httpd: code shrink via "split-globals" trick

function                                             old     new   delta
httpd_main                                           957     968     +11
log_and_exit                                          25      26      +1
send_headers                                         712     708      -4
handle_incoming_and_exit                            2292    2285      -7
sigalrm_handler                                      102      93      -9
parse_conf                                          1332    1323      -9
send_cgi_and_exit                                    803     790     -13
cgi_io_loop_and_exit                                 656     635     -21
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/6 up/down: 12/-63)            Total: -51 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 8d252d455..17c9bc785 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -457,6 +457,11 @@ void *xmmap_anon(size_t size) FAST_FUNC;
 //sparc64,alpha,openrisc: fixed 8k pages
 #endif
 
+#if defined(__x86_64__) || defined(i386)
+/* 0x7f would be better, but it causes alignment problems */
+# define ARCH_GLOBAL_PTR_OFF 0x80
+#endif
+
 #if defined BB_ARCH_FIXED_PAGESIZE
 # define IF_VARIABLE_ARCH_PAGESIZE(...) /*nothing*/
 # define bb_getpagesize()     BB_ARCH_FIXED_PAGESIZE
@@ -2423,6 +2428,16 @@ void XZALLOC_CONST_PTR(const void *pptr, size_t size) FAST_FUNC;
         } \
 } while (0)
 
+#if defined(ARCH_GLOBAL_PTR_OFF)
+# define SET_OFFSET_PTR_TO_GLOBALS(x) \
+        ASSIGN_CONST_PTR(&ptr_to_globals, (char*)(x) + ARCH_GLOBAL_PTR_OFF)
+# define OFFSET_PTR_TO_GLOBALS \
+        ((struct globals*)((char*)ptr_to_globals - ARCH_GLOBAL_PTR_OFF))
+#else
+# define SET_OFFSET_PTR_TO_GLOBALS(x) SET_PTR_TO_GLOBALS(x)
+# define OFFSET_PTR_TO_GLOBALS ptr_to_globals
+#endif
+
 
 /* You can change LIBBB_DEFAULT_LOGIN_SHELL, but don't use it,
  * use bb_default_login_shell and following defines.