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

diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 7a4e4eb95706e82931e89384f8902db4193467fd..a89d72fc5cfec45f6110b1bdf133bb4f00ed44f7 100644 (file)
--- 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);
 }