open_transformer: do not duplicate "<program> -cf -"

   text    data     bss     dec     hex filename
 677858     738    7236  685832   a7708 busybox_old
 677804     738    7236  685778   a76d2 busybox_unstripped

4 files changed, 17 insertions, 15 deletions

diff --git a/archival/libunarchive/get_header_tar_bz2.c b/archival/libunarchive/get_header_tar_bz2.c
index 6d4f5851e..c2cbaff5f 100644
--- a/archival/libunarchive/get_header_tar_bz2.c
+++ b/archival/libunarchive/get_header_tar_bz2.c
@@ -11,7 +11,7 @@ char get_header_tar_bz2(archive_handle_t *archive_handle)
 	/* Can't lseek over pipes */
 	archive_handle->seek = seek_by_read;
 
-	archive_handle->src_fd = open_transformer(archive_handle->src_fd, unpack_bz2_stream, "bunzip2", "bunzip2", "-cf", "-", NULL);
+	archive_handle->src_fd = open_transformer(archive_handle->src_fd, unpack_bz2_stream, "bunzip2");
 	archive_handle->offset = 0;
 	while (get_header_tar(archive_handle) == EXIT_SUCCESS)
 		continue;
diff --git a/archival/libunarchive/get_header_tar_gz.c b/archival/libunarchive/get_header_tar_gz.c
index dd655f557..9772e33fb 100644
--- a/archival/libunarchive/get_header_tar_gz.c
+++ b/archival/libunarchive/get_header_tar_gz.c
@@ -25,7 +25,7 @@ char get_header_tar_gz(archive_handle_t *archive_handle)
 	}
 #endif
 
-	archive_handle->src_fd = open_transformer(archive_handle->src_fd, unpack_gz_stream, "gunzip", "gunzip", "-cf", "-", NULL);
+	archive_handle->src_fd = open_transformer(archive_handle->src_fd, unpack_gz_stream, "gunzip");
 	archive_handle->offset = 0;
 	while (get_header_tar(archive_handle) == EXIT_SUCCESS)
 		continue;
diff --git a/archival/libunarchive/get_header_tar_lzma.c b/archival/libunarchive/get_header_tar_lzma.c
index cf73824e3..c859dcc58 100644
--- a/archival/libunarchive/get_header_tar_lzma.c
+++ b/archival/libunarchive/get_header_tar_lzma.c
@@ -14,7 +14,7 @@ char get_header_tar_lzma(archive_handle_t * archive_handle)
 	/* Can't lseek over pipes */
 	archive_handle->seek = seek_by_read;
 
-	archive_handle->src_fd = open_transformer(archive_handle->src_fd, unpack_lzma_stream, "unlzma", "unlzma", "-cf", "-", NULL);
+	archive_handle->src_fd = open_transformer(archive_handle->src_fd, unpack_lzma_stream, "unlzma");
 	archive_handle->offset = 0;
 	while (get_header_tar(archive_handle) == EXIT_SUCCESS)
 		continue;
diff --git a/archival/libunarchive/open_transformer.c b/archival/libunarchive/open_transformer.c
index 355613a67..757a2a389 100644
--- a/archival/libunarchive/open_transformer.c
+++ b/archival/libunarchive/open_transformer.c
@@ -8,12 +8,12 @@
 
 /* transformer(), more than meets the eye */
 /*
- * On MMU machine, the transform_prog and ... are stripped
- * by a macro in include/unarchive.h. On NOMMU, transformer is stripped.
+ * On MMU machine, the transform_prog is removed by macro magic
+ * in include/unarchive.h. On NOMMU, transformer is removed.
  */
 int open_transformer(int src_fd,
 	USE_DESKTOP(long long) int (*transformer)(int src_fd, int dst_fd),
-	const char *transform_prog, ...)
+	const char *transform_prog)
 {
 	int fd_pipe[2];
 	int pid;
@@ -29,9 +29,6 @@ int open_transformer(int src_fd,
 		bb_perror_msg_and_die("fork failed");
 
 	if (pid == 0) {
-#if !BB_MMU
-		va_list ap;
-#endif
 		/* child process */
 		close(fd_pipe[0]); /* We don't wan't to read from the parent */
 		// FIXME: error check?
@@ -43,12 +40,17 @@ int open_transformer(int src_fd,
 		}
 		exit(0);
 #else
-		xmove_fd(src_fd, 0);
-		xmove_fd(fd_pipe[1], 1);
-		va_start(ap, transform_prog);
-		/* hoping that va_list -> char** on our CPU is working... */
-		BB_EXECVP(transform_prog, (void*)ap);
-		bb_perror_msg_and_die("exec failed");
+		{
+			char *argv[4];
+			xmove_fd(src_fd, 0);
+			xmove_fd(fd_pipe[1], 1);
+			argv[0] = (char*)transform_prog;
+			argv[1] = (char*)"-cf";
+			argv[2] = (char*)"-";
+			argv[3] = NULL;
+			BB_EXECVP(transform_prog, argv);
+			bb_perror_msg_and_die("exec failed");
+		}
 #endif
 		/* notreached */
 	}