vx32

commit 59b30ab1404c3c97b232afb51dea024f499fd4ea
parent 130276062d937dc40b5c9b757b526d099d4da412
Author: rminnich@gmail.com <none@none>
Date:   Wed, 19 May 2010 14:33:20 -0700

hg mv did not add this file!

Diffstat:
src/9vx/ratrace/ratrace.c
 | 
173
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 173 insertions(+), 0 deletions(-)
diff --git a/src/9vx/ratrace/ratrace.c b/src/9vx/ratrace/ratrace.c
@@ -0,0 +1,173 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <thread.h>
+
+Channel *out;
+Channel *quit;
+Channel *forkc;
+int nread = 0;
+
+typedef struct Str Str;
+struct Str {
+	char *buf;
+	int len;
+};
+
+void
+die(char *s)
+{
+	fprint(2, "%s\n", s);
+	exits(s);
+}
+void
+cwrite(int fd, char *path, char *cmd, int len)
+{
+	if (write(fd, cmd, len)  < len) {
+		fprint(2, "cwrite: %s: failed %d bytes: %r\n", path, len);
+		sendp(quit, nil);
+		threadexits(nil);
+	}
+}
+void
+reader(void *v)
+{
+	char *ctl, *truss;
+	int pid, newpid;
+	int cfd, tfd;
+	Str *s;
+	int forking = 0;
+
+	pid = (int)v;
+	ctl = smprint("/proc/%d/ctl", pid);
+	if ((cfd = open(ctl, OWRITE)) < 0)
+		die(smprint("%s: %r", ctl));
+	truss = smprint("/proc/%d/syscall", pid);
+	if ((tfd = open(truss, OREAD)) < 0)
+		die(smprint("%s: %r", truss));
+
+	cwrite(cfd, ctl, "stop", 4);
+	cwrite(cfd, truss, "startsyscall", 12);
+
+	s = mallocz(sizeof(Str) + 8192, 1);
+	s->buf = (char *)&s[1];
+	/* 8191 is not a typo. It ensures a null-terminated string. The device currently limits to 4096 anyway */
+	while((s->len = pread(tfd, s->buf, 8191, 0ULL)) > 0){
+		if (forking && (s->buf[1] == '=') && (s->buf[3] != '-')) {
+			forking = 0;
+			newpid = strtol(&s->buf[3], 0, 0);
+			sendp(forkc, (void*)newpid);
+			procrfork(reader, (void*)newpid, 8192, 0);
+		}
+
+		/* There are three tests here and they (I hope) guarantee no false positives */
+		if (strstr(s->buf, " Rfork") != nil) {
+			char *a[8];
+			char *rf;
+			rf = strdup(s->buf);
+         		if (tokenize(rf, a, 8) == 5) {
+				unsigned long flags;
+				flags = strtoul(a[4], 0, 16);
+				if (flags & RFPROC)
+					forking = 1;
+			}
+			free(rf);			
+		}
+		sendp(out, s);			
+		cwrite(cfd, truss, "startsyscall", 12);
+		s = mallocz(sizeof(Str) + 8192, 1);
+		s->buf = (char *)&s[1];
+
+	}
+	sendp(quit, nil);
+	threadexitsall(nil);
+}
+
+
+void
+writer(void *)
+{
+	Alt a[4];
+	Str *s;
+	int newpid;
+
+	a[0].op = CHANRCV;
+	a[0].c = quit;
+	a[0].v = nil;
+	a[1].op = CHANRCV;
+	a[1].c = out;
+	a[1].v = &s;
+	a[2].op = CHANRCV;
+	a[2].c = forkc;
+	a[2].v = &newpid;
+	a[3].op = CHANEND;
+
+	for(;;) { 
+	switch(alt(a)){
+	case 0:
+		nread--;
+		if(nread <= 0)
+			goto done;
+		break;
+	case 1:
+		/* it's a nice null terminated thing */
+		fprint(2, "%s", s->buf);
+		free(s);
+		break;
+	case 2:
+//		procrfork(reader, (void*)newpid, 8192, 0);
+		nread++;
+		break;
+	}
+	}
+done:
+	exits(nil);
+}
+
+void
+usage(void){
+	fprint(2, "Usage: syscalltrace [-c cmd] [pid] (one of these is required)\n");
+	exits("usage");
+}
+
+void
+threadmain(int argc, char **argv)
+{
+	int pid;
+	char *cmd = nil;
+	char **args = nil;
+
+	ARGBEGIN{
+	case 'c':
+		cmd = strdup(EARGF(usage()));
+		args = argv;
+		break;
+	default:
+		usage();
+	}ARGEND;
+
+	/* run a command? */
+	if(cmd) {
+		pid = fork();
+		if (pid < 0) {
+			fprint(2, "No fork: %r\n");
+			exits("fork failed");
+		}
+		if(pid == 0) {
+			exec(cmd, args);
+			fprint(2, "Bad exec: %s: %r\n", cmd);
+			exits("Bad exec");
+		}
+	} else {
+		if(argc != 1)
+			sysfatal("usage");
+		pid = atoi(argv[0]);
+	}
+
+	out = chancreate(sizeof(char*), 0);
+	quit = chancreate(sizeof(char*), 0);
+	forkc = chancreate(sizeof(ulong *), 0);
+	nread++;
+	procrfork(writer, nil, 8192, 0);
+	reader((void*)pid);
+}