Avoid creating files when download fails

.travis.yml

@@ -128,7 +128,7 @@ script:
     - export JULIA_CPU_CORES=2 && export JULIA_TEST_MAXRSS_MB=600 &&
         cd /tmp/julia/share/julia/test &&
         /tmp/julia/bin/julia --check-bounds=yes runtests.jl $TESTSTORUN &&
-        /tmp/julia/bin/julia --check-bounds=yes runtests.jl libgit2-online pkg
+        /tmp/julia/bin/julia --check-bounds=yes runtests.jl libgit2-online download pkg
     - cd `dirname $TRAVIS_BUILD_DIR` && mv julia2 julia &&
         rm -f julia/deps/scratch/libgit2-*/CMakeFiles/CMakeOutput.log
 # uncomment the following if failures are suspected to be due to the out-of-memory killer

appveyor.yml

@@ -56,4 +56,4 @@ test_script:
   - usr\bin\julia -e "versioninfo()"
   - usr\bin\julia --precompiled=no -e "true"
   - cd test && ..\usr\bin\julia --check-bounds=yes runtests.jl all &&
-      ..\usr\bin\julia --check-bounds=yes runtests.jl libgit2-online pkg
+      ..\usr\bin\julia --check-bounds=yes runtests.jl libgit2-online download pkg

base/interactiveutil.jl

@@ -587,9 +587,14 @@ else
             end
         end
         if downloadcmd == :wget
-            run(`wget -O $filename $url`)
+            try
+                run(`wget -O $filename $url`)
+            catch
+                rm(filename)  # wget always creates a file
+                rethrow()
+            end
         elseif downloadcmd == :curl
-            run(`curl -o $filename -L $url`)
+            run(`curl -L -f -o $filename $url`)
         elseif downloadcmd == :fetch
             run(`fetch -f $filename $url`)
         else

test/download.jl

@@ -0,0 +1,26 @@
+# This file is a part of Julia. License is MIT: http://julialang.org/license
+
+mktempdir() do temp_dir
+    # Download a file
+    file = joinpath(temp_dir, "ip")
+    @test download("http://httpbin.org/ip", file) == file
+    @test isfile(file)
+    @test !isempty(read(file))
+
+    # Download an empty file
+    empty_file = joinpath(temp_dir, "empty")
+    @test download("http://httpbin.org/status/200", empty_file) == empty_file
+
+    # Windows and older versions of curl do not create the empty file (https://github.com/curl/curl/issues/183)
+    @test !isfile(empty_file) || isempty(read(empty_file))
+
+    # Make sure that failed downloads do not leave files around
+    missing_file = joinpath(temp_dir, "missing")
+    @test_throws ErrorException download("http://httpbin.org/status/404", missing_file)
+    @test !isfile(missing_file)
+
+    # Use a TEST-NET (192.0.2.0/24) address which shouldn't be bound
+    invalid_host_file = joinpath(temp_dir, "invalid_host")
+    @test_throws ErrorException download("http://192.0.2.1", invalid_host_file)
+    @test !isfile(invalid_host_file)
+end