cp: add -u/--update and --remove-destination

Based on the patch by wdlkmpx@gmail.com

function                                             old     new   delta
copy_file                                           1546    1644     +98
add_partition                                       1270    1362     +92
ask_and_unlink                                        95     133     +38
do_iproute                                           132     157     +25
decode_one_format                                    710     715      +5
cp_main                                              369     374      +5
ubirename_main                                       198     202      +4
read_package_field                                   232     230      -2
bb_make_directory                                    421     412      -9
packed_usage                                       30505   30476     -29
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 7/3 up/down: 267/-40)           Total: 227 bytes

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

1 files changed, 21 insertions, 0 deletions

diff --git a/libbb/copy_file.c b/libbb/copy_file.c
index a4be875d2..23bcf2e82 100644
--- a/libbb/copy_file.c
+++ b/libbb/copy_file.c
@@ -64,6 +64,11 @@ static int ask_and_unlink(const char *dest, int flags)
                 bb_perror_msg("can't create '%s'", dest);
                 return -1; /* error */
         }
+#if ENABLE_FEATURE_CP_LONG_OPTIONS
+        if (flags & FILEUTILS_RMDEST)
+                if (flags & FILEUTILS_VERBOSE)
+                        printf("removed '%s'\n", dest);
+#endif
         return 1; /* ok (to try again) */
 }
 
@@ -210,6 +215,22 @@ int FAST_FUNC copy_file(const char *source, const char *dest, int flags)
                 goto preserve_mode_ugid_time;
         }
 
+        if (dest_exists) {
+                if (flags & FILEUTILS_UPDATE) {
+                        if (source_stat.st_mtime <= dest_stat.st_mtime) {
+                                return 0; /* source file must be newer */
+                        }
+                }
+#if ENABLE_FEATURE_CP_LONG_OPTIONS
+                if (flags & FILEUTILS_RMDEST) {
+                        ovr = ask_and_unlink(dest, flags);
+                        if (ovr <= 0)
+                                return ovr;
+                        dest_exists = 0;
+                }
+#endif
+        }
+
         if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
                 int (*lf)(const char *oldpath, const char *newpath);
  make_links: