Replace pgwin32_is_junction() with lstat().

Now that lstat() reports junction points with S_IFLNK/S_ISLINK(), and
unlink() can unlink them, there is no need for conditional code for
Windows in a few places.  That was expressed by testing for WIN32 or
S_ISLNK, which we can now constant-fold.

The coding around pgwin32_is_junction() was a bit suspect anyway, as we
never checked for errors, and we also know that errors can be spuriously
reported because of transient sharing violations on this OS.  The
lstat()-based code has handling for that.

This also reverts 4fc6b6ee on master only.  That was done because
lstat() didn't previously work for symlinks (junction points), but now
it does.

Tested-by: Andrew Dunstan 
Discussion: https://postgr.es/m/CA%2BhUKGLfOOeyZpm5ByVcAt7x5Pn-%3DxGRNCvgiUPVVzjFLtnY0w%40mail.gmail.com
(cherry picked from commit 5fc88c5d53e43fa7dcea93499d230a0bf70f4f77)

Author: Thomas Munro 
Author: Alexandra Wang 

diff --git a/src/backend/commands/tablespace.c b/src/backend/commands/tablespace.c
index edd1ac033060eb68284aa762ec7243d8f9651818..9d895960aaf649e3479834949d9cffc37a7ffb04 100644 (file)
--- a/src/backend/commands/tablespace.c
+++ b/src/backend/commands/tablespace.c
@@ -787,8 +787,7 @@ destroy_tablespace_directories(Oid tablespaceoid, bool redo)
    /*
     * Try to remove the symlink.  We must however deal with the possibility
     * that it's a directory instead of a symlink --- this could happen during
-    * WAL replay (see TablespaceCreateDbspace), and it is also the case on
-    * Windows where junction points lstat() as directories.
+    * WAL replay (see TablespaceCreateDbspace).
     *
     * Note: in the redo case, we'll return true if this final step fails;
     * there's no point in retrying it.  Also, ENOENT should provoke no more
@@ -818,7 +817,6 @@ remove_symlink:
                            linkloc)));
        }
    }
-#ifdef S_ISLNK
    else if (S_ISLNK(st.st_mode))
    {
        if (unlink(linkloc) < 0)
@@ -831,7 +829,6 @@ remove_symlink:
                            linkloc)));
        }
    }
-#endif
    else
    {
        /* Refuse to remove anything that's not a directory or symlink */
@@ -909,7 +906,6 @@ remove_tablespace_symlink(const char *linkloc)
                     errmsg("could not remove directory \"%s\": %m",
                            linkloc)));
    }
-#ifdef S_ISLNK
    else if (S_ISLNK(st.st_mode))
    {
        if (unlink(linkloc) < 0 && errno != ENOENT)
@@ -918,7 +914,6 @@ remove_tablespace_symlink(const char *linkloc)
                     errmsg("could not remove symbolic link \"%s\": %m",
                            linkloc)));
    }
-#endif
    else
    {
        /* Refuse to remove anything that's not a directory or symlink */

diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index d142cc213191a310710dbdd283696f85303f6990..a535180ba41f45ce06716e1250deeaafd09e2236 100644 (file)
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -1415,13 +1415,7 @@ sendDir(const char *path, int basepathlen, bool sizeonly, List *tablespaces,
        }
 
        /* Allow symbolic links in pg_tblspc only */
-       if (strcmp(path, "./pg_tblspc") == 0 &&
-#ifndef WIN32
-           S_ISLNK(statbuf.st_mode)
-#else
-           pgwin32_is_junction(pathbuf)
-#endif
-           )
+       if (strcmp(path, "./pg_tblspc") == 0 && S_ISLNK(statbuf.st_mode))
        {
 #if defined(HAVE_READLINK) || defined(WIN32)
            char        linkpath[MAXPGPATH];
@@ -1884,11 +1878,7 @@ _tarWriteDir(const char *pathbuf, int basepathlen, struct stat *statbuf,
             bool sizeonly)
 {
    /* If symlink, write it as a directory anyway */
-#ifndef WIN32
    if (S_ISLNK(statbuf->st_mode))
-#else
-   if (pgwin32_is_junction(pathbuf))
-#endif
        statbuf->st_mode = S_IFDIR | pg_dir_create_mode;
 
    return _tarWriteHeader(pathbuf + basepathlen + 1, NULL, statbuf, sizeonly);

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 3933c06ecc84308f990f0c8cf22e0c492af73042..09c4a93e40b0a2135613be132adbdd510b845c13 100644 (file)
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -3351,7 +3351,6 @@ SyncDataDirectory(void)
     */
    xlog_is_symlink = false;
 
-#ifndef WIN32
    {
        struct stat st;
 
@@ -3363,10 +3362,6 @@ SyncDataDirectory(void)
        else if (S_ISLNK(st.st_mode))
            xlog_is_symlink = true;
    }
-#else
-   if (pgwin32_is_junction("pg_wal"))
-       xlog_is_symlink = true;
-#endif
 
 #ifdef HAVE_SYNCFS
    if (recovery_init_sync_method == RECOVERY_INIT_SYNC_METHOD_SYNCFS)

diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c
index 10b8384ef7082d3231992229fa104cfc867e42c7..6617cb8adc21f44c1f85944de5ca8dbf52a396b8 100644 (file)
--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@@ -310,9 +310,7 @@ pg_tablespace_location(PG_FUNCTION_ARGS)
    char        sourcepath[MAXPGPATH];
    char        targetpath[MAXPGPATH];
    int         rllen;
-#ifndef WIN32
    struct stat st;
-#endif
 
    /*
     * It's useful to apply this function to pg_class.reltablespace, wherein
@@ -343,10 +341,6 @@ pg_tablespace_location(PG_FUNCTION_ARGS)
     * created with allow_in_place_tablespaces enabled.  If a directory is
     * found, a relative path to the data directory is returned.
     */
-#ifdef WIN32
-   if (!pgwin32_is_junction(sourcepath))
-       PG_RETURN_TEXT_P(cstring_to_text(sourcepath));
-#else
    if (lstat(sourcepath, &st) < 0)
    {
        ereport(ERROR,
@@ -357,7 +351,6 @@ pg_tablespace_location(PG_FUNCTION_ARGS)
 
    if (!S_ISLNK(st.st_mode))
        PG_RETURN_TEXT_P(cstring_to_text(sourcepath));
-#endif
 
    /*
     * In presence of a link or a junction point, return the path pointing to.

diff --git a/src/bin/pg_checksums/pg_checksums.c b/src/bin/pg_checksums/pg_checksums.c
index 831cf42d3ad19fcca76cdd4454f5bc98520f0f6a..8f80d8b89163744fa72a922d0d3b51df7213b383 100644 (file)
--- a/src/bin/pg_checksums/pg_checksums.c
+++ b/src/bin/pg_checksums/pg_checksums.c
@@ -391,11 +391,7 @@ scan_directory(const char *basedir, const char *subdir, bool sizeonly)
            if (!sizeonly)
                scan_file(fn, segmentno);
        }
-#ifndef WIN32
        else if (S_ISDIR(st.st_mode) || S_ISLNK(st.st_mode))
-#else
-       else if (S_ISDIR(st.st_mode) || pgwin32_is_junction(fn))
-#endif
        {
            /*
             * If going through the entries of pg_tblspc, we assume to operate

diff --git a/src/bin/pg_rewind/file_ops.c b/src/bin/pg_rewind/file_ops.c
index c50f283ede41b840575b2b6bbfb83ae736bef920..1671feea68fb21bfe2462f9042672fe94a0ce928 100644 (file)
--- a/src/bin/pg_rewind/file_ops.c
+++ b/src/bin/pg_rewind/file_ops.c
@@ -431,11 +431,7 @@ recurse_dir(const char *datadir, const char *parentpath,
            /* recurse to handle subdirectories */
            recurse_dir(datadir, path, callback);
        }
-#ifndef WIN32
        else if (S_ISLNK(fst.st_mode))
-#else
-       else if (pgwin32_is_junction(fullpath))
-#endif
        {
 #if defined(HAVE_READLINK) || defined(WIN32)
            char        link_target[MAXPGPATH];

diff --git a/src/common/file_utils.c b/src/common/file_utils.c
index fd2d11375c95adce381dfbb37ac3d71258289530..f37c89317f70056e005f11e16f9aae2c92f8acb2 100644 (file)
--- a/src/common/file_utils.c
+++ b/src/common/file_utils.c
@@ -79,7 +79,6 @@ fsync_pgdata(const char *pg_data,
     */
    xlog_is_symlink = false;
 
-#ifndef WIN32
    {
        struct stat st;
 
@@ -88,10 +87,6 @@ fsync_pgdata(const char *pg_data,
        else if (S_ISLNK(st.st_mode))
            xlog_is_symlink = true;
    }
-#else
-   if (pgwin32_is_junction(pg_wal))
-       xlog_is_symlink = true;
-#endif
 
    /*
     * If possible, hint to the kernel that we're soon going to fsync the data
@@ -459,27 +454,9 @@ get_dirent_type(const char *path,
            result = PGFILETYPE_REG;
        else if (S_ISDIR(fst.st_mode))
            result = PGFILETYPE_DIR;
-#ifdef S_ISLNK
        else if (S_ISLNK(fst.st_mode))
            result = PGFILETYPE_LNK;
-#endif
    }
 
-#if defined(WIN32) && !defined(_MSC_VER)
-
-   /*
-    * If we're on native Windows (not Cygwin, which has its own POSIX
-    * symlinks), but not using the MSVC compiler, then we're using a
-    * readdir() emulation provided by the MinGW runtime that has no d_type.
-    * Since the lstat() fallback code reports junction points as directories,
-    * we need an extra system call to check if we should report them as
-    * symlinks instead, following our convention.
-    */
-   if (result == PGFILETYPE_DIR &&
-       !look_through_symlinks &&
-       pgwin32_is_junction(path))
-       result = PGFILETYPE_LNK;
-#endif
-
    return result;
 }

diff --git a/src/include/port.h b/src/include/port.h
index 2368e9c654df5e5667c2c136aae4e0dce0f33cec..da18268d17db254bf18a983f07066e41d7fafa97 100644 (file)
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -284,7 +284,6 @@ extern int  pgunlink(const char *path);
 #if defined(WIN32) && !defined(__CYGWIN__)
 extern int pgsymlink(const char *oldpath, const char *newpath);
 extern int pgreadlink(const char *path, char *buf, size_t size);
-extern bool pgwin32_is_junction(const char *path);
 
 #define symlink(oldpath, newpath)  pgsymlink(oldpath, newpath)
 #define readlink(path, buf, size)  pgreadlink(path, buf, size)

diff --git a/src/include/port/win32_port.h b/src/include/port/win32_port.h
index 2537e583abe83dbba042aa8ed5f7cb676a8838b0..9ca80e574e9e464402de12be2d79639dd96afc79 100644 (file)
--- a/src/include/port/win32_port.h
+++ b/src/include/port/win32_port.h
@@ -228,7 +228,6 @@ extern pgoff_t _pgftello64(FILE *stream);
  */
 extern int pgsymlink(const char *oldpath, const char *newpath);
 extern int pgreadlink(const char *path, char *buf, size_t size);
-extern bool pgwin32_is_junction(const char *path);
 
 #define symlink(oldpath, newpath)  pgsymlink(oldpath, newpath)
 #define readlink(path, buf, size)  pgreadlink(path, buf, size)

diff --git a/src/port/dirmod.c b/src/port/dirmod.c
index 9403c8adb8acb093f4ae1d94397ec990808dd7ba..bc2ad75966e1a7c44f2a8cb91bb67d595b8d0652 100644 (file)
--- a/src/port/dirmod.c
+++ b/src/port/dirmod.c
@@ -362,20 +362,4 @@ pgreadlink(const char *path, char *buf, size_t size)
    return r;
 }
 
-/*
- * Assumes the file exists, so will return false if it doesn't
- * (since a nonexistent file is not a junction)
- */
-bool
-pgwin32_is_junction(const char *path)
-{
-   DWORD       attr = GetFileAttributes(path);
-
-   if (attr == INVALID_FILE_ATTRIBUTES)
-   {
-       _dosmaperr(GetLastError());
-       return false;
-   }
-   return ((attr & FILE_ATTRIBUTE_REPARSE_POINT) == FILE_ATTRIBUTE_REPARSE_POINT);
-}
 #endif                         /* defined(WIN32) && !defined(__CYGWIN__) */