'perforce' src code mgt support for patch

[Tony E. Bennett]

Perforce is a popular cross-platform source code management
system.

This patch of patch 2.5.4 adds perforce awareness:

{~/src/patch-2.5.4}. diffb util.c
*** util.c~     Mon Aug 30 02:20:08 1999
--- util.c      Wed Feb  7 12:52:09 2001
***************
*** 253,258 ****
--- 253,260 ----
  static char const SCCSDIFF1[] = "get -p ";
  static char const SCCSDIFF2[] = "|diff - %s";
  
+ static char const PERFORCE_CO[] = "p4 edit ";
+ 
  static char const CLEARTOOL_CO[] = "cleartool co -unr -nc ";
  
  /* Return "RCS" if FILENAME is controlled by RCS,
***************
*** 362,367 ****
--- 364,386 ----
        *diffbuf = 0;
  
        r = "ClearCase";
+     }
+   else if (!readonly && filestat &&
+            (getenv("P4PORT") || getenv("P4USER") || getenv("P4CONFIG")))
+     {
+       if (getbuf)
+       {
+         char *p = *getbuf = xmalloc (maxgetsize);
+         strcpy (p, PERFORCE_CO);
+         p += sizeof PERFORCE_CO - 1;
+         p += quote_system_arg (p, filename);
+         *p = '\0';
+       }
+ 
+       if (diffbuf)
+       *diffbuf = 0;
+ 
+       r = "Perforce";
      }
  
    free (trybuf);