[glibc/release/2.33/master] support: Add xclone

[glibc/release/2.33/master] support: Add xclone

[Aurelien Jarno]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=46a70c49ba5a40059c76d5df387ff6e3b045de21

commit 46a70c49ba5a40059c76d5df387ff6e3b045de21
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Mar 10 12:26:30 2021 -0300

    support: Add xclone
    
    It is a wrapper for Linux clone syscall, to simplify the call to the
    use only the most common arguments and remove architecture specific
    handling (such as ia64 different name and signature).
    
    (cherry picked from commit de8995a2a04163617c1a233b4b81356ef9f9741f)

Diff:
---
 support/Makefile |  1 +
 support/xclone.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 support/xsched.h | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+)

diff --git a/support/Makefile b/support/Makefile
index 3c0eb200c2..f631846c07 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -92,6 +92,7 @@ libsupport-routines = \
   xchdir \
   xchroot \
   xclock_gettime \
+  xclone \
   xclose \
   xchmod \
   xconnect \
diff --git a/support/xclone.c b/support/xclone.c
new file mode 100644
index 0000000000..924d2b8754
--- /dev/null
+++ b/support/xclone.c
@@ -0,0 +1,50 @@
+/* Auxiliary functions to issue the clone syscall.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifdef __linux__
+# include <support/check.h>
+# include <stackinfo.h>  /* For _STACK_GROWS_{UP,DOWN}.  */
+# include <xsched.h>
+
+pid_t
+xclone (int (*fn) (void *arg), void *arg, void *stack, size_t stack_size,
+	int flags)
+{
+  pid_t r = -1;
+
+# ifdef __ia64__
+  extern int __clone2 (int (*fn) (void *arg), void *stack, size_t stack_size,
+		       int flags, void *arg, ...);
+  r = __clone2 (f, stack, stack_size, flags, arg, /* ptid */ NULL,
+		/* tls */ NULL, /* ctid  */ ctid);
+# else
+#  if _STACK_GROWS_DOWN
+  r = clone (fn, stack + stack_size, flags, arg, /* ptid */ NULL,
+	     /* tls */ NULL, /* ctid */  NULL);
+#  elif _STACK_GROWS_UP
+  r = clone (fn, stack, flags, arg, /* ptid */ NULL, /* tls */ NULL,
+	     &ctid);
+#  endif
+# endif
+
+  if (r < 0)
+    FAIL_EXIT1 ("clone: %m");
+
+  return r;
+}
+#endif
diff --git a/support/xsched.h b/support/xsched.h
new file mode 100644
index 0000000000..eefd731940
--- /dev/null
+++ b/support/xsched.h
@@ -0,0 +1,34 @@
+/* Wrapper for sched.h functions.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_XSCHED_H
+#define SUPPORT_XSCHED_H
+
+__BEGIN_DECLS
+
+#include <sched.h>
+#include <sys/types.h>
+
+#ifdef __linux__
+pid_t xclone (int (*fn) (void *arg), void *arg, void *stack,
+	      size_t stack_size, int flags);
+#endif
+
+__END_DECLS
+
+#endif