rm: move open DLLs to temp dir to allow dir to be deleted

base/file.jl

@@ -249,6 +249,10 @@ function mkpath(path::AbstractString; mode::Integer = 0o777)
     path
 end
 
+# Files that were requested to be deleted but can't be by the current process
+# i.e. loaded DLLs on Windows
+delayed_delete_dir() = joinpath(tempdir(), "julia_delayed_deletes")
+
 """
     rm(path::AbstractString; force::Bool=false, recursive::Bool=false)
 
@@ -270,33 +274,41 @@ Stacktrace:
 [...]
 ```
 """
-function rm(path::AbstractString; force::Bool=false, recursive::Bool=false)
+function rm(path::AbstractString; force::Bool=false, recursive::Bool=false, allow_delayed_delete::Bool=true)
+    # allow_delayed_delete is used by Pkg.gc() but is otherwise not part of the public API
     if islink(path) || !isdir(path)
         try
-            @static if Sys.iswindows()
-                # is writable on windows actually means "is deletable"
-                st = lstat(path)
-                if ispath(st) && (filemode(st) & 0o222) == 0
-                    chmod(path, 0o777)
-                end
-            end
             unlink(path)
         catch err
-            if force && isa(err, IOError) && err.code==Base.UV_ENOENT
-                return
+            if isa(err, IOError)
+                force && err.code==Base.UV_ENOENT && return
+                @static if Sys.iswindows()
+                    if allow_delayed_delete && err.code==Base.UV_EACCES && endswith(path, ".dll")
+                        # Loaded DLLs cannot be deleted on Windows, even with posix delete mode
+                        # but they can be moved. So move out to allow the dir to be deleted
+                        # TODO: Add a mechanism to delete these moved files after dlclose or process exit
+                        dir = mkpath(delayed_delete_dir())
+                        temp_path = tempname(dir, cleanup = false, suffix = string("_", basename(path)))
+                        @debug "Could not delete DLL most likely because it is loaded, moving to tempdir" path temp_path
+                        mv(path, temp_path)
+                        return
+                    end
+                end
             end
             rethrow()
         end
     else
         if recursive
             try
                 for p in readdir(path)
-                    rm(joinpath(path, p), force=force, recursive=true)
+                    try
+                        rm(joinpath(path, p), force=force, recursive=true)
+                    catch err
+                        (isa(err, IOError) && err.code==Base.UV_EACCES) || rethrow()
+                    end
                 end
             catch err
-                if !(isa(err, IOError) && err.code==Base.UV_EACCES)
-                    rethrow(err)
-                end
+                (isa(err, IOError) && err.code==Base.UV_EACCES) || rethrow()
             end
         end
         req = Libc.malloc(_sizeof_uv_fs)

base/loading.jl

@@ -2902,26 +2902,10 @@ function compilecache(pkg::PkgId, path::String, internal_stderr::IO = stderr, in
             end
 
             if cache_objects
-                try
-                    rename(tmppath_so, ocachefile::String; force=true)
-                catch e
-                    e isa IOError || rethrow()
-                    isfile(ocachefile::String) || rethrow()
-                    # Windows prevents renaming a file that is in use so if there is a Julia session started
-                    # with a package image loaded, we cannot rename that file.
-                    # The code belows append a `_i` to the name of the cache file where `i` is the smallest number such that
-                    # that cache file does not exist.
-                    ocachename, ocacheext = splitext(ocachefile::String)
-                    old_cachefiles = Set(readdir(cachepath))
-                    num = 1
-                    while true
-                        ocachefile = ocachename * "_$num" * ocacheext
-                        in(basename(ocachefile), old_cachefiles) || break
-                        num += 1
-                    end
-                    # TODO: Risk for a race here if some other process grabs this name before us
-                    cachefile = cachefile_from_ocachefile(ocachefile)
-                    rename(tmppath_so, ocachefile::String; force=true)
+                ocachefile_new = rename_unique_ocachefile(tmppath_so, ocachefile)
+                if ocachefile_new != ocachefile
+                    cachefile = cachefile_from_ocachefile(ocachefile_new)
+                    ocachefile = ocachefile_new
                 end
                 @static if Sys.isapple()
                     run(`$(Linking.dsymutil()) $ocachefile`, Base.DevNull(), Base.DevNull(), Base.DevNull())
@@ -2945,6 +2929,27 @@ function compilecache(pkg::PkgId, path::String, internal_stderr::IO = stderr, in
     end
 end
 
+function rename_unique_ocachefile(tmppath_so::String, ocachefile_orig::String, ocachefile::String = ocachefile_orig, num = 0)
+    try
+        rename(tmppath_so, ocachefile; force=true)
+    catch e
+        e isa IOError || rethrow()
+        # If `rm` was called on a dir containing a loaded DLL, we moved it to temp for cleanup
+        # on restart. However the old path cannot be used (UV_EACCES) while the DLL is loaded
+        if !isfile(ocachefile) && e.code != Base.UV_EACCES
+            rethrow()
+        end
+        # Windows prevents renaming a file that is in use so if there is a Julia session started
+        # with a package image loaded, we cannot rename that file.
+        # The code belows append a `_i` to the name of the cache file where `i` is the smallest number such that
+        # that cache file does not exist.
+        ocachename, ocacheext = splitext(ocachefile_orig)
+        ocachefile_unique = ocachename * "_$num" * ocacheext
+        ocachefile = rename_unique_ocachefile(tmppath_so, ocachefile_orig, ocachefile_unique, num + 1)
+    end
+    return ocachefile
+end
+
 function module_build_id(m::Module)
     hi, lo = ccall(:jl_module_build_id, NTuple{2,UInt64}, (Any,), m)
     return (UInt128(hi) << 64) | lo