From cd0be131ba6f7e8b1323d188db20d15c2504b021 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Tue, 14 Oct 2025 16:20:42 +0900 Subject: Introduce frontend API able to retrieve the contents of PG_VERSION get_pg_version() is able to return a version number, that can be used for comparisons based on PG_VERSION_NUM. A macro is added to convert the result to a major version number, to work with PG_MAJORVERSION_NUM. It is possible to pass to the routine an optional argument, where the contents retrieved from PG_VERSION are saved. This requirement matters for some of the frontend code (one example: pg_upgrade wants that for tablespace paths with a version number strictly older than v10). This will be used by a set of follow-up patches, to be consumed in various frontend tools that duplicate a logic similar to do what this new routine does, like: - pg_resetwal - pg_combinebackup - pg_createsubscriber - pg_upgrade This routine supports both the post-v10 version number and the older flavor (aka 9.6), as required at least by pg_upgrade. Author: Michael Paquier Reviewed-by: Masahiko Sawada Discussion: https://postgr.es/m/aOiirvWJzwdVCXph@paquier.xyz --- src/fe_utils/version.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) create mode 100644 src/fe_utils/version.c (limited to 'src/fe_utils/version.c') diff --git a/src/fe_utils/version.c b/src/fe_utils/version.c new file mode 100644 index 00000000000..94f09233c01 --- /dev/null +++ b/src/fe_utils/version.c @@ -0,0 +1,86 @@ +/*------------------------------------------------------------------------- + * + * version.c + * Routine to retrieve information of PG_VERSION + * + * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * src/fe_utils/version.c + * + *------------------------------------------------------------------------- + */ + +#include "postgres_fe.h" + +#include + +#include "common/logging.h" +#include "fe_utils/version.h" + +/* + * Assumed maximum size of PG_VERSION. This should be more than enough for + * any version numbers that need to be handled. + */ +#define PG_VERSION_MAX_SIZE 64 + +/* + * get_pg_version + * + * Retrieve the major version number of the given data folder, from + * PG_VERSION. The result returned is a version number, that can be used + * for comparisons based on PG_VERSION_NUM. For example, if PG_VERSION + * contains "18\n", this function returns 180000. + * + * This supports both the pre-v10 and the post-v10 version numbering. + * + * Optionally, "version_str" can be specified to store the contents + * retrieved from PG_VERSION. It is allocated by this routine; the + * caller is responsible for pg_free()-ing it. + */ +uint32 +get_pg_version(const char *datadir, char **version_str) +{ + FILE *version_fd; + char ver_filename[MAXPGPATH]; + char buf[PG_VERSION_MAX_SIZE]; + int v1 = 0, + v2 = 0; + struct stat st; + + snprintf(ver_filename, sizeof(ver_filename), "%s/PG_VERSION", + datadir); + + if ((version_fd = fopen(ver_filename, "r")) == NULL) + pg_fatal("could not open version file \"%s\": %m", ver_filename); + + if (fstat(fileno(version_fd), &st) != 0) + pg_fatal("could not stat file \"%s\": %m", ver_filename); + if (st.st_size > PG_VERSION_MAX_SIZE) + pg_fatal("file \"%s\" is too large", ver_filename); + + if (fscanf(version_fd, "%63s", buf) == 0 || + sscanf(buf, "%d.%d", &v1, &v2) < 1) + pg_fatal("could not parse version file \"%s\"", ver_filename); + + fclose(version_fd); + + if (version_str) + { + *version_str = pg_malloc(PG_VERSION_MAX_SIZE); + memcpy(*version_str, buf, st.st_size); + } + + if (v1 < 10) + { + /* pre-v10 style, e.g. 9.6.1 */ + return v1 * 10000 + v2 * 100; + } + else + { + /* post-v10 style, e.g. 10.1 */ + return v1 * 10000; + } +} -- cgit v1.2.3