Patch from Dennis Vlasenko to add the option to compress help text.

Config.in

@@ -56,6 +56,14 @@ config CONFIG_FEATURE_VERBOSE_USAGE
 	  busybox binary.  In the default configuration, this will add about
 	  13k, but it can add much more depending on your configuration.
 
+config CONFIG_FEATURE_COMPRESS_USAGE
+	bool "Store applet usage messages in compressed form"
+	default y
+	depends on CONFIG_SHOW_USAGE
+	help
+	  Store usage messages in compressed form, uncompress them on-the-fly
+	  when <applet> --help is called.
+
 config CONFIG_FEATURE_INSTALLER
 	bool "Support --install [-s] to install applet links at runtime"
 	default n

Makefile

@@ -405,6 +405,13 @@ include/bbconfigopts.h: .config
 	$(Q)$(top_srcdir)/scripts/config/mkconfigs > $@
 endif
 
+scripts/usage: $(top_srcdir)/scripts/usage.c .config
+	$(HOSTCC) $(HOSTCFLAGS) -I$(top_srcdir)/include -o $@ $<
+
+DEP_INCLUDES += include/usage_compressed.h
+include/usage_compressed.h: .config scripts/usage
+	$(Q)sh $(top_srcdir)/scripts/usage_compressed "$(top_srcdir)/scripts" > $@
+
 depend dep: .depend
 .depend: scripts/bb_mkdep $(DEP_INCLUDES)
 	$(disp_gen)

applets/applets.c

@@ -32,24 +32,20 @@
 #include <assert.h>
 #include "busybox.h"
 
-#if ENABLE_SHOW_USAGE
-const char usage_messages[] =
-
+#if ENABLE_SHOW_USAGE && !ENABLE_FEATURE_COMPRESS_USAGE
+static const char usage_messages[] =
 #define MAKE_USAGE
 #include "usage.h"
-
 #include "applets.h"
-
 ;
-
 #undef MAKE_USAGE
 #endif /* ENABLE_SHOW_USAGE */
+
 #undef APPLET
 #undef APPLET_NOUSAGE
 #undef PROTOTYPES
 #include "applets.h"
 
-
 static struct BB_applet *applet_using;
 
 /* The -1 arises because of the {0,NULL,0,-1} entry above. */
@@ -405,27 +401,69 @@ static void check_suid (struct BB_applet *applet)
 
 
 
+#if ENABLE_FEATURE_COMPRESS_USAGE
 
+#include "usage_compressed.h"
+#include "unarchive.h"
+
+static const char *unpack_usage_messages(void)
+{
+	int input[2], output[2], pid;
+	char *buf;
+
+	if(pipe(input) < 0 || pipe(output) < 0)
+		exit(1);
+
+	pid = fork();
+	switch (pid) {
+	case -1: /* error */
+		exit(1);
+	case 0: /* child */
+		close(input[1]);
+		close(output[0]);
+		uncompressStream(input[0], output[1]);
+		exit(0);
+	}
+	/* parent */
+
+	close(input[0]);
+	close(output[1]);
+	pid = fork();
+	switch (pid) {
+	case -1: /* error */
+		exit(1);
+	case 0: /* child */
+		bb_full_write(input[1], packed_usage, sizeof(packed_usage));
+		exit(0);
+	}
+	/* parent */
+	close(input[1]);
+
+	buf = xmalloc(SIZEOF_usage_messages);
+	bb_full_read(output[0], buf, SIZEOF_usage_messages);
+	return buf;
+}
+
+#else
+#define unpack_usage_messages() usage_messages;
+#endif /* ENABLE_FEATURE_COMPRESS_USAGE */
 
 void bb_show_usage (void)
 {
-#if ENABLE_SHOW_USAGE
+	if (ENABLE_SHOW_USAGE) {
 		const char *format_string;
-  const char *usage_string = usage_messages;
+		const char *usage_string = unpack_usage_messages();
 		int i;
 
-  for (i = applet_using - applets; i > 0;) {
-	if (!*usage_string++) {
-	  --i;
-	}
-  }
+		for (i = applet_using - applets; i > 0;)
+			if (!*usage_string++) --i;
 
 		format_string = "%s\n\nUsage: %s %s\n\n";
 		if (*usage_string == '\b')
 			format_string = "%s\n\nNo help available.\n\n";
-  fprintf (stderr, format_string, bb_msg_full_version, applet_using->name,
-		   usage_string);
-#endif /* ENABLE_SHOW_USAGE */
+		fprintf (stderr, format_string, bb_msg_full_version,
+			applet_using->name, usage_string);
+	}
 
   exit (bb_default_error_retval);
 }

archival/libunarchive/Makefile.in

@@ -67,6 +67,7 @@ LIBUNARCHIVE-$(CONFIG_FEATURE_TAR_GZIP) += $(GUNZIP_FILES) get_header_tar_gz.o
 LIBUNARCHIVE-$(CONFIG_FEATURE_TAR_COMPRESS) += decompress_uncompress.o
 LIBUNARCHIVE-$(CONFIG_UNCOMPRESS) += decompress_uncompress.o
 LIBUNARCHIVE-$(CONFIG_UNZIP) += $(GUNZIP_FILES)
+LIBUNARCHIVE-$(CONFIG_FEATURE_COMPRESS_USAGE) += decompress_bunzip2.o
 
 
 LIBUNARCHIVE-y:=$(sort $(LIBUNARCHIVE-y))

include/applets.h

@@ -19,7 +19,6 @@
 # define APPLET(a,b,c,d) extern int b(int argc, char **argv);
 # define APPLET_NOUSAGE(a,b,c,d) extern int b(int argc, char **argv);
 # define APPLET_ODDNAME(a,b,c,d,e) extern int b(int argc, char **argv);
-  extern const char usage_messages[];
 #elif defined(MAKE_USAGE)
 # ifdef CONFIG_FEATURE_VERBOSE_USAGE
 #  define APPLET(a,b,c,d) a##_trivial_usage "\n\n" a##_full_usage "\0"

scripts/usage.c

@@ -0,0 +1,14 @@
+#include <unistd.h>
+#include "busybox.h"
+
+static const char usage_messages[] =
+#define MAKE_USAGE
+#include "usage.h"
+#include "applets.h"
+;
+
+int main(void)
+{
+	write(1, usage_messages, sizeof(usage_messages));
+	return 0;
+}

scripts/usage_compressed

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+loc="$1"
+
+test "$loc" || loc=.
+
+echo 'static const char packed_usage[] = '
+"$loc"/usage | bzip2 -9 | od -v -t x1 \
+| sed -e 's/^[^ ]*//' -e 's/ \(..\)/\\x\1/g' -e 's/^\(.*\)$/"\1"/'
+echo ';'
+echo '#define SIZEOF_usage_messages' $((0 + `"$loc"/usage | wc -c `))