libarchive: add a function to unpack embedded data

Similar code to unpack embedded data is used to decompress usage
messages, embedded scripts and the config file (in the non-default
bbconfig applet).

Moving this code to a common function reduces the size of the default
build and hides more of the internals of libarchive.

function                                             old     new   delta
unpack_bz2_data                                        -     135    +135
bb_show_usage                                        137     157     +20
get_script_content                                    32      47     +15
unpack_scripts                                       119       -    -119
unpack_usage_messages                                124       -    -124
------------------------------------------------------------------------------
(add/remove: 1/2 grow/shrink: 2/0 up/down: 170/-243)          Total: -73 bytes

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

4 files changed, 54 insertions, 99 deletions

diff --git a/archival/libarchive/decompress_bunzip2.c b/archival/libarchive/decompress_bunzip2.c
index 7ef4e035f..6f2c49fbc 100644
--- a/archival/libarchive/decompress_bunzip2.c
+++ b/archival/libarchive/decompress_bunzip2.c
@@ -107,7 +107,7 @@ struct bunzip_data {
         uint8_t selectors[32768];  /* nSelectors=15 bits */
         struct group_data groups[MAX_GROUPS];  /* Huffman coding tables */
 };
-/* typedef struct bunzip_data bunzip_data; -- done in .h file */
+typedef struct bunzip_data bunzip_data;
 
 
 /* Return the next nnn bits of input.  All reads from the compressed input
@@ -575,7 +575,7 @@ static int get_next_block(bunzip_data *bd)
    in outbuf. IOW: on EOF returns len ("all bytes are not filled"), not 0.
    (Why? This allows to get rid of one local variable)
 */
-int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
+static int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
 {
         const uint32_t *dbuf;
         int pos, current, previous;
@@ -699,7 +699,7 @@ int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
 /* Because bunzip2 is used for help text unpacking, and because bb_show_usage()
    should work for NOFORK applets too, we must be extremely careful to not leak
    any allocations! */
-int FAST_FUNC start_bunzip(
+static int FAST_FUNC start_bunzip(
                 void *jmpbuf,
                 bunzip_data **bdp,
                 int in_fd,
@@ -759,7 +759,7 @@ int FAST_FUNC start_bunzip(
         return RETVAL_OK;
 }
 
-void FAST_FUNC dealloc_bunzip(bunzip_data *bd)
+static void FAST_FUNC dealloc_bunzip(bunzip_data *bd)
 {
         free(bd->dbuf);
         free(bd);
@@ -847,6 +847,36 @@ unpack_bz2_stream(transformer_state_t *xstate)
         return i ? i : IF_DESKTOP(total_written) + 0;
 }
 
+char* FAST_FUNC
+unpack_bz2_data(const char *packed, int packed_len, int unpacked_len)
+{
+        char *outbuf = NULL;
+        bunzip_data *bd;
+        int i;
+        jmp_buf jmpbuf;
+
+        /* Setup for I/O error handling via longjmp */
+        i = setjmp(jmpbuf);
+        if (i == 0) {
+                i = start_bunzip(&jmpbuf,
+                        &bd,
+                        /* src_fd: */ -1,
+                        /* inbuf:  */ packed,
+                        /* len:    */ packed_len
+                );
+        }
+        /* read_bunzip can longjmp and end up here with i != 0
+         * on read data errors! Not trivial */
+        if (i == 0) {
+                /* Cannot use xmalloc: will leak bd in NOFORK case! */
+                outbuf = malloc_or_warn(unpacked_len);
+                if (outbuf)
+                        read_bunzip(bd, outbuf, unpacked_len);
+        }
+        dealloc_bunzip(bd);
+        return outbuf;
+}
+
 #ifdef TESTING
 
 static char *const bunzip_errors[] = {
diff --git a/include/bb_archive.h b/include/bb_archive.h
index d2022336b..561dd0c9d 100644
--- a/include/bb_archive.h
+++ b/include/bb_archive.h
@@ -214,12 +214,7 @@ const llist_t *find_list_entry(const llist_t *list, const char *filename) FAST_F
 const llist_t *find_list_entry2(const llist_t *list, const char *filename) FAST_FUNC;
 
 /* A bit of bunzip2 internals are exposed for compressed help support: */
-typedef struct bunzip_data bunzip_data;
-int start_bunzip(void *, bunzip_data **bdp, int in_fd, const void *inbuf, int len) FAST_FUNC;
-/* NB: read_bunzip returns < 0 on error, or the number of *unfilled* bytes
- * in outbuf. IOW: on EOF returns len ("all bytes are not filled"), not 0: */
-int read_bunzip(bunzip_data *bd, char *outbuf, int len) FAST_FUNC;
-void dealloc_bunzip(bunzip_data *bd) FAST_FUNC;
+char *unpack_bz2_data(const char *packed, int packed_len, int unpacked_len) FAST_FUNC;
 
 /* Meaning and direction (input/output) of the fields are transformer-specific */
 typedef struct transformer_state_t {
diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index d48b2ea60..6dfaf1f41 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -107,34 +107,8 @@ static const char usage_messages[] ALIGN1 = UNPACKED_USAGE;
 
 static const char packed_usage[] ALIGN1 = { PACKED_USAGE };
 # include "bb_archive.h"
-static const char *unpack_usage_messages(void)
-{
-        char *outbuf = NULL;
-        bunzip_data *bd;
-        int i;
-        jmp_buf jmpbuf;
-
-        /* Setup for I/O error handling via longjmp */
-        i = setjmp(jmpbuf);
-        if (i == 0) {
-                i = start_bunzip(&jmpbuf,
-                        &bd,
-                        /* src_fd: */ -1,
-                        /* inbuf:  */ packed_usage,
-                        /* len:    */ sizeof(packed_usage)
-                );
-        }
-        /* read_bunzip can longjmp and end up here with i != 0
-         * on read data errors! Not trivial */
-        if (i == 0) {
-                /* Cannot use xmalloc: will leak bd in NOFORK case! */
-                outbuf = malloc_or_warn(sizeof(UNPACKED_USAGE));
-                if (outbuf)
-                        read_bunzip(bd, outbuf, sizeof(UNPACKED_USAGE));
-        }
-        dealloc_bunzip(bd);
-        return outbuf;
-}
+# define unpack_usage_messages() \
+        unpack_bz2_data(packed_usage, sizeof(packed_usage), sizeof(UNPACKED_USAGE))
 # define dealloc_usage_messages(s) free(s)
 
 #else
@@ -152,21 +126,23 @@ void FAST_FUNC bb_show_usage(void)
                 /* Imagine that this applet is "true". Dont suck in printf! */
                 const char *usage_string = unpack_usage_messages();
 
-                if (*usage_string == '\b') {
-                        full_write2_str("No help available.\n\n");
-                } else {
-                        full_write2_str("Usage: "SINGLE_APPLET_STR" ");
-                        full_write2_str(usage_string);
-                        full_write2_str("\n\n");
+                if (usage_string) {
+                        if (*usage_string == '\b') {
+                                full_write2_str("No help available.\n\n");
+                        } else {
+                                full_write2_str("Usage: "SINGLE_APPLET_STR" ");
+                                full_write2_str(usage_string);
+                                full_write2_str("\n\n");
+                        }
+                        if (ENABLE_FEATURE_CLEAN_UP)
+                                dealloc_usage_messages((char*)usage_string);
                 }
-                if (ENABLE_FEATURE_CLEAN_UP)
-                        dealloc_usage_messages((char*)usage_string);
 #else
                 const char *p;
                 const char *usage_string = p = unpack_usage_messages();
                 int ap = find_applet_by_name(applet_name);
 
-                if (ap < 0) /* never happens, paranoia */
+                if (ap < 0 || usage_string == NULL)
                         xfunc_die();
                 while (ap) {
                         while (*p++) continue;
@@ -986,38 +962,11 @@ find_script_by_name(const char *name)
         return -0x10000; /* make it so that NUM_APPLETS + <error> is still < 0 */
 }
 
-static char *
-unpack_scripts(void)
-{
-        char *outbuf = NULL;
-        bunzip_data *bd;
-        int i;
-        jmp_buf jmpbuf;
-
-        /* Setup for I/O error handling via longjmp */
-        i = setjmp(jmpbuf);
-        if (i == 0) {
-                i = start_bunzip(&jmpbuf,
-                        &bd,
-                        /* src_fd: */ -1,
-                        /* inbuf:  */ packed_scripts,
-                        /* len:    */ sizeof(packed_scripts)
-                );
-        }
-        /* read_bunzip can longjmp and end up here with i != 0
-         * on read data errors! Not trivial */
-        if (i == 0) {
-                outbuf = xmalloc(UNPACKED_SCRIPTS_LENGTH);
-                read_bunzip(bd, outbuf, UNPACKED_SCRIPTS_LENGTH);
-        }
-        dealloc_bunzip(bd);
-        return outbuf;
-}
-
 char* FAST_FUNC
 get_script_content(unsigned n)
 {
-        char *t = unpack_scripts();
+        char *t = unpack_bz2_data(packed_scripts, sizeof(packed_scripts),
+                                        UNPACKED_SCRIPTS_LENGTH);
         if (t) {
                 while (n != 0) {
                         while (*t++ != '\0')
diff --git a/miscutils/bbconfig.c b/miscutils/bbconfig.c
index 501349548..fe02516a8 100644
--- a/miscutils/bbconfig.c
+++ b/miscutils/bbconfig.c
@@ -43,29 +43,10 @@ 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;
-        jmp_buf jmpbuf;
-
-        /* Setup for I/O error handling via longjmp */
-        i = setjmp(jmpbuf);
-        if (i == 0) {
-                i = start_bunzip(&jmpbuf,
-                        &bd,
-                        /* src_fd: */ -1,
-                        /* inbuf:  */ bbconfig_config_bz2,
-                        /* len:    */ sizeof(bbconfig_config_bz2)
-                );
-        }
-        /* read_bunzip can longjmp and end up here with i != 0
-         * on read data errors! Not trivial */
-        if (i == 0) {
-                /* 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);
-                }
+        const char *outbuf = unpack_bz2_data(bbconfig_config_bz2,
+                        sizeof(bbconfig_config_bz2), sizeof(bbconfig_config));
+        if (outbuf) {
+                full_write1_str(outbuf);
         }
 #else
         full_write1_str(bbconfig_config);