def _buildImg(col, latex: str, fname: str, model: NoteType) -> Optional[str]:
# add header/footer
latex = model["latexPre"] + "\n" + latex + "\n" + model["latexPost"]
# it's only really secure if run in a jail, but these are the most common
tmplatex = latex.replace("\\includegraphics", "")
for bad in (
"\\write18",
"\\readline",
"\\input",
"\\include",
"\\catcode",
"\\openout",
"\\write",
"\\loop",
"\\def",
"\\shipout",
):
# don't mind if the sequence is only part of a command
bad_re = "\\" + bad + "[^a-zA-Z]"
if re.search(bad_re, tmplatex):
return (
_(
"""\
For security reasons, '%s' is not allowed on cards. You can still use \
it by placing the command in a different package, and importing that \
package in the LaTeX header instead."""
)
% bad
)
# commands to use?
if model.get("latexsvg", False):
latexCmds = svgCommands
ext = "svg"
else:
latexCmds = pngCommands
ext = "png"
# write into a temp file
log = open(namedtmp("latex_log.txt"), "w")
texpath = namedtmp("tmp.tex")
texfile = open(texpath, "w", encoding="utf8")
texfile.write(latex)
texfile.close()
mdir = col.media.dir()
oldcwd = os.getcwd()
png = namedtmp("tmp.%s" % ext)
try:
# generate png
os.chdir(tmpdir())
for latexCmd in latexCmds:
if call(latexCmd, stdout=log, stderr=log):
return _errMsg(latexCmd[0], texpath)
# add to media
shutil.copyfile(png, os.path.join(mdir, fname))
return None
finally:
os.chdir(oldcwd)
log.close()
def _imgLink(col, latex: str, model: NoteType) -> str:
"Return an img link for LATEX, creating if necesssary."
txt = _latexFromHtml(col, latex)
if model.get("latexsvg", False):
ext = "svg"
else:
ext = "png"
# is there an existing file?
fname = "latex-%s.%s" % (checksum(txt.encode("utf8")), ext)
link = '<img class=latex src="%s">' % fname
if os.path.exists(fname):
return link
# building disabled?
if not build:
return "[latex]%s[/latex]" % latex
err = _buildImg(col, txt, fname, model)
if err:
return err
else:
return link