# HG changeset patch
# User Bakul Shah <bakul@bitblocks.com>
# Date 1317319550 -7200
# Node ID 9c93e936f28e4066db82d2198b1b30e293ac97b9
# Parent  0984ccf0ffe686ae3ab3e06653f86493501667c5
ratrace: Added option -o to send trace output to a file.

R=nix-dev, nemo, john, noah.evans
CC=nix-dev
http://codereview.appspot.com/5152044

Committer: Francisco J Ballesteros <nemo.mbox@gmail.com>

diff -r 0984ccf0ffe6 -r 9c93e936f28e sys/man/1/ratrace
--- a/sys/man/1/ratrace	Thu Sep 29 19:08:29 2011 +0200
+++ b/sys/man/1/ratrace	Thu Sep 29 20:05:50 2011 +0200
@@ -4,6 +4,9 @@
 .SH SYNOPSIS
 .B ratrace
 [
+.I -o tracefile
+]
+[
 .I pid
 ] | [
 .I -c command
@@ -19,6 +22,9 @@
 Trace output is determined by the kernel, not
 .IR ratrace .
 Certain fixed rules apply.
+Trace output by default goes to file descriptor 2.
+Option \fB-o\fP can be used to switch trace output to \fItracefile\fP.
+.PP
 The first four fields of the output are
 pid, text name, system call name, and the PC of the user program.
 Data is always printed as
diff -r 0984ccf0ffe6 -r 9c93e936f28e sys/src/cmd/ratrace.c
--- a/sys/src/cmd/ratrace.c	Thu Sep 29 19:08:29 2011 +0200
+++ b/sys/src/cmd/ratrace.c	Thu Sep 29 20:05:50 2011 +0200
@@ -12,6 +12,7 @@
 Channel *quit;
 Channel *forkc;
 int nread = 0;
+int trace = 2; /* trace out fd */
 
 typedef struct Str Str;
 struct Str {
@@ -141,7 +142,7 @@
 			break;
 		case 1:			/* out */
 			/* it's a nice null terminated thing */
-			fprint(2, "%s", s->buf);
+			fprint(trace, "%s", s->buf);
 			free(s);
 			break;
 		case 2:			/* forkc */
@@ -156,7 +157,7 @@
 void
 usage(void)
 {
-	fprint(2, "Usage: ratrace [-c cmd [arg...]] | [pid]\n");
+	fprint(2, "Usage: ratrace [-o tracefile] [-c cmd [arg...]] | [pid]\n");
 	exits("usage");
 }
 
@@ -182,6 +183,7 @@
 	int pid;
 	char *cmd = nil;
 	char **args = nil;
+	char *tracefile = nil;
 
 	/*
 	 * don't bother with fancy arg processing, because it picks up options
@@ -198,12 +200,27 @@
 			cmd = strdup(argv[2]);
 			args = &argv[2];
 			break;
+		case 'o':
+			if (!argv[1][2]) {
+				tracefile = argv[2];
+				++argv;
+				--argc;
+			} else
+				tracefile = &argv[1][2];
+			break;
+		
 		default:
 			usage();
 		}
 		++argv;
 		--argc;
 	}
+	
+	if (tracefile) {
+		trace = create(tracefile, OWRITE, 0666);
+		if (trace < 0)
+			sysfatal("%s: %r", tracefile);
+	}
 
 	/* run a command? */
 	if(cmd) {