Draft: Implement ishidden for ZFS filesystems

src/HiddenFiles.jl

@@ -28,16 +28,15 @@ include("docs.jl")
 
 @static if Sys.isunix()
     include("utils/zfs.jl")
-    if iszfs()  # @static breaks here # ZFS
+
+    function _ishidden_zfs(f::AbstractString, rp::AbstractString)
         error("not yet implemented")
-        _ishidden_zfs(f::AbstractString, rp::AbstractString) = error("not yet implemented")
-        _ishidden = _ishidden_zfs
     end
-    
+
     # Trivial Unix check
     _isdotfile(f::AbstractString) = startswith(basename(f), '.')
     # Check dotfiles, but also account for ZFS
-    _ishidden_unix(f::AbstractString, rp::AbstractString) = _isdotfile(rp) || (iszfs() && _ishidden_zfs("", ""))
+    _ishidden_unix(f::AbstractString, rp::AbstractString) = _isdotfile(rp) || (iszfs() && _ishidden_zfs(f, rp))
 
     @static if Sys.isbsd()  # BDS-related; this is true for macOS as well
         # https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/chflags.2.html

src/docs.jl

@@ -14,8 +14,17 @@ See also: [`_ishidden_unix`](@ref), [`_ishidden_windows`](@ref), [`_ishidden_mac
 _ishidden
 
 ### ZFS ###
-"This function is not yet implemented"
-iszfs
+"""
+```julia
+_iszfs(f::AbstractString) -> Bool
+```
+
+Determines if the file system that `f` exists on is ZFS.
+
+!!! note
+    This is only implemented for Unix-like systems, as I have not seen ZFS for Windows.
+"""
+_iszfs
 
 "This function is not yet implemented"
 _ishidden_zfs

src/utils/zfs.jl

@@ -1,5 +1,95 @@
-function iszfs()
-    # TODO
-    return false
+# TODO: Correct < 1.6 error codes
+
+# https://lists.freebsd.org/pipermail/freebsd-hackers/2018-February/052295.html
+const SUN_ZFS_SUPER_MAGIC = 0x1b
+const BSD_ZFS_SUPER_MAGIC = 0xde  # Obtained from testing
+# https://reviews.freebsd.org/rS320069
+const LINUX_ZFS_SUPER_MAGIC = 0x2fc12fc1
+
+const ZFS_SUPER_MAGICS = (SUN_ZFS_SUPER_MAGIC, BSD_ZFS_SUPER_MAGIC, LINUX_ZFS_SUPER_MAGIC)
+
+@static if VERSION ≥ v"1.6"
+    @static if VERSION < v"1.8"
+        # Adapted from Julia 1.8's diskstat: https://github.com/JuliaLang/julia/pull/42248
+        # C calls for UV statfs requires Julia 1.6
+        # http://docs.libuv.org/en/v1.x/fs.html#c.uv_fs_statfs
+        struct DiskStat
+            ftype::UInt64
+            bsize::UInt64
+            blocks::UInt64
+            bfree::UInt64
+            bavail::UInt64
+            files::UInt64
+            ffree::UInt64
+            fspare::NTuple{4, UInt64} # reserved
+        end
+        function statfs(f::AbstractString)
+            buf = Vector{UInt8}(undef, ccall(:jl_sizeof_uv_fs_t, Int32, ()))
+            i = ccall(:uv_fs_statfs, Cint, (Ptr{Cvoid}, Ptr{Cvoid}, Cstring, Ptr{Cvoid}),
+                      C_NULL, buf, f, C_NULL)
+            i < 0 && Base.uv_error("statfs($(repr(f)))", i)
+            p = ccall(:jl_uv_fs_t_ptr, Ptr{UInt32}, (Ptr{Cvoid},), buf)
+
+            return unsafe_load(reinterpret(Ptr{DiskStat}, p))
+        end
+    else
+        statfs = diskstat
+    end
+
+    function _iszfs(f::AbstractString)
+        s = statfs(f)
+        @info s.ftype
+        return s.ftype ∈ ZFS_SUPER_MAGICS
+    end
+else
+    # If Julia version < 1.6, we have to write our own, not very nice solution
+
+    # It occurred to me that UInt8 wasn't always enough to store the f_type (eda1c22)
+    const STATFS_BUF_ELTYPE = UInt32
+    const SIZEOF_STATFS_BUF_ELTYPE = Int8(sizeof(STATFS_BUF_ELTYPE))
+
+    @static if Sys.isapple()
+        # macOS: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/statfs.2.html
+        const SIZEOF_STATFS = cld(2168, SIZEOF_STATFS_BUF_ELTYPE)
+        const F_TYPE_OFFSET = cld(0x3d, SIZEOF_STATFS_BUF_ELTYPE)
+        const F_FSSUBTYPE_OFFSET = cld(0x45, SIZEOF_STATFS_BUF_ELTYPE)
+
+        function _iszfs(f::AbstractString)
+            buf = Vector{STATFS_BUF_ELTYPE}(undef, SIZEOF_STATFS)
+            # statfs(const char *path, struct statfs *buf);
+            i = ccall(:statfs, Int, (Cstring, Ptr{Cvoid}), f, buf)
+            i < 0 && Base.uv_error("statfs($(repr(f)))", i)
+            @info buf[F_TYPE_OFFSET], buf[F_FSSUBTYPE_OFFSET], buf, f
+            return buf[F_TYPE_OFFSET] ∈ ZFS_SUPER_MAGICS || buf[F_FSSUBTYPE_OFFSET] ∈ ZFS_SUPER_MAGICS
+        end
+    elseif Sys.isbsd()
+        # https://www.freebsd.org/cgi/man.cgi?query=statfs&sektion=2
+        const SIZEOF_STATFS = cld(2344, SIZEOF_STATFS_BUF_ELTYPE)
+        const F_TYPE_OFFSET = cld(0x05, SIZEOF_STATFS_BUF_ELTYPE)
+
+        function _iszfs(f::AbstractString)
+            buf = Vector{STATFS_BUF_ELTYPE}(undef, SIZEOF_STATFS)
+            # statfs(const char *path, struct statfs *buf);
+            i = ccall(:statfs, Int, (Cstring, Ptr{Cvoid}), f, buf)
+            i < 0 && Base.uv_error("statfs($(repr(f)))", i)
+            @info buf[F_TYPE_OFFSET], buf, f
+            return buf[F_TYPE_OFFSET] ∈ ZFS_SUPER_MAGICS
+        end
+    elseif Sys.isunix()
+        # Linux: https://man7.org/linux/man-pages/man2/statfs.2.html
+        const SIZEOF_STATFS = cld(120, SIZEOF_STATFS_BUF_ELTYPE)
+        const F_TYPE_OFFSET = cld(0x01, SIZEOF_STATFS_BUF_ELTYPE)
+
+        function _iszfs(f::AbstractString)
+            buf = Vector{STATFS_BUF_ELTYPE}(undef, SIZEOF_STATFS)
+            # statfs(const char *path, struct statfs *buf);
+            i = ccall(:statfs, Int, (Cstring, Ptr{Cvoid}), f, buf)
+            i < 0 && Base.uv_error("statfs($(repr(f)))", i)
+            @info buf[F_TYPE_OFFSET], buf, f
+            return buf[F_TYPE_OFFSET] ∈ ZFS_SUPER_MAGICS
+        end
+    else
+        _iszfs(_f::AbstractString) = error("Cannot call statfs for non-Unix operating systems")
+    end
 end