Merge pull request #622 from pallene-lang/util-quote

util.shell_quote: don't quote obviously clean chars

spec/util_spec.lua

@@ -8,33 +8,45 @@ local util = require "pallene.util"
 
 describe("Pallene utils", function()
 
-     it("returns error when a file doesn't exist", function()
+    it("can quote special shell chars", function()
+        assert.equals([[' ']], util.shell_quote([[ ]]))
+        assert.equals([['$']], util.shell_quote([[$]]))
+        assert.equals([['"']], util.shell_quote([["]]))
+        assert.equals([['a'\''b']], util.shell_quote([[a'b]]))
+    end)
+
+    it("does not quote clean shell chars", function()
+        assert.equals("foo/bar.txt", util.shell_quote("foo/bar.txt"))
+        assert.equals("100", util.shell_quote("100"))
+    end)
+
+    it("returns error when a file doesn't exist", function()
         local filename = "does_not_exist.pln"
         local ok, err = util.get_file_contents(filename)
         assert.falsy(ok)
         assert.matches(filename, err)
-     end)
+    end)
 
-     it("writes a file to disk", function()
+    it("writes a file to disk", function()
         local filename = "a_file.pln"
         local ok = util.set_file_contents(filename, "return {}")
         assert.truthy(ok)
         os.remove(filename)
-     end)
+    end)
 
-     it("can extract stdout from commands", function()
+    it("can extract stdout from commands", function()
          local cmd = [[lua -e 'io.stdout:write("hello")']]
          local ok, err, stdout, stderr = util.outputs_of_execute(cmd)
          assert(ok, err)
          assert.equals("hello", stdout)
          assert.equals("",      stderr)
-     end)
+    end)
 
-     it("can extract stderr from commands", function()
+    it("can extract stderr from commands", function()
          local cmd = [[lua -e 'io.stderr:write("hello")']]
          local ok, err, stdout, stderr = util.outputs_of_execute(cmd)
          assert(ok, err)
          assert.equals("",      stdout)
          assert.equals("hello", stderr)
-     end)
+    end)
 end)

src/pallene/util.lua

@@ -77,8 +77,13 @@ function util.set_file_contents(file_name, contents)
 end
 
 -- Quotes a command-line argument according to POSIX shell syntax.
+-- Uses a whitelist of safe chars to avoid quoting too much
 function util.shell_quote(str)
-    return "'" .. string.gsub(str, "'", "'\\''") .. "'"
+    if string.match(str, "^[%w./_-]+$") then
+        return str
+    else
+        return "'" .. string.gsub(str, "'", "'\\''") .. "'"
+    end
 end
 
 function util.execute(cmd)