bbconfig: add COMPRESS_BBCONFIG option

function                                             old     new   delta
bbconfig_config_bz2                                    -    4905   +4905
bbconfig_main                                         13      70     +57
bbconfig_config                                    21811       -  -21811
------------------------------------------------------------------------------
(add/remove: 1/1 grow/shrink: 1/0 up/down: 4962/-21811)    Total: -16849 bytes

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

2 files changed, 36 insertions, 0 deletions

diff --git a/miscutils/Config.src b/miscutils/Config.src
index cadaabb65..151f61bcc 100644
--- a/miscutils/Config.src
+++ b/miscutils/Config.src
@@ -22,6 +22,20 @@ config BBCONFIG
           The bbconfig applet will print the config file with which
           busybox was built.
 
+config FEATURE_COMPRESS_BBCONFIG
+        bool "Compress bbconfig data"
+        default y
+        depends on BBCONFIG
+        help
+          Store bbconfig data in compressed form, uncompress them on-the-fly
+          before output.
+
+          If you have a really tiny busybox with few applets enabled (and
+          bunzip2 isn't one of them), the overhead of the decompressor might
+          be noticeable. Also, if you run executables directly from ROM
+          and have very little memory, this might not be a win. Otherwise,
+          you probably want this.
+
 config BEEP
         bool "beep"
         default y
diff --git a/miscutils/bbconfig.c b/miscutils/bbconfig.c
index 0d649b4e5..286077168 100644
--- a/miscutils/bbconfig.c
+++ b/miscutils/bbconfig.c
@@ -3,10 +3,32 @@
  */
 #include "libbb.h"
 #include "bbconfigopts.h"
+#if ENABLE_FEATURE_COMPRESS_BBCONFIG
+# include "unarchive.h"
+# include "bbconfigopts_bz2.h"
+#endif
 
 int bbconfig_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int bbconfig_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
 {
+#if ENABLE_FEATURE_COMPRESS_BBCONFIG
+        bunzip_data *bd;
+        int i = start_bunzip(&bd,
+                        /* src_fd: */ -1,
+                        /* inbuf:  */ (void *)bbconfig_config_bz2,
+                        /* len:    */ sizeof(bbconfig_config_bz2));
+        /* read_bunzip can longjmp to start_bunzip, and ultimately
+         * end up here with i != 0 on read data errors! Not trivial */
+        if (!i) {
+                /* Cannot use xmalloc: will leak bd in NOFORK case! */
+                char *outbuf = malloc_or_warn(sizeof(bbconfig_config));
+                if (outbuf) {
+                        read_bunzip(bd, outbuf, sizeof(bbconfig_config));
+                        full_write1_str(outbuf);
+                }
+        }
+#else
         full_write1_str(bbconfig_config);
+#endif
         return 0;
 }