git-p4: Detect changes to executable bit and include them in p4 submit.

This changeset takes advantage of the new parseDiffTreeEntry(...) function to
detect changes to the execute bit in the git repository.  During submit, git-p4
now looks for changes to the executable bit and if it finds them it "reopens"
the file in perforce, which allows it to change the file type.

The logic for adding the executable bit in perforce is straightforward: the +x
modifier can be used. Removing the executable bit in perforce requires that the
entire filetype be redefined (there is no way to join remove the bit with a -x
modifier, for example). This changeset includes logic to remove the executable
bit from the full file type while preserving the base file type and other
modifiers.

Signed-off-by: Chris Pettitt <cpettitt@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/fast-import/git-p4

@@ -71,6 +71,31 @@ def isP4Exec(kind):
     a plus sign, it is also executable"""
     return (re.search(r"(^[cku]?x)|\+.*x", kind) != None)
 
+def setP4ExecBit(file, mode):
+    # Reopens an already open file and changes the execute bit to match
+    # the execute bit setting in the passed in mode.
+
+    p4Type = "+x"
+
+    if not isModeExec(mode):
+        p4Type = getP4OpenedType(file)
+        p4Type = re.sub('^([cku]?)x(.*)', '\\1\\2', p4Type)
+        p4Type = re.sub('(.*?\+.*?)x(.*?)', '\\1\\2', p4Type)
+        if p4Type[-1] == "+":
+            p4Type = p4Type[0:-1]
+
+    system("p4 reopen -t %s %s" % (p4Type, file))
+
+def getP4OpenedType(file):
+    # Returns the perforce file type for the given file.
+
+    result = read_pipe("p4 opened %s" % file)
+    match = re.match(".*\((.+)\)$", result)
+    if match:
+        return match.group(1)
+    else:
+        die("Could not determine file type for %s" % file)
+
 def diffTreePattern():
     # This is a simple generator for the diff tree regex pattern. This could be
     # a class variable if this and parseDiffTreeEntry were a part of a class.
@@ -111,6 +136,14 @@ def parseDiffTreeEntry(entry):
         }
     return None
 
+def isModeExec(mode):
+    # Returns True if the given git mode represents an executable file,
+    # otherwise False.
+    return mode[-3:] == "755"
+
+def isModeExecChanged(src_mode, dst_mode):
+    return isModeExec(src_mode) != isModeExec(dst_mode)
+
 def p4CmdList(cmd, stdin=None, stdin_mode='w+b'):
     cmd = "p4 -G %s" % cmd
     if verbose:
@@ -538,15 +571,19 @@ class P4Submit(Command):
         filesToAdd = set()
         filesToDelete = set()
         editedFiles = set()
+        filesToChangeExecBit = {}
         for line in diff:
             diff = parseDiffTreeEntry(line)
             modifier = diff['status']
             path = diff['src']
             if modifier == "M":
                 system("p4 edit \"%s\"" % path)
+                if isModeExecChanged(diff['src_mode'], diff['dst_mode']):
+                    filesToChangeExecBit[path] = diff['dst_mode']
                 editedFiles.add(path)
             elif modifier == "A":
                 filesToAdd.add(path)
+                filesToChangeExecBit[path] = diff['dst_mode']
                 if path in filesToDelete:
                     filesToDelete.remove(path)
             elif modifier == "D":
@@ -557,6 +594,8 @@ class P4Submit(Command):
                 src, dest = diff['src'], diff['dst']
                 system("p4 integrate -Dt \"%s\" \"%s\"" % (src, dest))
                 system("p4 edit \"%s\"" % (dest))
+                if isModeExecChanged(diff['src_mode'], diff['dst_mode']):
+                    filesToChangeExecBit[dest] = diff['dst_mode']
                 os.unlink(dest)
                 editedFiles.add(dest)
                 filesToDelete.add(src)
@@ -609,6 +648,11 @@ class P4Submit(Command):
             system("p4 revert \"%s\"" % f)
             system("p4 delete \"%s\"" % f)
 
+        # Set/clear executable bits
+        for f in filesToChangeExecBit.keys():
+            mode = filesToChangeExecBit[f]
+            setP4ExecBit(f, mode)
+
         logMessage = ""
         if not self.directSubmit:
             logMessage = extractLogMessageFromGitCommit(id)