[master] 31baed29c Revert "On linux, use close_range() if available and prefer it over closefrom()"

[Dridi Boukelmoune]

commit 31baed29c5e77bafe8850d935240acefdb33cd4c
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Wed Feb 8 15:02:06 2023 +0100

    Revert "On linux, use close_range() if available and prefer it over closefrom()"
    
    This reverts commit 0c1aef58e57a5935116bf55176cbf48aad3d3a08.
    
    The close_range(2) system call is too recent and not recognized by the
    host system on CircleCI, so the fedora-latest container detects it but
    is denied execution (EPERM) from the host's libseccomp.
    
    Also, on platforms with neither close_range(2) nor closefrom(2) we ended
    up not including <dirent.h> and failing virtually everywhere in our CI.
    
    The ifdef dance could have looked like this:
    
        #ifdef HAVE_LINUX_CLOSE_RANGE_H
        #  include <linux/close_range.h>
        #elif HAVE_CLOSEFROM
        #else
        #  include <dirent.h>
        #endif
    
    Note the extra #else missing from the original patch.
    
    This is reverted for now because we need to check that close_range(2)
    works at configure time to circumvent the host mismatch problem.

diff --git a/configure.ac b/configure.ac
index e5b4a188a..dc0153c50 100644
--- a/configure.ac
+++ b/configure.ac
@@ -227,7 +227,6 @@ AC_CHECK_HEADERS([sys/vfs.h])
 AC_CHECK_HEADERS([endian.h])
 AC_CHECK_HEADERS([pthread_np.h], [], [], [#include <pthread.h>])
 AC_CHECK_HEADERS([priv.h])
-AC_CHECK_HEADERS([linux/close_range.h])
 AC_CHECK_HEADERS([fnmatch.h], [], [AC_MSG_ERROR([fnmatch.h is required])])
 
 # Checks for library functions.
diff --git a/lib/libvarnish/vsub.c b/lib/libvarnish/vsub.c
index 0cdac7364..b528c12c4 100644
--- a/lib/libvarnish/vsub.c
+++ b/lib/libvarnish/vsub.c
@@ -38,9 +38,7 @@
 #include <stdlib.h>		// Solaris closefrom(3c)
 #include <string.h>
 #include <unistd.h>
-#ifdef HAVE_LINUX_CLOSE_RANGE_H
-#  include <linux/close_range.h>
-#elif HAVE_CLOSEFROM
+#ifndef HAVE_CLOSEFROM
 #  include <dirent.h>
 #endif
 
@@ -67,10 +65,7 @@ VSUB_closefrom(int fd)
 
 	assert(fd >= 0);
 
-#ifdef HAVE_LINUX_CLOSE_RANGE_H
-	AZ(close_range(fd, ~0U, 0));
-	return;
-#elif HAVE_CLOSEFROM
+#ifdef HAVE_CLOSEFROM
 	closefrom(fd);
 	return;
 #else