document mingw linker fix and close associated bug

[debian/gzip] / m4 / lstat.m4

diff --git a/m4/lstat.m4 b/m4/lstat.m4
index 5dbd16e28ffe875a46d4696df5a4a164b32b929f..3694e4ceaf74f594c7c7da147ba3d702c43c1341 100644 (file)
--- a/m4/lstat.m4
+++ b/m4/lstat.m4
@@ -1,6 +1,6 @@
-# serial 20
+# serial 32
 
-# Copyright (C) 1997-2001, 2003-2010 Free Software Foundation, Inc.
+# Copyright (C) 1997-2001, 2003-2018 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -10,19 +10,70 @@ dnl From Jim Meyering.
 
 AC_DEFUN([gl_FUNC_LSTAT],
 [
+  AC_REQUIRE([AC_CANONICAL_HOST])
   AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
   dnl If lstat does not exist, the replacement <sys/stat.h> does
   dnl "#define lstat stat", and lstat.c is a no-op.
   AC_CHECK_FUNCS_ONCE([lstat])
   if test $ac_cv_func_lstat = yes; then
-    AC_REQUIRE([AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
-    if test $ac_cv_func_lstat_dereferences_slashed_symlink = no; then
-      dnl Note: AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK does AC_LIBOBJ([lstat]).
-      REPLACE_LSTAT=1
-    fi
-    # Prerequisites of lib/lstat.c.
-    AC_REQUIRE([AC_C_INLINE])
+    AC_REQUIRE([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
+    case $host_os,$gl_cv_func_lstat_dereferences_slashed_symlink in
+      solaris* | *no)
+        REPLACE_LSTAT=1
+        ;;
+    esac
   else
     HAVE_LSTAT=0
   fi
 ])
+
+# Prerequisites of lib/lstat.c.
+AC_DEFUN([gl_PREREQ_LSTAT], [:])
+
+AC_DEFUN([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK],
+[
+  dnl We don't use AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK any more, because it
+  dnl is no longer maintained in Autoconf and because it invokes AC_LIBOBJ.
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether lstat correctly handles trailing slash],
+    [gl_cv_func_lstat_dereferences_slashed_symlink],
+    [rm -f conftest.sym conftest.file
+     echo >conftest.file
+     AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [AC_INCLUDES_DEFAULT],
+          [[struct stat sbuf;
+            if (symlink ("conftest.file", "conftest.sym") != 0)
+              return 1;
+            /* Linux will dereference the symlink and fail, as required by
+               POSIX.  That is better in the sense that it means we will not
+               have to compile and use the lstat wrapper.  */
+            return lstat ("conftest.sym/", &sbuf) == 0;
+          ]])],
+       [gl_cv_func_lstat_dereferences_slashed_symlink=yes],
+       [gl_cv_func_lstat_dereferences_slashed_symlink=no],
+       [case "$host_os" in
+          linux-* | linux)
+            # Guess yes on Linux systems.
+            gl_cv_func_lstat_dereferences_slashed_symlink="guessing yes" ;;
+          *-gnu* | gnu*)
+            # Guess yes on glibc systems.
+            gl_cv_func_lstat_dereferences_slashed_symlink="guessing yes" ;;
+          mingw*)
+            # Guess no on native Windows.
+            gl_cv_func_lstat_dereferences_slashed_symlink="guessing no" ;;
+          *)
+            # If we don't know, assume the worst.
+            gl_cv_func_lstat_dereferences_slashed_symlink="guessing no" ;;
+        esac
+       ])
+     rm -f conftest.sym conftest.file
+    ])
+  case "$gl_cv_func_lstat_dereferences_slashed_symlink" in
+    *yes)
+      AC_DEFINE_UNQUOTED([LSTAT_FOLLOWS_SLASHED_SYMLINK], [1],
+        [Define to 1 if 'lstat' dereferences a symlink specified
+         with a trailing slash.])
+      ;;
+  esac
+])