From 2b1f580ee2ca373d0451d89a40fc8f0a5f55ede9 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Fri, 5 Aug 2022 09:22:56 +1200 Subject: [PATCH] Remove configure probes for symlink/readlink, and dead code. symlink() and readlink() are in SUSv2 and all targeted Unix systems have them. We have partial emulation on Windows. Code that raised runtime errors on systems without it has been dead for years, so we can remove that and also references to such systems in the documentation. Define HAVE_READLINK and HAVE_SYMLINK macros on Unix. Our Windows replacement functions based on junction points can't be used for relative paths or for non-directories, so the macros can be used to check for full symlink support. The places that deal with tablespaces can just use symlink functions without checking the macros. (If they did check the macros, they'd need to provide an #else branch with a runtime or compile time error, and it'd be dead code.) Reviewed-by: Tom Lane Reviewed-by: Andres Freund Discussion: https://postgr.es/m/CA+hUKGJ3LHeP9w5Fgzdr4G8AnEtJ=z=p6hGDEm4qYGEUX5B6fQ@mail.gmail.com --- configure | 5 +---- configure.ac | 4 ---- doc/src/sgml/manage-ag.sgml | 7 ------- doc/src/sgml/ref/create_tablespace.sgml | 4 ---- src/backend/access/transam/xlog.c | 12 ------------ src/backend/commands/tablespace.c | 13 ------------- src/backend/replication/basebackup.c | 13 ------------- src/backend/utils/adt/misc.c | 8 -------- src/bin/initdb/initdb.c | 4 ---- src/bin/pg_basebackup/pg_basebackup.c | 4 ---- src/bin/pg_rewind/file_ops.c | 5 ----- src/common/exec.c | 4 ++++ src/include/pg_config.h.in | 6 ------ src/include/port.h | 8 ++++++++ src/tools/msvc/Solution.pm | 2 -- 15 files changed, 13 insertions(+), 86 deletions(-) diff --git a/configure b/configure index 232f19a0cd2..1f852078e75 100755 --- a/configure +++ b/configure @@ -16039,7 +16039,7 @@ fi LIBS_including_readline="$LIBS" LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'` -for ac_func in backtrace_symbols clock_gettime copyfile fdatasync getifaddrs getpeerucred inet_pton kqueue mbstowcs_l memset_s poll posix_fallocate ppoll pthread_is_threaded_np readlink readv setproctitle setproctitle_fast strchrnul strsignal symlink syncfs sync_file_range uselocale wcstombs_l writev +for ac_func in backtrace_symbols clock_gettime copyfile fdatasync getifaddrs getpeerucred inet_pton kqueue mbstowcs_l memset_s poll posix_fallocate ppoll pthread_is_threaded_np readv setproctitle setproctitle_fast strchrnul strsignal syncfs sync_file_range uselocale wcstombs_l writev do : as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh` ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var" @@ -17083,9 +17083,6 @@ esac ;; esac - -$as_echo "#define HAVE_SYMLINK 1" >>confdefs.h - ac_fn_c_check_type "$LINENO" "MINIDUMP_TYPE" "ac_cv_type_MINIDUMP_TYPE" " #define WIN32_LEAN_AND_MEAN #include diff --git a/configure.ac b/configure.ac index 33dffe0ce55..ca0c65fbd9a 100644 --- a/configure.ac +++ b/configure.ac @@ -1805,13 +1805,11 @@ AC_CHECK_FUNCS(m4_normalize([ posix_fallocate ppoll pthread_is_threaded_np - readlink readv setproctitle setproctitle_fast strchrnul strsignal - symlink syncfs sync_file_range uselocale @@ -1963,8 +1961,6 @@ if test "$PORTNAME" = "win32"; then AC_LIBOBJ(win32security) AC_LIBOBJ(win32setlocale) AC_LIBOBJ(win32stat) - AC_DEFINE([HAVE_SYMLINK], 1, - [Define to 1 if you have the `symlink' function.]) AC_CHECK_TYPES(MINIDUMP_TYPE, [pgac_minidump_type=yes], [pgac_minidump_type=no], [ #define WIN32_LEAN_AND_MEAN #include diff --git a/doc/src/sgml/manage-ag.sgml b/doc/src/sgml/manage-ag.sgml index 8903ab2fc9c..192c5009945 100644 --- a/doc/src/sgml/manage-ag.sgml +++ b/doc/src/sgml/manage-ag.sgml @@ -530,13 +530,6 @@ SELECT spcname FROM pg_tablespace; is also useful for listing the existing tablespaces. - - PostgreSQL makes use of symbolic links - to simplify the implementation of tablespaces. This - means that tablespaces can be used only on systems - that support symbolic links. - - The directory $PGDATA/pg_tblspc contains symbolic links that point to each of the non-built-in tablespaces defined in the cluster. diff --git a/doc/src/sgml/ref/create_tablespace.sgml b/doc/src/sgml/ref/create_tablespace.sgml index 84fa7ee5e29..9d5ab025261 100644 --- a/doc/src/sgml/ref/create_tablespace.sgml +++ b/doc/src/sgml/ref/create_tablespace.sgml @@ -127,10 +127,6 @@ CREATE TABLESPACE tablespace_name Notes - - Tablespaces are only supported on systems that support symbolic links. - - CREATE TABLESPACE cannot be executed inside a transaction block. diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 15ab8d90d4b..26fbed00a4d 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -8305,7 +8305,6 @@ do_pg_backup_start(const char *backupidstr, bool fast, TimeLineID *starttli_p, if (get_dirent_type(fullpath, de, false, ERROR) != PGFILETYPE_LNK) continue; -#if defined(HAVE_READLINK) || defined(WIN32) rllen = readlink(fullpath, linkpath, sizeof(linkpath)); if (rllen < 0) { @@ -8358,17 +8357,6 @@ do_pg_backup_start(const char *backupidstr, bool fast, TimeLineID *starttli_p, ti->oid, escapedpath.data); pfree(escapedpath.data); -#else - - /* - * If the platform does not have symbolic links, it should not be - * possible to have tablespaces - clearly somebody else created - * them. Warn about it and ignore. - */ - ereport(WARNING, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("tablespaces are not supported on this platform"))); -#endif } FreeDir(tblspcdir); diff --git a/src/backend/commands/tablespace.c b/src/backend/commands/tablespace.c index 570ce3dbd54..526e82e388b 100644 --- a/src/backend/commands/tablespace.c +++ b/src/backend/commands/tablespace.c @@ -213,7 +213,6 @@ TablespaceCreateDbspace(Oid spcOid, Oid dbOid, bool isRedo) Oid CreateTableSpace(CreateTableSpaceStmt *stmt) { -#ifdef HAVE_SYMLINK Relation rel; Datum values[Natts_pg_tablespace]; bool nulls[Natts_pg_tablespace] = {0}; @@ -391,12 +390,6 @@ CreateTableSpace(CreateTableSpaceStmt *stmt) table_close(rel, NoLock); return tablespaceoid; -#else /* !HAVE_SYMLINK */ - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("tablespaces are not supported on this platform"))); - return InvalidOid; /* keep compiler quiet */ -#endif /* HAVE_SYMLINK */ } /* @@ -407,7 +400,6 @@ CreateTableSpace(CreateTableSpaceStmt *stmt) void DropTableSpace(DropTableSpaceStmt *stmt) { -#ifdef HAVE_SYMLINK char *tablespacename = stmt->tablespacename; TableScanDesc scandesc; Relation rel; @@ -573,11 +565,6 @@ DropTableSpace(DropTableSpaceStmt *stmt) /* We keep the lock on pg_tablespace until commit */ table_close(rel, NoLock); -#else /* !HAVE_SYMLINK */ - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("tablespaces are not supported on this platform"))); -#endif /* HAVE_SYMLINK */ } diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c index 7f85071229b..09f071300d4 100644 --- a/src/backend/replication/basebackup.c +++ b/src/backend/replication/basebackup.c @@ -1330,7 +1330,6 @@ sendDir(bbsink *sink, const char *path, int basepathlen, bool sizeonly, #endif ) { -#if defined(HAVE_READLINK) || defined(WIN32) char linkpath[MAXPGPATH]; int rllen; @@ -1349,18 +1348,6 @@ sendDir(bbsink *sink, const char *path, int basepathlen, bool sizeonly, size += _tarWriteHeader(sink, pathbuf + basepathlen + 1, linkpath, &statbuf, sizeonly); -#else - - /* - * If the platform does not have symbolic links, it should not be - * possible to have tablespaces - clearly somebody else created - * them. Warn about it and ignore. - */ - ereport(WARNING, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("tablespaces are not supported on this platform"))); - continue; -#endif /* HAVE_READLINK */ } else if (S_ISDIR(statbuf.st_mode)) { diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c index 89690be2ed1..af0d924459e 100644 --- a/src/backend/utils/adt/misc.c +++ b/src/backend/utils/adt/misc.c @@ -302,8 +302,6 @@ pg_tablespace_location(PG_FUNCTION_ARGS) tablespaceOid == GLOBALTABLESPACE_OID) PG_RETURN_TEXT_P(cstring_to_text("")); -#if defined(HAVE_READLINK) || defined(WIN32) - /* * Find the location of the tablespace by reading the symbolic link that * is in pg_tblspc/. @@ -349,12 +347,6 @@ pg_tablespace_location(PG_FUNCTION_ARGS) targetpath[rllen] = '\0'; PG_RETURN_TEXT_P(cstring_to_text(targetpath)); -#else - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("tablespaces are not supported on this platform"))); - PG_RETURN_NULL(); -#endif } /* diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c index 89b888eaa5a..2c93ffe8114 100644 --- a/src/bin/initdb/initdb.c +++ b/src/bin/initdb/initdb.c @@ -2646,13 +2646,9 @@ create_xlog_or_symlink(void) pg_fatal("could not access directory \"%s\": %m", xlog_dir); } -#ifdef HAVE_SYMLINK if (symlink(xlog_dir, subdirloc) != 0) pg_fatal("could not create symbolic link \"%s\": %m", subdirloc); -#else - pg_fatal("symlinks are not supported on this platform"); -#endif } else { diff --git a/src/bin/pg_basebackup/pg_basebackup.c b/src/bin/pg_basebackup/pg_basebackup.c index 1a877ba54e4..8694b05e68c 100644 --- a/src/bin/pg_basebackup/pg_basebackup.c +++ b/src/bin/pg_basebackup/pg_basebackup.c @@ -2763,12 +2763,8 @@ main(int argc, char **argv) PQserverVersion(conn) < MINIMUM_VERSION_FOR_PG_WAL ? "pg_xlog" : "pg_wal"); -#ifdef HAVE_SYMLINK if (symlink(xlog_dir, linkloc) != 0) pg_fatal("could not create symbolic link \"%s\": %m", linkloc); -#else - pg_fatal("symlinks are not supported on this platform"); -#endif free(linkloc); } diff --git a/src/bin/pg_rewind/file_ops.c b/src/bin/pg_rewind/file_ops.c index 6cb288f0992..5e6d8b89c49 100644 --- a/src/bin/pg_rewind/file_ops.c +++ b/src/bin/pg_rewind/file_ops.c @@ -437,7 +437,6 @@ recurse_dir(const char *datadir, const char *parentpath, else if (pgwin32_is_junction(fullpath)) #endif { -#if defined(HAVE_READLINK) || defined(WIN32) char link_target[MAXPGPATH]; int len; @@ -460,10 +459,6 @@ recurse_dir(const char *datadir, const char *parentpath, if ((parentpath && strcmp(parentpath, "pg_tblspc") == 0) || strcmp(path, "pg_wal") == 0) recurse_dir(datadir, path, callback); -#else - pg_fatal("\"%s\" is a symbolic link, but symbolic links are not supported on this platform", - fullpath); -#endif /* HAVE_READLINK */ } } diff --git a/src/common/exec.c b/src/common/exec.c index f7d44b09569..fdcad0ee8cf 100644 --- a/src/common/exec.c +++ b/src/common/exec.c @@ -250,6 +250,10 @@ find_my_exec(const char *argv0, char *retpath) * Note: we are not particularly tense about producing nice error messages * because we are not really expecting error here; we just determined that * the symlink does point to a valid executable. + * + * Here we test HAVE_READLINK, which excludes Windows. There's no point in + * using our junction point-based replacement code for this, because that only + * works for directories. */ static int resolve_symlinks(char *path) diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in index 120eacfb200..15e01efa068 100644 --- a/src/include/pg_config.h.in +++ b/src/include/pg_config.h.in @@ -427,9 +427,6 @@ /* Define to 1 if you have the header file. */ #undef HAVE_READLINE_READLINE_H -/* Define to 1 if you have the `readlink' function. */ -#undef HAVE_READLINK - /* Define to 1 if you have the `readv' function. */ #undef HAVE_READV @@ -556,9 +553,6 @@ /* Define to 1 if `tm_zone' is a member of `struct tm'. */ #undef HAVE_STRUCT_TM_TM_ZONE -/* Define to 1 if you have the `symlink' function. */ -#undef HAVE_SYMLINK - /* Define to 1 if you have the `syncfs' function. */ #undef HAVE_SYNCFS diff --git a/src/include/port.h b/src/include/port.h index 7a1a02f6598..7dad6caa639 100644 --- a/src/include/port.h +++ b/src/include/port.h @@ -522,11 +522,19 @@ extern bool wait_result_is_any_signal(int exit_status, bool include_command_not_ /* * Interfaces that we assume all Unix system have. We retain individual macros * for better documentation. + * + * For symlink-related functions, there is often no need to test these macros, + * because we provided basic support on Windows that can work with absolute + * paths to directories. Code that wants to test for complete symlink support + * (including relative paths and non-directories) should be conditional on + * HAVE_READLINK or HAVE_SYMLINK. */ #ifndef WIN32 #define HAVE_GETRLIMIT 1 +#define HAVE_READLINK 1 #define HAVE_SETSID 1 #define HAVE_SHM_OPEN 1 +#define HAVE_SYMLINK 1 #endif #endif /* PG_PORT_H */ diff --git a/src/tools/msvc/Solution.pm b/src/tools/msvc/Solution.pm index a9680dc8630..71db5f60f8a 100644 --- a/src/tools/msvc/Solution.pm +++ b/src/tools/msvc/Solution.pm @@ -337,7 +337,6 @@ sub GenerateFiles HAVE_READLINE_H => undef, HAVE_READLINE_HISTORY_H => undef, HAVE_READLINE_READLINE_H => undef, - HAVE_READLINK => undef, HAVE_READV => undef, HAVE_RL_COMPLETION_MATCHES => undef, HAVE_RL_COMPLETION_SUPPRESS_QUOTE => undef, @@ -380,7 +379,6 @@ sub GenerateFiles HAVE_STRUCT_SOCKADDR_UN => undef, HAVE_STRUCT_TM_TM_ZONE => undef, HAVE_SYNC_FILE_RANGE => undef, - HAVE_SYMLINK => 1, HAVE_SYNCFS => undef, HAVE_SYSLOG => undef, HAVE_SYS_EPOLL_H => undef,