WIP: Continue work on checking for package/budle

Addresses #1.

In this commit I have removed any old work using getxattr, as getxattr
deals with extended attributes (metadata) attached to files. They're
actually unrelated to ext. attrs.: mdls involves higher level stuff
that makes calls into LaunchServices and uses the LS database.

I have discovered (using nm) that in particular, mdls makes calls to
MDItemCopyAttributeNames and MDItemCopyAttributes.  As such I have
been working on porting over logic using these C calls.  However,
MDItem* functions require path names to be CFStrings, so a lot of work
has gone into different encodings (thanks Apple).

I still need to get the _mdls function working as expected, as
currently I presumably have the attribute list using MDItemCreate and
MDItemCopyAttributeNames, however I need to parse it correctly and
extract the attribute that I want to use to determine if the path is a
package or a bundle.

src/HiddenFiles.jl

@@ -6,17 +6,17 @@ export ishidden
     _ishidden_unix(f::AbstractString) = startswith(basename(realpath(f)), '.')
 
     @static if Sys.isapple()
-        ### Hidden Files and Directories: Simplifying the User Experience ###
-        ### https://developer.apple.com/library/archive/documentation/FileManagement/Conceptual/FileSystemProgrammingGuide/FileSystemOverview/FileSystemOverview.html ###
+        ###=== Hidden Files and Directories: Simplifying the User Experience ===##
+        ##=== https://developer.apple.com/library/archive/documentation/FileManagement/Conceptual/FileSystemProgrammingGuide/FileSystemOverview/FileSystemOverview.html ===##
 
-        ## Case 1: Dot directories and files ##
+        #=== Case 1: Dot directories and files ===#
         # Any file or directory whose name starts with a period (`.`) character is hidden automatically.  This convention is taken from UNIX, 
         # which used it to hide system scripts and other special types of files and directories.  Two special directories in this category 
         # are the `.` and `..` directories, which are references to the current and parent directories respectively.  This case is handled by
         # _ishidden_unix
 
 
-        ## Case 2: UNIX-specific directories ##
+        #=== Case 2: UNIX-specific directories ===#
         # The directories in this category are inherited from traditional UNIX installations.  They are an important part of the system’s 
         # BSD layer but are more useful to software developers than end users. Some of the more important directories that are hidden include:
         #   - `/bin`—Contains essential command-line binaries. Typically, you execute these binaries from command-line scripts.
@@ -28,7 +28,7 @@ export ishidden
         #   - `/var`—Contains log files and other files whose content is variable. (Log files are typically viewed using the Console app.)
 
 
-        ## Case 3: Explicitly hidden files and directories ##
+        #=== Case 3: Explicitly hidden files and directories ===#
         # The Finder may hide specific files or directories that should not be accessed directly by the user.  The most notable example of 
         # this is the /Volumes directory, which contains a subdirectory for each mounted disk in the local file system from the command line. 
         # (The Finder provides a different user interface for accessing local disks.)  In macOS 10.7 and later, the Finder also hides the
@@ -53,24 +53,117 @@ export ishidden
         _isinvisible(f::AbstractString) = (_st_flags(f) & UF_HIDDEN) == UF_HIDDEN
 
 
-        ## Case 4: Packages and bundles ##
+        #=== Case 4: Packages and bundles ===#
         # Packages and bundles are directories that the Finder presents to the user as if they were files.  Bundles hide the internal workings 
         # of executables such as apps and just present a single entity that can be moved around the file system easily.  Similarly, packages 
         # allow apps to implement complex document formats consisting of multiple individual files while still presenting what appears to be a 
         # single document to the user.
 
+        # https://superuser.com/questions/1739420/
+        # https://stackoverflow.com/a/9858910/12069968
         # http://developer.apple.com/library/mac/#documentation/CoreFoundation/Conceptual/CFBundles/Introduction/Introduction.html/
+        # https://opensource.apple.com/source/CF/CF-550/CFBase.c.auto.html
+
+        # https://opensource.apple.com/source/CF/CF-635/CFString.h.auto.html
+        # https://developer.apple.com/documentation/corefoundation/cfstringbuiltinencodings
+        const K_CFSTRING_ENCODING_MACROMAN = 0x0
+        const K_CFSTRING_ENCODING_WINDOWSLATIN1 = 0x0500 # ANSI codepage 1252
+        const K_CFSTRING_ENCODING_ISOLATIN1 = 0x0201     # ISO 8859-1
+        const K_CFSTRING_ENCODING_NEXTSTEPLATIN = 0x0B01 # NextStep encoding
+        const K_CFSTRING_ENCODING_ASCII = 0x0600         # 0..127 (in creating CFString, values greater than 0x7F are treated as corresponding Unicode value)
+        const K_CFSTRING_ENCODING_UNICODE = 0x0100       # kTextEncodingUnicodeDefault  + kTextEncodingDefaultFormat (aka kUnicode16BitFormat)
+        const K_CFSTRING_ENCODING_UTF8 = 0x08000100      # kTextEncodingUnicodeDefault + kUnicodeUTF8Format
+        const K_CFSTRING_ENCODING_NONLOSSYASCII = 0x0BFF # 7bit Unicode variants used by Cocoa & Java
+        const K_CFSTRING_ENCODING_UTF16 = 0x0100         # kTextEncodingUnicodeDefault + kUnicodeUTF16Format (alias of kCFStringEncodingUnicode)
+        const K_CFSTRING_ENCODING_UTF16BE = 0x10000100   # kTextEncodingUnicodeDefault + kUnicodeUTF16BEFormat
+        const K_CFSTRING_ENCODING_UTF16LE = 0x14000100   # kTextEncodingUnicodeDefault + kUnicodeUTF16LEFormat
+        const K_CFSTRING_ENCODING_UTF32 = 0x0c000100     # kTextEncodingUnicodeDefault + kUnicodeUTF32Format
+        const K_CFSTRING_ENCODING_UTF32BE = 0x18000100   # kTextEncodingUnicodeDefault + kUnicodeUTF32BEFormat
+        const K_CFSTRING_ENCODING_UTF32LE = 0x1c000100   # kTextEncodingUnicodeDefault + kUnicodeUTF32LEFormat
+
+        # https://opensource.apple.com/source/CF/CF-368/String.subproj/CFStringUtilities.c.auto.html
+        # https://developer.apple.com/documentation/corefoundation/1542942-cfstringcreatewithcstring
+        const K_CF_STRING_ENCODING_UTF8 = UInt32(65001)  # THIS DOES NOT SEEM TO WORK
+        function _cfstring_create_with_cstring(s::AbstractString, encoding::Unsigned = K_CFSTRING_ENCODING_MACROMAN)
+            return ccall(:CFStringCreateWithCString, Cstring, 
+                         (Ptr{Cvoid}, Cstring, UInt32),
+                         C_NULL, s, encoding)
+            # TODO: check if result is null (if so, there was a problem creating the string)
+        end
+
+        # https://github.com/osquery/osquery/blob/598983db97459f858e7a9cc5c731409ffc089b48/osquery/tables/system/darwin/extended_attributes.cpp#L111-L144
+        # https://github.com/objective-see/ProcInfo/blob/ec51090fcf741a9e045dd3e5119cb5cc8750efd3/procInfo/Binary.m#L121-L172
+        function _mditem_create(cstr_f::Cstring)
+            return ccall(:MDItemCreate, Ptr{UInt32}, (Ptr{Cvoid}, Cstring), C_NULL, cstr_f)
+        end
+        function _mditem_copy_attribute_names(mditem::Ptr{UInt32})
+            mdattrs = Vector{UInt32}(undef, 10000)
+            ccall(:MDItemCopyAttributeNames, Ptr{UInt32}, (Ptr{UInt32}, Ptr{Cvoid}), mditem, mdattrs)
+            return mdattrs
+            # TODO: check if we do indeed need to return mdattrs.  Do we still need mditem?  I don't think so
+            # TODO: check if attributes found (if ccall returns null, failed)
+        end
+
+        # https://developer.apple.com/documentation/corefoundation/1388741-cfarraycreate
+        function _cfarray_create(arr::Vector{T}) where {T <: Unsigned}
+            return ccall(:CFArrayCreate, Ptr{UInt32}, 
+                         (Ptr{Cvoid}, Ptr{Cvoid}, Int32, Ptr{Cvoid}), 
+                         C_NULL, pointer(arr), length(arr), C_NULL)
+        end
+
+        # https://developer.apple.com/documentation/corefoundation/1388772-cfarraygetcount
+        function _cfarray_get_count(cfarr_ptr::Ptr{UInt32})
+            return ccall(:CFArrayGetCount, Int32, (Ptr{UInt32},), cfarr_ptr)
+        end
 
-        # https://opensource.apple.com/source/xnu/xnu-1228.0.2/bsd/sys/xattr.h.auto.html
-        const XATTR_NOFOLLOW = 0x0001
+        # https://developer.apple.com/documentation/corefoundation/1388767-cfarraygetvalueatindex
+        function _cfarray_get_value_at_index(cfarr_ptr::Ptr{UInt32}, idx::T) where {T <: Integer}
+            return ccall(:CFArrayGetValueAtIndex, Cstring, (Ptr{UInt32}, Int32), cfarr_ptr, idx)
+        end
+
+        # https://developer.apple.com/documentation/corefoundation/1542853-cfstringgetlength
+        function _cfstring_get_length(cfstr::Cstring)
+            return ccall(:CFStringGetLength, Int32, (Cstring,), cfstr)
+        end
+
+        # https://developer.apple.com/documentation/corefoundation/1542143-cfstringgetmaximumsizeforencodin
+        function _cfstring_get_maximum_size_for_encoding(strlen::T, encoding::Unsigned = K_CFSTRING_ENCODING_MACROMAN) where {T <: Integer}
+             return ccall(:CFStringGetMaximumSizeForEncoding, Int32, (Int32, UInt32), strlen, encoding)
+        end
+
+        #=function _cfstring_get_c_string(s::AbstractString, encoding::Unsigned = K_CFSTRING_ENCODING_MACROMAN)
+            # cfbuf = Vector{UInt32}(undef, 1000)
+            ccall(:CFStringGetCString, Bool,
+                  (Cstring, Ptr{Cvoid}, Int32, UInt32),
+                  _cfstring_create_with_cstring(s, encoding), cfbuf, sizeof(cfbuf), 0) || error("Problem calling CFStringGetCString")
+            return cfbuf
+        end=#
+
+        # https://github.com/vovkasm/input-source-switcher/blob/c5bab3de716db5e3dae3703ed3b72f2bf1cd51d3/utils.cpp#L9-L18
+        function _string_from_cf_string(cfstr::Cstring, encoding::Unsigned = K_CFSTRING_ENCODING_MACROMAN)
+            strlen = _cfstring_get_length(cfstr)
+            maxsz = _cfstring_get_maximum_size_for_encoding(strlen, encoding)
+            cfbuf = Vector{Char}(undef, maxsz)
+            ccall(:CFStringGetCString, Bool,
+                  (Cstring, Ptr{Cvoid}, Int32, UInt32),
+                  cfstr, cfbuf, sizeof(cfbuf), 0) || error("Problem calling CFStringGetCString")
+            return String(cfbuf)
+        end
 
-        # https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/getxattr.2.html
-        const XATTR_SIZE = 10_000
-        function _getxattr(f::AbstractString, value_name::String)
-            value = Vector{Char}(undef, XATTR_SIZE)
-            value_len = ccall(:getxattr, Cssize_t, (Cstring, Cstring, Ptr{Cvoid}, Csize_t, UInt32), f, value_name, value, XATTR_SIZE, XATTR_NOFOLLOW)
-            value_len == -1 && error("Couldn't get value \"$value_name\" from path \"$f\"")
-            return value
+        function _mdls(f::AbstractString, str_encoding::Unsigned = K_CFSTRING_ENCODING_MACROMAN)
+            cfstr = _cfstring_create_with_cstring(f, str_encoding)
+            mditem = _mditem_create(cfstr)
+            mdattrs = _mditem_copy_attribute_names(mditem)
+            # TODO: release/free mditem
+            attribs = _cfarray_create(mdattrs)
+            cfarr_len = _cfarray_get_count(attribs)
+            mddict = Dict{CString, Cstring}()
+            for cfidx in 1:cfarr_len
+                attr = _cfarray_get_value_at_index(attribs, i)
+                attr != C_NULL && (mddict[attr] = attr)
+            end
+            return mddict
+            # TODO: release/free mdattrs
         end
 
         # https://stackoverflow.com/a/12233785
@@ -80,7 +173,8 @@ export ishidden
         _ispackage_or_bundle(f::AbstractString) = any(t ∈ PKG_BUNDLE_TYPES for t in _kmd_item_content_type_tree(f))
 
 
-        ## All together ##
+        # TODO: follow every function and ensure I have all correct links
+        #=== All cases ===#
         _ishidden(f::AbstractString) = any((_ishidden_unix(f), _isinvisible(f), _ispackage_or_bundle(f)))
     else
         _ishidden = _ishidden_unix