From 3516b8b7558a69dfd06410b0c997d096a78221c9 Mon Sep 17 00:00:00 2001
From: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Date: Thu, 1 Sep 2016 11:20:05 +0200
Subject: Add libmissing

This patch adds a libmissing library to mtd-utils, containing
implementations of functionality found in glibc but typically
missing from embedded C libraries such as uclibc ot musl.

For now, the library only contains stub implementations of
the backtrace*() family of functions.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Signed-off-by: Richard Weinberger <richard@nod.at>
---
 Makefile.am                        |  4 ++++
 configure.ac                       |  3 +++
 include/libmissing.h               | 15 +++++++++++++++
 lib/Makemodule.am                  |  5 ++++-
 lib/execinfo.c                     | 25 +++++++++++++++++++++++++
 tests/fs-tests/Makemodule.am       |  5 +++++
 tests/fs-tests/integrity/integck.c |  2 +-
 7 files changed, 57 insertions(+), 2 deletions(-)
 create mode 100644 include/libmissing.h
 create mode 100644 lib/execinfo.c

diff --git a/Makefile.am b/Makefile.am
index 53c6ec3..686a747 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -10,6 +10,10 @@ if WITHOUT_LZO
 AM_CPPFLAGS += -DWITHOUT_LZO
 endif
 
+if HAVE_EXECINFO
+AM_CPPFLAGS += -DHAVE_EXECINFO
+endif
+
 sbin_PROGRAMS =
 sbin_SCRIPTS =
 noinst_LIBRARIES =
diff --git a/configure.ac b/configure.ac
index 9c8666c..637d692 100644
--- a/configure.ac
+++ b/configure.ac
@@ -72,6 +72,9 @@ AC_ARG_WITH([lzo],
 	[AM_CONDITIONAL([WITHOUT_LZO], [false])])
 
 
+AC_CHECK_HEADERS([execinfo.h], [execinfo_found=yes])
+AM_CONDITIONAL([HAVE_EXECINFO], [test "x$execinfo_found" == "xyes"])
+
 PKG_CHECK_MODULES(ZLIB, [ zlib ])
 PKG_CHECK_MODULES(UUID, [ uuid ])
 
diff --git a/include/libmissing.h b/include/libmissing.h
new file mode 100644
index 0000000..c765f6d
--- /dev/null
+++ b/include/libmissing.h
@@ -0,0 +1,15 @@
+#ifndef LIBMISSING_H
+#define LIBMISSING_H
+
+#ifdef HAVE_EXECINFO
+#include <execinfo.h>
+#endif
+
+#ifndef HAVE_EXECINFO
+int backtrace(void **buffer, int size);
+char **backtrace_symbols(void *const *buffer, int size);
+void backtrace_symbols_fd(void *const *buffer, int size, int fd);
+#endif
+
+#endif /* LIBMISSING_H */
+
diff --git a/lib/Makemodule.am b/lib/Makemodule.am
index 2fd933d..b30a8aa 100644
--- a/lib/Makemodule.am
+++ b/lib/Makemodule.am
@@ -5,4 +5,7 @@ libmtd_a_SOURCES = \
 	lib/libmtd_legacy.c \
 	lib/libmtd_int.h
 
-noinst_LIBRARIES += libmtd.a
+libmissing_a_SOURCES = \
+	lib/execinfo.c
+
+noinst_LIBRARIES += libmtd.a libmissing.a
diff --git a/lib/execinfo.c b/lib/execinfo.c
new file mode 100644
index 0000000..a39df83
--- /dev/null
+++ b/lib/execinfo.c
@@ -0,0 +1,25 @@
+#include "libmissing.h"
+
+#ifndef HAVE_EXECINFO
+#define PROGRAM_NAME "libmissing"
+#include "common.h"
+
+int backtrace(void **buffer, int size)
+{
+	void *addr = __builtin_return_address(0);
+
+	errmsg("backtrace() is not implemented. Called from %p", addr);
+	return 0;
+}
+
+char **backtrace_symbols(void *const *buffer, int size)
+{
+	errmsg("backtrace_symbols() is not implemented");
+	return NULL;
+}
+
+void backtrace_symbols_fd(void *const *buffer, int size, int fd)
+{
+	errmsg("backtrace_symbols_fd() is not implemented");
+}
+#endif /* !HAVE_EXECINFO */
diff --git a/tests/fs-tests/Makemodule.am b/tests/fs-tests/Makemodule.am
index 031355a..d3acaa5 100644
--- a/tests/fs-tests/Makemodule.am
+++ b/tests/fs-tests/Makemodule.am
@@ -2,6 +2,11 @@ integck_SOURCES = tests/fs-tests/integrity/integck.c
 integck_LDADD = libubi.a
 integck_CPPFLAGS = $(AM_CPPFLAGS) -I$(top_srcdir)/ubi-utils/include
 
+if HAVE_EXECINFO
+else
+integck_LDADD += libmissing.a
+endif
+
 test_1_SOURCES = tests/fs-tests/simple/test_1.c tests/fs-tests/lib/tests.c
 test_1_CPPFLAGS = $(AM_CPPFLAGS) -I$(top_srcdir)/tests/fs-tests/lib
 
diff --git a/tests/fs-tests/integrity/integck.c b/tests/fs-tests/integrity/integck.c
index 67384fa..7cb5305 100644
--- a/tests/fs-tests/integrity/integck.c
+++ b/tests/fs-tests/integrity/integck.c
@@ -31,7 +31,6 @@
 #include <getopt.h>
 #include <assert.h>
 #include <mntent.h>
-#include <execinfo.h>
 #include <sys/mman.h>
 #include <sys/vfs.h>
 #include <sys/mount.h>
@@ -40,6 +39,7 @@
 #define PROGRAM_NAME "integck"
 #include "common.h"
 #include "libubi.h"
+#include "libmissing.h"
 
 /*
  * WARNING! This is a dirty hack! The symbols for static functions are not
-- 
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