modif: fcopy: use lstat when copying directory

[gerasiov]

When copying directories use lstat when reading info about source files.

Closes #5378.

[glitsj16]

LGTM

[kmk3]

@gerasiov

Actually, I just realized that the issue is probably because it is both a
directory and a symlink and the directory test appears before the symlink test.

Does it work with only the following changes?

diff --git a/src/fcopy/main.c b/src/fcopy/main.c
index a56e8a91b..72fb8e01f 100644
--- a/src/fcopy/main.c
+++ b/src/fcopy/main.c
@@ -503,12 +503,12 @@ int main(int argc, char **argv) {
                exit(1);
        }

-       if (S_ISDIR(s.st_mode))
+       if (S_ISLNK(s.st_mode))
+               duplicate_link(src, dest, &s);
+       else if (S_ISDIR(s.st_mode))
                duplicate_dir(src, dest, &s);
        else if (S_ISREG(s.st_mode))
                duplicate_file(src, dest, &s);
-       else if (S_ISLNK(s.st_mode))
-               duplicate_link(src, dest, &s);
        else {
                fprintf(stderr, "Error fcopy: src %s is an unsupported type of file\n", src);
                exit(1);

[gerasiov]

In my case the problem was with nvidia driver libs, like
/etc/alternatives/nvidia--libnvidia-ml.so.1-x86_64-linux-gnu -> /usr/lib/x86_64-linux-gnu/nvidia/current/libnvidia-ml.so.525.125.06
there are bunch of them.
They're symlinks, but not directories.

[kmk3]

In my case the problem was with nvidia driver libs, like
/etc/alternatives/nvidia--libnvidia-ml.so.1-x86_64-linux-gnu -> /usr/lib/x86_64-linux-gnu/nvidia/current/libnvidia-ml.so.525.125.06 there
are bunch of them. They're symlinks, but not directories.

Ah that makes sense now, S_ISDIR(s.st_mode) -> duplicate_dir ->
fs_copydir is called because /etc/alternatives is a directory, but then the
paths in it are files.

I see that there is some code in main() that chooses between stat and lstat
based on the arg_follow_links variable:

	// copy files
	if ((arg_follow_link ? stat : lstat)(src, &s) == -1) {
		fprintf(stderr, "Error fcopy: src %s: %s\n", src, strerror(errno));
		exit(1);
	}

Though I'm not sure if it is indeed only intended to apply to the top-level
path or to every symlink, in which case it might make sense to reuse the same
construct in fs_copydir.

Cc: @netblue30 @smitsohu