How to make Python use a path that contains colons in it?
Question:
I have a program that includes an embedded Python 2.6 interpreter. When I invoke the interpreter, I call PySys_SetPath() to set the interpreter’s import-path to the subdirectories installed next to my executable that contain my Python script files… like this:
PySys_SetPath("/path/to/my/program/scripts/type1:/path/to/my/program/scripts/type2");
(except that the path strings are dynamically generated based on the current location of my program’s executable, not hard-coded as in the example above)
This works fine… except when the clever user decides to install my program underneath a folder that has a colon in its name. In that case, my PySys_SetPath() command ends up looking like this (note the presence of a folder named “path:to”):
PySys_SetPath("/path:to/my/program/scripts/type1:/path:to/my/program/scripts/type2");
… and this breaks all my Python scripts, because now Python looks for script files in “/path”, and “to/my/program/scripts/type1” instead of in “/path:to/myprogram/scripts/type1”, and so none of the import statements work.
My question is, is there any fix for this issue, other than telling the user to avoid colons in his folder names?
I looked at the makepathobject() function in Python/sysmodule.c, and it doesn’t appear to support any kind of quoting or escaping to handle literal colons…. but maybe I am missing some nuance.
Answers:
Supporting colons in a file path opens up a huge can of worms on multiple operating systems; it is not a valid path character on Windows or Mac OS X, for example, and it doesn’t seem like a particularly reasonable thing to support in the context of a scripting environment either for exactly this reason. I’m actually a bit surprised that Linux allows colon filenames too, especially since : is a very common path separator character.
You might try escaping the colon out, i.e. converting /path:to/ to /path:to/ and see if that works. Other than that, just tell the user to avoid using colons in their file names. They will run into all sorts of problems in quite a few different environments and it’s a just plain bad idea.
The problem you’re running into is the PySys_SetPath function parses the string you pass using a colon as the delimiter. That parser sees each : character as delimiting a path, and there isn’t a way around this (can’t be escaped).
However, you can bypass this by creating a list of the individual paths (each of which may contain colons) and use PySys_SetObject to set the sys.path:
PyListObject *path;
path = (PyListObject *)PyList_New(0);
PyList_Append((PyObject *) path, PyString_FromString("foo:bar"));
PySys_SetObject("path", (PyObject *)path);
Now the interpreter will see "foo:bar" as a distinct component of the sys.path.
I have a program that includes an embedded Python 2.6 interpreter. When I invoke the interpreter, I call PySys_SetPath() to set the interpreter’s import-path to the subdirectories installed next to my executable that contain my Python script files… like this:
PySys_SetPath("/path/to/my/program/scripts/type1:/path/to/my/program/scripts/type2");
(except that the path strings are dynamically generated based on the current location of my program’s executable, not hard-coded as in the example above)
This works fine… except when the clever user decides to install my program underneath a folder that has a colon in its name. In that case, my PySys_SetPath() command ends up looking like this (note the presence of a folder named “path:to”):
PySys_SetPath("/path:to/my/program/scripts/type1:/path:to/my/program/scripts/type2");
… and this breaks all my Python scripts, because now Python looks for script files in “/path”, and “to/my/program/scripts/type1” instead of in “/path:to/myprogram/scripts/type1”, and so none of the import statements work.
My question is, is there any fix for this issue, other than telling the user to avoid colons in his folder names?
I looked at the makepathobject() function in Python/sysmodule.c, and it doesn’t appear to support any kind of quoting or escaping to handle literal colons…. but maybe I am missing some nuance.
Supporting colons in a file path opens up a huge can of worms on multiple operating systems; it is not a valid path character on Windows or Mac OS X, for example, and it doesn’t seem like a particularly reasonable thing to support in the context of a scripting environment either for exactly this reason. I’m actually a bit surprised that Linux allows colon filenames too, especially since : is a very common path separator character.
You might try escaping the colon out, i.e. converting /path:to/ to /path:to/ and see if that works. Other than that, just tell the user to avoid using colons in their file names. They will run into all sorts of problems in quite a few different environments and it’s a just plain bad idea.
The problem you’re running into is the PySys_SetPath function parses the string you pass using a colon as the delimiter. That parser sees each : character as delimiting a path, and there isn’t a way around this (can’t be escaped).
However, you can bypass this by creating a list of the individual paths (each of which may contain colons) and use PySys_SetObject to set the sys.path:
PyListObject *path;
path = (PyListObject *)PyList_New(0);
PyList_Append((PyObject *) path, PyString_FromString("foo:bar"));
PySys_SetObject("path", (PyObject *)path);
Now the interpreter will see "foo:bar" as a distinct component of the sys.path.