From a4741725a9596b25a9b7308b6a47e85b889d4557 Mon Sep 17 00:00:00 2001 From: Craig Ringer Date: Mon, 26 Oct 2020 20:43:24 +0800 Subject: [PATCH v1 2/3] Add libpq version information to dynamic symbol table Add three new data symbols LIBPQ_VERSION_STR, LIBPQ_VERSION_NUM and LIBPQ_CONFIGURE_ARGS to libpq's symbol table. These make it much easier to identify a given libpq without debuginfo, even if it cannot be executed (e.g. due to dependency problems or mismatched platforms). $ strip libpq.so $ gdb -batch -ex 'p (int)LIBPQ_VERSION_NUM' \ -ex 'p (const char *)LIBPQ_VERSION_STR' \ -ex 'p (const char *)LIBPQ_CONFIGURE_ARGS' \ ./libpq.so.stripped $1 = 140000 $2 = 0x285f0 "PostgreSQL 14devel on x86_64 ...." $3 = 0x28660 " '--enable-debug' '--enable-cassert' ...." --- src/interfaces/libpq/exports.txt | 3 +++ src/interfaces/libpq/libpq-version.c | 32 +++++++++++++++++++++++++--- 2 files changed, 32 insertions(+), 3 deletions(-) diff --git a/src/interfaces/libpq/exports.txt b/src/interfaces/libpq/exports.txt index 1d8600f0d8..64fb62c802 100644 --- a/src/interfaces/libpq/exports.txt +++ b/src/interfaces/libpq/exports.txt @@ -181,3 +181,6 @@ PQgetSSLKeyPassHook_OpenSSL 178 PQdefaultSSLKeyPassHook_OpenSSL 179 PQlibInfo 180 PQlibInfoPrint 181 +LIBPQ_VERSION_STR 182 +LIBPQ_VERSION_NUM 183 +LIBPQ_CONFIGURE_ARGS 184 diff --git a/src/interfaces/libpq/libpq-version.c b/src/interfaces/libpq/libpq-version.c index 51a5c608c8..bab0263848 100644 --- a/src/interfaces/libpq/libpq-version.c +++ b/src/interfaces/libpq/libpq-version.c @@ -47,21 +47,47 @@ #define libinfo_boolstr(x) (x) == 1 ? gettext_noop("1") : gettext_noop("0") +/* + * Store postgres version information in const symbols in the read-only data + * section of the libpq binary so they are exposed in the export symbol table, + * not just as macros. + * + * This way the exact version of a given libpq.so / libpq.dll can be determined + * even if it was built without macros in debuginfo or if is stripped, and + * without necessarily being able to execute the binary (e.g. due to linker + * issues). + * + * We need to store these for PGlibInfoEntries anyway, this just makes them + * individually addressable for the use of trace/diagnostic tools and + * debuggers. + * + * The linker will put these in read-only data segments so they won't use extra + * dynamic memory at runtime. + * + * You should prefer to use the normal methods of getting version info in your + * applications - PQlibVersion(), PG_VERSION_NUM, the server_version_num GUC, + * etc. + */ + +const char * const LIBPQ_VERSION_STR = PG_VERSION_STR; +const int LIBPQ_VERSION_NUM = PG_VERSION_NUM; +const char * const LIBPQ_CONFIGURE_ARGS = CONFIGURE_ARGS; + static const PGlibInfoEntry PGlibInfoEntries[] = { { PGRES_LIBINFO_VERSION_NUM, gettext_noop("VERSION_NUM"), - CppAsString2(PG_VERSION_NUM), 1, PG_VERSION_NUM + CppAsString2(PG_VERSION_NUM), 1, LIBPQ_VERSION_NUM }, { PGRES_LIBINFO_VERSION_STR, gettext_noop("VERSION"), - PG_VERSION_STR, 0, 0 + LIBPQ_VERSION_STR, 0, 0 }, { PGRES_LIBINFO_CONFIGURE_ARGS, gettext_noop("CONFIGURE_ARGS"), - CONFIGURE_ARGS, 0, 0 + LIBPQ_CONFIGURE_ARGS, 0, 0 }, { PGRES_LIBINFO_USE_SSL, -- 2.26.2