#338 Try and stop ALE from throwing ALEs when run from a sandbox

autoload/ale.vim

@@ -4,9 +4,17 @@
 
 let s:lint_timer = -1
 
+" A function for checking various conditions whereby ALE just shouldn't
+" attempt to do anything, say if particular buffer types are open in Vim.
+function! ale#ShouldDoNothing() abort
+    " Do nothing for blacklisted files
+    " OR if ALE is running in the sandbox
+    return index(g:ale_filetype_blacklist, &filetype) >= 0
+    \   || ale#util#InSandbox()
+endfunction
+
 function! ale#Queue(delay) abort
-    " Do nothing for blacklisted files.
+    if ale#ShouldDoNothing()
-    if index(g:ale_filetype_blacklist, &filetype) >= 0
         return
     endif
 
@@ -29,8 +37,7 @@ function! ale#Queue(delay) abort
 endfunction
 
 function! ale#Lint(...) abort
-    " Do nothing for blacklisted files.
+    if ale#ShouldDoNothing()
-    if index(g:ale_filetype_blacklist, &filetype) >= 0
         return
     endif
 

autoload/ale/cursor.vim

@@ -73,8 +73,7 @@ let s:cursor_timer = -1
 let s:last_pos = [0, 0, 0]
 
 function! ale#cursor#EchoCursorWarningWithDelay() abort
-    " Do nothing for blacklisted files.
+    if ale#ShouldDoNothing()
-    if index(g:ale_filetype_blacklist, &filetype) >= 0
         return
     endif
 

autoload/ale/engine.vim

@@ -155,6 +155,12 @@ function! ale#engine#RemoveManagedFiles(buffer) abort
         return
     endif
 
+    " We can't delete anything in a sandbox, so wait until we escape from
+    " it to delete temporary files and directories.
+    if ale#util#InSandbox()
+        return
+    endif
+
     " Delete files with a call akin to a plan `rm` command.
     for l:filename in g:ale_buffer_info[a:buffer].temporary_file_list
         call delete(l:filename)
@@ -195,6 +201,12 @@ function! s:HandleExit(job) abort
     " which just closed.
     call s:StopPreviousJobs(l:buffer, l:linter)
 
+    " Stop here if we land in the handle for a job completing if we're in
+    " a sandbox.
+    if ale#util#InSandbox()
+        return
+    endif
+
     if l:next_chain_index < len(get(l:linter, 'command_chain', []))
         call s:InvokeChain(l:buffer, l:linter, l:next_chain_index, l:output)
         return

autoload/ale/util.vim

@@ -118,3 +118,19 @@ function! ale#util#BinarySearch(loclist, line, column) abort
         endif
     endwhile
 endfunction
+
+" A function for testing if a function is running inside a sandbox.
+" See :help sandbox
+function! ale#util#InSandbox() abort
+    try
+        call setbufvar('%', '', '')
+    catch /^Vim\%((\a\+)\)\=:E48/
+        " E48 is the sandbox error.
+        return 1
+    catch
+        " If we're not in a sandbox, we'll get another error about an
+        " invalid buffer variable name.
+    endtry
+
+    return 0
+endfunction

test/test_sandbox_execution.vader

@@ -0,0 +1,51 @@
+Before:
+  function! TestCallback(buffer, output)
+    return [
+    \ {
+    \   'lnum': 1,
+    \   'bufnr': 1,
+    \   'vcol': 0,
+    \   'linter_name': 'testlinter',
+    \   'nr': -1,
+    \   'type': 'E',
+    \   'col': 1,
+    \   'text': 'Test Error',
+    \ },
+    \]
+  endfunction
+
+  call ale#linter#Define('foobar', {
+  \ 'name': 'testlinter',
+  \ 'callback': 'TestCallback',
+  \ 'executable': 'echo',
+  \ 'command': 'echo',
+  \})
+
+  let g:ale_buffer_info = {}
+
+After:
+  delfunction TestCallback
+  call ale#linter#Reset()
+  let g:ale_buffer_info = {}
+
+Given foobar (Some imaginary filetype):
+  foo
+  bar
+  baz
+
+Execute(ALE shouldn't blow up when run from a sandbox):
+  AssertEqual 'foobar', &filetype
+
+  sandbox call ale#Queue(0)
+  sandbox call ale#Queue(1)
+  sandbox call ale#Lint()
+
+Execute(ALE shouldn't blow up if file cleanup happens in a sandbox):
+  let g:ale_buffer_info[3] = {
+  \ 'temporary_file_list': ['/tmp/foo'],
+  \ 'temporary_directory_list': ['/tmp/bar'],
+  \}
+  sandbox call ale#engine#RemoveManagedFiles(3)
+
+  AssertEqual ['/tmp/foo'], g:ale_buffer_info[3].temporary_file_list
+  AssertEqual ['/tmp/bar'], g:ale_buffer_info[3].temporary_directory_list