#!/usr/bin/python
# 
#  Copyright (C) 2016 Kyle Walker <kwalker@redhat.com>
#  
#  This copyrighted material is made available to anyone wishing to use,
#  modify, copy, or redistribute it subject to the terms and conditions
#  of the GNU General Public License, either version 2 of the License, or
#  (at your option) any later version
# 
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software Foundation,
#  Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
# 
#  Description:
#    When an strace is needing to be run in the background for an extended
#    period of time, the resulting files can become unnecessarily large.
#    This utility allows a individual file size limit and number of files to
#    to be specified. The remainder of the arguments are then passed
#    immediately to the strace utility in the traditional manner.
# 
#  Author: Kyle Walker <kwalker@redhat.com>
#
#  ChangeLog:
#   * Wed Apr 13 - Kyle Walker <kwalker@redhat.com>
#     Initial release.
#
# Example of usage:
#
#  ~]$ stracelogger.py --name test --num 5 --size 100M -- -p 1 -ttfv &
#  ~]$ ls -l
#  total 0
#  -rw-rw-r--. 1 kwalker kwalker 0 Apr 13 08:32 test-4-13-2016-08:32:24
# 


from __future__ import print_function

import os
import sys
import time

import argparse
import subprocess

# Global tracker of files used
class files:
    def __init__(self):
        self.filelist  = []
        self.openfile  = self.newfile()
        self.lastprint = time.time()

    def newfile(self):
        filename = args.name + "-" + time.strftime("%m-%d-%Y-%I:%M:%S")
        f = open(filename, "w")

        # Initialize to zero since this avoids having to stat the file outside of the write operation
        self.cachetell = 0

        self.filelist.append(f.name)
        print("\tOpened: %s" %(f.name))

        return f
    
    def deletefile(self):
        print("\tDeleting %s" %(self.filelist[0]))
        os.remove(self.filelist[0])
        self.filelist.pop(0)


    def cleanup(self):
        if args.debug:
            if int(time.time() - self.lastprint) > 1:
                print("\t\tDEBUG: File: %s\tWrote: %fMib (%db)\tLimit: %db" %(self.openfile.name, btomib(self.cachetell), self.cachetell, mibtob(args.size)))
                self.lastprint = time.time()

        if self.cachetell > mibtob( args.size ):
            if args.debug:
                print("\t%s - Over size limit of %sMiB - " %(self.openfile.name, args.size), end="")

            self.openfile = self.newfile()

            # Check to see if we are over the passed number of overall files
            if len(self.filelist) >= (args.num + 1):
                if args.debug:
                    print("\t\tNumber of open files %d exceeds the limit of %d." %(len(self.filelist), args.num))

                self.deletefile()
    
    def write(self, buf):
        self.openfile.write(buf)
        self.cachetell = self.openfile.tell()


parser = argparse.ArgumentParser(description='Captures a rolling strace limited by defined values.')
parser.add_argument('-d', '--debug', action="count", help='Debugging output. Add additional flags to increase verbosity.')
parser.add_argument('--name', required=True, help='The name to prepend to each strace output file.')
parser.add_argument('--num', type=int, default=5, help='The number of files to write prior to cleaning up the initial file.')
parser.add_argument('--size', type=int, default=100, help='Size limit imposed to any individual strace file (In MiB).')
parser.add_argument('-- <straceargs>', help='Arguments for the strace utility. Note, the "--" delimiter must be used to note the start of strace arguments.')
args, unknown = parser.parse_known_args()


def btomib(val):
    return ( val / 1024 / 1024 )

def mibtob(val):
    return ( val * 1024 * 1024 )


# Check the strace arguments passed. If an incompatible argument is included, the
# function returns true
def incompatiblearg(straceargs):
    if "-o" in straceargs:
        print("-o in the passed strace arguments. Please rerun the command without this flag.")
        return True

    if "ff" in straceargs:
        print("-ff in the passed strace arguments. Please rerun the command without this flag.")
        return True

    return None

def parsestraceargs():
    ignoredargs = ["-d", "--debug", "--name", "--num", "--size"]
    retstr  = ""
    strargs = None
    for entry in sys.argv:
        if "--" in entry and entry not in ignoredargs:
            strargs = True
            continue

        else:
            if strargs:
                retstr = "%s %s" %(retstr, entry)
                if args.debug:
                    print("DEBUG - Adding - %s" %(entry))

    if args.debug:
        retstr = ' '.join(retstr.split())
        print("DEBUG - Arguments - '%s'" %(retstr))

    # Put the strace arguments into the args member just to simplify things
    args.straceargs = retstr.split()

    return incompatiblearg(retstr)

def main():
    print("Starting:\n\tstrace %s" %(args.straceargs))
    try:
        strace = subprocess.Popen(["strace"] + args.straceargs, stderr=subprocess.PIPE)
    except OSError as e:
        if e.errno == os.errno.ENOENT:
            print("Unable to find the strace utility")


    # Initialize the tracker variables
    exit = None
    buf  = ""
    f    = files()

    # Primary work cycle
    while not exit:
        buf = strace.stderr.readline()
        if args.debug > 3:
            print("Raw: '%s'" %(buf), end="")

        f.cleanup()
        f.write(buf)

        if not buf:
            exit = True

if __name__ == "__main__":
    if not parsestraceargs():
        main()