[PATCH 03/19] libctf: lowest-level memory allocation and debug-dumping wrappers

[Nick Alcock]

Note for reviewers:

I could easily be convinced that all of these wrappers serve no purpose
and should be globally removed, but the debugging tracer is frequently
useful, and the malloc/free/mmap/munmap wrappers have proved mildly
useful in conjunction with symbol interposition for allocation debugging
in the (relatively distant) past.

(The debugging dumper is initialized via an ELF constructor in a different
TU, ctf-lib.c, because this ELF constructor also does other things, mostly
specific ctf-lib.c, which will be introduced in later commits, and we wanted
to keep the number of ELF constructors down.)

(I am amenable to replacing the environment-variable triggering of
ctf_dprintf() with something else in the binutils commit, and dropping
the other wrappers entirely, if you prefer.  If some other way of triggering
debugging trace output is preferred, or if the tracer should be replaced with
a do-nothing wrapper in binutils, that is fine too.)

libctf/
	* ctf-impl.h: New file.
	* ctf-lib.c: New file.
	* ctf-subr.c: New file.
---
 libctf/ctf-impl.h | 71 +++++++++++++++++++++++++++++++++++++++++++++
 libctf/ctf-lib.c  | 26 +++++++++++++++++
 libctf/ctf-subr.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 171 insertions(+)
 create mode 100644 libctf/ctf-impl.h
 create mode 100644 libctf/ctf-lib.c
 create mode 100644 libctf/ctf-subr.c

diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
new file mode 100644
index 0000000000..108c89d2c5
--- /dev/null
+++ b/libctf/ctf-impl.h
@@ -0,0 +1,71 @@
+/* Implementation header.
+   Copyright (C) 2006-2019 Free Software Foundation, Inc.
+
+   This file is part of libctf.
+
+   libctf is free software; you can redistribute it and/or modify it under
+   the terms of the GNU General Public License as published by the Free
+   Software Foundation; either version 2, or (at your option) any later
+   version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; see the file COPYING.  If not see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef	_CTF_IMPL_H
+#define	_CTF_IMPL_H
+
+#include "config.h"
+#include <sys/errno.h>
+#include <ctf-api.h>
+#include <sys/types.h>
+
+#ifdef	__cplusplus
+extern "C"
+  {
+#endif
+
+/* Compiler attributes.  */
+
+#if defined (__GNUC__)
+
+/* GCC.  We assume that all compilers claiming to be GCC support sufficiently
+   many GCC attributes that the code below works.  If some non-GCC compilers
+   masquerading as GCC in fact do not implement these attributes, version checks
+   may be required.  */
+
+/* We use the _libctf_*_ pattern to avoid clashes with any future attribute
+   macros glibc may introduce, which have names of the pattern
+   __attribute_blah__.  */
+
+#define _libctf_constructor_(x) __attribute__ ((__constructor__))
+#define _libctf_destructor_(x) __attribute__ ((__destructor__))
+#define _libctf_printflike_(string_index,first_to_check) \
+    __attribute__ ((__format__ (__printf__, (string_index), (first_to_check))))
+#define _libctf_unlikely_(x) __builtin_expect ((x), 0)
+#define _libctf_unused_ __attribute__ ((__unused__))
+
+#endif
+
+extern void *ctf_data_alloc (size_t);
+extern void ctf_data_free (void *, size_t);
+extern void ctf_data_protect (void *, size_t);
+
+extern void *ctf_alloc (size_t);
+extern void ctf_free (void *, size_t);
+
+_libctf_printflike_ (1, 2)
+extern void ctf_dprintf (const char *, ...);
+
+extern int _libctf_debug;	/* debugging messages enabled */
+
+#ifdef	__cplusplus
+}
+#endif
+
+#endif /* _CTF_IMPL_H */
diff --git a/libctf/ctf-lib.c b/libctf/ctf-lib.c
new file mode 100644
index 0000000000..1e81f3d20e
--- /dev/null
+++ b/libctf/ctf-lib.c
@@ -0,0 +1,26 @@
+/* Miscellary.
+   Copyright (C) 2003-2019 Free Software Foundation, Inc.
+
+   This file is part of libctf.
+
+   libctf is free software; you can redistribute it and/or modify it under
+   the terms of the GNU General Public License as published by the Free
+   Software Foundation; either version 2, or (at your option) any later
+   version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; see the file COPYING.  If not see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <ctf-impl.h>
+
+_libctf_constructor_(_libctf_init)
+static void _libctf_init (void)
+{
+  _libctf_debug = getenv ("LIBCTF_DEBUG") != NULL;
+}
diff --git a/libctf/ctf-subr.c b/libctf/ctf-subr.c
new file mode 100644
index 0000000000..f358298b7d
--- /dev/null
+++ b/libctf/ctf-subr.c
@@ -0,0 +1,74 @@
+/* Simple subrs.
+   Copyright (C) 2003-2019 Free Software Foundation, Inc.
+
+   This file is part of libctf.
+
+   libctf is free software; you can redistribute it and/or modify it under
+   the terms of the GNU General Public License as published by the Free
+   Software Foundation; either version 2, or (at your option) any later
+   version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; see the file COPYING.  If not see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <ctf-impl.h>
+#include <sys/mman.h>
+#include <stdarg.h>
+#include <string.h>
+
+void *
+ctf_data_alloc (size_t size)
+{
+  return (mmap (NULL, size, PROT_READ | PROT_WRITE,
+		MAP_PRIVATE | MAP_ANON, -1, 0));
+}
+
+void
+ctf_data_free (void *buf, size_t size)
+{
+  (void) munmap (buf, size);
+}
+
+void
+ctf_data_protect (void *buf, size_t size)
+{
+  (void) mprotect (buf, size, PROT_READ);
+}
+
+void *
+ctf_alloc (size_t size)
+{
+  return (malloc (size));
+}
+
+void
+ctf_free (void *buf, size_t size _libctf_unused_)
+{
+  free (buf);
+}
+
+const char *
+ctf_strerror (int err)
+{
+  return (const char *) (strerror (err));
+}
+
+_libctf_printflike_ (1, 2)
+void ctf_dprintf (const char *format, ...)
+{
+  if (_libctf_debug)
+    {
+      va_list alist;
+
+      va_start (alist, format);
+      (void) fputs ("libctf DEBUG: ", stderr);
+      (void) vfprintf (stderr, format, alist);
+      va_end (alist);
+    }
+}
-- 
2.21.0.237.gd0cfaa883d