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[wizard.git] / wizard / util.py
index 3d5f342636b21368495b586cb327157804cfd4a3..47588e5482b39cd21e92dffea34ecaeddec4f0d7 100644 (file)
@@ -11,9 +11,38 @@ import os
 import subprocess
 import pwd
 import sys
+import socket
+import errno
+import itertools
+import signal
+import httplib
+import urllib
+import time
+import logging
+import random
+import string
 
 import wizard
-from wizard import shell
+from wizard import user
+
+def boolish(val):
+    """
+    Parse the contents of an environment variable as a boolean.
+    This recognizes more values as ``False`` than :func:`bool` would.
+
+        >>> boolish("0")
+        False
+        >>> boolish("no")
+        False
+        >>> boolish("1")
+        True
+    """
+    try:
+        return bool(int(val))
+    except (ValueError, TypeError):
+        if val == "No" or val == "no" or val == "false" or val == "False":
+            return False
+        return bool(val)
 
 class ChangeDirectory(object):
     """
@@ -28,9 +57,9 @@ class ChangeDirectory(object):
         self.olddir = None
     def __enter__(self):
         self.olddir = os.getcwd()
-        os.chdir(self.dir)
+        chdir(self.dir)
     def __exit__(self, *args):
-        os.chdir(self.olddir)
+        chdir(self.olddir)
 
 class Counter(object):
     """
@@ -52,6 +81,105 @@ class Counter(object):
         return self.dict[key]
     def __iter__(self):
         return self.dict.__iter__()
+    def max(self):
+        """Returns the max counter value seen."""
+        return max(self.dict.values())
+    def sum(self):
+        """Returns the sum of all counter values."""
+        return sum(self.dict.values())
+    def keys(self):
+        """Returns the keys of counters."""
+        return self.dict.keys()
+
+class PipeToLess(object):
+    """
+    Context for printing output to a pager.  Use this if output
+    is expected to be long.
+    """
+    def __enter__(self):
+        self.proc = subprocess.Popen("less", stdin=subprocess.PIPE)
+        self.old_stdout = sys.stdout
+        sys.stdout = self.proc.stdin
+    def __exit__(self, *args):
+        if self.proc:
+            self.proc.stdin.close()
+            self.proc.wait()
+            sys.stdout = self.old_stdout
+
+class IgnoreKeyboardInterrupts(object):
+    """
+    Context for temporarily ignoring keyboard interrupts.  Use this
+    if aborting would cause more harm than finishing the job.
+    """
+    def __enter__(self):
+        signal.signal(signal.SIGINT,signal.SIG_IGN)
+    def __exit__(self, *args):
+        signal.signal(signal.SIGINT, signal.default_int_handler)
+
+class LockDirectory(object):
+    """
+    Context for locking a directory.
+    """
+    def __init__(self, lockfile, expiry = 3600):
+        self.lockfile = lockfile
+        self.expiry = expiry # by default an hour
+    def __enter__(self):
+        # It's A WAVY
+        for i in range(0, 3):
+            try:
+                os.open(self.lockfile, os.O_CREAT | os.O_EXCL)
+                open(self.lockfile, "w").write("%d" % os.getpid())
+            except OSError as e:
+                if e.errno == errno.EEXIST:
+                    # There is a possibility of infinite recursion, but we
+                    # expect it to be unlikely, and not harmful if it does happen
+                    with LockDirectory(self.lockfile + "_"):
+                        # See if we can break the lock
+                        try:
+                            pid = open(self.lockfile, "r").read().strip()
+                            if not os.path.exists("/proc/%s" % pid):
+                                # break the lock, try again
+                                logging.warning("Breaking orphaned lock at %s", self.lockfile)
+                                os.unlink(self.lockfile)
+                                continue
+                            try:
+                                # check if the file is expiry old, if so, break the lock, try again
+                                if time.time() - os.stat(self.lockfile).st_mtime > self.expiry:
+                                    logging.warning("Breaking stale lock at %s", self.lockfile)
+                                    os.unlink(self.lockfile)
+                                    continue
+                            except OSError as e:
+                                if e.errno == errno.ENOENT:
+                                    continue
+                                raise
+                        except IOError:
+                            # oh hey, it went away; try again
+                            continue
+                    raise DirectoryLockedError(os.getcwd())
+                elif e.errno == errno.EACCES:
+                    raise PermissionsError(os.getcwd())
+                raise
+            return
+        raise DirectoryLockedError(os.getcwd())
+    def __exit__(self, *args):
+        try:
+            os.unlink(self.lockfile)
+        except OSError:
+            pass
+
+def chdir(dir):
+    """
+    Changes a directory, but has special exceptions for certain
+    classes of errors.
+    """
+    try:
+        os.chdir(dir)
+    except OSError as e:
+        if e.errno == errno.EACCES:
+            raise PermissionsError()
+        elif e.errno == errno.ENOENT:
+            raise NoSuchDirectoryError()
+        else: raise e
 
 def dictmap(f, d):
     """
@@ -62,108 +190,86 @@ def dictmap(f, d):
     """
     return dict((k,f(v)) for k,v in d.items())
 
+def dictkmap(f, d):
+    """
+    A map function for dictionaries that passes key and value.
+
+        >>> dictkmap(lambda x, y: x + y, {1: 4, 3: 4})
+        {1: 5, 3: 7}
+    """
+    return dict((k,f(k,v)) for k,v in d.items())
+
 def get_exception_name(output):
     """
     Reads the traceback from a Python program and grabs the
     fully qualified exception name.
     """
     lines = output.split("\n")
-    for line in lines[1:]: # skip the "traceback" line
+    cue = False
+    result = "(unknown)"
+    for line in lines[1:]:
         line = line.rstrip()
-        if line[0] == ' ': continue
-        if line[-1] == ":":
-            return line[:-1]
-        else:
-            return line
+        if not line: continue
+        if line[0] == ' ':
+            cue = True
+            continue
+        if cue:
+            cue = False
+            return line.partition(':')[0]
+    return result
 
 def get_dir_uid(dir):
     """Finds the uid of the person who owns this directory."""
     return os.stat(dir).st_uid
 
-def get_dir_owner(dir = "."):
-    """
-    Finds the name of the locker this directory is in.
-
-    .. note::
-
-        This function uses the passwd database and thus
-        only works on scripts servers.
-    """
-    return pwd.getpwuid(get_dir_uid(dir)).pw_name
-
-def get_dir_tag():
-    """Finds the output of git describe --tags of the current directory."""
-    return shell.Shell().safeCall("git", "describe", "--tags")[0].rstrip()
-
 def get_revision():
     """Returns the commit ID of the current Wizard install."""
+    # If you decide to convert this to use wizard.shell, be warned
+    # that there is a circular dependency, so this function would
+    # probably have to live somewhere else, probably wizard.git
     wizard_git = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), ".git")
     return subprocess.Popen(["git", "--git-dir=" + wizard_git, "rev-parse", "HEAD"], stdout=subprocess.PIPE).communicate()[0].rstrip()
 
-def get_operator_info():
-    """
-    Returns tuple of ``(realname, email)`` from Hesiod about the
-    this operator of this script from :func:`get_operator_name`.
-    Useful when generating commit messages.
-    """
-    username = get_operator_name()
-    hesinfo = subprocess.Popen(["hesinfo", username, "passwd"],stdout=subprocess.PIPE).communicate()[0]
-    fields = hesinfo.partition(",")[0]
-    realname = fields.rpartition(":")[2]
-    return realname, username + "@mit.edu"
-
 def get_operator_git():
     """
     Returns ``Real Name <username@mit.edu>`` suitable for use in
-    Git ``Something-by:`` string.
+    Git ``Something-by:`` string.  Throws :exc:`NoOperatorInfo` if
+    no operator information is available.
     """
-    return "%s <%s>" % get_operator_info()
-
-def get_operator_name():
-    """
-    Returns username of the person operating this script based
-    off of the :envvar:`SSH_GSSAPI_NAME` environment variable.  Throws
-    :exc:`NoOperatorInfo` if environment variable is not available.
-
-    .. note::
-
-        :envvar:`SSH_GSSAPI_NAME` is not set by a vanilla OpenSSH
-        distributions.  Scripts servers are patched to support this
-        environment variable.
-    """
-    principal = os.getenv("SSH_GSSAPI_NAME")
-    if not principal: raise NoOperatorInfo
-    instance, _, _ = principal.partition("@")
-    if instance.endswith("/root"):
-        username, _, _ = principal.partition("/")
-    else:
-        username = instance
-    return username
+    op = user.operator()
+    if op is None:
+        raise NoOperatorInfo
+    info = user.pwnam(op)
+    return "%s <%s>" % (info.realname, info.email)
 
 def set_operator_env():
     """
     Sets :envvar:`GIT_COMMITTER_NAME` and :envvar:`GIT_COMMITTER_EMAIL`
-    environment variables if applicable.  Does nothing if
-    :func:`get_operator_info` throws :exc:`NoOperatorInfo`.
+    environment variables if applicable.  Does nothing if no information
+    is available
     """
-    try:
-        op_realname, op_email = get_operator_info()
-        os.putenv("GIT_COMMITTER_NAME", op_realname)
-        os.putenv("GIT_COMMITTER_EMAIL", op_email)
-    except NoOperatorInfo:
-        pass
+    op = user.operator()
+    if op is None:
+        return
+    info = user.pwnam(op)
+    if not info.realname:
+        return
+    os.putenv("GIT_COMMITTER_NAME", info.realname)
+    os.putenv("GIT_COMMITTER_EMAIL", info.email)
 
 def set_author_env():
     """
-    Sets :envvar:`GIT_AUTHOR_NAME` and :envvar:`GIT_AUTHOR_EMAIL` environment
-    variables if applicable. Does nothing if :func:`get_dir_owner` fails.
+    Sets :envvar:`GIT_AUTHOR_NAME` and :envvar:`GIT_AUTHOR_EMAIL`
+    environment variables if applicable. Does nothing if
+    :func:`wizard.user.passwd` fails.
     """
-    try:
-        lockername = get_dir_owner()
-        os.putenv("GIT_AUTHOR_NAME", "%s locker" % lockername)
-        os.putenv("GIT_AUTHOR_EMAIL", "%s@scripts.mit.edu" % lockername)
-    except KeyError: # XXX: This doesn't actually make sense
-        pass
+    info = user.passwd()
+    if info is None:
+        return
+    if not info.realname:
+        return
+    os.putenv("GIT_AUTHOR_NAME", "%s" % info.realname)
+    os.putenv("GIT_AUTHOR_EMAIL", "%s" % info.email)
 
 def set_git_env():
     """Sets all appropriate environment variables for Git commits."""
@@ -176,7 +282,142 @@ def get_git_footer():
         ,"Wizard-args: %s" % " ".join(sys.argv)
         ])
 
+def safe_unlink(file):
+    """Moves a file/dir to a backup location."""
+    if not os.path.lexists(file):
+        return None
+    prefix = "%s.bak" % file
+    name = None
+    for i in itertools.count():
+        name = "%s.%d" % (prefix, i)
+        if not os.path.lexists(name):
+            break
+    os.rename(file, name)
+    return name
+
+def soft_unlink(file):
+    """Unlink a file, but don't complain if it doesn't exist."""
+    try:
+        os.unlink(file)
+    except OSError:
+        pass
+
+def makedirs(path):
+    """
+    Create a directory path (a la ``mkdir -p`` or ``os.makedirs``),
+    but don't complain if it already exists.
+    """
+    try:
+        os.makedirs(path)
+    except OSError as exc:
+        if exc.errno == errno.EEXIST:
+            pass
+        else:
+            raise
+
+def fetch(host, path, subpath, post=None):
+    try:
+        # XXX: Should use urllib instead
+        h = httplib.HTTPConnection(host)
+        fullpath = path.rstrip("/") + "/" + subpath.lstrip("/") # to be lenient about input we accept
+        if post:
+            headers = {"Content-type": "application/x-www-form-urlencoded"}
+            logging.info("POST request to http://%s%s", host, fullpath)
+            logging.debug("POST contents:\n" + urllib.urlencode(post))
+            h.request("POST", fullpath, urllib.urlencode(post), headers)
+        else:
+            logging.info("GET request to http://%s%s", host, fullpath)
+            h.request("GET", fullpath)
+        r = h.getresponse()
+        logging.debug("Response code: %d", r.status)
+        logging.debug("Response headers: %s", r.msg)
+        data = r.read()
+        h.close()
+        return data
+    except socket.gaierror as e:
+        if e.errno == socket.EAI_NONAME:
+            raise DNSError(host)
+        else:
+            raise
+
+def mixed_newlines(filename):
+    """Returns ``True`` if ``filename`` has mixed newlines."""
+    f = open(filename, "U") # requires universal newline support
+    f.read()
+    ret = isinstance(f.newlines, tuple)
+    f.close() # just to be safe
+    return ret
+
+def disk_usage(dir=None, excluded_dir=".git"):
+    """
+    Recursively determines the disk usage of a directory, excluding
+    .git directories.  Value is in bytes.  If ``dir`` is omitted, the
+    current working directory is assumed.
+    """
+    if dir is None: dir = os.getcwd()
+    sum_sizes = 0
+    for root, _, files in os.walk(dir):
+        for name in files:
+            if not os.path.join(root, name).startswith(os.path.join(dir, excluded_dir)):
+                file = os.path.join(root, name)
+                try:
+                    if os.path.islink(file): continue
+                    sum_sizes += os.path.getsize(file)
+                except OSError as e:
+                    if e.errno == errno.ENOENT:
+                        logging.warning("%s disappeared before we could stat", file)
+                    else:
+                        raise
+    return sum_sizes
+
+def random_key(length=30):
+    """Generates a random alphanumeric key of ``length`` size."""
+    return ''.join(random.choice(string.letters + string.digits) for i in xrange(length))
+
+def truncate(version):
+    """Truncates the Scripts specific version number."""
+    return str(version).partition('-scripts')[0]
+
+def init_wizard_dir():
+    """
+    Generates a .wizard directory and initializes it with some common
+    files.  This operation is idempotent.
+    """
+    # no harm in doing this repeatedly
+    wizard_dir = ".wizard"
+    if not os.path.isdir(wizard_dir):
+        os.mkdir(wizard_dir)
+    open(os.path.join(wizard_dir, ".htaccess"), "w").write("Deny from all\n")
+    open(os.path.join(wizard_dir, ".gitignore"), "w").write("*\n")
+
 class NoOperatorInfo(wizard.Error):
     """No information could be found about the operator from Kerberos."""
     pass
 
+class PermissionsError(IOError):
+    errno = errno.EACCES
+
+class NoSuchDirectoryError(IOError):
+    errno = errno.ENOENT
+
+class DirectoryLockedError(wizard.Error):
+    def __init__(self, dir):
+        self.dir = dir
+    def __str__(self):
+        return """
+
+ERROR: Could not acquire lock on directory.  Maybe there is
+another migration process running?
+"""
+
+class DNSError(socket.gaierror):
+    errno = socket.EAI_NONAME
+    #: Hostname that could not resolve name
+    host = None
+    def __init__(self, host):
+        self.host = host
+    def __str__(self):
+        return """
+
+ERROR: Could not resolve hostname %s.
+""" % self.host