reviving libbusybox, adding CONFIG_INDIVIDUAL part 4

Config.in

@@ -311,24 +311,32 @@ config BUILD_LIBBUSYBOX
 ###
 ###	  Say 'N' if in doubt.
 
-config FEATURE_SHARED_BUSYBOX
-	bool "Produce additional busybox binary linked against libbusybox"
-	default y if BUILD_LIBBUSYBOX
+config FEATURE_INDIVIDUAL
+	bool "Produce a binary for each applet, linked against libbusybox"
+	default y
 	depends on !STATIC && BUILD_LIBBUSYBOX
 	help
-	  You need to have a working dynamic linker to use this variant.
+	  If your CPU architecture doesn't allow for sharing text/rodata
+	  sections of running binaries, but allows for runtime dynamic
+	  libraries, this option will allow you to reduce memory footprint
+	  when you have many different applets running at once.
 
-config LFS
-	bool "Build with Large File Support (for accessing files > 2 GB)"
-	default n
-	select FDISK_SUPPORT_LARGE_DISKS
+	  If your CPU architecture allows for sharing text/rodata,
+	  having single binary is more optimal.
+
+	  Each applet will be a tiny program, dynamically linked
+	  against libbusybox.so.N.N.N.
+
+	  You need to have a working dynamic linker.
+
+config FEATURE_SHARED_BUSYBOX
+	bool "Produce additional busybox binary linked against libbusybox"
+	default y
+	depends on !STATIC && BUILD_LIBBUSYBOX
 	help
-	  If you want to build BusyBox with large file support, then enable
-	  this option.  This will have no effect if your kernel or your C
-	  library lacks large file support for large files.  Some of the
-	  programs that can benefit from large file support include dd, gzip,
-	  cp, mount, tar, and many others.  If you want to access files larger
-	  than 2 Gigabytes, enable this option.  Otherwise, leave it set to 'N'.
+	  Build busybox, dynamically linked against libbusybox.so.N.N.N.
+
+	  You need to have a working dynamic linker.
 
 ### config BUILD_AT_ONCE
 ###	bool "Compile all sources at once"
@@ -349,6 +357,18 @@ config LFS
 ###
 ###	  Say 'N' unless you know what you are doing.
 
+config LFS
+	bool "Build with Large File Support (for accessing files > 2 GB)"
+	default n
+	select FDISK_SUPPORT_LARGE_DISKS
+	help
+	  If you want to build BusyBox with large file support, then enable
+	  this option.  This will have no effect if your kernel or your C
+	  library lacks large file support for large files.  Some of the
+	  programs that can benefit from large file support include dd, gzip,
+	  cp, mount, tar, and many others.  If you want to access files larger
+	  than 2 Gigabytes, enable this option.  Otherwise, leave it set to 'N'.
+
 endmenu
 
 menu 'Debugging Options'

include/applets.h

@@ -30,6 +30,13 @@ s     - suid type:
 # define APPLET_NOEXEC(name,main,l,s,name2)  int main##_main(int argc, char **argv);
 # define APPLET_NOFORK(name,main,l,s,name2)  int main##_main(int argc, char **argv);
 
+#elif defined(NAME_MAIN_CNAME)
+# define APPLET(name,l,s)                    name name##_main name
+# define APPLET_NOUSAGE(name,main,l,s)       name main##_main name
+# define APPLET_ODDNAME(name,main,l,s,name2) name main##_main name2
+# define APPLET_NOEXEC(name,main,l,s,name2)  name main##_main name2
+# define APPLET_NOFORK(name,main,l,s,name2)  name main##_main name2
+
 #elif defined(MAKE_USAGE) && ENABLE_FEATURE_VERBOSE_USAGE
 # define APPLET(name,l,s)                    name##_trivial_usage "\n\n" name##_full_usage "\0"
 # define APPLET_NOUSAGE(name,main,l,s)       "\b\0"
@@ -373,7 +380,7 @@ USE_YES(APPLET_NOFORK(yes, yes, _BB_DIR_USR_BIN, _BB_SUID_NEVER, yes))
 USE_GUNZIP(APPLET_ODDNAME(zcat, gunzip, _BB_DIR_BIN, _BB_SUID_NEVER, zcat))
 USE_ZCIP(APPLET(zcip, _BB_DIR_SBIN, _BB_SUID_NEVER))
 
-#if !defined(PROTOTYPES) && !defined(MAKE_USAGE)
+#if !defined(PROTOTYPES) && !defined(NAME_MAIN_CNAME) && !defined(MAKE_USAGE)
 	{ NULL }
 };
 #endif

scripts/trylink

@@ -137,7 +137,7 @@ if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
 	-o $EXE -Wl,-Map -Wl,$EXE.map \
 	-Wl,--warn-common -Wl,--sort-common -Wl,--gc-sections \
 	-Wl,--start-group $O_FILES -Wl,--end-group \
-	$l_list -Wl,--verbose \
+	-Wl,--verbose \
 	-L"$sharedlib_dir" -lbusybox \
 	>/dev/null \
     || {
@@ -148,3 +148,70 @@ if test "$CONFIG_FEATURE_SHARED_BUSYBOX" = y; then
     strip -s --remove-section=.note --remove-section=.comment $EXE -o "$sharedlib_dir/busybox"
     echo "busybox linked against libbusybox: $sharedlib_dir/busybox"
 fi
+
+if test "$CONFIG_FEATURE_INDIVIDUAL" = y; then
+    gcc -DNAME_MAIN_CNAME -E -include include/autoconf.h include/applets.h \
+    | grep -v "^#" \
+    | grep -v "^$" \
+    > applet.lst
+    while read name main cname; do
+
+	test x"$cname" = "x[" && cname=test
+	test x"$cname" = "x[[" && cname=test
+
+	echo "\
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include \"../include/autoconf.h\"
+#include \"../include/usage.h\"
+
+#ifdef __GLIBC__
+/* Make it reside in R/W memory: */
+int *const bb_errno __attribute__ ((section (\".data\")));
+#endif
+
+const char *applet_name = \"$name\";
+
+void bb_show_usage(void)
+{
+	fprintf(stderr, \"Usage: $name \"
+#ifdef ${cname}_trivial_usage
+		${cname}_trivial_usage
+#endif
+#ifdef ${cname}_full_usage
+		\"\\n\\n\" ${cname}_full_usage
+#endif
+		\"\\n\\n\");
+	exit(1);
+}
+
+int $main(int argc, char **argv);
+
+int main(int argc, char **argv)
+{
+#ifdef __GLIBC__
+        (*(int **)&bb_errno) = __errno_location();
+#endif
+        return $main(argc, argv);
+}
+" >"$sharedlib_dir/applet.c"
+
+	EXE="$sharedlib_dir/$name"
+	try $CC $LDFLAGS "$sharedlib_dir/applet.c" \
+	    -o $EXE \
+	    -Wl,--warn-common -Wl,--sort-common -Wl,--gc-sections \
+	    -L"$sharedlib_dir" -lbusybox \
+	    >/dev/null \
+	|| {
+	    echo "Linking $EXE failed"
+	    cat -- $EXE.out
+	    exit 1
+	}
+	rm -- "$sharedlib_dir/applet.c" $EXE.out
+	strip -s --remove-section=.note --remove-section=.comment $EXE
+	echo "applet linked against libbusybox: $EXE"
+
+    done <applet.lst
+fi