From dc9c4d454a5106437c58fc4ba1addadfe2aef05c Mon Sep 17 00:00:00 2001
From: Rolf Eike Beer <eb@emlix.com>
Date: Wed, 2 Aug 2017 14:09:19 +0200
Subject: [PATCH] CMake: detect the presence of entropy functions

---
 expat/CMakeLists.txt        |  4 ++++
 expat/ConfigureChecks.cmake | 21 +++++++++++++++++++++
 expat/expat_config.h.cmake  | 12 ++++++++++++
 expat/lib/xmlparse.c        |  3 ---
 4 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/expat/CMakeLists.txt b/expat/CMakeLists.txt
index 76e99c39..128966be 100644
--- a/expat/CMakeLists.txt
+++ b/expat/CMakeLists.txt
@@ -15,6 +15,7 @@ option(BUILD_examples "build the examples for expat library" ON)
 option(BUILD_tests "build the tests for expat library" ON)
 option(BUILD_shared "build a shared expat library" ON)
 option(BUILD_doc "build man page for xmlwf" ON)
+option(USE_libbsd "utilize libbsd (for arc4random_buf)" OFF)
 option(INSTALL "install expat files in cmake install target" ON)
 
 # configuration options
@@ -78,6 +79,9 @@ else(BUILD_shared)
 endif(BUILD_shared)
 
 add_library(expat ${_SHARED} ${expat_SRCS})
+if(USE_libbsd)
+    target_link_libraries(expat bsd)
+endif()
 
 set(LIBCURRENT 7)   # sync
 set(LIBREVISION 5)  # with
diff --git a/expat/ConfigureChecks.cmake b/expat/ConfigureChecks.cmake
index 6e440ca0..7d44ec1a 100644
--- a/expat/ConfigureChecks.cmake
+++ b/expat/ConfigureChecks.cmake
@@ -1,4 +1,5 @@
 include(CheckCCompilerFlag)
+include(CheckCSourceCompiles)
 include(CheckIncludeFile)
 include(CheckIncludeFiles)
 include(CheckFunctionExists)
@@ -21,6 +22,16 @@ check_function_exists("getpagesize" HAVE_GETPAGESIZE)
 check_function_exists("bcopy" HAVE_BCOPY)
 check_symbol_exists("memmove" "string.h" HAVE_MEMMOVE)
 check_function_exists("mmap" HAVE_MMAP)
+check_function_exists("getrandom" HAVE_GETRANDOM)
+
+if(USE_libbsd)
+    set(CMAKE_REQUIRED_LIBRARIES "bsd")
+endif()
+check_function_exists("arc4random_buf" HAVE_ARC4RANDOM_BUF)
+if(NOT HAVE_ARC4RANDOM_BUF)
+    check_function_exists("arc4random" HAVE_ARC4RANDOM)
+endif()
+set(CMAKE_REQUIRED_LIBRARIES)
 
 #/* Define to 1 if you have the ANSI C header files. */
 check_include_files("stdlib.h;stdarg.h;string.h;float.h" STDC_HEADERS)
@@ -41,6 +52,16 @@ else(HAVE_SYS_TYPES_H)
     set(SIZE_T "unsigned")
 endif(HAVE_SYS_TYPES_H)
 
+check_c_source_compiles("
+        #include <stdlib.h>  /* for NULL */
+        #include <unistd.h>  /* for syscall */
+        #include <sys/syscall.h>  /* for SYS_getrandom */
+        int main() {
+            syscall(SYS_getrandom, NULL, 0, 0);
+            return 0;
+        }"
+    HAVE_SYSCALL_GETRANDOM)
+
 configure_file(expat_config.h.cmake "${CMAKE_CURRENT_BINARY_DIR}/expat_config.h")
 add_definitions(-DHAVE_EXPAT_CONFIG_H)
 
diff --git a/expat/expat_config.h.cmake b/expat/expat_config.h.cmake
index e5147915..41829c04 100644
--- a/expat/expat_config.h.cmake
+++ b/expat/expat_config.h.cmake
@@ -3,6 +3,12 @@
 /* 1234 = LIL_ENDIAN, 4321 = BIGENDIAN */
 #cmakedefine BYTEORDER @BYTEORDER@
 
+/* Define to 1 if you have the `arc4random' function. */
+#cmakedefine HAVE_ARC4RANDOM
+
+/* Define to 1 if you have the `arc4random_buf' function. */
+#cmakedefine HAVE_ARC4RANDOM_BUF
+
 /* Define to 1 if you have the `bcopy' function. */
 #cmakedefine HAVE_BCOPY
 
@@ -15,6 +21,9 @@
 /* Define to 1 if you have the `getpagesize' function. */
 #cmakedefine HAVE_GETPAGESIZE
 
+/* Define to 1 if you have the `getrandom' function. */
+#cmakedefine HAVE_GETRANDOM
+
 /* Define to 1 if you have the <inttypes.h> header file. */
 #cmakedefine HAVE_INTTYPES_H
 
@@ -39,6 +48,9 @@
 /* Define to 1 if you have the <string.h> header file. */
 #cmakedefine HAVE_STRING_H
 
+/* Define to 1 if you have `syscall' and `SYS_getrandom'. */
+#cmakedefine HAVE_SYSCALL_GETRANDOM
+
 /* Define to 1 if you have the <sys/stat.h> header file. */
 #cmakedefine HAVE_SYS_STAT_H
 
diff --git a/expat/lib/xmlparse.c b/expat/lib/xmlparse.c
index b703e61a..86c79f26 100644
--- a/expat/lib/xmlparse.c
+++ b/expat/lib/xmlparse.c
@@ -80,9 +80,6 @@
     If insist on not using any of these, bypass this error by defining \
     XML_POOR_ENTROPY; you have been warned. \
     \
-    For CMake, one way to pass the define is: \
-        cmake -DCMAKE_C_FLAGS="-pipe -O2 -DHAVE_SYSCALL_GETRANDOM" . \
-    \
     If you have reasons to patch this detection code away or need changes \
     to the build system, please open a bug.  Thank you!
 #endif
-- 
2.40.0