 
 	/* get a copy of the control file */
-	ControlFile = get_controlfile(DataDir, progname);
-	if (!ControlFile)
+	ControlFile = get_controlfile(DataDir, progname, &crc_ok);
+	if (!crc_ok)
 		printf(_("WARNING: Calculated CRC checksum does not match value stored in file.\n"
 				 "Either the file is corrupt, or it has a different layout than this program\n"
 				 "is expecting.  The results below are untrustworthy.\n\n"));

src/bin/pg_ctl/pg_ctl.c

@@ -2147,28 +2147,18 @@ static DBState
 get_control_dbstate(void)
 {
 	DBState ret;
+	bool	crc_ok;
+	ControlFileData *control_file_data = get_controlfile(pg_data, progname, &crc_ok);
 
-	for (;;)
+	if (!crc_ok)
 	{
-		ControlFileData *control_file_data = get_controlfile(pg_data, progname);
-
-		if (control_file_data)
-		{
-			ret = control_file_data->state;
-			pfree(control_file_data);
-			return ret;
-		}
-
-		if (wait_seconds > 0)
-		{
-			pg_usleep(1000000);		/* 1 sec */
-			wait_seconds--;
-			continue;
-		}
-
 		write_stderr(_("%s: control file appears to be corrupt\n"), progname);
 		exit(1);
 	}
+
+	ret = control_file_data->state;
+	pfree(control_file_data);
+	return ret;
 }
 
 

src/common/controldata_utils.c

@@ -29,21 +29,24 @@
 #include "port/pg_crc32c.h"
 
 /*
- * get_controlfile(char *DataDir, const char *progname)
+ * get_controlfile(char *DataDir, const char *progname, bool *crc_ok_p)
  *
- * Get controlfile values. The caller is responsible
- * for pfreeing the result.
+ * Get controlfile values.  The result is returned as a palloc'd copy of the
+ * control file data.
  *
- * Returns NULL if the CRC did not match.
+ * crc_ok_p can be used by the caller to see whether the CRC of the control
+ * file data is correct.
  */
 ControlFileData *
-get_controlfile(const char *DataDir, const char *progname)
+get_controlfile(const char *DataDir, const char *progname, bool *crc_ok_p)
 {
 	ControlFileData *ControlFile;
 	int			fd;
 	char		ControlFilePath[MAXPGPATH];
 	pg_crc32c	crc;
 
+	AssertArg(crc_ok_p);
+
 	ControlFile = palloc(sizeof(ControlFileData));
 	snprintf(ControlFilePath, MAXPGPATH, "%s/global/pg_control", DataDir);
 
@@ -83,11 +86,7 @@ get_controlfile(const char *DataDir, const char *progname)
 				offsetof(ControlFileData, crc));
 	FIN_CRC32C(crc);
 
-	if (!EQ_CRC32C(crc, ControlFile->crc))
-	{
-		pfree(ControlFile);
-		return NULL;
-	}
+	*crc_ok_p = EQ_CRC32C(crc, ControlFile->crc);
 
 	/* Make sure the control file is valid byte order. */
 	if (ControlFile->pg_control_version % 65536 == 0 &&

src/include/common/controldata_utils.h

@@ -12,6 +12,6 @@
 
 #include "catalog/pg_control.h"
 
-extern ControlFileData *get_controlfile(const char *DataDir, const char *progname);
+extern ControlFileData *get_controlfile(const char *DataDir, const char *progname, bool *crc_ok_p);
 
 #endif   /* COMMON_CONTROLDATA_UTILS_H */