silentslice

#!/usr/bin/env python

import os
import sys
# if you pip installed this is wrong but you have silent_tools installed anyways
silent_tools_dir = os.path.dirname(os.path.realpath(__file__))
if silent_tools_dir not in sys.path:
    sys.path.append(silent_tools_dir)

import silent_tools
from silent_tools import eprint
import stat

# Don't throw an error when someone uses head
from signal import signal, SIGPIPE, SIG_DFL
signal(SIGPIPE, SIG_DFL) 


all_args = sys.argv[1:]
e_flag = False
for i in range(len(all_args)-1, -1, -1):
    elem = all_args[i]
    if elem[0] != '-':
        continue
    if elem[1] == 'e':
        e_flag = True
        all_args.pop(i)
        break
    assert False, 'silentslice: Unknown flag ' + elem



if (len(all_args) == 0):
    eprint("")
    eprint('silentslice by bcov - a tool to allow you extract a smaller silent file from a larger one')
    eprint("Usage:")
    eprint("        cat list_of_tags.list | silentslice myfile.silent > new.silent")
    eprint("                             or")
    eprint("        silentslice myfile.silent tag1 tag2 tag3 > new.silent")
    eprint("Flags:")
    eprint("        -e Old behavior that preserves input order of tags (new way is file-order which is faster")
    sys.exit(1)

silent_file = all_args[0]

tag_buffers = []
if ( stat.S_ISFIFO(os.stat("/dev/stdin").st_mode) ):
    tag_buffers += sys.stdin.readlines()
tag_buffers += all_args[1:]

tags = []
for line in tag_buffers:
    line = line.strip()
    if (len(line) == 0):
        continue
    sp = line.split(" ")
    for tag in sp:
        tags.append(tag)

if (len(tags) != len(set(tags))):
    eprint("silentslice: Warning: duplicate tags specified")

silent_index = silent_tools.get_silent_index( silent_file )

sys.stdout.write( silent_tools.silent_header( silent_index ) )
sys.stdout.flush()

if not e_flag:
    existing_tags = []
    for tag in tags:
        if ( tag not in silent_index['index'] ):
            eprint("silentslice: Unable to find tag: %s"%tag)
            continue
        else:
            existing_tags.append(tag)

    tags = sorted(existing_tags, key=lambda x: silent_index['index'][x]['seek'])

with open(silent_file, errors='ignore') as sf:
    for tag in tags:

        if ( tag not in silent_index['index'] ):
            eprint("silentslice: Unable to find tag: %s"%tag)
            continue
        structure = silent_tools.get_silent_structure_file_open( sf, silent_index, tag )

        sys.stdout.write("".join(structure))
        sys.stdout.flush()