copy_file: handle "cp /dev/foo file" (almost) compatibly to coreutils.

(almost because we do not copy mode, which is probably wasn't intended).
+61 bytes.

1 files changed, 29 insertions, 8 deletions

diff --git a/libbb/copy_file.c b/libbb/copy_file.c
index d37d51562..3b83e1216 100644
--- a/libbb/copy_file.c
+++ b/libbb/copy_file.c
@@ -81,6 +81,7 @@ int copy_file(const char *source, const char *dest, int flags)
         signed char dest_exists = 0;
         signed char ovr;
 
+/* Inverse of cp -d ("cp without -d") */
 #define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE)
 
         if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
@@ -229,12 +230,22 @@ int copy_file(const char *source, const char *dest, int flags)
                 return 0;
         }
 
-        if (S_ISREG(source_stat.st_mode)
-         /* DEREF uses stat, which never returns S_ISLNK() == true. */
+        if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */
+            !(flags & FILEUTILS_RECUR)
+            /* "cp [-opts] regular_file thing2" */
+         || S_ISREG(source_stat.st_mode)
+         /* DEREF uses stat, which never returns S_ISLNK() == true.
+          * So the below is never true: */
          /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
         ) {
                 int src_fd;
                 int dst_fd;
+                mode_t new_mode;
+
+                if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) {
+                        /* "cp -d symlink dst": create a link */
+                        goto dont_cat;
+                }
 
                 if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
                         const char *link_target;
@@ -258,18 +269,24 @@ int copy_file(const char *source, const char *dest, int flags)
                 if (src_fd < 0)
                         return -1;
 
+                /* Do not try to open with weird mode fields */
+                new_mode = source_stat.st_mode;
+                if (!S_ISREG(source_stat.st_mode))
+                        new_mode = 0666;
+
                 /* POSIX way is a security problem versus symlink attacks,
                  * we do it only for non-symlinks, and only for non-recursive,
                  * non-interactive cp. NB: it is still racy
                  * for "cp file /home/bad_user/file" case
                  * (user can rm file and create a link to /etc/passwd) */
                 if (DO_POSIX_CP
-                 || (dest_exists && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE))
+                 || (dest_exists
+                     && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE))
                      && !S_ISLNK(dest_stat.st_mode))
                 ) {
-                        dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
+                        dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode);
                 } else  /* safe way: */
-                        dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
+                        dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
                 if (dst_fd == -1) {
                         ovr = ask_and_unlink(dest, flags);
                         if (ovr <= 0) {
@@ -277,7 +294,7 @@ int copy_file(const char *source, const char *dest, int flags)
                                 return ovr;
                         }
                         /* It shouldn't exist. If it exists, do not open (symlink attack?) */
-                        dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
+                        dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
                         if (dst_fd < 0) {
                                 close(src_fd);
                                 return -1;
@@ -285,8 +302,7 @@ int copy_file(const char *source, const char *dest, int flags)
                 }
 
 #if ENABLE_SELINUX
-                if (((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT)
-                    || (flags & FILEUTILS_SET_SECURITY_CONTEXT))
+                if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT|FILEUTILS_SET_SECURITY_CONTEXT))
                  && is_selinux_enabled() > 0
                 ) {
                         security_context_t con;
@@ -313,8 +329,13 @@ int copy_file(const char *source, const char *dest, int flags)
                 }
                 /* ...but read size is already checked by bb_copyfd_eof */
                 close(src_fd);
+                /* "cp /dev/something new_file" should not
+                 * copy mode of /dev/something */
+                if (!S_ISREG(source_stat.st_mode))
+                        return retval;
                 goto preserve_mode_ugid_time;
         }
+ dont_cat:
 
         /* Source is a symlink or a special file */
         /* We are lazy here, a bit lax with races... */