From 1ec9ab429b54ee09d3c9f0cf6d857f12fd72d1f0 Mon Sep 17 00:00:00 2001
From: Stefan Karpinski <stefan@karpinski.org>
Date: Thu, 29 Aug 2019 12:21:29 -0400
Subject: [PATCH] readdir: add `join` option to join `dir` with names

---
 NEWS.md      |  1 +
 base/file.jl | 69 +++++++++++++++++++++++++++++++++++++++++++---------
 test/file.jl | 28 +++++++++++++++++++++
 3 files changed, 86 insertions(+), 12 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index 321b61246f9fd..2ff018ce96ce4 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -24,6 +24,7 @@ New library functions
 * The `splitpath` function now accepts any `AbstractString` whereas previously it only accepted paths of type `String` ([#33012]).
 * The `tempname` function now takes an optional `parent::AbstractString` argument to give it a directory in which to attempt to produce a temporary path name ([#33090]).
 * The `tempname` function now takes a `cleanup::Bool` keyword argument defaulting to `true`, which causes the process to try to ensure that any file or directory at the path returned by `tempname` is deleted upon process exit ([#33090]).
+* The `readdir` function now takes a `join::Bool` keyword argument defaulting to `false`, which when set causes `readdir` to join its directory argument with each listed name ([#33113]).
 
 
 Standard library changes
diff --git a/base/file.jl b/base/file.jl
index ec07dddd221be..b1dcee009d5e3 100644
--- a/base/file.jl
+++ b/base/file.jl
@@ -671,27 +671,73 @@ struct uv_dirent_t
 end
 
 """
-    readdir(dir::AbstractString=".") -> Vector{String}
+    readdir(dir::AbstractString=pwd(); join::Bool=true) -> Vector{String}
 
-Return the files and directories in the directory `dir` (or the current working directory if not given).
+Return the names in the directory `dir` or the current working directory if not
+given. When `join` is false, `readdir` returns just the names in the directory
+as is; when `join` is true, it returns `joinpath(dir, name)` for each `name` so
+that the returned strings are full paths. If you want to get absolute paths
+back, call `readdir` with an absolute directory path and `join` set to true.
+
+!!! compat "Julia 1.4"
+    The `join` keyword argument requires at least Julia 1.4.
 
 # Examples
 ```julia-repl
-julia> readdir("/home/JuliaUser/Projects/julia")
-34-element Array{String,1}:
- ".circleci"
- ".freebsdci.sh"
+julia> cd("/home/JuliaUser/dev/julia")
+
+julia> readdir()
+30-element Array{String,1}:
+ ".appveyor.yml"
  ".git"
  ".gitattributes"
- ".github"
  ⋮
- "test"
  "ui"
  "usr"
  "usr-staging"
+
+julia> readdir(join=true)
+30-element Array{String,1}:
+ "/home/JuliaUser/dev/julia/.appveyor.yml"
+ "/home/JuliaUser/dev/julia/.git"
+ "/home/JuliaUser/dev/julia/.gitattributes"
+ ⋮
+ "/home/JuliaUser/dev/julia/ui"
+ "/home/JuliaUser/dev/julia/usr"
+ "/home/JuliaUser/dev/julia/usr-staging"
+
+julia> readdir("base")
+145-element Array{String,1}:
+ ".gitignore"
+ "Base.jl"
+ "Enums.jl"
+ ⋮
+ "version_git.sh"
+ "views.jl"
+ "weakkeydict.jl"
+
+julia> readdir("base", join=true)
+145-element Array{String,1}:
+ "base/.gitignore"
+ "base/Base.jl"
+ "base/Enums.jl"
+ ⋮
+ "base/version_git.sh"
+ "base/views.jl"
+ "base/weakkeydict.jl"```
+
+julia> readdir(abspath("base"), join=true)
+145-element Array{String,1}:
+ "/home/JuliaUser/dev/julia/base/.gitignore"
+ "/home/JuliaUser/dev/julia/base/Base.jl"
+ "/home/JuliaUser/dev/julia/base/Enums.jl"
+ ⋮
+ "/home/JuliaUser/dev/julia/base/version_git.sh"
+ "/home/JuliaUser/dev/julia/base/views.jl"
+ "/home/JuliaUser/dev/julia/base/weakkeydict.jl"
 ```
 """
-function readdir(dir::AbstractString)
+function readdir(dir::AbstractString=pwd(); join::Bool=false)
     # Allocate space for uv_fs_t struct
     uv_readdir_req = zeros(UInt8, ccall(:jl_sizeof_uv_fs_t, Int32, ()))
 
@@ -704,7 +750,8 @@ function readdir(dir::AbstractString)
     entries = String[]
     ent = Ref{uv_dirent_t}()
     while Base.UV_EOF != ccall(:uv_fs_scandir_next, Cint, (Ptr{Cvoid}, Ptr{uv_dirent_t}), uv_readdir_req, ent)
-        push!(entries, unsafe_string(ent[].name))
+        name = unsafe_string(ent[].name)
+        push!(entries, join ? joinpath(dir, name) : name)
     end
 
     # Clean up the request string
@@ -713,8 +760,6 @@ function readdir(dir::AbstractString)
     return entries
 end
 
-readdir() = readdir(".")
-
 """
     walkdir(dir; topdown=true, follow_symlinks=false, onerror=throw)
 
diff --git a/test/file.jl b/test/file.jl
index fe93448adabbe..d4e042adf0842 100644
--- a/test/file.jl
+++ b/test/file.jl
@@ -1404,3 +1404,31 @@ end
         @test sizeof(basename(tmpdir)) == 6
     end
 end
+
+@testset "readir tests" begin
+    ≛(a, b) = sort(a) == sort(b)
+    mktempdir() do dir
+        d = cd(pwd, dir) # might resolve symlinks
+        @test isempty(readdir(d))
+        @test isempty(readdir(d, join=true))
+        cd(d) do
+            @test isempty(readdir())
+            @test isempty(readdir(join=true))
+        end
+        touch(joinpath(d, "file"))
+        mkdir(joinpath(d, "dir"))
+        names = ["dir", "file"]
+        paths = [joinpath(d, x) for x in names]
+        @test readdir(d) ≛ names
+        @test readdir(d, join=true) ≛ paths
+        cd(d) do
+            @test readdir() ≛ names
+            @test readdir(join=true) ≛ paths
+        end
+        t, b = splitdir(d)
+        cd(t) do
+            @test readdir(b) ≛ names
+            @test readdir(b, join=true) ≛ [joinpath(b, x) for x in names]
+        end
+    end
+end