Proper way to consistently read `/proc/mounts`.

gistfile1.py

import re
import collections

def get_current_mounts():
    """ Get the currently mounted filesystems. """

    # Reading from /proc/mounts is only consistent within a single read(3)
    # call. Unfortunately, the maximum amount of data you can get from
    # this file in a single call is hardcoded by the kernel to PAGE_SIZE
    # (4096 bytes on x86). As a consequence, there is no way to read
    # from this file in a consistent manner.
    #
    # As a (arguably ugly) workaround, we read from /proc/mounts until we
    # get two reads in a row that are consistent with each other.
    #
    previous_data = None
    data = None
    while True:
        with open("/proc/mounts", "rb") as f:
            data = f.read()
        if data == previous_data:
            break
        else:
            previous_data = data

    mounts = collections.OrderedDict()
    for line in data.split("\n"):
        line = line.strip()
        if len(line) == 0:
            continue

        info = {}
        cols = re.split("\s+", line)

        info["source"] = cols[0].rstrip("/")
        info["mount-point"] = cols[1]
        info["fs-type"] = cols[2]
        info["options"] = cols[3]
        info["dump"] = cols[4]
        info["pass"] = cols[5]

        mounts[info["mount-point"]] = info

    return mounts