projects / OpenSPARC-T2-SAM / blame
| Commit | Line | Data |
|---|---|---|
| 920dae64 AT |
1 | # !/usr/bin/env python |
| 2 | """Guess which db package to use to open a db file.""" | |
| 3 | ||
| 4 | import os | |
| 5 | import struct | |
| 6 | import sys | |
| 7 | ||
| 8 | try: | |
| 9 | import dbm | |
| 10 | _dbmerror = dbm.error | |
| 11 | except ImportError: | |
| 12 | dbm = None | |
| 13 | # just some sort of valid exception which might be raised in the | |
| 14 | # dbm test | |
| 15 | _dbmerror = IOError | |
| 16 | ||
| 17 | def whichdb(filename): | |
| 18 | """Guess which db package to use to open a db file. | |
| 19 | ||
| 20 | Return values: | |
| 21 | ||
| 22 | - None if the database file can't be read; | |
| 23 | - empty string if the file can be read but can't be recognized | |
| 24 | - the module name (e.g. "dbm" or "gdbm") if recognized. | |
| 25 | ||
| 26 | Importing the given module may still fail, and opening the | |
| 27 | database using that module may still fail. | |
| 28 | """ | |
| 29 | ||
| 30 | # Check for dbm first -- this has a .pag and a .dir file | |
| 31 | try: | |
| 32 | f = open(filename + os.extsep + "pag", "rb") | |
| 33 | f.close() | |
| 34 | # dbm linked with gdbm on OS/2 doesn't have .dir file | |
| 35 | if not (dbm.library == "GNU gdbm" and sys.platform == "os2emx"): | |
| 36 | f = open(filename + os.extsep + "dir", "rb") | |
| 37 | f.close() | |
| 38 | return "dbm" | |
| 39 | except IOError: | |
| 40 | # some dbm emulations based on Berkeley DB generate a .db file | |
| 41 | # some do not, but they should be caught by the dbhash checks | |
| 42 | try: | |
| 43 | f = open(filename + os.extsep + "db", "rb") | |
| 44 | f.close() | |
| 45 | # guarantee we can actually open the file using dbm | |
| 46 | # kind of overkill, but since we are dealing with emulations | |
| 47 | # it seems like a prudent step | |
| 48 | if dbm is not None: | |
| 49 | d = dbm.open(filename) | |
| 50 | d.close() | |
| 51 | return "dbm" | |
| 52 | except (IOError, _dbmerror): | |
| 53 | pass | |
| 54 | ||
| 55 | # Check for dumbdbm next -- this has a .dir and a .dat file | |
| 56 | try: | |
| 57 | # First check for presence of files | |
| 58 | os.stat(filename + os.extsep + "dat") | |
| 59 | size = os.stat(filename + os.extsep + "dir").st_size | |
| 60 | # dumbdbm files with no keys are empty | |
| 61 | if size == 0: | |
| 62 | return "dumbdbm" | |
| 63 | f = open(filename + os.extsep + "dir", "rb") | |
| 64 | try: | |
| 65 | if f.read(1) in ["'", '"']: | |
| 66 | return "dumbdbm" | |
| 67 | finally: | |
| 68 | f.close() | |
| 69 | except (OSError, IOError): | |
| 70 | pass | |
| 71 | ||
| 72 | # See if the file exists, return None if not | |
| 73 | try: | |
| 74 | f = open(filename, "rb") | |
| 75 | except IOError: | |
| 76 | return None | |
| 77 | ||
| 78 | # Read the start of the file -- the magic number | |
| 79 | s16 = f.read(16) | |
| 80 | f.close() | |
| 81 | s = s16[0:4] | |
| 82 | ||
| 83 | # Return "" if not at least 4 bytes | |
| 84 | if len(s) != 4: | |
| 85 | return "" | |
| 86 | ||
| 87 | # Convert to 4-byte int in native byte order -- return "" if impossible | |
| 88 | try: | |
| 89 | (magic,) = struct.unpack("=l", s) | |
| 90 | except struct.error: | |
| 91 | return "" | |
| 92 | ||
| 93 | # Check for GNU dbm | |
| 94 | if magic == 0x13579ace: | |
| 95 | return "gdbm" | |
| 96 | ||
| 97 | # Check for old Berkeley db hash file format v2 | |
| 98 | if magic in (0x00061561, 0x61150600): | |
| 99 | return "bsddb185" | |
| 100 | ||
| 101 | # Later versions of Berkeley db hash file have a 12-byte pad in | |
| 102 | # front of the file type | |
| 103 | try: | |
| 104 | (magic,) = struct.unpack("=l", s16[-4:]) | |
| 105 | except struct.error: | |
| 106 | return "" | |
| 107 | ||
| 108 | # Check for BSD hash | |
| 109 | if magic in (0x00061561, 0x61150600): | |
| 110 | return "dbhash" | |
| 111 | ||
| 112 | # Unknown | |
| 113 | return "" | |
| 114 | ||
| 115 | if __name__ == "__main__": | |
| 116 | for filename in sys.argv[1:]: | |
| 117 | print whichdb(filename) or "UNKNOWN", filename |