improve --install operation in chroot jails

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

1 files changed, 16 insertions, 5 deletions

diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index fc3e962d5..69cac2e9a 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -713,12 +713,23 @@ static int busybox_main(char **argv)
         if (ENABLE_FEATURE_INSTALLER && strcmp(argv[1], "--install") == 0) {
                 int use_symbolic_links;
                 const char *busybox;
+
                 busybox = xmalloc_readlink(bb_busybox_exec_path);
-                if (!busybox)
-                        busybox = bb_busybox_exec_path;
-                /* busybox --install [-s] [DIR]: */
-                /* -s: make symlinks */
-                /* DIR: directory to install links to */
+                if (!busybox) {
+                        /* bb_busybox_exec_path is usually "/proc/self/exe".
+                         * In chroot, readlink("/proc/self/exe") usually fails.
+                         * In such case, better use argv[0] as symlink target
+                         * if it is a full path name.
+                         */
+                        if (argv[0][0] == '/')
+                                busybox = argv[0];
+                        else
+                                busybox = bb_busybox_exec_path;
+                }
+                /* busybox --install [-s] [DIR]:
+                 * -s: make symlinks
+                 * DIR: directory to install links to
+                 */
                 use_symbolic_links = (argv[2] && strcmp(argv[2], "-s") == 0 && argv++);
                 install_links(busybox, use_symbolic_links, argv[2]);
                 return 0;