Switch to check_symbol_exists() in simplest cases

There are a few exceptions. Some require _GNU_SOURCE, some are in the
weird strings.h header, some are probably too new to be found in the
standard locations.

Fixes #1077

2 files changed, 23 insertions, 18 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 048f6cf..a7574af 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -200,21 +200,23 @@ else()
         set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
 endif()
 
+# XXX - needs _GNU_SOURCE on linux
 check_function_exists(asprintf HAVE_ASPRINTF)
 if(HAVE_ASPRINTF)
         add_definitions(-DHAVE_ASPRINTF)
 endif()
 
-check_function_exists(getopt HAVE_GETOPT)
+check_symbol_exists(getopt "unistd.h" HAVE_GETOPT)
 if(HAVE_GETOPT)
         add_definitions(-DHAVE_GETOPT)
 endif()
 
-check_function_exists(reallocarray HAVE_REALLOCARRAY)
+check_symbol_exists(reallocarray "stdlib.h" HAVE_REALLOCARRAY)
 if(HAVE_REALLOCARRAY)
         add_definitions(-DHAVE_REALLOCARRAY)
 endif()
 
+# XXX strcasecmp() is in strings.h which isn't available everywhere
 check_function_exists(strcasecmp HAVE_STRCASECMP)
 if(HAVE_STRCASECMP)
         add_definitions(-DHAVE_STRCASECMP)
@@ -222,18 +224,18 @@ endif()
 
 # Emscripten's strlcat and strlcpy triggers ASAN errors
 if(NOT EMSCRIPTEN)
-        check_function_exists(strlcat HAVE_STRLCAT)
+        check_symbol_exists(strlcat "string.h" HAVE_STRLCAT)
         if(HAVE_STRLCAT)
                 add_definitions(-DHAVE_STRLCAT)
         endif()
 
-        check_function_exists(strlcpy HAVE_STRLCPY)
+        check_symbol_exists(strlcpy "string.h" HAVE_STRLCPY)
         if(HAVE_STRLCPY)
                 add_definitions(-DHAVE_STRLCPY)
         endif()
 endif()
 
-check_function_exists(strndup HAVE_STRNDUP)
+check_symbol_exists(strndup "string.h" HAVE_STRNDUP)
 if(HAVE_STRNDUP)
         add_definitions(-DHAVE_STRNDUP)
 endif()
@@ -242,62 +244,64 @@ if(WIN32)
         set(HAVE_STRNLEN true)
         add_definitions(-DHAVE_STRNLEN)
 else()
-        check_function_exists(strnlen HAVE_STRNLEN)
+        check_symbol_exists(strnlen "string.h" HAVE_STRNLEN)
         if(HAVE_STRNLEN)
                 add_definitions(-DHAVE_STRNLEN)
         endif()
 endif()
 
-check_function_exists(strsep HAVE_STRSEP)
+check_symbol_exists(strsep "string.h" HAVE_STRSEP)
 if(HAVE_STRSEP)
         add_definitions(-DHAVE_STRSEP)
 endif()
 
-check_function_exists(strtonum HAVE_STRTONUM)
+check_symbol_exists(strtonum "stdlib.h" HAVE_STRTONUM)
 if(HAVE_STRTONUM)
         add_definitions(-DHAVE_STRTONUM)
 endif()
 
-check_function_exists(arc4random_buf HAVE_ARC4RANDOM_BUF)
+check_symbol_exists(arc4random_buf "stdlib.h" HAVE_ARC4RANDOM_BUF)
 if(HAVE_ARC4RANDOM_BUF)
         add_definitions(-DHAVE_ARC4RANDOM_BUF)
 endif()
 
-check_function_exists(arc4random_uniform HAVE_ARC4RANDOM_UNIFORM)
+check_symbol_exists(arc4random_uniform "stdlib.h" HAVE_ARC4RANDOM_UNIFORM)
 if(HAVE_ARC4RANDOM_UNIFORM)
         add_definitions(-DHAVE_ARC4RANDOM_UNIFORM)
 endif()
 
-check_function_exists(explicit_bzero HAVE_EXPLICIT_BZERO)
+check_symbol_exists(explicit_bzero "string.h" HAVE_EXPLICIT_BZERO)
 if(HAVE_EXPLICIT_BZERO)
         add_definitions(-DHAVE_EXPLICIT_BZERO)
 endif()
 
-check_function_exists(getauxval HAVE_GETAUXVAL)
+check_symbol_exists(getauxval "sys/auxv.h" HAVE_GETAUXVAL)
 if(HAVE_GETAUXVAL)
         add_definitions(-DHAVE_GETAUXVAL)
 endif()
 
+# XXX macos fails to find getentropy with check_symbol_exists()
 check_function_exists(getentropy HAVE_GETENTROPY)
 if(HAVE_GETENTROPY)
         add_definitions(-DHAVE_GETENTROPY)
 endif()
 
-check_symbol_exists(getpagesize unistd.h HAVE_GETPAGESIZE)
+check_symbol_exists(getpagesize "unistd.h" HAVE_GETPAGESIZE)
 if(HAVE_GETPAGESIZE)
         add_definitions(-DHAVE_GETPAGESIZE)
 endif()
 
-check_function_exists(getprogname HAVE_GETPROGNAME)
+check_symbol_exists(getprogname "stdlib.h" HAVE_GETPROGNAME)
 if(HAVE_GETPROGNAME)
         add_definitions(-DHAVE_GETPROGNAME)
 endif()
 
-check_function_exists(syslog_r HAVE_SYSLOG_R)
+check_symbol_exists(syslog_r "syslog.h stdarg.h" HAVE_SYSLOG_R)
 if(HAVE_SYSLOG_R)
         add_definitions(-DHAVE_SYSLOG_R)
 endif()
 
+# XXX - needs _GNU_SOURCE on linux
 check_function_exists(syslog HAVE_SYSLOG)
 if(HAVE_SYSLOG)
         add_definitions(-DHAVE_SYSLOG)
@@ -308,16 +312,17 @@ if(HAVE_TIMESPECSUB)
         add_definitions(-DHAVE_TIMESPECSUB)
 endif()
 
-check_function_exists(timingsafe_bcmp HAVE_TIMINGSAFE_BCMP)
+check_symbol_exists(timingsafe_bcmp "string.h" HAVE_TIMINGSAFE_BCMP)
 if(HAVE_TIMINGSAFE_BCMP)
         add_definitions(-DHAVE_TIMINGSAFE_BCMP)
 endif()
 
-check_function_exists(timingsafe_memcmp HAVE_TIMINGSAFE_MEMCMP)
+check_symbol_exists(timingsafe_memcmp "string.h" HAVE_TIMINGSAFE_MEMCMP)
 if(HAVE_TIMINGSAFE_MEMCMP)
         add_definitions(-DHAVE_TIMINGSAFE_MEMCMP)
 endif()
 
+# XXX - needs _GNU_SOURCE on linux
 check_function_exists(memmem HAVE_MEMMEM)
 if(HAVE_MEMMEM)
         add_definitions(-DHAVE_MEMMEM)
diff --git a/apps/nc/CMakeLists.txt b/apps/nc/CMakeLists.txt
index 7bbdb02..d5f7813 100644
--- a/apps/nc/CMakeLists.txt
+++ b/apps/nc/CMakeLists.txt
@@ -22,7 +22,7 @@ else()
         set(NC_SRC ${NC_SRC} compat/accept4.c)
 endif()
 
-check_function_exists(readpassphrase HAVE_READPASSPHRASE)
+check_symbol_exists(readpassphrase "readpassphrase.h" HAVE_READPASSPHRASE)
 if(HAVE_READPASSPHRASE)
         add_definitions(-DHAVE_READPASSPHRASE)
 else()