1 """distutils.spawn 2 3 Provides the 'spawn()' function, a front-end to various platform- 4 specific functions for launching another program in a sub-process. 5 Also provides the 'find_executable()' to search the path for a given 6 executable name. 7 """ 8 9 import sys 10 import os 11 12 from distutils.errors import DistutilsPlatformError, DistutilsExecError 13 from distutils.debug import DEBUG 14 from distutils import log 15 16 def spawn(cmd, search_path=1, verbose=0, dry_run=0): 17 """Run another program, specified as a command list 'cmd', in a new process. 18 19 'cmd' is just the argument list for the new process, ie. 20 cmd[0] is the program to run and cmd[1:] are the rest of its arguments. 21 There is no way to run a program with a name different from that of its 22 executable. 23 24 If 'search_path' is true (the default), the system's executable 25 search path will be used to find the program; otherwise, cmd[0] 26 must be the exact path to the executable. If 'dry_run' is true, 27 the command will not actually be run. 28 29 Raise DistutilsExecError if running the program fails in any way; just 30 return on success. 31 """ 32 # cmd is documented as a list, but just in case some code passes a tuple 33 # in, protect our %-formatting code against horrible death 34 cmd = list(cmd) 35 if os.name == 'posix': 36 _spawn_posix(cmd, search_path, dry_run=dry_run) 37 elif os.name == 'nt': 38 _spawn_nt(cmd, search_path, dry_run=dry_run) 39 else: 40 raise DistutilsPlatformError( 41 "don't know how to spawn programs on platform '%s'" % os.name) 42 43 def _nt_quote_args(args): 44 """Quote command-line arguments for DOS/Windows conventions. 45 46 Just wraps every argument which contains blanks in double quotes, and 47 returns a new argument list. 48 """ 49 # XXX this doesn't seem very robust to me -- but if the Windows guys 50 # say it'll work, I guess I'll have to accept it. (What if an arg 51 # contains quotes? What other magic characters, other than spaces, 52 # have to be escaped? Is there an escaping mechanism other than 53 # quoting?) 54 for i, arg in enumerate(args): 55 if ' ' in arg: 56 args[i] = '"%s"' % arg 57 return args 58 59 def _spawn_nt(cmd, search_path=1, verbose=0, dry_run=0): 60 executable = cmd[0] 61 cmd = _nt_quote_args(cmd) 62 if search_path: 63 # either we find one or it stays the same 64 executable = find_executable(executable) or executable 65 log.info(' '.join([executable] + cmd[1:])) 66 if not dry_run: 67 # spawn for NT requires a full path to the .exe 68 try: 69 rc = os.spawnv(os.P_WAIT, executable, cmd) 70 except OSError as exc: 71 # this seems to happen when the command isn't found 72 if not DEBUG: 73 cmd = executable 74 raise DistutilsExecError( 75 "command %r failed: %s" % (cmd, exc.args[-1])) 76 if rc != 0: 77 # and this reflects the command running but failing 78 if not DEBUG: 79 cmd = executable 80 raise DistutilsExecError( 81 "command %r failed with exit status %d" % (cmd, rc)) 82 83 if sys.platform == 'darwin': 84 from distutils import sysconfig 85 _cfg_target = None 86 _cfg_target_split = None 87 88 def _spawn_posix(cmd, search_path=1, verbose=0, dry_run=0): 89 log.info(' '.join(cmd)) 90 if dry_run: 91 return 92 executable = cmd[0] 93 exec_fn = search_path and os.execvp or os.execv 94 env = None 95 if sys.platform == 'darwin': 96 global _cfg_target, _cfg_target_split 97 if _cfg_target is None: 98 _cfg_target = sysconfig.get_config_var( 99 'MACOSX_DEPLOYMENT_TARGET') or '' 100 if _cfg_target: 101 _cfg_target_split = [int(x) for x in _cfg_target.split('.')] 102 if _cfg_target: 103 # ensure that the deployment target of build process is not less 104 # than that used when the interpreter was built. This ensures 105 # extension modules are built with correct compatibility values 106 cur_target = os.environ.get('MACOSX_DEPLOYMENT_TARGET', _cfg_target) 107 if _cfg_target_split > [int(x) for x in cur_target.split('.')]: 108 my_msg = ('$MACOSX_DEPLOYMENT_TARGET mismatch: ' 109 'now "%s" but "%s" during configure' 110 % (cur_target, _cfg_target)) 111 raise DistutilsPlatformError(my_msg) 112 env = dict(os.environ, 113 MACOSX_DEPLOYMENT_TARGET=cur_target) 114 exec_fn = search_path and os.execvpe or os.execve 115 pid = os.fork() 116 if pid == 0: # in the child 117 try: 118 if env is None: 119 exec_fn(executable, cmd) 120 else: 121 exec_fn(executable, cmd, env) 122 except OSError as e: 123 if not DEBUG: 124 cmd = executable 125 sys.stderr.write("unable to execute %r: %s\n" 126 % (cmd, e.strerror)) 127 os._exit(1) 128 129 if not DEBUG: 130 cmd = executable 131 sys.stderr.write("unable to execute %r for unknown reasons" % cmd) 132 os._exit(1) 133 else: # in the parent 134 # Loop until the child either exits or is terminated by a signal 135 # (ie. keep waiting if it's merely stopped) 136 while True: 137 try: 138 pid, status = os.waitpid(pid, 0) 139 except OSError as exc: 140 if not DEBUG: 141 cmd = executable 142 raise DistutilsExecError( 143 "command %r failed: %s" % (cmd, exc.args[-1])) 144 if os.WIFSIGNALED(status): 145 if not DEBUG: 146 cmd = executable 147 raise DistutilsExecError( 148 "command %r terminated by signal %d" 149 % (cmd, os.WTERMSIG(status))) 150 elif os.WIFEXITED(status): 151 exit_status = os.WEXITSTATUS(status) 152 if exit_status == 0: 153 return # hey, it succeeded! 154 else: 155 if not DEBUG: 156 cmd = executable 157 raise DistutilsExecError( 158 "command %r failed with exit status %d" 159 % (cmd, exit_status)) 160 elif os.WIFSTOPPED(status): 161 continue 162 else: 163 if not DEBUG: 164 cmd = executable 165 raise DistutilsExecError( 166 "unknown error executing %r: termination status %d" 167 % (cmd, status)) 168 169 def find_executable(executable, path=None): 170 """Tries to find 'executable' in the directories listed in 'path'. 171 172 A string listing directories separated by 'os.pathsep'; defaults to 173 os.environ['PATH']. Returns the complete filename or None if not found. 174 """ 175 if path is None: 176 path = os.environ['PATH'] 177 178 paths = path.split(os.pathsep) 179 base, ext = os.path.splitext(executable) 180 181 if (sys.platform == 'win32') and (ext != '.exe'): 182 executable = executable + '.exe' 183 184 if not os.path.isfile(executable): 185 for p in paths: 186 f = os.path.join(p, executable) 187 if os.path.isfile(f): 188 # the file exists, we have a shot at spawn working 189 return f 190 return None 191 else: 192 return executable 193
