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 <tgl@sss.pgh.pa.us>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CA+hUKGJ3LHeP9w5Fgzdr4G8AnEtJ=z=p6hGDEm4qYGEUX5B6fQ@mail.gmail.com
This commit is contained in:
Thomas Munro 2022-08-05 09:22:56 +12:00
parent adeef67834
commit 2b1f580ee2
15 changed files with 13 additions and 86 deletions

5
configure vendored
View File

@ -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 <windows.h>

View File

@ -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 <windows.h>

View File

@ -530,13 +530,6 @@ SELECT spcname FROM pg_tablespace;
is also useful for listing the existing tablespaces.
</para>
<para>
<productname>PostgreSQL</productname> makes use of symbolic links
to simplify the implementation of tablespaces. This
means that tablespaces can be used <emphasis>only</emphasis> on systems
that support symbolic links.
</para>
<para>
The directory <filename>$PGDATA/pg_tblspc</filename> contains symbolic links that
point to each of the non-built-in tablespaces defined in the cluster.

View File

@ -127,10 +127,6 @@ CREATE TABLESPACE <replaceable class="parameter">tablespace_name</replaceable>
<refsect1>
<title>Notes</title>
<para>
Tablespaces are only supported on systems that support symbolic links.
</para>
<para>
<command>CREATE TABLESPACE</command> cannot be executed inside a transaction
block.

View File

@ -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);

View File

@ -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 */
}

View File

@ -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))
{

View File

@ -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/<oid>.
@ -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
}
/*

View File

@ -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
{

View File

@ -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);
}

View File

@ -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 */
}
}

View File

@ -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)

View File

@ -427,9 +427,6 @@
/* Define to 1 if you have the <readline/readline.h> 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

View File

@ -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 */

View File

@ -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,