diff options
| -rw-r--r-- | Lib/posixpath.py | 356 |
1 files changed, 194 insertions, 162 deletions
diff --git a/Lib/posixpath.py b/Lib/posixpath.py index 9960801..1166881 100644 --- a/Lib/posixpath.py +++ b/Lib/posixpath.py @@ -5,6 +5,10 @@ # on other systems (e.g. Mac, Windows), os.path provides the same # operations in a manner specific to that platform, and is an alias # to another module (e.g. macpath, ntpath). +"""Common pathname manipulations, Posix version. +Instead of importing this module +directly, import os and refer to this module as os.path. +""" import os import stat @@ -16,14 +20,16 @@ import stat # (another function should be defined to do that). def normcase(s): - return s + """Normalize case of pathname. Has no effect under Posix""" + return s # Return wheter a path is absolute. # Trivial in Posix, harder on the Mac or MS-DOS. def isabs(s): - return s[:1] == '/' + """Test whether a path is absolute""" + return s[:1] == '/' # Join pathnames. @@ -31,15 +37,16 @@ def isabs(s): # Insert a '/' unless the first part is empty or already ends in '/'. def join(a, *p): - path = a - for b in p: - if b[:1] == '/': - path = b - elif path == '' or path[-1:] == '/': - path = path + b - else: - path = path + '/' + b - return path + """Join two or more pathname components, inserting '/' as needed""" + path = a + for b in p: + if b[:1] == '/': + path = b + elif path == '' or path[-1:] == '/': + path = path + b + else: + path = path + '/' + b + return path # Split a path in head (everything up to the last '/') and tail (the @@ -48,13 +55,15 @@ def join(a, *p): # Trailing '/'es are stripped from head unless it is the root. def split(p): - import string - i = string.rfind(p, '/') + 1 - head, tail = p[:i], p[i:] - if head and head <> '/'*len(head): - while head[-1] == '/': - head = head[:-1] - return head, tail + """Split a pathname. Returns tuple "(head, tail)" where "tail" is +everything after the final slash. Either part may be empty""" + import string + i = string.rfind(p, '/') + 1 + head, tail = p[:i], p[i:] + if head and head <> '/'*len(head): + while head[-1] == '/': + head = head[:-1] + return head, tail # Split a path in root and extension. @@ -63,75 +72,84 @@ def split(p): # It is always true that root + ext == p. def splitext(p): - root, ext = '', '' - for c in p: - if c == '/': - root, ext = root + ext + c, '' - elif c == '.': - if ext: - root, ext = root + ext, c - else: - ext = c - elif ext: - ext = ext + c - else: - root = root + c - return root, ext + """Split the extension from a pathname. Extension is everything from the +last dot to the end. Returns "(root, ext)", either part may be empty""" + root, ext = '', '' + for c in p: + if c == '/': + root, ext = root + ext + c, '' + elif c == '.': + if ext: + root, ext = root + ext, c + else: + ext = c + elif ext: + ext = ext + c + else: + root = root + c + return root, ext # Split a pathname into a drive specification and the rest of the # path. Useful on DOS/Windows/NT; on Unix, the drive is always empty. def splitdrive(p): - return '', p + """Split a pathname into drive and path. On Posix, drive is always +empty""" + return '', p # Return the tail (basename) part of a path. def basename(p): - return split(p)[1] + """Returns the final component of a pathname""" + return split(p)[1] # Return the head (dirname) part of a path. def dirname(p): - return split(p)[0] + """Returns the directory component of a pathname""" + return split(p)[0] # Return the longest prefix of all list elements. def commonprefix(m): - if not m: return '' - prefix = m[0] - for item in m: - for i in range(len(prefix)): - if prefix[:i+1] <> item[:i+1]: - prefix = prefix[:i] - if i == 0: return '' - break - return prefix + "Given a list of pathnames, returns the longest common leading component" + if not m: return '' + prefix = m[0] + for item in m: + for i in range(len(prefix)): + if prefix[:i+1] <> item[:i+1]: + prefix = prefix[:i] + if i == 0: return '' + break + return prefix # Is a path a symbolic link? # This will always return false on systems where os.lstat doesn't exist. def islink(path): - try: - st = os.lstat(path) - except (os.error, AttributeError): - return 0 - return stat.S_ISLNK(st[stat.ST_MODE]) + """Test whether a path is a symbolic link""" + try: + st = os.lstat(path) + except (os.error, AttributeError): + return 0 + return stat.S_ISLNK(st[stat.ST_MODE]) # Does a path exist? # This is false for dangling symbolic links. def exists(path): - try: - st = os.stat(path) - except os.error: - return 0 - return 1 + """Test whether a path exists. Returns false for broken symbolic links""" + try: + st = os.stat(path) + except os.error: + return 0 + return 1 # Is a path a directory? @@ -139,11 +157,12 @@ def exists(path): # for the same path. def isdir(path): - try: - st = os.stat(path) - except os.error: - return 0 - return stat.S_ISDIR(st[stat.ST_MODE]) + """Test whether a path is a directory""" + try: + st = os.stat(path) + except os.error: + return 0 + return stat.S_ISDIR(st[stat.ST_MODE]) # Is a path a regular file? @@ -151,78 +170,87 @@ def isdir(path): # for the same path. def isfile(path): - try: - st = os.stat(path) - except os.error: - return 0 - return stat.S_ISREG(st[stat.ST_MODE]) + """Test whether a path is a regular file""" + try: + st = os.stat(path) + except os.error: + return 0 + return stat.S_ISREG(st[stat.ST_MODE]) # Are two filenames really pointing to the same file? def samefile(f1, f2): - s1 = os.stat(f1) - s2 = os.stat(f2) - return samestat(s1, s2) + """Test whether two pathnames reference the same actual file""" + s1 = os.stat(f1) + s2 = os.stat(f2) + return samestat(s1, s2) # Are two open files really referencing the same file? # (Not necessarily the same file descriptor!) def sameopenfile(fp1, fp2): - s1 = os.fstat(fp1) - s2 = os.fstat(fp2) - return samestat(s1, s2) + """Test whether two open file objects reference the same file""" + s1 = os.fstat(fp1) + s2 = os.fstat(fp2) + return samestat(s1, s2) # Are two stat buffers (obtained from stat, fstat or lstat) # describing the same file? def samestat(s1, s2): - return s1[stat.ST_INO] == s2[stat.ST_INO] and \ - s1[stat.ST_DEV] == s2[stat.ST_DEV] + """Test whether two stat buffers reference the same file""" + return s1[stat.ST_INO] == s2[stat.ST_INO] and \ + s1[stat.ST_DEV] == s2[stat.ST_DEV] # Is a path a mount point? # (Does this work for all UNIXes? Is it even guaranteed to work by Posix?) def ismount(path): - try: - s1 = os.stat(path) - s2 = os.stat(join(path, '..')) - except os.error: - return 0 # It doesn't exist -- so not a mount point :-) - dev1 = s1[stat.ST_DEV] - dev2 = s2[stat.ST_DEV] - if dev1 != dev2: - return 1 # path/.. on a different device as path - ino1 = s1[stat.ST_INO] - ino2 = s2[stat.ST_INO] - if ino1 == ino2: - return 1 # path/.. is the same i-node as path - return 0 + """Test whether a path is a mount point""" + try: + s1 = os.stat(path) + s2 = os.stat(join(path, '..')) + except os.error: + return 0 # It doesn't exist -- so not a mount point :-) + dev1 = s1[stat.ST_DEV] + dev2 = s2[stat.ST_DEV] + if dev1 != dev2: + return 1 # path/.. on a different device as path + ino1 = s1[stat.ST_INO] + ino2 = s2[stat.ST_INO] + if ino1 == ino2: + return 1 # path/.. is the same i-node as path + return 0 # Directory tree walk. # For each directory under top (including top itself, but excluding # '.' and '..'), func(arg, dirname, filenames) is called, where # dirname is the name of the directory and filenames is the list -# files files (and subdirectories etc.) in the directory. +# of files (and subdirectories etc.) in the directory. # The func may modify the filenames list, to implement a filter, # or to impose a different order of visiting. def walk(top, func, arg): - try: - names = os.listdir(top) - except os.error: - return - func(arg, top, names) - exceptions = ('.', '..') - for name in names: - if name not in exceptions: - name = join(top, name) - if isdir(name) and not islink(name): - walk(name, func, arg) + """walk(top,func,args) calls func(arg, d, files) for each directory "d" +in the tree rooted at "top" (including "top" itself). "files" is a list +of all the files and subdirs in directory "d". +""" + try: + names = os.listdir(top) + except os.error: + return + func(arg, top, names) + exceptions = ('.', '..') + for name in names: + if name not in exceptions: + name = join(top, name) + if isdir(name) and not islink(name): + walk(name, func, arg) # Expand paths beginning with '~' or '~user'. @@ -235,24 +263,26 @@ def walk(top, func, arg): # variable expansion.) def expanduser(path): - if path[:1] <> '~': - return path - i, n = 1, len(path) - while i < n and path[i] <> '/': - i = i+1 - if i == 1: - if not os.environ.has_key('HOME'): - return path - userhome = os.environ['HOME'] - else: - import pwd - try: - pwent = pwd.getpwnam(path[1:i]) - except KeyError: - return path - userhome = pwent[5] - if userhome[-1:] == '/': i = i+1 - return userhome + path[i:] + """Expand ~ and ~user constructions. If user or $HOME is unknown, +do nothing""" + if path[:1] <> '~': + return path + i, n = 1, len(path) + while i < n and path[i] <> '/': + i = i+1 + if i == 1: + if not os.environ.has_key('HOME'): + return path + userhome = os.environ['HOME'] + else: + import pwd + try: + pwent = pwd.getpwnam(path[1:i]) + except KeyError: + return path + userhome = pwent[5] + if userhome[-1:] == '/': i = i+1 + return userhome + path[i:] # Expand paths containing shell variable substitutions. @@ -262,29 +292,31 @@ def expanduser(path): _varprog = None def expandvars(path): - global _varprog - if '$' not in path: - return path - if not _varprog: - import re - _varprog = re.compile(r'\$(\w+|\{[^}]*\})') - i = 0 - while 1: - m = _varprog.search(path, i) - if not m: - break - i, j = m.span(0) - name = m.group(1) - if name[:1] == '{' and name[-1:] == '}': - name = name[1:-1] - if os.environ.has_key(name): - tail = path[j:] - path = path[:i] + os.environ[name] - i = len(path) - path = path + tail - else: - i = j - return path + """Expand shell variables of form $var and ${var}. Unknown variables +are left unchanged""" + global _varprog + if '$' not in path: + return path + if not _varprog: + import re + _varprog = re.compile(r'\$(\w+|\{[^}]*\})') + i = 0 + while 1: + m = _varprog.search(path, i) + if not m: + break + i, j = m.span(0) + name = m.group(1) + if name[:1] == '{' and name[-1:] == '}': + name = name[1:-1] + if os.environ.has_key(name): + tail = path[j:] + path = path[:i] + os.environ[name] + i = len(path) + path = path + tail + else: + i = j + return path # Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B. @@ -292,26 +324,26 @@ def expandvars(path): # if it contains symbolic links! def normpath(path): - import string - # Treat initial slashes specially - slashes = '' - while path[:1] == '/': - slashes = slashes + '/' - path = path[1:] - comps = string.splitfields(path, '/') - i = 0 - while i < len(comps): - if comps[i] == '.': - del comps[i] - elif comps[i] == '..' and i > 0 and \ - comps[i-1] not in ('', '..'): - del comps[i-1:i+1] - i = i-1 - elif comps[i] == '' and i > 0 and comps[i-1] <> '': - del comps[i] - else: - i = i+1 - # If the path is now empty, substitute '.' - if not comps and not slashes: - comps.append('.') - return slashes + string.joinfields(comps, '/') + """Normalize path, eliminating double slashes, etc.""" + import string + # Treat initial slashes specially + slashes = '' + while path[:1] == '/': + slashes = slashes + '/' + path = path[1:] + comps = string.splitfields(path, '/') + i = 0 + while i < len(comps): + if comps[i] == '.': + del comps[i] + elif comps[i] == '..' and i > 0 and comps[i-1] not in ('', '..'): + del comps[i-1:i+1] + i = i-1 + elif comps[i] == '' and i > 0 and comps[i-1] <> '': + del comps[i] + else: + i = i+1 + # If the path is now empty, substitute '.' + if not comps and not slashes: + comps.append('.') + return slashes + string.joinfields(comps, '/') |