file_util.py revision 70a74eb2c46e18f77cf75106a7ee07767fa90aaf
1"""distutils.file_util 2 3Utility functions for operating on single files. 4""" 5 6__revision__ = "$Id$" 7 8import os 9from distutils.errors import DistutilsFileError 10from distutils import log 11 12# for generating verbose output in 'copy_file()' 13_copy_action = { None: 'copying', 14 'hard': 'hard linking', 15 'sym': 'symbolically linking' } 16 17 18def _copy_file_contents(src, dst, buffer_size=16*1024): 19 """Copy the file 'src' to 'dst'; both must be filenames. Any error 20 opening either file, reading from 'src', or writing to 'dst', raises 21 DistutilsFileError. Data is read/written in chunks of 'buffer_size' 22 bytes (default 16k). No attempt is made to handle anything apart from 23 regular files. 24 """ 25 # Stolen from shutil module in the standard library, but with 26 # custom error-handling added. 27 fsrc = None 28 fdst = None 29 try: 30 try: 31 fsrc = open(src, 'rb') 32 except os.error as e: 33 raise DistutilsFileError("could not open '%s': %s" % (src, e.strerror)) 34 35 if os.path.exists(dst): 36 try: 37 os.unlink(dst) 38 except os.error as e: 39 raise DistutilsFileError( 40 "could not delete '%s': %s" % (dst, e.strerror)) 41 42 try: 43 fdst = open(dst, 'wb') 44 except os.error as e: 45 raise DistutilsFileError( 46 "could not create '%s': %s" % (dst, e.strerror)) 47 48 while True: 49 try: 50 buf = fsrc.read(buffer_size) 51 except os.error as e: 52 raise DistutilsFileError( 53 "could not read from '%s': %s" % (src, e.strerror)) 54 55 if not buf: 56 break 57 58 try: 59 fdst.write(buf) 60 except os.error as e: 61 raise DistutilsFileError( 62 "could not write to '%s': %s" % (dst, e.strerror)) 63 finally: 64 if fdst: 65 fdst.close() 66 if fsrc: 67 fsrc.close() 68 69def copy_file(src, dst, preserve_mode=1, preserve_times=1, update=0, 70 link=None, verbose=1, dry_run=0): 71 """Copy a file 'src' to 'dst'. If 'dst' is a directory, then 'src' is 72 copied there with the same name; otherwise, it must be a filename. (If 73 the file exists, it will be ruthlessly clobbered.) If 'preserve_mode' 74 is true (the default), the file's mode (type and permission bits, or 75 whatever is analogous on the current platform) is copied. If 76 'preserve_times' is true (the default), the last-modified and 77 last-access times are copied as well. If 'update' is true, 'src' will 78 only be copied if 'dst' does not exist, or if 'dst' does exist but is 79 older than 'src'. 80 81 'link' allows you to make hard links (os.link) or symbolic links 82 (os.symlink) instead of copying: set it to "hard" or "sym"; if it is 83 None (the default), files are copied. Don't set 'link' on systems that 84 don't support it: 'copy_file()' doesn't check if hard or symbolic 85 linking is available. 86 87 Under Mac OS, uses the native file copy function in macostools; on 88 other systems, uses '_copy_file_contents()' to copy file contents. 89 90 Return a tuple (dest_name, copied): 'dest_name' is the actual name of 91 the output file, and 'copied' is true if the file was copied (or would 92 have been copied, if 'dry_run' true). 93 """ 94 # XXX if the destination file already exists, we clobber it if 95 # copying, but blow up if linking. Hmmm. And I don't know what 96 # macostools.copyfile() does. Should definitely be consistent, and 97 # should probably blow up if destination exists and we would be 98 # changing it (ie. it's not already a hard/soft link to src OR 99 # (not update) and (src newer than dst). 100 101 from distutils.dep_util import newer 102 from stat import ST_ATIME, ST_MTIME, ST_MODE, S_IMODE 103 104 if not os.path.isfile(src): 105 raise DistutilsFileError( 106 "can't copy '%s': doesn't exist or not a regular file" % src) 107 108 if os.path.isdir(dst): 109 dir = dst 110 dst = os.path.join(dst, os.path.basename(src)) 111 else: 112 dir = os.path.dirname(dst) 113 114 if update and not newer(src, dst): 115 if verbose == 1: 116 log.debug("not copying %s (output up-to-date)", src) 117 return (dst, 0) 118 119 try: 120 action = _copy_action[link] 121 except KeyError: 122 raise ValueError("invalid value '%s' for 'link' argument" % link) 123 124 if verbose == 1: 125 if os.path.basename(dst) == os.path.basename(src): 126 log.info("%s %s -> %s", action, src, dir) 127 else: 128 log.info("%s %s -> %s", action, src, dst) 129 130 if dry_run: 131 return (dst, 1) 132 133 # On Mac OS, use the native file copy routine 134 if os.name == 'mac': 135 import macostools 136 try: 137 macostools.copy(src, dst, 0, preserve_times) 138 except os.error as exc: 139 raise DistutilsFileError( 140 "could not copy '%s' to '%s': %s" % (src, dst, exc.args[-1])) 141 142 # If linking (hard or symbolic), use the appropriate system call 143 # (Unix only, of course, but that's the caller's responsibility) 144 elif link == 'hard': 145 if not (os.path.exists(dst) and os.path.samefile(src, dst)): 146 os.link(src, dst) 147 elif link == 'sym': 148 if not (os.path.exists(dst) and os.path.samefile(src, dst)): 149 os.symlink(src, dst) 150 151 # Otherwise (non-Mac, not linking), copy the file contents and 152 # (optionally) copy the times and mode. 153 else: 154 _copy_file_contents(src, dst) 155 if preserve_mode or preserve_times: 156 st = os.stat(src) 157 158 # According to David Ascher <da@ski.org>, utime() should be done 159 # before chmod() (at least under NT). 160 if preserve_times: 161 os.utime(dst, (st[ST_ATIME], st[ST_MTIME])) 162 if preserve_mode: 163 os.chmod(dst, S_IMODE(st[ST_MODE])) 164 165 return (dst, 1) 166 167 168# XXX I suspect this is Unix-specific -- need porting help! 169def move_file (src, dst, 170 verbose=1, 171 dry_run=0): 172 173 """Move a file 'src' to 'dst'. If 'dst' is a directory, the file will 174 be moved into it with the same name; otherwise, 'src' is just renamed 175 to 'dst'. Return the new full name of the file. 176 177 Handles cross-device moves on Unix using 'copy_file()'. What about 178 other systems??? 179 """ 180 from os.path import exists, isfile, isdir, basename, dirname 181 import errno 182 183 if verbose == 1: 184 log.info("moving %s -> %s", src, dst) 185 186 if dry_run: 187 return dst 188 189 if not isfile(src): 190 raise DistutilsFileError("can't move '%s': not a regular file" % src) 191 192 if isdir(dst): 193 dst = os.path.join(dst, basename(src)) 194 elif exists(dst): 195 raise DistutilsFileError( 196 "can't move '%s': destination '%s' already exists" % 197 (src, dst)) 198 199 if not isdir(dirname(dst)): 200 raise DistutilsFileError( 201 "can't move '%s': destination '%s' not a valid path" % 202 (src, dst)) 203 204 copy_it = False 205 try: 206 os.rename(src, dst) 207 except os.error as e: 208 (num, msg) = e 209 if num == errno.EXDEV: 210 copy_it = True 211 else: 212 raise DistutilsFileError( 213 "couldn't move '%s' to '%s': %s" % (src, dst, msg)) 214 215 if copy_it: 216 copy_file(src, dst, verbose=verbose) 217 try: 218 os.unlink(src) 219 except os.error as e: 220 (num, msg) = e 221 try: 222 os.unlink(dst) 223 except os.error: 224 pass 225 raise DistutilsFileError( 226 "couldn't move '%s' to '%s' by copy/delete: " 227 "delete '%s' failed: %s" 228 % (src, dst, src, msg)) 229 return dst 230 231 232def write_file (filename, contents): 233 """Create a file with the specified name and write 'contents' (a 234 sequence of strings without line terminators) to it. 235 """ 236 f = open(filename, "w") 237 for line in contents: 238 f.write(line + "\n") 239 f.close() 240