From 4c6da5546c69efd2637319b71f6057c51fc428ec Mon Sep 17 00:00:00 2001
From: Thomas Devoogdt <thomas@devoogdt.com>
Date: Sat, 8 Jun 2024 15:51:53 +0200
Subject: [PATCH] build: use the system provided backtrace if found

e.g. buildroot has logic to build backtrace,
so if find_path/find_library can find a suitable version,
then use that one.

Signed-off-by: Thomas Devoogdt <thomas@devoogdt.com>
---
 CMakeLists.txt     | 43 ++++++++++++++++++++++++++-----------------
 src/CMakeLists.txt |  2 +-
 2 files changed, 27 insertions(+), 18 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c21597f6179..69094b38e1b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -998,25 +998,34 @@ endif()
 # =========================================
 if(FLB_BACKTRACE)
   FLB_DEFINITION(FLB_HAVE_LIBBACKTRACE)
-  if (CMAKE_OSX_SYSROOT)
-    # From macOS Mojave, /usr/include does not store C SDK headers.
-    # For libbacktrace building on macOS, we have to tell C headers where they are located.
-    set(DEPS_C_COMPILER "${CMAKE_C_COMPILER} -isysroot ${CMAKE_OSX_SYSROOT}")
+  find_path(LIBBACKTRACE_INCLUDE_DIRS NAMES backtrace.h)
+  find_library(LIBBACKTRACE_LIBRARIES NAMES backtrace)
+  if(LIBBACKTRACE_INCLUDE_DIRS_NOTFOUND OR LIBBACKTRACE_LIBRARIES_NOTFOUND)
+    message(STATUS "libbacktrace not found, building ourselves")
+    if (CMAKE_OSX_SYSROOT)
+      # From macOS Mojave, /usr/include does not store C SDK headers.
+      # For libbacktrace building on macOS, we have to tell C headers where they are located.
+      set(DEPS_C_COMPILER "${CMAKE_C_COMPILER} -isysroot ${CMAKE_OSX_SYSROOT}")
+    else()
+      set(DEPS_C_COMPILER "${CMAKE_C_COMPILER}")
+    endif()
+    set(FLB_LIBBACKTRACE_PATH "${CMAKE_CURRENT_BINARY_DIR}/backtrace-prefix/lib/libbacktrace.a")
+    ExternalProject_Add(backtrace
+      SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/lib/libbacktrace-8602fda/
+      CONFIGURE_COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/lib/libbacktrace-8602fda/configure ${AUTOCONF_HOST_OPT} --prefix=<INSTALL_DIR> --enable-shared=no --enable-static=yes
+      BUILD_COMMAND ${EXTERNAL_BUILD_TOOL}
+      BUILD_BYPRODUCTS ${FLB_LIBBACKTRACE_PATH}
+      INSTALL_COMMAND ${EXTERNAL_BUILD_TOOL} DESTDIR= install
+      )
+    add_library(libbacktrace STATIC IMPORTED GLOBAL)
+    set_target_properties(libbacktrace PROPERTIES IMPORTED_LOCATION ${FLB_LIBBACKTRACE_PATH})
+    add_dependencies(libbacktrace backtrace)
+    include_directories("${CMAKE_CURRENT_BINARY_DIR}/backtrace-prefix/include/")
+    set(LIBBACKTRACE_LIBRARIES "libbacktrace")
   else()
-    set(DEPS_C_COMPILER "${CMAKE_C_COMPILER}")
+    message(STATUS "libbacktrace found (${LIBBACKTRACE_LIBRARIES})")
+    include_directories(${LIBBACKTRACE_INCLUDE_DIRS})
   endif()
-  set(FLB_LIBBACKTRACE_PATH "${CMAKE_CURRENT_BINARY_DIR}/backtrace-prefix/lib/libbacktrace.a")
-  ExternalProject_Add(backtrace
-    SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/lib/libbacktrace-8602fda/
-    CONFIGURE_COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/lib/libbacktrace-8602fda/configure ${AUTOCONF_HOST_OPT} --prefix=<INSTALL_DIR> --enable-shared=no --enable-static=yes
-    BUILD_COMMAND ${EXTERNAL_BUILD_TOOL}
-    BUILD_BYPRODUCTS ${FLB_LIBBACKTRACE_PATH}
-    INSTALL_COMMAND ${EXTERNAL_BUILD_TOOL} DESTDIR= install
-    )
-  add_library(libbacktrace STATIC IMPORTED GLOBAL)
-  set_target_properties(libbacktrace PROPERTIES IMPORTED_LOCATION ${FLB_LIBBACKTRACE_PATH})
-  add_dependencies(libbacktrace backtrace)
-  include_directories("${CMAKE_CURRENT_BINARY_DIR}/backtrace-prefix/include/")
 endif()
 
 if(FLB_IN_KAFKA OR FLB_OUT_KAFKA)
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 17d4db17aca..6b81f517175 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -499,7 +499,7 @@ if(FLB_BINARY)
 
   if(FLB_BACKTRACE)
     add_definitions(-DFLB_DUMP_STACKTRACE=1)
-    target_link_libraries(fluent-bit-bin libbacktrace)
+    target_link_libraries(fluent-bit-bin ${LIBBACKTRACE_LIBRARIES})
   endif()
 
   target_link_libraries(fluent-bit-bin fluent-bit-static ${CMAKE_THREAD_LIBS_INIT})