mingw: add magic '--busybox' flag

If BusyBox is invoked with argv[1] set to --busybox skip the first
two arguments so that argv[2] becomes the applet name and argv[3]
et seq are its arguments.

This is needed when BusyBox is run as sh.exe and the executable is
reexecuted to invoke compress/decompress applets.

3 files changed, 7 insertions, 2 deletions

diff --git a/archival/libarchive/open_transformer.c b/archival/libarchive/open_transformer.c
index 24524f6ee..c7ec4a74d 100644
--- a/archival/libarchive/open_transformer.c
+++ b/archival/libarchive/open_transformer.c
@@ -163,7 +163,8 @@ void FAST_FUNC fork_transformer(int fd, const char *transform_prog)
         int fd1;
 
         if (find_applet_by_name(transform_prog) >= 0) {
-                cmd = xasprintf("%s %s -cf -", bb_busybox_exec_path, transform_prog);
+                cmd = xasprintf("%s --busybox %s -cf -", bb_busybox_exec_path,
+                                                transform_prog);
         }
         else {
                 cmd = xasprintf("%s -cf -", transform_prog);
diff --git a/archival/tar.c b/archival/tar.c
index 1f9dd23d2..d1b0e475d 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -685,7 +685,7 @@ static pid_t vfork_compressor(int tar_fd, const char *gzip)
         pid_t pid;
 
         if (find_applet_by_name(gzip) >= 0) {
-                cmd = xasprintf("%s %s -cf -", bb_busybox_exec_path, gzip);
+                cmd = xasprintf("%s --busybox %s -cf -", bb_busybox_exec_path, gzip);
         }
         else {
                 cmd = xasprintf("%s -cf -", gzip);
diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index 841494a70..e99d3a5c4 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -864,6 +864,10 @@ int main(int argc UNUSED_PARAM, char **argv)
                         applet_name = applet_name_env;
                         unsetenv("BUSYBOX_APPLET_NAME");
                 }
+                else if ( argv[1] && argv[2] && strcmp(argv[1], "--busybox") == 0 ) {
+                        argv += 2;
+                        applet_name = argv[0];
+                }
                 else {
                         char *s = argv[0];
                         int i, len = strlen(s);