[distcc] Re: detecting architecture of DISTCC HOSTS ?

[Han-Wen Nienhuys]

In article <dtcb5g$7ss$1 at sea.gmane.org>,
Han-Wen Nienhuys <hanwen at xs4all.nl> wrote:
>>There is not anything like that at the moment, but you could add it
>>fairly easily, probably without modifying the server code.  It'd be a
>>worthy addition.
>
>Come to think of it, having another feature would actually be even
>better: it would be nice if I could setup a mapping, so that if distcc
>gets invoked on Linux
>
>  distcc gcc
>
>it will call
>
>  i686-linux-gcc
>
>on other hosts, while it will do
>
>  powerpc-darwin-gcc
>
>if distcc was started on a Mac.

See this patch, also on 

  http://www.xs4all.nl/~hanwen/public/software/distcc-substitute.patch

For example

  DISTCC_SUBSTITUTE_GXX='i686-linux-g++' distcc

will remotely invoke i686-linux-g++ when g++ is run locally.

This is useful as cross-building some packages require both a native
gcc and a cross-compiling gcc to be present.  Setting
DISTCC_SUBSTITUTE_GCC= allows the native compiler invocations to be
distcc'd to different machine types as well.

Arguably, there it might even be sensible to have

  DISTCC_SUBSTITUTE_<compilername>_<hostname>

but I have left it out, as I don't need it.

My groff knowledge is non-existent. Could someone review my diffs to
the manpage? Thanks!


diff -ur distcc-2.18.3/man/distcc.1 distcc-2.18.3.subs/man/distcc.1
--- distcc-2.18.3/man/distcc.1	2004-10-24 07:05:23.000000000 +0200
+++ distcc-2.18.3.subs/man/distcc.1	2006-02-20 13:50:35.000000000 +0100
@@ -420,6 +420,19 @@
 error stream or in the log file.  This can be helpful in debugging
 problems.  Bug reports should include verbose output.
 .TP
+.B "DISTCC_SUBSTITUTE_compilername"
+Before shipping a job to a remote client, distcc will substitute
+the value of this variable for
+.B compiler;
+compilername should uppercase, with non-alphanumeric characters
+replaced by Xs.  For example, a call of g++ can be changed to by
+i686-linux-g++-3.4 remotely by setting
+.PP
+.nf
+  DISTCC_SUBSTITUTE_GXX="i686-linux-g++-3.4" 
+.fi
+.PP
+.TP
 .B "DISTCC_LOG"
 Log file to receive messages from distcc itself, rather
 than stderr.
@@ -469,10 +482,11 @@
 mixed-architecture machines, although some changes to the
 compilation commands may be required.
 .PP
-The compilation command passed to distcc must be one that
-will execute properly on every volunteer machine to produce
-an object file of the appropriate type.  If the machines
-have different processors, then simply using 
+The compilation command passed to distcc or set in
+DISTCC_SUBSTITUTE_compilername must be one that will execute properly
+on every volunteer machine to produce an object file of the
+appropriate type.  If the machines have different processors, then
+simply using
 .B distcc cc
 will probably not work, because that will normally invoke the
 volunteer's native compiler.
diff -ur distcc-2.18.3/src/distcc.c distcc-2.18.3.subs/src/distcc.c
--- distcc-2.18.3/src/distcc.c	2004-10-02 02:47:07.000000000 +0200
+++ distcc-2.18.3.subs/src/distcc.c	2006-02-20 13:11:49.000000000 +0100
@@ -136,7 +136,6 @@
 }
 
 
-
 /**
  * distcc client entry point.
  *
diff -ur distcc-2.18.3/src/remote.c distcc-2.18.3.subs/src/remote.c
--- distcc-2.18.3/src/remote.c	2004-10-24 07:05:49.000000000 +0200
+++ distcc-2.18.3.subs/src/remote.c	2006-02-20 13:44:02.000000000 +0100
@@ -33,6 +33,7 @@
 #include <string.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <ctype.h>
 
 #include <sys/types.h>
 #include <sys/time.h>
@@ -115,6 +116,44 @@
     return 0;
 }
 
+static int isidchar (int c)
+{
+    return isalnum (c) || c == '_' || c == '-';
+}
+
+/*
+ * On a remote host of different architecture, we might want to
+ * execute TARGET-gcc iso. gcc.
+ * this is controlled with DISTCC_SUBSTITUTE_<upcase compiler name>
+ */
+static char *
+dcc_substitute_compiler_name (char *name)
+{
+    const char *generic = "DISTCC_SUBSTITUTE_" ;
+    size_t n = strlen (generic);
+    char *key = malloc (strlen (name) + n + 1);
+    char *p = key;
+    char *q = name;
+    
+    if (!key) {
+        rs_log_crit("allocation failed!");
+        return NULL;
+    }
+    
+    strncpy (key, generic, n);
+    for (p = key + n, q = name; *q; q++, p++) {
+        *p = toupper (*q);
+        if (!isidchar(*p))
+            *p = 'X';
+    }
+    *p = 0;
+
+    if (getenv (key)) 
+        return strdup (getenv (key));
+    
+    return name;
+}
+
 
 /* Send a request across to the already-open server.
  *
@@ -187,6 +226,8 @@
     if (gettimeofday(&before, NULL))
         rs_log_warning("gettimeofday failed");
 
+    argv[0] = dcc_substitute_compiler_name (argv[0]);
+    
     dcc_note_execution(host, argv);
     dcc_note_state(DCC_PHASE_CONNECT, input_fname, host->hostname);