cp: fix -i for POSIX mode. Closes 9106

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

diff --git a/libbb/copy_file.c b/libbb/copy_file.c
index 7801b58c71b35ce29f24e580991ba955927d1c52..23c0f8320b86f19f5d1a478368843340bd1bf51b 100644 (file)
--- a/libbb/copy_file.c
+++ b/libbb/copy_file.c
@@ -296,11 +296,16 @@ int FAST_FUNC copy_file(const char *source, const char *dest, int flags)
                if (!S_ISREG(source_stat.st_mode))
                        new_mode = 0666;
 
-               // POSIX way is a security problem versus (sym)link attacks
-               if (!ENABLE_FEATURE_NON_POSIX_CP) {
-                       dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode);
-               } else { /* safe way: */
+               if (ENABLE_FEATURE_NON_POSIX_CP || (flags & FILEUTILS_INTERACTIVE)) {
+                       /*
+                        * O_CREAT|O_EXCL: require that file did not exist before creation
+                        */
                        dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
+               } else { /* POSIX, and not "cp -i" */
+                       /*
+                        * O_CREAT|O_TRUNC: create, or truncate (security problem versus (sym)link attacks)
+                        */
+                       dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode);
                }
                if (dst_fd == -1) {
                        ovr = ask_and_unlink(dest, flags);