Enable auto-generation of a size-optimized sysconf function (saves .5k on i386).

Makefile

@@ -29,7 +29,7 @@
 include Rules.mak
 
 
-DIRS = misc pwd_grp stdio string termios unistd net signal stdlib sysdeps extra
+DIRS = extra misc pwd_grp stdio string termios net signal stdlib sysdeps unistd
 
 ifeq ($(HAS_MMU),true)
 	DO_SHARED=shared

libc/unistd/.cvsignore

@@ -0,0 +1,2 @@
+sysconf_*.c
+gen_sysconf

libc/unistd/Makefile

@@ -24,9 +24,16 @@ TOPDIR=../
 include $(TOPDIR)Rules.mak
 LIBC=$(TOPDIR)libc.a
 
-
 CSRC=execl.c execlp.c execv.c execvep.c execvp.c getcwd.c getopt.c \
-	sleep.c sysconf.c getpass.c
+	sleep.c getpass.c sysconf_src.c
+
+# TESTING -- comment this out if it breaks for you
+ifeq ($(TARGET_ARCH), $(NATIVE_ARCH))
+	SYSCONF = sysconf_native
+else
+	SYSCONF = sysconf_$(TARGET_ARCH).c
+endif
+
 COBJS=$(patsubst %.c,%.o, $(CSRC))
 
 MSRC=gnu_getopt.c
@@ -36,13 +43,44 @@ MOBJ=_gnu_getopt_internal.o gnu_getopt_long.o gnu_getopt_long_only.o
 # over gnu_getopt when appropriate.
 OBJS=$(COBJS) $(MOBJ)
 
-all: $(OBJS) $(LIBC)
+all: $(SYSCONF) $(OBJS) $(LIBC)
 
 $(LIBC): ar-target subdirs
 
 ar-target: $(OBJS)
 	$(AR) $(ARFLAGS) $(LIBC) $(OBJS)
 
+# We are cross-compiling so use the generic sysconf.c.
+sysconf_$(TARGET_ARCH).c: sysconf.c
+	@echo warning: sysconf_$(NATIVE_ARCH).c is older then sysconf.c so using generic sysconf.c
+	@echo To build sysconf_$(NATIVE_ARCH).c run gen_sysconf \> sysconf_$(NATIVE_ARCH).c on
+	@echo your target platform, place in the unistd directory, and rebuild
+	cp -f sysconf.c sysconf_src.c
+
+# We are compiling for the native platform, so build an optimized sysconf.c.
+sysconf_native: sysconf.c
+	$(CC) $(CFLAGS) -D_UCLIBC_GENERATE_SYSCONF_ARCH -c sysconf.c -o sysconf_tester.o
+	$(CC) $(CFLAGS) -D_UCLIBC_GENERATE_SYSCONF_ARCH -c ../sysdeps/linux/common/getpagesize.c -o getpagesize_tester.o
+	@ld -r -o gen_sysconf_tester.o sysconf_tester.o getpagesize_tester.o
+	@if nm -s gen_sysconf_tester.o | grep -v "U errno" | grep " U " ;\
+	then \
+		echo warning: missing symbols in gen_sysconf_tester.o so using generic sysconf.c ;\
+		cp -f sysconf.c sysconf_src.c ;\
+	else \
+		if ../extra/gcc-uClibc/gcc-uClibc-$(NATIVE_ARCH) -static -D_UCLIBC_GENERATE_SYSCONF_MAIN sysconf.c sysconf_tester.o -o gen_sysconf && \
+			./gen_sysconf > sysconf_$(NATIVE_ARCH).c ;\
+		then \
+			echo successfully built sysconf_$(NATIVE_ARCH).c ;\
+		else \
+			echo warning: build of gen_sysconf failed so using generic sysconf.c ;\
+			cp -f sysconf.c sysconf_$(NATIVE_ARCH).c ;\
+		fi ;\
+	fi
+
+sysconf_src.c: sysconf_$(TARGET_ARCH).c
+	cp -f sysconf_$(TARGET_ARCH).c sysconf_src.c
+
+
 $(COBJS): %.o : %.c
 	$(CC) $(CFLAGS) -c $< -o $@
 	$(STRIPTOOL) -x -R .note -R .comment $*.o
@@ -63,5 +101,5 @@ $(patsubst %, _dirclean_%, $(DIRS)) : dummy
 	$(MAKE) -C $(patsubst _dirclean_%, %, $@) clean
 
 clean:
-	rm -f *.[oa] *~ core
+	rm -f *.[oa] *~ core gen_sysconf sysconf_*.c
 

libc/unistd/sysconf.c

@@ -29,6 +29,36 @@
 #include <sys/types.h>
 #include <regex.h>
 
+/***********************************************************************/
+/*
+ * Manuel Novoa III        Jan 2001
+ *
+ * On i386, the switch-based implementation generates 796 bytes of code.
+ * However, many of the return values are repeats.  By collecting these
+ * repeats and moving to a table-based implementation, we generate 283
+ * bytes on i386 (-Os -fomit-frame-pointer).
+ */
+#ifndef _UCLIBC_GENERATE_SYSCONF_MAIN
+
+#ifdef _UCLIBC_GENERATE_SYSCONF_ARCH
+/*
+ * Set some errno's so the auto-gen code knows what it is dealing with.
+ *    1) ENOSYS signifies that we're returning a default value.
+ *       This is just extra info for development.
+ *    2) EISNAM signifies that the value returned varies at runtime.
+ *
+ * Option: GETPAGESIZE_IS_DYNAMIC
+ *    The current implementation of getpagesize in uClibc returns
+ *    a constant.  The pagesize on the target arch should not vary,
+ *    so it should be safe to set this as 0.
+ */
+#define RETURN_NEG_1 errno = ENOSYS; return -1
+#define RETURN_FUNCTION(f) errno = EISNAM ; return (long int) #f
+#define GETPAGESIZE_IS_DYNAMIC 0
+#else
+#define RETURN_NEG_1 return -1
+#define RETURN_FUNCTION(f) return f;
+#endif /* _UCLIBC_GENERATE_SYSCONF_ARCH */
 
 /* Get the value of the system variable NAME.  */
 long int sysconf(int name)
@@ -43,14 +73,14 @@ long int sysconf(int name)
 #ifdef	ARG_MAX
       return ARG_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_CHILD_MAX:
 #ifdef	CHILD_MAX
       return CHILD_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_CLK_TCK:
@@ -64,14 +94,14 @@ long int sysconf(int name)
 #ifdef	NGROUPS_MAX
       return NGROUPS_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_OPEN_MAX:
 #if 0
-      return getdtablesize ();
+      RETURN_FUNCTION(getdtablesize());
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_STREAM_MAX:
@@ -83,372 +113,376 @@ long int sysconf(int name)
 
     case _SC_TZNAME_MAX:
 #if 0
-      return tzname_max ();
+      RETURN_FUNCTION(tzname_max ());
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_JOB_CONTROL:
 #ifdef	_POSIX_JOB_CONTROL
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_SAVED_IDS:
 #ifdef	_POSIX_SAVED_IDS
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_REALTIME_SIGNALS:
 #ifdef	_POSIX_REALTIME_SIGNALS
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PRIORITY_SCHEDULING:
 #ifdef	_POSIX_PRIORITY_SCHEDULING
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_TIMERS:
 #ifdef	_POSIX_TIMERS
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_ASYNCHRONOUS_IO:
 #ifdef	_POSIX_ASYNCHRONOUS_IO
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PRIORITIZED_IO:
 #ifdef	_POSIX_PRIORITIZED_IO
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_SYNCHRONIZED_IO:
 #ifdef	_POSIX_SYNCHRONIZED_IO
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_FSYNC:
 #ifdef	_POSIX_FSYNC
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_MAPPED_FILES:
 #ifdef	_POSIX_MAPPED_FILES
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_MEMLOCK:
 #ifdef	_POSIX_MEMLOCK
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_MEMLOCK_RANGE:
 #ifdef	_POSIX_MEMLOCK_RANGE
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_MEMORY_PROTECTION:
 #ifdef	_POSIX_MEMORY_PROTECTION
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_MESSAGE_PASSING:
 #ifdef	_POSIX_MESSAGE_PASSING
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_SEMAPHORES:
 #ifdef	_POSIX_SEMAPHORES
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_SHARED_MEMORY_OBJECTS:
 #ifdef	_POSIX_SHARED_MEMORY_OBJECTS
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_VERSION:
       return _POSIX_VERSION;
 
     case _SC_PAGESIZE:
-      return getpagesize();
+#if defined(GETPAGESIZE_IS_DYNAMIC) && (GETPAGESIZE_IS_DYNAMIC == 1)
+      RETURN_FUNCTION(getpagesize());
+#else
+      return getpagesize();		/* note: currently this is not dynamic */
+#endif
 
     case _SC_AIO_LISTIO_MAX:
 #ifdef	AIO_LISTIO_MAX
       return AIO_LISTIO_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_AIO_MAX:
 #ifdef	AIO_MAX
       return AIO_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_AIO_PRIO_DELTA_MAX:
 #ifdef	AIO_PRIO_DELTA_MAX
       return AIO_PRIO_DELTA_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_DELAYTIMER_MAX:
 #ifdef	DELAYTIMER_MAX
       return DELAYTIMER_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_MQ_OPEN_MAX:
 #ifdef	MQ_OPEN_MAX
       return MQ_OPEN_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_MQ_PRIO_MAX:
 #ifdef	MQ_PRIO_MAX
       return MQ_PRIO_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_RTSIG_MAX:
 #ifdef	RTSIG_MAX
       return RTSIG_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_SEM_NSEMS_MAX:
 #ifdef	SEM_NSEMS_MAX
       return SEM_NSEMS_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_SEM_VALUE_MAX:
 #ifdef	SEM_VALUE_MAX
       return SEM_VALUE_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_SIGQUEUE_MAX:
 #ifdef	SIGQUEUE_MAX
       return SIGQUEUE_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_TIMER_MAX:
 #ifdef	TIMER_MAX
       return TIMER_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_BC_BASE_MAX:
 #ifdef	BC_BASE_MAX
       return BC_BASE_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_BC_DIM_MAX:
 #ifdef	BC_DIM_MAX
       return BC_DIM_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_BC_SCALE_MAX:
 #ifdef	BC_SCALE_MAX
       return BC_SCALE_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_BC_STRING_MAX:
 #ifdef	BC_STRING_MAX
       return BC_STRING_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_COLL_WEIGHTS_MAX:
 #ifdef	COLL_WEIGHTS_MAX
       return COLL_WEIGHTS_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_EQUIV_CLASS_MAX:
 #ifdef	EQUIV_CLASS_MAX
       return EQUIV_CLASS_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_EXPR_NEST_MAX:
 #ifdef	EXPR_NEST_MAX
       return EXPR_NEST_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_LINE_MAX:
 #ifdef	LINE_MAX
       return LINE_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_RE_DUP_MAX:
 #ifdef	RE_DUP_MAX
       return RE_DUP_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_CHARCLASS_NAME_MAX:
 #ifdef	CHARCLASS_NAME_MAX
       return CHARCLASS_NAME_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PII:
 #ifdef	_POSIX_PII
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PII_XTI:
 #ifdef	_POSIX_PII_XTI
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PII_SOCKET:
 #ifdef	_POSIX_PII_SOCKET
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PII_INTERNET:
 #ifdef	_POSIX_PII_INTERNET
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PII_OSI:
 #ifdef	_POSIX_PII_OSI
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_POLL:
 #ifdef	_POSIX_POLL
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_SELECT:
 #ifdef	_POSIX_SELECT
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_UIO_MAXIOV:
 #ifdef	UIO_MAXIOV
       return UIO_MAXIOV;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PII_INTERNET_STREAM:
 #ifdef	_POSIX_PII_INTERNET_STREAM
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PII_INTERNET_DGRAM:
 #ifdef	_POSIX_PII_INTERNET_DGRAM
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PII_OSI_COTS:
 #ifdef	_POSIX_PII_OSI_COTS
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PII_OSI_CLTS:
 #ifdef	_POSIX_PII_OSI_CLTS
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PII_OSI_M:
 #ifdef	_POSIX_PII_OSI_M
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_T_IOV_MAX:
 #ifdef	_T_IOV_MAX
       return _T_IOV_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_2_VERSION:
@@ -458,63 +492,63 @@ long int sysconf(int name)
 #ifdef	_POSIX2_C_BIND
       return _POSIX2_C_BIND;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_2_C_DEV:
 #ifdef	_POSIX2_C_DEV
       return _POSIX2_C_DEV;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_2_C_VERSION:
 #ifdef	_POSIX2_C_VERSION
       return _POSIX2_C_VERSION;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_2_FORT_DEV:
 #ifdef	_POSIX2_FORT_DEV
       return _POSIX2_FORT_DEV;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_2_FORT_RUN:
 #ifdef	_POSIX2_FORT_RUN
       return _POSIX2_FORT_RUN;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_2_LOCALEDEF:
 #ifdef	_POSIX2_LOCALEDEF
       return _POSIX2_LOCALEDEF;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_2_SW_DEV:
 #ifdef	_POSIX2_SW_DEV
       return _POSIX2_SW_DEV;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_2_CHAR_TERM:
 #ifdef	_POSIX2_CHAR_TERM
       return _POSIX2_CHAR_TERM;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_2_UPE:
 #ifdef	_POSIX2_UPE
       return _POSIX2_UPE;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
       /* POSIX 1003.1c (POSIX Threads).  */
@@ -522,140 +556,140 @@ long int sysconf(int name)
 #ifdef	_POSIX_THREADS
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_SAFE_FUNCTIONS:
 #ifdef	_POSIX_THREAD_SAFE_FUNCTIONS
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_GETGR_R_SIZE_MAX:
 #ifdef	NSS_BUFLEN_GROUP
       return NSS_BUFLEN_GROUP;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_GETPW_R_SIZE_MAX:
 #ifdef	NSS_BUFLEN_PASSWD
       return NSS_BUFLEN_PASSWD;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_LOGIN_NAME_MAX:
 #ifdef	_POSIX_LOGIN_NAME_MAX
       return _POSIX_LOGIN_NAME_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_TTY_NAME_MAX:
 #ifdef	_POSIX_TTY_NAME_MAX
       return _POSIX_TTY_NAME_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_DESTRUCTOR_ITERATIONS:
 #ifdef	_POSIX_THREAD_DESTRUCTOR_ITERATIONS
       return _POSIX_THREAD_DESTRUCTOR_ITERATIONS;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_KEYS_MAX:
 #ifdef	PTHREAD_KEYS_MAX
       return PTHREAD_KEYS_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_STACK_MIN:
 #ifdef	PTHREAD_STACK_MIN
       return PTHREAD_STACK_MIN;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_THREADS_MAX:
 #ifdef	PTHREAD_THREADS_MAX
       return PTHREAD_THREADS_MAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_ATTR_STACKADDR:
 #ifdef	_POSIX_THREAD_ATTR_STACKADDR
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_ATTR_STACKSIZE:
 #ifdef	_POSIX_THREAD_ATTR_STACKSIZE
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_PRIORITY_SCHEDULING:
 #ifdef	_POSIX_THREAD_PRIORITY_SCHEDULING
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_PRIO_INHERIT:
 #ifdef	_POSIX_THREAD_PRIO_INHERIT
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_PRIO_PROTECT:
 #ifdef	_POSIX_THREAD_PRIO_PROTECT
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_THREAD_PROCESS_SHARED:
 #ifdef	_POSIX_THREAD_PROCESS_SHARED
       return 1;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_NPROCESSORS_CONF:
 #if 0
-      return get_nprocs_conf ();
+      RETURN_FUNCTION(get_nprocs_conf());
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_NPROCESSORS_ONLN:
 #if 0
-      return get_nprocs ();
+      RETURN_FUNCTION(get_nprocs());
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_PHYS_PAGES:
 #if 0
-      return get_phys_pages ();
+      RETURN_FUNCTION(get_phys_pages());
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_AVPHYS_PAGES:
 #if 0
-      return get_avphys_pages ();
+      RETURN_FUNCTION(get_avphys_pages());
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_ATEXIT_MAX:
@@ -679,42 +713,42 @@ long int sysconf(int name)
 #ifdef	_XOPEN_CRYPT
       return _XOPEN_CRYPT;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_XOPEN_ENH_I18N:
 #ifdef	_XOPEN_ENH_I18N
       return _XOPEN_ENH_I18N;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_XOPEN_SHM:
 #ifdef	_XOPEN_SHM
       return _XOPEN_SHM;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_XOPEN_XPG2:
 #ifdef	_XOPEN_XPG2
       return _XOPEN_XPG2;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_XOPEN_XPG3:
 #ifdef	_XOPEN_XPG3
       return _XOPEN_XPG3;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_XOPEN_XPG4:
 #ifdef	_XOPEN_XPG4
       return _XOPEN_XPG4;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_CHAR_BIT:
@@ -775,67 +809,67 @@ long int sysconf(int name)
 #ifdef	NL_ARGMAX
       return NL_ARGMAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_NL_LANGMAX:
 #ifdef	NL_LANGMAX
       return NL_LANGMAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_NL_MSGMAX:
 #ifdef	NL_MSGMAX
       return NL_MSGMAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_NL_NMAX:
 #ifdef	NL_NMAX
       return NL_NMAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_NL_SETMAX:
 #ifdef	NL_SETMAX
       return NL_SETMAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_NL_TEXTMAX:
 #ifdef	NL_TEXTMAX
       return NL_TEXTMAX;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_XBS5_ILP32_OFF32:
 #ifdef _XBS5_ILP32_OFF32
       return _XBS5_ILP32_OFF32;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
     case _SC_XBS5_ILP32_OFFBIG:
 #ifdef _XBS5_ILP32_OFFBIG
       return _XBS5_ILP32_OFFBIG;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
     case _SC_XBS5_LP64_OFF64:
 #ifdef _XBS5_LP64_OFF64
       return _XBS5_LP64_OFF64;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
     case _SC_XBS5_LPBIG_OFFBIG:
 #ifdef _XBS5_LPBIG_OFFBIG
       return _XBS5_LPBIG_OFFBIG;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
 
     case _SC_XOPEN_LEGACY:
@@ -845,14 +879,175 @@ long int sysconf(int name)
 #ifdef _XOPEN_REALTIME
       return _XOPEN_REALTIME;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
     case _SC_XOPEN_REALTIME_THREADS:
 #ifdef _XOPEN_REALTIME_THREADS
       return _XOPEN_REALTIME_THREADS;
 #else
-      return -1;
+      RETURN_NEG_1;
 #endif
     }
 }
 
+#endif /* _UCLIBC_GENERATE_SYSCONF_MAIN */
+/***********************************************************************/
+#ifdef _UCLIBC_GENERATE_SYSCONF_MAIN
+
+static long int ret_vals[_UCLIBC_SYSCONF_NUM_VALID_ARGS];
+
+static const char *type_str[] = {
+	"char", "short", "int", "long"
+};
+
+static const char *type_fmt[] = { " %4ld", " %6ld", " %8ld", " %8ld" };
+static const int type_mod[] = { 13, 9, 6, 6 };
+
+static int find_or_add_in_table(int index, long int val, int *table, 
+								int *num_in_table, int add_flag)
+{
+	int i;
+
+	for (i=0 ; i<*num_in_table ; i++) {
+		if (ret_vals[table[i]] == val) {
+			return i;
+		}
+	}
+	if (add_flag) {
+		table[(*num_in_table)++] = index;
+		return i;
+	} else {
+		return -1;
+	}
+}
+
+
+int main(void)
+{
+	long int r;
+	int type_table[5][_UCLIBC_SYSCONF_NUM_VALID_ARGS];
+	int ret_type[_UCLIBC_SYSCONF_NUM_VALID_ARGS];
+	int num_type[5];
+	int i, j, k, code;
+
+	for (i=0 ; i<5 ; i++) {
+		num_type[i] = 0;
+	}
+
+	for (i=0; i<_UCLIBC_SYSCONF_NUM_VALID_ARGS ; i++) {
+		errno = 0;
+		r = ret_vals[i] = sysconf(i);
+		switch(errno) {
+			case EINVAL:		/* we're missing a case! */
+				fprintf(stderr,"sysconf.c is broken! case %d missing!\n", i);
+				return EXIT_FAILURE;
+			case EISNAM:		/* function */
+				find_or_add_in_table(i,r,type_table[4],num_type+4,1);
+				ret_type[i] = 4;
+				break;
+			case ENOSYS:		/* defaults to -1 */
+				/* why does this break for shared???? */
+				fprintf(stderr,"gen_sysconf advisory --"
+						"case %d defaults to -1\n", i);
+				/* fall through */
+			case 0:
+				if ((r>=CHAR_MIN) && (r<=CHAR_MAX)) {
+					ret_type[i] = 0;
+					find_or_add_in_table(i,r,type_table[0],num_type+0,1);
+				} else if ((r>=SHRT_MIN) && (r<=SHRT_MAX)) {
+					ret_type[i] = 1;
+					find_or_add_in_table(i,r,type_table[1],num_type+1,1);
+				} else if ((r>=INT_MIN) && (r<=INT_MAX)) {
+					ret_type[i] = 2;
+					find_or_add_in_table(i,r,type_table[2],num_type+2,1);
+				} else {
+					ret_type[i] = 3;
+					find_or_add_in_table(i,r,type_table[3],num_type+3,1);
+				}
+				break;
+			default:
+				fprintf(stderr,"sysconf.c is broken! errno = %d!\n", errno);
+				break;
+		}
+	}
+
+	printf("#include <errno.h>\n#include <unistd.h>\n#include <limits.h>\n\n");
+
+	printf("static const unsigned char index[%d] = {",
+		   _UCLIBC_SYSCONF_NUM_VALID_ARGS);
+	for (i=0 ; i<_UCLIBC_SYSCONF_NUM_VALID_ARGS ; i++) {
+		if (i) printf(",");
+		if (i%15 == 0) printf("\n");
+		code = 0;
+		for (j=0 ; j<4 ; j++) {
+			k = find_or_add_in_table(i,ret_vals[i],type_table[j],num_type+j,0);
+			if (k>=0) {
+				code += k;
+				break;
+			}
+			code += num_type[j];
+		}
+		printf(" %3d", code);
+	}
+	printf("\n};\n\n");
+
+	for (j=0 ; j < 4 ; j++) {
+		if (num_type[j]) {
+			printf("static const %s %s_vals[%d] = {",
+				   type_str[j], type_str[j], num_type[j]);
+			for (i = 0 ; i<num_type[j] ; i++) {
+				if (i) printf(",");
+				if (i%13 == 0) printf("\n");
+				if (ret_vals[type_table[j][i]] == INT_MIN) {
+					printf("%12s","INT_MIN");
+				} else {
+					printf(type_fmt[j], ret_vals[type_table[j][i]]);
+				}
+
+			}
+			printf("\n};\n\n");
+		}
+	}
+
+	printf("long int sysconf(int name)\n{\n\tint i;\n\n"
+		   "\tif ((name < 0) || (name >= %d)) {\n"
+		   "\t\terrno=EINVAL;\n"
+		   "\t\treturn -1;\n"
+		   "\t}\n\n", _UCLIBC_SYSCONF_NUM_VALID_ARGS);
+
+	printf("\ti = index[name];\n\n");
+	k = 0;
+	for (i=0 ; i<4 ; i++) {
+		if (num_type[i]) {
+			if (k>0) {
+				printf("\ti -= %d;\n", k);
+			}
+			printf("\tif (i < %d) {\n"
+				   "\t\treturn %s_vals[i];\n"
+				   "\t}\n\n",
+				   num_type[i], type_str[i]);
+			k = num_type[i];
+		}
+	}
+
+	if (num_type[4]) {
+		if (k>0) {
+			printf("\ti -= %d;\n", k);
+		}
+		printf("\tswitch(i) {\n");
+		for (i = 0 ; i<num_type[4] ; i++) {
+			printf("\t\tcase %d:\n"
+				   "\t\t\treturn %s;\n",
+				   i, (const char *)ret_vals[type_table[4][i]]);
+		}
+		printf("\t}\n\n");
+	}
+
+	printf("\treturn -1;\n"
+		   "}\n");
+
+
+	return EXIT_SUCCESS;
+}
+/***********************************************************************/
+#endif