1 files changed, 65 insertions, 16 deletions

diff --git a/archival/cpio.c b/archival/cpio.c
index 1c30d89a8..929d544ff 100644
--- a/archival/cpio.c
+++ b/archival/cpio.c
@@ -259,8 +259,9 @@ int cpio_main(int argc UNUSED_PARAM, char **argv)
                 CPIO_OPT_FILE               = (1 << 4),
                 CPIO_OPT_CREATE_LEADING_DIR = (1 << 5),
                 CPIO_OPT_PRESERVE_MTIME     = (1 << 6),
-                CPIO_OPT_CREATE             = (1 << 7),
-                CPIO_OPT_FORMAT             = (1 << 8),
+                CPIO_OPT_CREATE             = (1 << 7) * ENABLE_FEATURE_CPIO_O,
+                CPIO_OPT_FORMAT             = (1 << 8) * ENABLE_FEATURE_CPIO_O,
+                CPIO_OPT_PASSTHROUGH        = (1 << 9) * ENABLE_FEATURE_CPIO_P,
         };
 
 #if ENABLE_GETOPT_LONG
@@ -270,21 +271,66 @@ int cpio_main(int argc UNUSED_PARAM, char **argv)
 #if ENABLE_FEATURE_CPIO_O
                 "create\0"       No_argument       "o"
                 "format\0"       Required_argument "H"
+#if ENABLE_FEATURE_CPIO_P
+                "pass-through\0" No_argument       "p"
+#endif
 #endif
                 ;
 #endif
 
-        /* Initialize */
-        archive_handle = init_handle();
-        archive_handle->src_fd = STDIN_FILENO;
-        archive_handle->seek = seek_by_read;
-        archive_handle->ah_flags = ARCHIVE_EXTRACT_NEWER;
-
-#if ENABLE_FEATURE_CPIO_O
-        opt = getopt32(argv, "ituvF:dmoH:", &cpio_filename, &cpio_fmt);
+        /* As of now we do not enforce this: */
+        /* -i,-t,-o,-p are mutually exclusive */
+        /* -u,-d,-m make sense only with -i or -p */
+        /* -F makes sense only with -o */
+#if !ENABLE_FEATURE_CPIO_O
+        opt = getopt32(argv, "ituvF:dm", &cpio_filename);
+#else
+        opt = getopt32(argv, "ituvF:dmoH:" USE_FEATURE_CPIO_P("p"), &cpio_filename, &cpio_fmt);
+        if (opt & CPIO_OPT_PASSTHROUGH) {
+                pid_t pid;
+                struct fd_pair pp;
 
+                if (argv[optind] == NULL)
+                        bb_show_usage();
+                if (opt & CPIO_OPT_CREATE_LEADING_DIR)
+                        mkdir(argv[optind], 0777);
+                /* Crude existence check:
+                 * close(xopen(argv[optind], O_RDONLY | O_DIRECTORY));
+                 * We can also xopen, fstat, IS_DIR, later fchdir.
+                 * This would check for existence earlier and cleaner.
+                 * As it stands now, if we fail xchdir later,
+                 * child dies on EPIPE, unless it caught
+                 * a diffrerent problem earlier.
+                 * This is good enough for now.
+                 */
+#if !BB_MMU
+                pp.rd = 3;
+                pp.wr = 4;
+                if (!re_execed) {
+                        close(3);
+                        close(4);
+                        xpiped_pair(pp);
+                }
+#else
+                xpiped_pair(pp);
+#endif
+                pid = fork_or_rexec(argv);
+                if (pid == 0) { /* child */
+                        close(pp.rd);
+                        xmove_fd(pp.wr, STDOUT_FILENO);
+                        goto dump;
+                }
+                /* parent */
+                xchdir(argv[optind++]);
+                close(pp.wr);
+                xmove_fd(pp.rd, STDIN_FILENO);
+                opt &= ~CPIO_OPT_PASSTHROUGH;
+                opt |= CPIO_OPT_EXTRACT;
+                goto skip;
+        }
+        /* -o */
         if (opt & CPIO_OPT_CREATE) {
-                if (*cpio_fmt != 'n')
+                if (*cpio_fmt != 'n') /* we _require_ "-H newc" */
                         bb_show_usage();
                 if (opt & CPIO_OPT_FILE) {
                         fclose(stdout);
@@ -292,13 +338,18 @@ int cpio_main(int argc UNUSED_PARAM, char **argv)
                         /* Paranoia: I don't trust libc that much */
                         xdup2(fileno(stdout), STDOUT_FILENO);
                 }
+ dump:
                 return cpio_o();
         }
-#else
-        opt = getopt32(argv, "ituvF:dm", &cpio_filename);
+ skip:
 #endif
         argv += optind;
 
+        archive_handle = init_handle();
+        archive_handle->src_fd = STDIN_FILENO;
+        archive_handle->seek = seek_by_read;
+        archive_handle->ah_flags = ARCHIVE_EXTRACT_NEWER;
+
         /* One of either extract or test options must be given */
         if ((opt & (CPIO_OPT_TEST | CPIO_OPT_EXTRACT)) == 0) {
                 bb_show_usage();
@@ -306,9 +357,7 @@ int cpio_main(int argc UNUSED_PARAM, char **argv)
 
         if (opt & CPIO_OPT_TEST) {
                 /* if both extract and test options are given, ignore extract option */
-                if (opt & CPIO_OPT_EXTRACT) {
-                        opt &= ~CPIO_OPT_EXTRACT;
-                }
+                opt &= ~CPIO_OPT_EXTRACT;
                 archive_handle->action_header = header_list;
         }
         if (opt & CPIO_OPT_EXTRACT) {