378 lines
9.8 KiB
Python
378 lines
9.8 KiB
Python
# Module 'riscospath' -- common operations on RISC OS pathnames.
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# contributed by Andrew Clover ( andrew@oaktree.co.uk )
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# The "os.path" name is an alias for this module on RISC OS systems;
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# on other systems (e.g. Mac, Windows), os.path provides the same
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# operations in a manner specific to that platform, and is an alias
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# to another module (e.g. macpath, ntpath).
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"""
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Instead of importing this module directly, import os and refer to this module
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as os.path.
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"""
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# Imports - make an error-generating swi object if the swi module is not
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# available (ie. we are not running on RISC OS Python)
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import os, stat, string
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try:
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import swi
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except ImportError:
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class _swi:
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def swi(*a):
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raise AttributeError, 'This function only available under RISC OS'
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block= swi
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swi= _swi()
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[_false, _true]= range(2)
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_roots= ['$', '&', '%', '@', '\\']
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# _allowMOSFSNames
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# After importing riscospath, set _allowMOSFSNames true if you want the module
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# to understand the "-SomeFS-" notation left over from the old BBC Master MOS,
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# as well as the standard "SomeFS:" notation. Set this to be fully backwards
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# compatible but remember that "-SomeFS-" can also be a perfectly valid file
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# name so care must be taken when splitting and joining paths.
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_allowMOSFSNames= _false
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## Path manipulation, RISC OS stylee.
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def _split(p):
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"""
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split filing system name (including special field) and drive specifier from rest
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of path. This is needed by many riscospath functions.
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"""
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dash= _allowMOSFSNames and p[:1]=='-'
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if dash:
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q= string.find(p, '-', 1)+1
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else:
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if p[:1]==':':
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q= 0
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else:
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q= string.find(p, ':')+1 # q= index of start of non-FS portion of path
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s= string.find(p, '#')
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if s==-1 or s>q:
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s= q # find end of main FS name, not including special field
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else:
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for c in p[dash:s]:
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if c not in string.ascii_letters:
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q= 0
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break # disallow invalid non-special-field characters in FS name
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r= q
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if p[q:q+1]==':':
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r= string.find(p, '.', q+1)+1
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if r==0:
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r= len(p) # find end of drive name (if any) following FS name (if any)
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return (p[:q], p[q:r], p[r:])
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def normcase(p):
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"""
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Normalize the case of a pathname. This converts to lowercase as the native RISC
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OS filesystems are case-insensitive. However, not all filesystems have to be,
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and there's no simple way to find out what type an FS is argh.
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"""
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return string.lower(p)
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def isabs(p):
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"""
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Return whether a path is absolute. Under RISC OS, a file system specifier does
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not make a path absolute, but a drive name or number does, and so does using the
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symbol for root, URD, library, CSD or PSD. This means it is perfectly possible
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to have an "absolute" URL dependent on the current working directory, and
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equally you can have a "relative" URL that's on a completely different device to
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the current one argh.
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"""
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(fs, drive, path)= _split(p)
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return drive!='' or path[:1] in _roots
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def join(a, *p):
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"""
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Join path elements with the directory separator, replacing the entire path when
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an absolute or FS-changing path part is found.
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"""
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j= a
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for b in p:
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(fs, drive, path)= _split(b)
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if j=='' or fs!='' or drive!='' or path[:1] in _roots:
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j= b
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elif j[-1]==':':
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j= j+b
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else:
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j= j+'.'+b
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return j
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def split(p):
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"""
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Split a path in head (everything up to the last '.') and tail (the rest). FS
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name must still be dealt with separately since special field may contain '.'.
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"""
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(fs, drive, path)= _split(p)
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q= string.rfind(path, '.')
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if q!=-1:
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return (fs+drive+path[:q], path[q+1:])
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return ('', p)
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def splitext(p):
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"""
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Split a path in root and extension. This assumes the 'using slash for dot and
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dot for slash with foreign files' convention common in RISC OS is in force.
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"""
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(tail, head)= split(p)
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if '/' in head:
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q= len(head)-string.rfind(head, '/')
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return (p[:-q], p[-q:])
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return (p, '')
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def splitdrive(p):
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"""
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Split a pathname into a drive specification (including FS name) and the rest of
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the path. The terminating dot of the drive name is included in the drive
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specification.
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"""
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(fs, drive, path)= _split(p)
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return (fs+drive, p)
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def basename(p):
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"""
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Return the tail (basename) part of a path.
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"""
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return split(p)[1]
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def dirname(p):
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"""
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Return the head (dirname) part of a path.
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"""
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return split(p)[0]
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def commonprefix(ps):
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"""
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Return the longest prefix of all list elements. Purely string-based; does not
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separate any path parts. Why am I in os.path?
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"""
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if len(ps)==0:
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return ''
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prefix= ps[0]
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for p in ps[1:]:
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prefix= prefix[:len(p)]
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for i in range(len(prefix)):
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if prefix[i] <> p[i]:
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prefix= prefix[:i]
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if i==0:
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return ''
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break
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return prefix
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## File access functions. Why are we in os.path?
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def getsize(p):
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"""
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Return the size of a file, reported by os.stat().
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"""
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st= os.stat(p)
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return st[stat.ST_SIZE]
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def getmtime(p):
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"""
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Return the last modification time of a file, reported by os.stat().
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"""
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st = os.stat(p)
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return st[stat.ST_MTIME]
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getatime= getmtime
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# RISC OS-specific file access functions
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def exists(p):
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"""
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Test whether a path exists.
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"""
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try:
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return swi.swi('OS_File', '5s;i', p)!=0
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except swi.error:
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return 0
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def isdir(p):
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"""
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Is a path a directory? Includes image files.
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"""
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try:
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return swi.swi('OS_File', '5s;i', p) in [2, 3]
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except swi.error:
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return 0
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def isfile(p):
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"""
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Test whether a path is a file, including image files.
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"""
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try:
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return swi.swi('OS_File', '5s;i', p) in [1, 3]
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except swi.error:
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return 0
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def islink(p):
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"""
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RISC OS has no links or mounts.
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"""
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return _false
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ismount= islink
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# Same-file testing.
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# samefile works on filename comparison since there is no ST_DEV and ST_INO is
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# not reliably unique (esp. directories). First it has to normalise the
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# pathnames, which it can do 'properly' using OS_FSControl since samefile can
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# assume it's running on RISC OS (unlike normpath).
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def samefile(fa, fb):
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"""
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Test whether two pathnames reference the same actual file.
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"""
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l= 512
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b= swi.block(l)
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swi.swi('OS_FSControl', 'isb..i', 37, fa, b, l)
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fa= b.ctrlstring()
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swi.swi('OS_FSControl', 'isb..i', 37, fb, b, l)
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fb= b.ctrlstring()
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return fa==fb
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def sameopenfile(a, b):
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"""
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Test whether two open file objects reference the same file.
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"""
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return os.fstat(a)[stat.ST_INO]==os.fstat(b)[stat.ST_INO]
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## Path canonicalisation
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# 'user directory' is taken as meaning the User Root Directory, which is in
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# practice never used, for anything.
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def expanduser(p):
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(fs, drive, path)= _split(p)
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l= 512
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b= swi.block(l)
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if path[:1]!='@':
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return p
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if fs=='':
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fsno= swi.swi('OS_Args', '00;i')
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swi.swi('OS_FSControl', 'iibi', 33, fsno, b, l)
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fsname= b.ctrlstring()
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else:
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if fs[:1]=='-':
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fsname= fs[1:-1]
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else:
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fsname= fs[:-1]
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fsname= string.split(fsname, '#', 1)[0] # remove special field from fs
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x= swi.swi('OS_FSControl', 'ib2s.i;.....i', 54, b, fsname, l)
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if x<l:
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urd= b.tostring(0, l-x-1)
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else: # no URD! try CSD
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x= swi.swi('OS_FSControl', 'ib0s.i;.....i', 54, b, fsname, l)
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if x<l:
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urd= b.tostring(0, l-x-1)
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else: # no CSD! use root
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urd= '$'
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return fsname+':'+urd+path[1:]
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# Environment variables are in angle brackets.
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def expandvars(p):
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"""
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Expand environment variables using OS_GSTrans.
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"""
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l= 512
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b= swi.block(l)
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return b.tostring(0, swi.swi('OS_GSTrans', 'sbi;..i', p, b, l))
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# Return an absolute path.
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def abspath(p):
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return normpath(join(os.getcwd(), p))
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# realpath is a no-op on systems without islink support
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realpath = abspath
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# Normalize a path. Only special path element under RISC OS is "^" for "..".
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def normpath(p):
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"""
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Normalize path, eliminating up-directory ^s.
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"""
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(fs, drive, path)= _split(p)
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rhs= ''
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ups= 0
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while path!='':
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(path, el)= split(path)
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if el=='^':
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ups= ups+1
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else:
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if ups>0:
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ups= ups-1
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else:
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if rhs=='':
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rhs= el
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else:
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rhs= el+'.'+rhs
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while ups>0:
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ups= ups-1
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rhs= '^.'+rhs
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return fs+drive+rhs
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# Directory tree walk.
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# Independent of host system. Why am I in os.path?
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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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for name in names:
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name= join(top, name)
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if isdir(name) and not islink(name):
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walk(name, func, arg)
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