pg_resetwal: Use new routine to retrieve data of PG_VERSION

pg_resetwal's custom logic to retrieve the version number of a data
folder's PG_VERSION can be replaced by the facility introduced in
cd0be131ba6f.  This removes some code.

One thing specific to pg_resetwal is that the first line of PG_VERSION
is read and reported in the error report generated when the major
version read does not match with the version pg_resetwal has been
compiled with.  The new logic preserves this property, without changes
to neither the error message nor the data used in the error report.

Note that as a chdir() is done within the data folder before checking the
data of PG_VERSION, get_pg_version() needs to be tweaked to look for
PG_VERSION in the current folder.

Author: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/aOiirvWJzwdVCXph@paquier.xyz

1 files changed, 7 insertions, 23 deletions

diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 7a4e4eb9570..a89d72fc5cf 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -55,6 +55,7 @@
 #include "common/restricted_token.h"
 #include "common/string.h"
 #include "fe_utils/option_utils.h"
+#include "fe_utils/version.h"
 #include "getopt_long.h"
 #include "pg_getopt.h"
 #include "storage/large_object.h"
@@ -539,35 +540,18 @@ main(int argc, char *argv[])
 static void
 CheckDataVersion(void)
 {
-	const char *ver_file = "PG_VERSION";
-	FILE	   *ver_fd;
-	char		rawline[64];
+	char	   *version_str;
+	uint32		version = get_pg_version(".", &version_str);
 
-	if ((ver_fd = fopen(ver_file, "r")) == NULL)
-		pg_fatal("could not open file \"%s\" for reading: %m",
-				 ver_file);
-
-	/* version number has to be the first line read */
-	if (!fgets(rawline, sizeof(rawline), ver_fd))
-	{
-		if (!ferror(ver_fd))
-			pg_fatal("unexpected empty file \"%s\"", ver_file);
-		else
-			pg_fatal("could not read file \"%s\": %m", ver_file);
-	}
-
-	/* strip trailing newline and carriage return */
-	(void) pg_strip_crlf(rawline);
-
-	if (strcmp(rawline, PG_MAJORVERSION) != 0)
+	if (GET_PG_MAJORVERSION_NUM(version) != PG_MAJORVERSION_NUM)
 	{
 		pg_log_error("data directory is of wrong version");
 		pg_log_error_detail("File \"%s\" contains \"%s\", which is not compatible with this program's version \"%s\".",
-							ver_file, rawline, PG_MAJORVERSION);
+							"PG_VERSION",
+							version_str,
+							PG_MAJORVERSION);
 		exit(1);
 	}
-
-	fclose(ver_fd);
 }