[PATCH v3 11/23] git-remote-testgit: fix error handling

[Sverre Rabbelier <srabbelier@gmail.com>]

If fast-export did not complete successfully the error handling code
itself would error out.

This was broken in commit 23b093ee0 (Brandon Casey, Wed Jun 9 2010,
Remove python 2.5'isms). Revert that commit an introduce our own copy
of check_call in util.py instead.

Tested by changing 'if retcode' to 'if not retcode' temporarily.

Signed-off-by: Sverre Rabbelier <srabbelier@gmail.com>
---

  Included the definition of CalledProcessError if subprocess does
  not already provide it to make sure everything still works on
  python 2.4.

 git_remote_helpers/git/exporter.py  |    6 ++--
 git_remote_helpers/git/importer.py  |    6 ++--
 git_remote_helpers/git/non_local.py |   18 +++---------
 git_remote_helpers/git/repo.py      |    7 +++--
 git_remote_helpers/util.py          |   47 +++++++++++++++++++++++++++++++++++
 5 files changed, 62 insertions(+), 22 deletions(-)

diff --git a/git_remote_helpers/git/exporter.py b/git_remote_helpers/git/exporter.py
index bc39163..9ee5f96 100644
--- a/git_remote_helpers/git/exporter.py
+++ b/git_remote_helpers/git/exporter.py
@@ -2,6 +2,8 @@ import os
 import subprocess
 import sys
 
+from git_remote_helpers.util import check_call
+
 
 class GitExporter(object):
     """An exporter for testgit repositories.
@@ -53,6 +55,4 @@ class GitExporter(object):
 
         args = ["sed", "s_refs/heads/_" + self.repo.prefix + "_g"]
 
-        child = subprocess.Popen(args, stdin=p1.stdout)
-        if child.wait() != 0:
-            raise CalledProcessError
+        check_call(args, stdin=p1.stdout)
diff --git a/git_remote_helpers/git/importer.py b/git_remote_helpers/git/importer.py
index 70a7127..02a719a 100644
--- a/git_remote_helpers/git/importer.py
+++ b/git_remote_helpers/git/importer.py
@@ -1,6 +1,8 @@
 import os
 import subprocess
 
+from git_remote_helpers.util import check_call
+
 
 class GitImporter(object):
     """An importer for testgit repositories.
@@ -35,6 +37,4 @@ class GitImporter(object):
         if os.path.exists(path):
             args.append("--import-marks=" + path)
 
-        child = subprocess.Popen(args)
-        if child.wait() != 0:
-            raise CalledProcessError
+        check_call(args)
diff --git a/git_remote_helpers/git/non_local.py b/git_remote_helpers/git/non_local.py
index c53e074..e700250 100644
--- a/git_remote_helpers/git/non_local.py
+++ b/git_remote_helpers/git/non_local.py
@@ -1,7 +1,7 @@
 import os
 import subprocess
 
-from git_remote_helpers.util import die, warn
+from git_remote_helpers.util import check_call, die, warn
 
 
 class NonLocalGit(object):
@@ -29,9 +29,7 @@ class NonLocalGit(object):
         os.makedirs(path)
         args = ["git", "clone", "--bare", "--quiet", self.repo.gitpath, path]
 
-        child = subprocess.Popen(args)
-        if child.wait() != 0:
-            raise CalledProcessError
+        check_call(args)
 
         return path
 
@@ -45,14 +43,10 @@ class NonLocalGit(object):
             die("could not find repo at %s", path)
 
         args = ["git", "--git-dir=" + path, "fetch", "--quiet", self.repo.gitpath]
-        child = subprocess.Popen(args)
-        if child.wait() != 0:
-            raise CalledProcessError
+        check_call(args)
 
         args = ["git", "--git-dir=" + path, "update-ref", "refs/heads/master", "FETCH_HEAD"]
-        child = subprocess.Popen(args)
-        if child.wait() != 0:
-            raise CalledProcessError
+        child = check_call(args)
 
     def push(self, base):
         """Pushes from the non-local repo to base.
@@ -64,6 +58,4 @@ class NonLocalGit(object):
             die("could not find repo at %s", path)
 
         args = ["git", "--git-dir=" + path, "push", "--quiet", self.repo.gitpath, "--all"]
-        child = subprocess.Popen(args)
-        if child.wait() != 0:
-            raise CalledProcessError
+        child = check_call(args)
diff --git a/git_remote_helpers/git/repo.py b/git_remote_helpers/git/repo.py
index 58e1cdb..acbf8d7 100644
--- a/git_remote_helpers/git/repo.py
+++ b/git_remote_helpers/git/repo.py
@@ -1,6 +1,9 @@
 import os
 import subprocess
 
+from git_remote_helpers.util import check_call
+
+
 def sanitize(rev, sep='\t'):
     """Converts a for-each-ref line to a name/value pair.
     """
@@ -53,9 +56,7 @@ class GitRepo(object):
         path = ".cached_revs"
         ofile = open(path, "w")
 
-        child = subprocess.Popen(args, stdout=ofile)
-        if child.wait() != 0:
-            raise CalledProcessError
+        check_call(args, stdout=ofile)
         output = open(path).readlines()
         self.revmap = dict(sanitize(i) for i in output)
         if "HEAD" in self.revmap:
diff --git a/git_remote_helpers/util.py b/git_remote_helpers/util.py
index dce83e6..1652c65 100644
--- a/git_remote_helpers/util.py
+++ b/git_remote_helpers/util.py
@@ -11,6 +11,21 @@ import sys
 import os
 import subprocess
 
+try:
+    from subprocess import CalledProcessError
+except ImportError:
+    # from python2.7:subprocess.py
+    # Exception classes used by this module.
+    class CalledProcessError(Exception):
+        """This exception is raised when a process run by check_call() returns
+        a non-zero exit status.  The exit status will be stored in the
+        returncode attribute."""
+        def __init__(self, returncode, cmd):
+            self.returncode = returncode
+            self.cmd = cmd
+        def __str__(self):
+            return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)
+
 
 # Whether or not to show debug messages
 DEBUG = False
@@ -128,6 +143,38 @@ def run_command (args, cwd = None, shell = False, add_env = None,
     return (exit_code, output, errors)
 
 
+# from python2.7:subprocess.py
+def call(*popenargs, **kwargs):
+    """Run command with arguments.  Wait for command to complete, then
+    return the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    retcode = call(["ls", "-l"])
+    """
+    return subprocess.Popen(*popenargs, **kwargs).wait()
+
+
+# from python2.7:subprocess.py
+def check_call(*popenargs, **kwargs):
+    """Run command with arguments.  Wait for command to complete.  If
+    the exit code was zero then return, otherwise raise
+    CalledProcessError.  The CalledProcessError object will have the
+    return code in the returncode attribute.
+
+    The arguments are the same as for the Popen constructor.  Example:
+
+    check_call(["ls", "-l"])
+    """
+    retcode = call(*popenargs, **kwargs)
+    if retcode:
+        cmd = kwargs.get("args")
+        if cmd is None:
+            cmd = popenargs[0]
+        raise CalledProcessError(retcode, cmd)
+    return 0
+
+
 def file_reader_method (missing_ok = False):
     """Decorator for simplifying reading of files.
 
-- 
1.7.5.1.292.g728120