Add disk stat functions

base/exports.jl

@@ -893,6 +893,7 @@ export
     chown,
     cp,
     ctime,
+    diskstat,
     download,
     filemode,
     filesize,

base/file.jl

@@ -8,6 +8,7 @@ export
     chown,
     cp,
     cptree,
+    diskstat,
     hardlink,
     mkdir,
     mkpath,
@@ -1168,3 +1169,72 @@ function chown(path::AbstractString, owner::Integer, group::Integer=-1)
     err < 0 && uv_error("chown($(repr(path)), $owner, $group)", err)
     path
 end
+
+
+# typedef struct uv_statfs_s {
+#     uint64_t f_type;
+#     uint64_t f_bsize;    <- block size
+#     uint64_t f_blocks;   <- total blocks
+#     uint64_t f_bfree;
+#     uint64_t f_bavail;   <- available blocks
+#     uint64_t f_files;
+#     uint64_t f_ffree;
+#     uint64_t f_spare[4];
+# } uv_statfs_t;
+# See also
+# - http://docs.libuv.org/en/v1.x/fs.html#c.uv_fs_statfs (libuv function docs)
+# - http://docs.libuv.org/en/v1.x/fs.html#c.uv_statfs_t (libuv docs of the returned struct)
+struct StatFS
+    ftype::UInt64
+    bsize::UInt64
+    blocks::UInt64
+    bfree::UInt64
+    bavail::UInt64
+    files::UInt64
+    ffree::UInt64
+    fspare1::UInt128
+    fspare2::UInt128
+end
+
+"""
+    DiskStat
+
+Stores the total size, available space, and currently used space of the disk in bytes.
+Populate by calling `diskstat`.
+"""
+struct DiskStat
+    total::Int
+    available::Int
+    used::Int
+end
+
+"""
+    diskstat(path=pwd())
+
+Returns statistics in bytes about the disk that contains the file or directory pointed at by
+`path`. If no argument is passed, statistics about the disk that contains the current
+working directory are returned.
+
+!!! compat "Julia 1.8"
+    This method was added in Julia 1.8.
+"""
+function diskstat(path::AbstractString=pwd())
+    ispath(path) || throw(ArgumentError("'$path' is not a file or directory."))
+
+    # Call libuv's cross-platform statfs implementation
+    req = Ref{NTuple{Int(_sizeof_uv_fs), UInt8}}()
+    err = ccall(:uv_fs_statfs, Cint, (Ptr{Cvoid}, Ptr{Cvoid}, Cstring, Ptr{Cvoid}),
+                C_NULL, req, path, C_NULL)
+    err < 0 && uv_error("statfs($(repr(path)))", err)
+    statfs_ptr = ccall(:jl_uv_fs_t_ptr, Ptr{Nothing}, (Ptr{Cvoid},), req)
+
+    stats = unsafe_load(reinterpret(Ptr{StatFS}, statfs_ptr))
+    total = Int(stats.bsize * stats.blocks)
+    available = Int(stats.bsize * stats.bavail)
+    disk_stats = DiskStat(total, available, total - available)
+
+    # Cleanup
+    uv_fs_req_cleanup(req)
+
+    return disk_stats
+end

test/file.jl

@@ -1692,3 +1692,12 @@ end
         @test !isnothing(Base.Filesystem.getgroupname(s.gid))
     end
 end
+
+@testset "diskstat() works" begin
+    dstat = diskstat()
+
+    # Sanity check assuming disk is smaller than 32TB
+    TB = 2^41
+    @test dstat.total < 32TB
+    @test dstat.used + dstat.available == dstat.total
+end