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341 lines
9.9 KiB
341 lines
9.9 KiB
"""Common operations on DOS pathnames.""" |
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import os |
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import stat |
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__all__ = ["normcase","isabs","join","splitdrive","split","splitext", |
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"basename","dirname","commonprefix","getsize","getmtime", |
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"getatime","islink","exists","isdir","isfile","ismount", |
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"walk","expanduser","expandvars","normpath","abspath"] |
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def normcase(s): |
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"""Normalize the case of a pathname. |
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On MS-DOS it maps the pathname to lowercase, turns slashes into |
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backslashes. |
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Other normalizations (such as optimizing '../' away) are not allowed |
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(this is done by normpath). |
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Previously, this version mapped invalid consecutive characters to a |
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single '_', but this has been removed. This functionality should |
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possibly be added as a new function.""" |
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return s.replace("/", "\\").lower() |
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def isabs(s): |
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"""Return whether a path is absolute. |
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Trivial in Posix, harder on the Mac or MS-DOS. |
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For DOS it is absolute if it starts with a slash or backslash (current |
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volume), or if a pathname after the volume letter and colon starts with |
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a slash or backslash.""" |
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s = splitdrive(s)[1] |
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return s != '' and s[:1] in '/\\' |
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def join(a, *p): |
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"""Join two (or more) paths.""" |
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path = a |
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for b in p: |
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if isabs(b): |
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path = b |
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elif path == '' or path[-1:] in '/\\:': |
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path = path + b |
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else: |
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path = path + "\\" + b |
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return path |
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def splitdrive(p): |
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"""Split a path into a drive specification (a drive letter followed |
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by a colon) and path specification. |
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It is always true that drivespec + pathspec == p.""" |
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if p[1:2] == ':': |
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return p[0:2], p[2:] |
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return '', p |
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def split(p): |
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"""Split a path into head (everything up to the last '/') and tail |
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(the rest). After the trailing '/' is stripped, the invariant |
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join(head, tail) == p holds. |
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The resulting head won't end in '/' unless it is the root.""" |
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d, p = splitdrive(p) |
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# set i to index beyond p's last slash |
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i = len(p) |
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while i and p[i-1] not in '/\\': |
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i = i - 1 |
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head, tail = p[:i], p[i:] # now tail has no slashes |
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# remove trailing slashes from head, unless it's all slashes |
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head2 = head |
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while head2 and head2[-1] in '/\\': |
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head2 = head2[:-1] |
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head = head2 or head |
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return d + head, tail |
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def splitext(p): |
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"""Split a path into root and extension. |
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The extension is everything starting at the first dot in the last |
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pathname component; the root is everything before that. |
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It is always true that root + ext == p.""" |
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root, ext = '', '' |
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for c in p: |
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if c in '/\\': |
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root, ext = root + ext + c, '' |
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elif c == '.' or ext: |
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ext = ext + c |
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else: |
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root = root + c |
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return root, ext |
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def basename(p): |
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"""Return the tail (basename) part of a path.""" |
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return split(p)[1] |
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def dirname(p): |
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"""Return the head (dirname) part of a path.""" |
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return split(p)[0] |
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def commonprefix(m): |
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"""Return the longest prefix of all list elements.""" |
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if not m: return '' |
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prefix = m[0] |
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for item in m: |
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for i in range(len(prefix)): |
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if prefix[:i+1] != item[:i+1]: |
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prefix = prefix[:i] |
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if i == 0: return '' |
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break |
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return prefix |
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# Get size, mtime, atime of files. |
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def getsize(filename): |
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"""Return the size of a file, reported by os.stat().""" |
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st = os.stat(filename) |
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return st[stat.ST_SIZE] |
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def getmtime(filename): |
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"""Return the last modification time of a file, reported by os.stat().""" |
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st = os.stat(filename) |
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return st[stat.ST_MTIME] |
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def getatime(filename): |
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"""Return the last access time of a file, reported by os.stat().""" |
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st = os.stat(filename) |
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return st[stat.ST_ATIME] |
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def islink(path): |
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"""Is a path a symbolic link? |
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This will always return false on systems where posix.lstat doesn't exist.""" |
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return 0 |
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def exists(path): |
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"""Does a path exist? |
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This is false for dangling symbolic links.""" |
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try: |
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st = os.stat(path) |
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except os.error: |
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return 0 |
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return 1 |
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def isdir(path): |
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"""Is a path a dos directory?""" |
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try: |
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st = os.stat(path) |
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except os.error: |
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return 0 |
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return stat.S_ISDIR(st[stat.ST_MODE]) |
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def isfile(path): |
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"""Is a path a regular file?""" |
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try: |
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st = os.stat(path) |
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except os.error: |
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return 0 |
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return stat.S_ISREG(st[stat.ST_MODE]) |
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def ismount(path): |
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"""Is a path a mount point?""" |
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# XXX This degenerates in: 'is this the root?' on DOS |
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return isabs(splitdrive(path)[1]) |
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def walk(top, func, arg): |
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"""Directory tree walk with callback function. |
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For each directory in the directory tree rooted at top (including top |
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itself, but excluding '.' and '..'), call func(arg, dirname, fnames). |
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dirname is the name of the directory, and fnames a list of the names of |
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the files and subdirectories in dirname (excluding '.' and '..'). func |
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may modify the fnames list in-place (e.g. via del or slice assignment), |
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and walk will only recurse into the subdirectories whose names remain in |
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fnames; this can be used to implement a filter, or to impose a specific |
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order of visiting. No semantics are defined for, or required of, arg, |
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beyond that arg is always passed to func. It can be used, e.g., to pass |
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a filename pattern, or a mutable object designed to accumulate |
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statistics. Passing None for arg is common.""" |
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try: |
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names = os.listdir(top) |
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except os.error: |
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return |
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func(arg, top, names) |
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exceptions = ('.', '..') |
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for name in names: |
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if name not in exceptions: |
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name = join(top, name) |
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if isdir(name): |
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walk(name, func, arg) |
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def expanduser(path): |
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"""Expand paths beginning with '~' or '~user'. |
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'~' means $HOME; '~user' means that user's home directory. |
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If the path doesn't begin with '~', or if the user or $HOME is unknown, |
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the path is returned unchanged (leaving error reporting to whatever |
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function is called with the expanded path as argument). |
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See also module 'glob' for expansion of *, ? and [...] in pathnames. |
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(A function should also be defined to do full *sh-style environment |
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variable expansion.)""" |
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if path[:1] != '~': |
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return path |
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i, n = 1, len(path) |
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while i < n and path[i] not in '/\\': |
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i = i+1 |
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if i == 1: |
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if not os.environ.has_key('HOME'): |
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return path |
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userhome = os.environ['HOME'] |
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else: |
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return path |
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return userhome + path[i:] |
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def expandvars(path): |
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"""Expand paths containing shell variable substitutions. |
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The following rules apply: |
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- no expansion within single quotes |
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- no escape character, except for '$$' which is translated into '$' |
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- ${varname} is accepted. |
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- varnames can be made out of letters, digits and the character '_'""" |
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# XXX With COMMAND.COM you can use any characters in a variable name, |
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# XXX except '^|<>='. |
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if '$' not in path: |
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return path |
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import string |
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varchars = string.ascii_letters + string.digits + "_-" |
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res = '' |
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index = 0 |
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pathlen = len(path) |
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while index < pathlen: |
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c = path[index] |
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if c == '\'': # no expansion within single quotes |
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path = path[index + 1:] |
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pathlen = len(path) |
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try: |
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index = path.index('\'') |
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res = res + '\'' + path[:index + 1] |
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except ValueError: |
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res = res + path |
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index = pathlen -1 |
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elif c == '$': # variable or '$$' |
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if path[index + 1:index + 2] == '$': |
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res = res + c |
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index = index + 1 |
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elif path[index + 1:index + 2] == '{': |
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path = path[index+2:] |
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pathlen = len(path) |
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try: |
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index = path.index('}') |
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var = path[:index] |
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if os.environ.has_key(var): |
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res = res + os.environ[var] |
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except ValueError: |
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res = res + path |
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index = pathlen - 1 |
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else: |
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var = '' |
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index = index + 1 |
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c = path[index:index + 1] |
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while c != '' and c in varchars: |
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var = var + c |
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index = index + 1 |
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c = path[index:index + 1] |
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if os.environ.has_key(var): |
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res = res + os.environ[var] |
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if c != '': |
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res = res + c |
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else: |
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res = res + c |
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index = index + 1 |
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return res |
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def normpath(path): |
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"""Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B. |
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Also, components of the path are silently truncated to 8+3 notation.""" |
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path = path.replace("/", "\\") |
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prefix, path = splitdrive(path) |
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while path[:1] == "\\": |
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prefix = prefix + "\\" |
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path = path[1:] |
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comps = path.split("\\") |
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i = 0 |
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while i < len(comps): |
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if comps[i] == '.': |
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del comps[i] |
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elif comps[i] == '..' and i > 0 and \ |
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comps[i-1] not in ('', '..'): |
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del comps[i-1:i+1] |
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i = i - 1 |
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elif comps[i] == '' and i > 0 and comps[i-1] != '': |
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del comps[i] |
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elif '.' in comps[i]: |
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comp = comps[i].split('.') |
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comps[i] = comp[0][:8] + '.' + comp[1][:3] |
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i = i + 1 |
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elif len(comps[i]) > 8: |
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comps[i] = comps[i][:8] |
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i = i + 1 |
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else: |
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i = i + 1 |
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# If the path is now empty, substitute '.' |
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if not prefix and not comps: |
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comps.append('.') |
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return prefix + "\\".join(comps) |
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def abspath(path): |
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"""Return an absolute path.""" |
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if not isabs(path): |
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path = join(os.getcwd(), path) |
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return normpath(path) |
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# realpath is a no-op on systems without islink support |
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realpath = abspath
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