glusterfs

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#!/usr/bin/python3
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# Copyright (c) 2015 Red Hat, Inc. <http://www.redhat.com/>
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# This file is part of GlusterFS.
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#
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# This file is licensed to you under your choice of the GNU Lesser
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# General Public License, version 3 or any later version (LGPLv3 or
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# later), or the GNU General Public License, version 2 (GPLv2), in all
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# cases as published by the Free Software Foundation.
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import sys
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import os
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import xattr
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import uuid
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import re
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import errno
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CHANGELOG_SEARCH_MAX_TRY = 31
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DEC_CTIME_START = 5
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ROOT_GFID = "00000000-0000-0000-0000-000000000001"
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MAX_NUM_CHANGELOGS_TRY = 2
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def output_not_found(gfid):
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    # Write GFID to stderr
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    sys.stderr.write("%s\n" % gfid)
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def output_success(path):
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    # Write converted Path to Stdout
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    sys.stdout.write("%s\n" % path)
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def full_dir_path(gfid):
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    out_path = ""
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    while True:
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        path = os.path.join(".glusterfs", gfid[0:2], gfid[2:4], gfid)
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        path_readlink = os.readlink(path)
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        pgfid = os.path.dirname(path_readlink)
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        out_path = os.path.join(os.path.basename(path_readlink), out_path)
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        if pgfid == "../../00/00/%s" % ROOT_GFID:
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            out_path = os.path.join("./", out_path)
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            break
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        gfid = os.path.basename(pgfid)
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    return out_path
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def find_path_from_changelog(fd, gfid):
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    """
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    In given Changelog File, finds using following pattern
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    <T><GFID>\x00<TYPE>\x00<MODE>\x00<UID>\x00<GID>\x00<PARGFID>/<BASENAME>
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    Pattern search finds PARGFID and BASENAME, Convert PARGFID to Path
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    Using readlink and add basename to form Full path.
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    """
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    content = fd.read()
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    pattern = "E%s" % gfid
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    pattern += "\x00(3|23)\x00\d+\x00\d+\x00\d+\x00([^\x00]+)/([^\x00]+)"
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    pat = re.compile(pattern)
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    match = pat.search(content)
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    if match:
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        pgfid = match.group(2)
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        basename = match.group(3)
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        if pgfid == ROOT_GFID:
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            return os.path.join("./", basename)
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        else:
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            full_path_parent = full_dir_path(pgfid)
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            if full_path_parent:
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                return os.path.join(full_path_parent, basename)
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    return None
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def gfid_to_path(gfid):
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    """
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    Try readlink, if it is directory it succeeds.
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    Get ctime of the GFID file, Decrement by 5 sec
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    Search for Changelog filename, Since Changelog file generated
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    every 15 sec, Search and get immediate next Changelog after the file
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    Creation. Get the Path by searching in Changelog file.
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    Get the resultant file's GFID and Compare with the input, If these
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    GFIDs are different then Some thing is changed(May be Rename)
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    """
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    gfid = gfid.strip()
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    gpath = os.path.join(".glusterfs", gfid[0:2], gfid[2:4], gfid)
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    try:
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        output_success(full_dir_path(gfid))
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        return
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    except OSError:
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        # Not an SymLink
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        pass
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    try:
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        ctime = int(os.stat(gpath).st_ctime)
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        ctime -= DEC_CTIME_START
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    except (OSError, IOError):
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        output_not_found(gfid)
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        return
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    path = None
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    found_changelog = False
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    changelog_parse_try = 0
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    for i in range(CHANGELOG_SEARCH_MAX_TRY):
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        cl = os.path.join(".glusterfs/changelogs", "CHANGELOG.%s" % ctime)
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        try:
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            with open(cl, "rb") as f:
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                changelog_parse_try += 1
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                found_changelog = True
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                path = find_path_from_changelog(f, gfid)
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                if not path and changelog_parse_try < MAX_NUM_CHANGELOGS_TRY:
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                    ctime += 1
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                    continue
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            break
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        except (IOError, OSError) as e:
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            if e.errno == errno.ENOENT:
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                ctime += 1
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            else:
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                break
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    if not found_changelog:
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        output_not_found(gfid)
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        return
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    if not path:
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        output_not_found(gfid)
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        return
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    gfid1 = str(uuid.UUID(bytes=xattr.get(path, "trusted.gfid")))
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    if gfid != gfid1:
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        output_not_found(gfid)
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        return
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    output_success(path)
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def main():
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    num_arguments = 3
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    if not sys.stdin.isatty():
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        num_arguments = 2
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    if len(sys.argv) != num_arguments:
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        sys.stderr.write("Invalid arguments\nUsage: "
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                         "%s <BRICK_PATH> <GFID_FILE>\n" % sys.argv[0])
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        sys.exit(1)
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    path = sys.argv[1]
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    if sys.stdin.isatty():
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        gfid_list = os.path.abspath(sys.argv[2])
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        os.chdir(path)
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        with open(gfid_list) as f:
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            for gfid in f:
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                gfid_to_path(gfid)
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    else:
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        os.chdir(path)
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        for gfid in sys.stdin:
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            gfid_to_path(gfid)
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if __name__ == "__main__":
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    main()
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