[Qemu-devel] [PATCH 2/2] check for utimensat() availability on configure

[Eduardo Habkost <ehabkost@redhat.com>]

Some glibc versions don't have utimensat() available, but have other xxxat()
functions. Make a separated check for utimensat() to make sure we can compile
linux-user against some older glibc versions.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 configure            |   24 ++++++++++++++++++++++++
 linux-user/syscall.c |   25 +++++++++++++++++--------
 2 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/configure b/configure
index 89e7f53..a5ea78f 100755
--- a/configure
+++ b/configure
@@ -1254,6 +1254,27 @@ EOF
   fi
 fi
 
+# Check for utimensat() separatedly, because some glibc versions
+# have unlinkat() but not utimensat() available
+utimensat=no
+if [ "$linux_user" = "yes" -a "$atfile" = "yes" ] ; then
+  cat > $TMPC << EOF
+#define _ATFILE_SOURCE
+#include <sys/stat.h>
+#include <fcntl.h>
+
+int
+main(void)
+{
+	struct timespec times[2];
+	return (utimensat(AT_FDCWD, "nonexistent_file", times, 0));
+}
+EOF
+  if $cc $ARCH_CFLAGS -o $TMPE $TMPC 2> /dev/null ; then
+    utimensat=yes
+  fi
+fi
+
 # Check for inotify functions when we are building linux-user
 # emulator.  This is done because older glibc versions don't
 # have syscall stubs for these implemented.  In that case we
@@ -1673,6 +1694,9 @@ fi
 if test "$atfile" = "yes" ; then
   echo "#define CONFIG_ATFILE 1" >> $config_h
 fi
+if test "$utimensat" = "yes" ; then
+  echo "#define CONFIG_UTIMENSAT 1" >> $config_h
+fi
 if test "$inotify" = "yes" ; then
   echo "#define CONFIG_INOTIFY 1" >> $config_h
 fi
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index d851edc..42e2b77 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -413,13 +413,6 @@ static int sys_unlinkat(int dirfd, const char *pathname, int flags)
   return (unlinkat(dirfd, pathname, flags));
 }
 #endif
-#ifdef TARGET_NR_utimensat
-static int sys_utimensat(int dirfd, const char *pathname,
-    const struct timespec times[2], int flags)
-{
-  return (utimensat(dirfd, pathname, times, flags));
-}
-#endif
 #else /* !CONFIG_ATFILE */
 
 /*
@@ -478,12 +471,28 @@ _syscall3(int,sys_symlinkat,const char *,oldpath,
 #if defined(TARGET_NR_unlinkat) && defined(__NR_unlinkat)
 _syscall3(int,sys_unlinkat,int,dirfd,const char *,pathname,int,flags)
 #endif
+
+#endif /* CONFIG_ATFILE */
+
+
+#ifdef CONFIG_UTIMENSAT
+
+#ifdef TARGET_NR_utimensat
+static int sys_utimensat(int dirfd, const char *pathname,
+    const struct timespec times[2], int flags)
+{
+  return (utimensat(dirfd, pathname, times, flags));
+}
+#endif
+
+#else /* !CONFIG_UTIMENSAT */
 #if defined(TARGET_NR_utimensat) && defined(__NR_utimensat)
 _syscall4(int,sys_utimensat,int,dirfd,const char *,pathname,
           const struct timespec *,tsp,int,flags)
 #endif
 
-#endif /* CONFIG_ATFILE */
+#endif /* CONFIG_UTIMENSAT */
+
 
 #ifdef CONFIG_INOTIFY
 #include <sys/inotify.h>
-- 
1.6.3.rc4.29.g8146