make copy_file() a bit easier to understand, and smaller

function                                             old     new   delta
copy_file                                           1565    1447    -118
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-118)           Total: -118 bytes
   text    data     bss     dec     hex filename
 770938    1063   10788  782789   bf1c5 busybox_old
 770814    1063   10788  782665   bf149 busybox_unstripped

2 files changed, 66 insertions, 69 deletions

diff --git a/libbb/copy_file.c b/libbb/copy_file.c
index 8a7db77e6..a86e497f0 100644
--- a/libbb/copy_file.c
+++ b/libbb/copy_file.c
@@ -60,9 +60,11 @@ static int ask_and_unlink(const char *dest, int flags)
  */
 int copy_file(const char *source, const char *dest, int flags)
 {
+        /* This is a recursive function, try to minimize stack usage */
+        /* NB: each struct stat is ~100 bytes */
         struct stat source_stat;
         struct stat dest_stat;
-        int status = 0;
+        signed char retval = 0;
         signed char dest_exists = 0;
         signed char ovr;
 
@@ -120,7 +122,7 @@ int copy_file(const char *source, const char *dest, int flags)
                         return -1;
                 }
 
-                /* Create DEST.  */
+                /* Create DEST */
                 if (dest_exists) {
                         if (!S_ISDIR(dest_stat.st_mode)) {
                                 bb_error_msg("target '%s' is not a directory", dest);
@@ -133,22 +135,21 @@ int copy_file(const char *source, const char *dest, int flags)
                         mode = source_stat.st_mode;
                         if (!(flags & FILEUTILS_PRESERVE_STATUS))
                                 mode = source_stat.st_mode & ~saved_umask;
+                        /* Allow owner to access new dir (at least for now) */
                         mode |= S_IRWXU;
-
                         if (mkdir(dest, mode) < 0) {
                                 umask(saved_umask);
                                 bb_perror_msg("cannot create directory '%s'", dest);
                                 return -1;
                         }
-
                         umask(saved_umask);
                 }
 
-                /* Recursively copy files in SOURCE.  */
+                /* Recursively copy files in SOURCE */
                 dp = opendir(source);
                 if (dp == NULL) {
-                        status = -1;
-                        goto preserve_status;
+                        retval = -1;
+                        goto preserve_mode_ugid_time;
                 }
 
                 while ((d = readdir(dp)) != NULL) {
@@ -159,7 +160,7 @@ int copy_file(const char *source, const char *dest, int flags)
                                 continue;
                         new_dest = concat_path_file(dest, d->d_name);
                         if (copy_file(new_source, new_dest, flags) < 0)
-                                status = -1;
+                                retval = -1;
                         free(new_source);
                         free(new_dest);
                 }
@@ -169,10 +170,12 @@ int copy_file(const char *source, const char *dest, int flags)
                  && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
                 ) {
                         bb_perror_msg("cannot change permissions of '%s'", dest);
-                        status = -1;
+                        retval = -1;
                 }
+                goto preserve_mode_ugid_time;
+        }
 
-        } else if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
+        if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
                 int (*lf)(const char *oldpath, const char *newpath);
  make_links:
                 // Hmm... maybe
@@ -188,39 +191,40 @@ int copy_file(const char *source, const char *dest, int flags)
                                 return -1;
                         }
                 }
+                /* _Not_ jumping to preserve_mode_ugid_time:
+                 * hard/softlinks don't have those */
                 return 0;
+        }
 
-        } else if (S_ISREG(source_stat.st_mode)
+        if (S_ISREG(source_stat.st_mode)
          /* Huh? DEREF uses stat, which never returns links! */
          /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
         ) {
                 int src_fd;
                 int dst_fd;
-                if (ENABLE_FEATURE_PRESERVE_HARDLINKS) {
+
+                if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
                         char *link_target;
 
-                        if (!FLAGS_DEREF) {
-                                link_target = is_in_ino_dev_hashtable(&source_stat);
-                                if (link_target) {
+                        link_target = is_in_ino_dev_hashtable(&source_stat);
+                        if (link_target) {
+                                if (link(link_target, dest) < 0) {
+                                        ovr = ask_and_unlink(dest, flags);
+                                        if (ovr <= 0)
+                                                return ovr;
                                         if (link(link_target, dest) < 0) {
-                                                ovr = ask_and_unlink(dest, flags);
-                                                if (ovr <= 0)
-                                                        return ovr;
-                                                if (link(link_target, dest) < 0) {
-                                                        bb_perror_msg("cannot create link '%s'", dest);
-                                                        return -1;
-                                                }
+                                                bb_perror_msg("cannot create link '%s'", dest);
+                                                return -1;
                                         }
-                                        return 0;
                                 }
+                                return 0;
                         }
                         add_to_ino_dev_hashtable(&source_stat, dest);
                 }
 
                 src_fd = open_or_warn(source, O_RDONLY);
-                if (src_fd < 0) {
+                if (src_fd < 0)
                         return -1;
-                }
 
 #if DO_POSIX_CP  /* POSIX way (a security problem versus symlink attacks!): */
                 dst_fd = open(dest, (flags & FILEUTILS_INTERACTIVE)
@@ -264,61 +268,56 @@ int copy_file(const char *source, const char *dest, int flags)
                 }
 #endif
                 if (bb_copyfd_eof(src_fd, dst_fd) == -1)
-                        status = -1;
+                        retval = -1;
                 if (close(dst_fd) < 0) {
                         bb_perror_msg("cannot close '%s'", dest);
-                        status = -1;
+                        retval = -1;
                 }
                 if (close(src_fd) < 0) {
                         bb_perror_msg("cannot close '%s'", source);
-                        status = -1;
+                        retval = -1;
                 }
+                goto preserve_mode_ugid_time;
+        }
 
-        } else if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
-         || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
-         || S_ISLNK(source_stat.st_mode)
-        ) {
-                // We are lazy here, a bit lax with races...
-                if (dest_exists) {
-                        errno = EEXIST;
-                        ovr = ask_and_unlink(dest, flags);
-                        if (ovr <= 0)
-                                return ovr;
-                }
-                if (S_ISFIFO(source_stat.st_mode)) {
-                        if (mkfifo(dest, source_stat.st_mode) < 0) {
-                                bb_perror_msg("cannot create fifo '%s'", dest);
-                                return -1;
-                        }
-                } else if (S_ISLNK(source_stat.st_mode)) {
-                        char *lpath;
+        /* Source is a symlink or a special file */
+        /* We are lazy here, a bit lax with races... */
+        if (dest_exists) {
+                errno = EEXIST;
+                ovr = ask_and_unlink(dest, flags);
+                if (ovr <= 0)
+                        return ovr;
+        }
+        if (S_ISLNK(source_stat.st_mode)) {
+                char *lpath;
 
-                        lpath = xmalloc_readlink_or_warn(source);
-                        if (lpath && symlink(lpath, dest) < 0) {
-                                bb_perror_msg("cannot create symlink '%s'", dest);
-                                free(lpath);
-                                return -1;
-                        }
+                lpath = xmalloc_readlink_or_warn(source);
+                if (lpath && symlink(lpath, dest) < 0) {
+                        bb_perror_msg("cannot create symlink '%s'", dest);
                         free(lpath);
-
-                        if (flags & FILEUTILS_PRESERVE_STATUS)
-                                if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
-                                        bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
-
-                        return 0;
-
-                } else {
-                        if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
-                                bb_perror_msg("cannot create '%s'", dest);
-                                return -1;
-                        }
+                        return -1;
+                }
+                free(lpath);
+                if (flags & FILEUTILS_PRESERVE_STATUS)
+                        if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
+                                bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
+                /* _Not_ jumping to preserve_mode_ugid_time:
+                 * symlinks don't have those */
+                return 0;
+        }
+        if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
+         || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
+        ) {
+                if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
+                        bb_perror_msg("cannot create '%s'", dest);
+                        return -1;
                 }
         } else {
-                bb_error_msg("internal error: unrecognized file type");
+                bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
                 return -1;
         }
 
- preserve_status:
+ preserve_mode_ugid_time:
 
         if (flags & FILEUTILS_PRESERVE_STATUS
         /* Cannot happen: */
@@ -338,5 +337,5 @@ int copy_file(const char *source, const char *dest, int flags)
                         bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
         }
 
-        return status;
+        return retval;
 }
diff --git a/libbb/inode_hash.c b/libbb/inode_hash.c
index 69e39af63..9cca74bcb 100644
--- a/libbb/inode_hash.c
+++ b/libbb/inode_hash.c
@@ -84,6 +84,4 @@ void reset_ino_dev_hashtable(void)
         free(ino_dev_hashtable);
         ino_dev_hashtable = NULL;
 }
-#else
-void reset_ino_dev_hashtable(void);
 #endif