Use uv_os_tmpdir instead

base/file.jl

@@ -420,22 +420,6 @@ const temp_prefix = "jl_"
 
 if Sys.iswindows()
 
-function ispathroot(path::String)
-    m = match(r"^([^\\]+:|\\\\[^\\]+\\[^\\]+|\\\\\?\\UNC\\[^\\]+\\[^\\]+|\\\\\?\\[^\\]+:|)(.*)$", path).captures[2]
-    return m == "\\" || isempty(m)
-end
-
-function tempdir()
-    temppath = Vector{UInt16}(undef, 32767)
-    lentemppath = ccall(:GetTempPathW, stdcall, UInt32, (UInt32, Ptr{UInt16}), length(temppath), temppath)
-    windowserror("GetTempPath", lentemppath >= length(temppath) || lentemppath == 0)
-    resize!(temppath, lentemppath - (temppath[lentemppath]==0x005c))  # ignore trailing `\` (according to docs GetTempPathW always adds '\')
-    path = transcode(String, temppath)
-    isroot = ispathroot(path)
-    # add trailing '\' back for drive root and UNC paths
-    return isroot ? path * '\\' : path
-end
-
 function _win_tempname(temppath::AbstractString, uunique::UInt32)
     tempp = cwstring(temppath)
     temppfx = cwstring(temp_prefix)
@@ -482,7 +466,14 @@ function tempname()
 end
 
 # Obtain a temporary directory's path.
-tempdir() = dirname(tempname())
+function tempdir()
+    path_max = 1024
+    buf = Vector{UInt8}(undef, path_max)
+    sz = Ref{Csize_t}(path_max)
+    rc = ccall(:uv_os_tmpdir, Cint, (Ptr{UInt8}, Ptr{Csize_t}), buf, sz)
+    resize!(buf, sz[])
+    return String(buf)
+end
 
 # Create and return the name of a temporary file along with an IOStream
 function mktemp(parent=tempdir())
@@ -499,7 +490,11 @@ end # os-test
 """
     tempdir()
 
-Obtain the path of a temporary directory (possibly shared with other processes).
+Obtain the path of a temporary directory (possibly shared with other processes). On Windows,
+`tempdir()` uses the first environment variable found in the ordered list `TMP`, `TEMP`,
+`USERPROFILE`. On all other operating systems, `tempdir()` uses the first environment
+variable found in the ordered list `TMPDIR`, `TMP`, `TEMP`, and `TEMPDIR`. If none of these are
+found, the path `"/tmp"` is used.
 """
 tempdir()