From 9bef473d17ec01efe760462271791dfaaea280c0 Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Wed, 29 Jul 2015 22:35:19 +0200 Subject: [PATCH 1/3] configure: refactor backtrace() detection The current code assumes that if __GLIBC__ is not defined, backtrace support is not available, and defines BTRFS_DISABLE_BACKTRACE. However, this macro is already defined by the configure.ac script when --disable-backtrace is passed. This means that if you are using a C library like musl which does not define __GLIBC__, and you pass --disable-backtrace, you get a macro redefinition. Instead of relying on __GLIBC__, this commit implements a proper configure.ac based detection of backtrace support: * If the user passes --enable-backtrace, we check if the backtrace() function is available. If not, we abort the configure process with an error. Otherwise we enable backtrace support by defining HAVE_BACKTRACE. * If the user passes --disable-backtrace, then we don't enable backtrace support. * If the user passes nothing special, we auto-detect: if backtrace() is available, we use it, otherwise we simply warn at configure time but not fail. Upstream-status: pending Signed-off-by: Thomas Petazzoni Signed-off-by: Brendan Heading --- configure.ac | 32 ++++++++++++++++++++++---------- kerncompat.h | 9 ++++----- 2 files changed, 26 insertions(+), 15 deletions(-) diff --git a/configure.ac b/configure.ac index c3a22d1..e936a10 100644 --- a/configure.ac +++ b/configure.ac @@ -63,22 +63,34 @@ AC_DEFUN([PKG_STATIC], [ fi ]) - +# Provide a --{enable,disable}-backtrace option. If not passed, set +# enable_backtrace to 'auto' so that we try to enable backtrace +# support if available, but if not available, we gracefully fallback +# without backtrace support. AC_ARG_ENABLE([backtrace], AS_HELP_STRING([--disable-backtrace], [disable btrfs backtrace]), - [], [enable_backtrace=yes] + [enable_backtrace=${enableval}], [enable_backtrace=auto] ) -AS_IF([test "x$enable_backtrace" = xno], [ - AC_DEFINE([BTRFS_DISABLE_BACKTRACE], [1], [disable backtrace stuff in kerncompat.h ]) -]) - -if test "x$enable_backtrace" = xyes; then - AC_CHECK_HEADERS([execinfo.h]) - AC_CHECK_FUNCS([backtrace backtrace_symbols_fd], [], - AC_MSG_ERROR([standard library does not have backtrace support])) +# Backtrace support requested (enable_backtrace is either 'yes' or +# 'auto'), so check for needed headers and functions. +if test "x$enable_backtrace" != xno; then + AC_CHECK_HEADERS([execinfo.h]) + AC_CHECK_FUNCS([backtrace backtrace_symbols_fd]) fi +if test "x$ac_cv_func_backtrace" = xno; then + # If backtrace support was requested but not available, we fail if + # --enable-backtrace was passed, or we simply warn if we're + # auto-detecting. + if test "x$enable_backtrace" = xyes ; then + AC_MSG_ERROR([standard library does not have backtrace support]) + elif test "x$enable_backtrace" = xauto ; then + AC_MSG_WARN([standard library does not have backtrace support, disabled]) + fi +else + AC_DEFINE([HAVE_BACKTRACE], [1], [Enable backtrace support]) +fi AC_ARG_ENABLE([documentation], AS_HELP_STRING([--disable-documentation], [do not build domumentation]), diff --git a/kerncompat.h b/kerncompat.h index 5d92856..8318665 100644 --- a/kerncompat.h +++ b/kerncompat.h @@ -33,11 +33,10 @@ #include #ifndef __GLIBC__ -#define BTRFS_DISABLE_BACKTRACE #define __always_inline __inline __attribute__ ((__always_inline__)) #endif -#ifndef BTRFS_DISABLE_BACKTRACE +#ifdef HAVE_BACKTRACE #include #endif @@ -65,7 +64,7 @@ #define ULONG_MAX (~0UL) #endif -#ifndef BTRFS_DISABLE_BACKTRACE +#ifdef HAVE_BACKTRACE #define MAX_BACKTRACE 16 static inline void print_trace(void) { @@ -285,7 +284,7 @@ static inline long IS_ERR(const void *ptr) #define vmalloc(x) malloc(x) #define vfree(x) free(x) -#ifndef BTRFS_DISABLE_BACKTRACE +#ifdef HAVE_BACKTRACE #define BUG_ON(c) assert_trace(#c, __FILE__, __func__, __LINE__, !(c)) #else #define BUG_ON(c) assert(!(c)) @@ -293,7 +292,7 @@ static inline long IS_ERR(const void *ptr) #define WARN_ON(c) BUG_ON(c) -#ifndef BTRFS_DISABLE_BACKTRACE +#ifdef HAVE_BACKTRACE #define ASSERT(c) assert_trace(#c, __FILE__, __func__, __LINE__, (c)) #else #define ASSERT(c) assert(c) -- 2.4.3