git-p4: input to "p4 files" by stdin instead of arguments

diff --git a/contrib/fast-import/git-p4 b/contrib/fast-import/git-p4
index 54a05eb99c3eb747fcf26cfa3fc51a12f9055bd3..54053e3f3d404567ce4b5734b2c7e94cdf666645 100755 (executable)
--- a/contrib/fast-import/git-p4
+++ b/contrib/fast-import/git-p4
@@ -63,21 +63,34 @@ def system(cmd):
     if os.system(cmd) != 0:
         die("command failed: %s" % cmd)
 
-def p4CmdList(cmd):
+def p4CmdList(cmd, stdin=None, stdin_mode='w+b'):
     cmd = "p4 -G %s" % cmd
     if verbose:
         sys.stderr.write("Opening pipe: %s\n" % cmd)
-    pipe = os.popen(cmd, "rb")
+
+    # Use a temporary file to avoid deadlocks without
+    # subprocess.communicate(), which would put another copy
+    # of stdout into memory.
+    stdin_file = None
+    if stdin is not None:
+        stdin_file = tempfile.TemporaryFile(prefix='p4-stdin', mode=stdin_mode)
+        stdin_file.write(stdin)
+        stdin_file.flush()
+        stdin_file.seek(0)
+
+    p4 = subprocess.Popen(cmd, shell=True,
+                          stdin=stdin_file,
+                          stdout=subprocess.PIPE)
 
     result = []
     try:
         while True:
-            entry = marshal.load(pipe)
+            entry = marshal.load(p4.stdout)
             result.append(entry)
     except EOFError:
         pass
-    exitCode = pipe.close()
-    if exitCode != None:
+    exitCode = p4.wait()
+    if exitCode != 0:
         entry = {}
         entry["p4ExitCode"] = exitCode
         result.append(entry)
@@ -712,23 +725,13 @@ class P4Sync(Command):
         if not files:
             return
 
-        # We cannot put all the files on the command line
-        # OS have limitations on the max lenght of arguments
-        # POSIX says it's 4096 bytes, default for Linux seems to be 130 K.
-        # and all OS from the table below seems to be higher than POSIX.
-        # See http://www.in-ulm.de/~mascheck/various/argmax/
-        argmax = min(4000, os.sysconf('SC_ARG_MAX'))
-        chunk = ''
-        filedata = []
-        for i in xrange(len(files)):
-            f = files[i]
-            chunk += '"%s#%s" ' % (f['path'], f['rev'])
-            if len(chunk) > argmax or i == len(files)-1:
-                data = p4CmdList('print %s' % chunk)
-                if "p4ExitCode" in data[0]:
-                    die("Problems executing p4. Error: [%d]." % (data[0]['p4ExitCode']));
-                filedata.extend(data)
-                chunk = ''
+        filedata = p4CmdList('-x - print',
+                             stdin='\n'.join(['%s#%s' % (f['path'], f['rev'])
+                                              for f in files]),
+                             stdin_mode='w+')
+        if "p4ExitCode" in filedata[0]:
+            die("Problems executing p4. Error: [%d]."
+                % (filedata[0]['p4ExitCode']));
 
         j = 0;
         contents = {}