Re: [PATCH v4 1/7] archive: optionally add "virtual" files

René Scharfe [off-list ref] writes:

Good point.  write_tar_entry() actually normalizes the permission bits
and applies tar.umask (0002 by default):

	if (S_ISDIR(mode) || S_ISGITLINK(mode)) {
		*header.typeflag = TYPEFLAG_DIR;
		mode = (mode | 0777) & ~tar_umask;
	} else if (S_ISLNK(mode)) {
		*header.typeflag = TYPEFLAG_LNK;
		mode |= 0777;
	} else if (S_ISREG(mode)) {
		*header.typeflag = TYPEFLAG_REG;
		mode = (mode | ((mode & 0100) ? 0777 : 0666)) & ~tar_umask;

Yeah, this side seems to care only about u+x bit, so
"add-executable" as a separate option would fly we..

But write_zip_entry() only normalizes (drops) the permission bits of
non-executable files:

                attr2 = S_ISLNK(mode) ? ((mode | 0777) << 16) :
                        (mode & 0111) ? ((mode) << 16) : 0;
                if (S_ISLNK(mode) || (mode & 0111))
                        creator_version = 0x0317;

attr2 corresponds to the field "external file attributes" mentioned in
the ZIP format specification, APPNOTE.TXT.  It's interpreted based on
the "version made by" (creator_version here); that 0x03 part above
means "UNIX".  The default is MS-DOS (FAT filesystem), with effectivly
no support for file permissions.

So we currently leak permission bits of executable files into ZIP
archives, but not tar files. :-|  Normalizing those to 0755 would be
more consistent.

Yup.

quoted

For tracked paths, we probably are normalizing the blobs
between 0644 and 0755 way before the values are passed as "mode"
parameter to the write_entry() functions, but for these extra files,
there is no such massaging.

Right, mode values from read_tree() pass through canon_mode(), so only
untracked files (those appended with --add-file) are affected by the
leakage mentioned above.

Thanks for sanity-checking.