Use tmpfile for passing data to pstoedit

Otherwise this fails on the web instance as itz is pretty old. This
patch is not needed with newer versions of pstoedit and should be
removed as soon as the web instance is on the new server.

boxes/formats.py

@@ -18,6 +18,7 @@
 import shutil
 import subprocess
 import io
+import tempfile
 
 from boxes.drawing import SVGSurface, PSSurface, LBRN2Surface, Context
 
@@ -34,9 +35,9 @@ class Formats:
         "svg_Ponoko": None,
         "ps": None,
         "lbrn2": None,
-        "dxf": "{pstoedit} -flat 0.1 -f dxf:-mm",
-        "gcode": "{pstoedit} -f gcode",
-        "plt": "{pstoedit} -f hpgl",
+        "dxf": "{pstoedit} -flat 0.1 -f dxf:-mm {input} -",
+        "gcode": "{pstoedit} -f gcode {input} -",
+        "plt": "{pstoedit} -f hpgl {input} -",
         # "ai": "{pstoedit} -f ps2ai",
         "pdf": "{ps2pdf} -dEPSCrop - -",
     }
@@ -82,11 +83,20 @@ def getSurface(self, fmt):
     def convert(self, data, fmt):
 
         if fmt not in self._BASE_FORMATS:
+            tmpfile = ""
+            if fmt in ("dxf", "gcode", "plt"):
+                fd, tmpfile = tempfile.mkstemp()
+                os.write(fd, data.getvalue())
+                input_ = None
+            else:
+                input_ = data.getvalue()
+
             cmd = self.formats[fmt].format(
                 pstoedit=self.pstoedit,
-                ps2pdf=self.ps2pdf).split()
+                ps2pdf=self.ps2pdf,
+                input=tmpfile).split()
 
-            result = subprocess.run(cmd, input=data.getvalue(), capture_output=True)
+            result = subprocess.run(cmd, input=input_, capture_output=True)
             if result.returncode:
                 # XXX show stderr output
                 raise ValueError("Conversion failed. pstoedit returned %i\n\n %s" % (result.returncode, result.stderr))