[PATCH] pager: preserve Hg's exit code (and fix Windows support) (issue3225)

brodie at bitheap.org brodie at bitheap.org
Fri May 11 08:49:03 CDT 2012


# HG changeset patch
# User Brodie Rao <brodie at sf.io>
# Date 1336743937 -7200
# Branch stable
# Node ID e11b4d33bf59e5f51fe5224e590f85bbfce8bde0
# Parent  e22d6b1dec1d4bda684a8d90e8d4852500d69495
pager: preserve Hg's exit code (and fix Windows support) (issue3225)

This changes how the pager extension invokes the pager. Prior to this change,
the extension would fork Hg and exec the pager in the parent process. This
loses Hg exit code, and it doesn't work on Windows.

Now the pager is invoked using the subprocess library, and an atexit handler is
registered that makes Hg wait for the pager to exit before it exits itself.

Note that if you exit the pager before Hg is done running, you'll get an exit
code of 255, which is caused by Python blowing up due to a broken pipe. If you
set pager.quiet=True, you'll get the OS-level return code of 141.

diff --git a/hgext/pager.py b/hgext/pager.py
--- a/hgext/pager.py
+++ b/hgext/pager.py
@@ -53,37 +53,27 @@ used. Use a boolean value like yes, no, 
 normal behavior.
 '''
 
-import sys, os, signal, shlex, errno
+import atexit, sys, os, signal, subprocess
 from mercurial import commands, dispatch, util, extensions
 from mercurial.i18n import _
 
 def _runpager(p):
-    if not util.safehasattr(os, 'fork'):
-        sys.stdout = util.popen(p, 'wb')
-        if util.isatty(sys.stderr):
-            sys.stderr = sys.stdout
-        return
-    fdin, fdout = os.pipe()
-    pid = os.fork()
-    if pid == 0:
-        os.close(fdin)
-        os.dup2(fdout, sys.stdout.fileno())
-        if util.isatty(sys.stderr):
-            os.dup2(fdout, sys.stderr.fileno())
-        os.close(fdout)
-        return
-    os.dup2(fdin, sys.stdin.fileno())
-    os.close(fdin)
-    os.close(fdout)
-    try:
-        os.execvp('/bin/sh', ['/bin/sh', '-c', p])
-    except OSError, e:
-        if e.errno == errno.ENOENT:
-            # no /bin/sh, try executing the pager directly
-            args = shlex.split(p)
-            os.execvp(args[0], args)
-        else:
-            raise
+    pager = subprocess.Popen(p, shell=True, bufsize=-1,
+                             close_fds=util.closefds, stdin=subprocess.PIPE,
+                             stdout=sys.stdout, stderr=sys.stderr)
+
+    stdout = os.dup(sys.stdout.fileno())
+    stderr = os.dup(sys.stderr.fileno())
+    os.dup2(pager.stdin.fileno(), sys.stdout.fileno())
+    if util.isatty(sys.stderr):
+        os.dup2(pager.stdin.fileno(), sys.stderr.fileno())
+
+    @atexit.register
+    def killpager():
+        pager.stdin.close()
+        os.dup2(stdout, sys.stdout.fileno())
+        os.dup2(stderr, sys.stderr.fileno())
+        pager.wait()
 
 def uisetup(ui):
     if ui.plain() or '--debugger' in sys.argv or not util.isatty(sys.stdout):


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