Merge pull request #7453 from takluyver/check-latex-commands

Check for latex commands to improve error messages when commands are missing

IPython/nbconvert/exporters/pdf.py

@@ -1,141 +1,147 b''
 """Export to PDF via latex"""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import subprocess
 import os
 import sys
 
+from IPython.utils.process import find_cmd
 from IPython.utils.traitlets import Integer, List, Bool, Instance
 from IPython.utils.tempdir import TemporaryWorkingDirectory
 from .latex import LatexExporter
 
 
 class PDFExporter(LatexExporter):
     """Writer designed to write to PDF files"""
 
     latex_count = Integer(3, config=True,
         help="How many times latex will be called."
     )
 
     latex_command = List([u"pdflatex", u"{filename}"], config=True, 
         help="Shell command used to compile latex."
     )
 
     bib_command = List([u"bibtex", u"{filename}"], config=True,
         help="Shell command used to run bibtex."
     )
 
     verbose = Bool(False, config=True,
         help="Whether to display the output of latex commands."
     )
 
     temp_file_exts = List(['.aux', '.bbl', '.blg', '.idx', '.log', '.out'], config=True,
         help="File extensions of temp files to remove after running."
     )
     
     writer = Instance("IPython.nbconvert.writers.FilesWriter", args=())
 
     def run_command(self, command_list, filename, count, log_function):
         """Run command_list count times.
         
         Parameters
         ----------
         command_list : list
             A list of args to provide to Popen. Each element of this
             list will be interpolated with the filename to convert.
         filename : unicode
             The name of the file to convert.
         count : int
             How many times to run the command.
         
         Returns
         -------
         success : bool
             A boolean indicating if the command was successful (True)
             or failed (False).
         """
         command = [c.format(filename=filename) for c in command_list]
-        #In windows and python 2.x there is a bug in subprocess.Popen and
+
+        # On windows with python 2.x there is a bug in subprocess.Popen and
         # unicode commands are not supported
         if sys.platform == 'win32' and sys.version_info < (3,0):
             #We must use cp1252 encoding for calling subprocess.Popen
             #Note that sys.stdin.encoding and encoding.DEFAULT_ENCODING
             # could be different (cp437 in case of dos console)
             command = [c.encode('cp1252') for c in command]        
+
+        # This will throw a clearer error if the command is not found
+        find_cmd(command_list[0])
+        
         times = 'time' if count == 1 else 'times'
         self.log.info("Running %s %i %s: %s", command_list[0], count, times, command)
         with open(os.devnull, 'rb') as null:
             stdout = subprocess.PIPE if not self.verbose else None
             for index in range(count):
                 p = subprocess.Popen(command, stdout=stdout, stdin=null)
                 out, err = p.communicate()
                 if p.returncode:
                     if self.verbose:
                         # verbose means I didn't capture stdout with PIPE,
                         # so it's already been displayed and `out` is None.
                         out = u''
                     else:
                         out = out.decode('utf-8', 'replace')
                     log_function(command, out)
                     return False # failure
         return True # success
 
     def run_latex(self, filename):
         """Run pdflatex self.latex_count times."""
 
         def log_error(command, out):
             self.log.critical(u"%s failed: %s\n%s", command[0], command, out)
 
         return self.run_command(self.latex_command, filename, 
             self.latex_count, log_error)
 
     def run_bib(self, filename):
         """Run bibtex self.latex_count times."""
         filename = os.path.splitext(filename)[0]
 
         def log_error(command, out):
             self.log.warn('%s had problems, most likely because there were no citations',
                 command[0])
             self.log.debug(u"%s output: %s\n%s", command[0], command, out)
 
         return self.run_command(self.bib_command, filename, 1, log_error)
 
     def clean_temp_files(self, filename):
         """Remove temporary files created by pdflatex/bibtex."""
         self.log.info("Removing temporary LaTeX files")
         filename = os.path.splitext(filename)[0]
         for ext in self.temp_file_exts:
             try:
                 os.remove(filename+ext)
             except OSError:
                 pass
 
     def from_notebook_node(self, nb, resources=None, **kw):
         latex, resources = super(PDFExporter, self).from_notebook_node(
             nb, resources=resources, **kw
         )
         with TemporaryWorkingDirectory() as td:
             notebook_name = "notebook"
             tex_file = self.writer.write(latex, resources, notebook_name=notebook_name)
             self.log.info("Building PDF")
             rc = self.run_latex(tex_file)
             if not rc:
                 rc = self.run_bib(tex_file)
             if not rc:
                 rc = self.run_latex(tex_file)
             
             pdf_file = notebook_name + '.pdf'
             if not os.path.isfile(pdf_file):
                 raise RuntimeError("PDF creating failed")
             self.log.info('PDF successfully created')
             with open(pdf_file, 'rb') as f:
                 pdf_data = f.read()
         
         # convert output extension to pdf
         # the writer above required it to be tex
         resources['output_extension'] = '.pdf'
         
         return pdf_data, resources