Attachment 155264 Details for Bug 240986 – Bugfix.

[patch] Bugfix.

strace-4.5.15-interrupt-during-attach.patch (text/plain), 8.20 KB, created by Jan Kratochvil on 2007-05-23 15:37:20 UTC

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Creator: Jan Kratochvil

Created: 2007-05-23 15:37:20 UTC

Size: 8.20 KB

patch

obsolete

>2007-05-23  Jan Kratochvil  <jan.kratochvil@redhat.com>
>
>	* strace.c [LINUX] (detach): Move the SIGSTOP wait () code with its
>	STATUS variable to ...
>	[LINUX] (waitstop): ... here as a new function.
>	(main): Move signals and BLOCKED_SET init before the options parsing.
>	[LINUX] (main): waitstop () once after each succeeded PTRACE_ATTACH.
>	SIG_BLOCK signals of BLOCKED_SET between PTRACE_ATTACH - waitstop ().
>
>diff -u -rup strace-4.5.15-detach-zombie-tkill/strace.c strace-4.5.15/strace.c
>--- strace-4.5.15-detach-zombie-tkill/strace.c	2007-05-23 16:32:55.000000000 +0200
>+++ strace-4.5.15/strace.c	2007-05-23 17:27:44.000000000 +0200
>@@ -325,6 +325,67 @@ newoutf(struct tcb *tcp)
> 	return 0;
> }
> 
>+#ifdef LINUX
>+
>+/* Each PTRACE_ATTACH generates one SIGSTOP.  We need to catch it as it would
>+   mess our later tracing otherwise.  Be aware the other signals may be
>+   received before SIGSTOP and these need to be redelivered.
>+   Function returns 1 on successful caught SIGSTOP, 0 died PID, -1 on error.  */
>+static int waitstop P((int pid));
>+static int
>+waitstop(pid)
>+int pid;
>+{
>+	int status;
>+
>+retry:
>+#ifdef __WALL
>+	if (wait4(pid, &status, __WALL, NULL) < 0) {
>+		if (errno == ECHILD) /* Already gone.  */
>+			return 0;
>+		if (errno != EINVAL) {
>+			perror("waitstop: waiting");
>+			return -1;
>+		}
>+#endif /* __WALL */
>+		/* No __WALL here.  */
>+		if (waitpid(pid, &status, 0) < 0) {
>+			if (errno != ECHILD) {
>+				perror("waitstop: waiting");
>+				return -1;
>+			}
>+#ifdef __WCLONE
>+			/* If no processes, try clones.  */
>+			if (wait4(pid, &status, __WCLONE, NULL) < 0) {
>+				if (errno == ECHILD)
>+					return 0;
>+				perror("waitstop: waiting");
>+				return -1;
>+			}
>+#endif /* __WCLONE */
>+		}
>+#ifdef __WALL
>+	}
>+#endif
>+	if (!WIFSTOPPED(status)) {
>+		/* Au revoir, mon ami. */
>+		return 0;
>+	}
>+	if (WSTOPSIG(status) == SIGSTOP) {
>+		return 1;
>+	}
>+	if (ptrace(PTRACE_CONT, pid, (char *) 1, WSTOPSIG(status) == SIGTRAP
>+						 ?  0 : WSTOPSIG(status)) < 0) {
>+		if (errno == ESRCH)
>+			return 0;
>+		perror("waitstop: ptrace(PTRACE_CONT, ...)");
>+		return -1;
>+	}
>+	goto retry;
>+}
>+
>+#endif /* LINUX */
>+
> int
> main(argc, argv)
> int argc;
>@@ -523,6 +584,43 @@ char *argv[];
> 		qflag = 1;
> 	}
> 
>+	sigemptyset(&empty_set);
>+	sigemptyset(&blocked_set);
>+	sa.sa_handler = SIG_IGN;
>+	sigemptyset(&sa.sa_mask);
>+	sa.sa_flags = 0;
>+	sigaction(SIGTTOU, &sa, NULL);
>+	sigaction(SIGTTIN, &sa, NULL);
>+	if (interactive) {
>+		sigaddset(&blocked_set, SIGHUP);
>+		sigaddset(&blocked_set, SIGINT);
>+		sigaddset(&blocked_set, SIGQUIT);
>+		sigaddset(&blocked_set, SIGPIPE);
>+		sigaddset(&blocked_set, SIGTERM);
>+		sa.sa_handler = interrupt;
>+#ifdef SUNOS4
>+		/* POSIX signals on sunos4.1 are a little broken. */
>+		sa.sa_flags = SA_INTERRUPT;
>+#endif /* SUNOS4 */
>+	}
>+	sigaction(SIGHUP, &sa, NULL);
>+	sigaction(SIGINT, &sa, NULL);
>+	sigaction(SIGQUIT, &sa, NULL);
>+	sigaction(SIGPIPE, &sa, NULL);
>+	sigaction(SIGTERM, &sa, NULL);
>+#ifdef USE_PROCFS
>+	sa.sa_handler = reaper;
>+	sigaction(SIGCHLD, &sa, NULL);
>+#else
>+	/* Make sure SIGCHLD has the default action so that waitpid
>+	   definitely works without losing track of children.  The user
>+	   should not have given us a bogus state to inherit, but he might
>+	   have.  Arguably we should detect SIG_IGN here and pass it on
>+	   to children, but probably noone really needs that.  */
>+	sa.sa_handler = SIG_DFL;
>+	sigaction(SIGCHLD, &sa, NULL);
>+#endif /* USE_PROCFS */
>+
> 	for (c = 0; c < tcbtabsize; c++) {
> 		tcp = tcbtab[c];
> 		if (!(tcp->flags & TCB_INUSE) || !(tcp->flags & TCB_ATTACHED))
>@@ -562,10 +660,16 @@ char *argv[];
> 					if (tid <= 0)
> 						continue;
> 					++ntid;
>+					/* We would leave the process SIGSTOPped if we would get terminated
>+					   between PTRACE_ATTACH and waitstop() catching the SIGSTOP.  */
>+					sigprocmask(SIG_BLOCK, &blocked_set, NULL);
> 					if (ptrace(PTRACE_ATTACH, tid,
> 						   (char *) 1, 0) < 0)
> 						++nerr;
>-					else if (tid != tcbtab[c]->pid) {
>+					else if (waitstop (tid) <= 0) {
>+						fprintf (stderr, "Error while attaching to tid %d!\n", tcp->pid);
>+						++nerr;
>+					} else if (tid != tcbtab[c]->pid) {
> 						if (nprocs == tcbtabsize &&
> 						    expand_tcbtab())
> 							tcp = NULL;
>@@ -579,6 +683,11 @@ char *argv[];
> 						tcbtab[c]->nclone_detached++;
> 						tcp->parent = tcbtab[c];
> 					}
>+					sigprocmask(SIG_SETMASK, &empty_set, NULL);
>+					if (interrupted) {
>+						cleanup();
>+						exit(0);
>+					}
> 				}
> 				closedir(dir);
> 				if (nerr == ntid) {
>@@ -601,11 +710,25 @@ Process %u attached - interrupt to quit\
> 			}
> 		}
> # endif
>+		/* We would leave the process SIGSTOPped if we would get terminated
>+		   between PTRACE_ATTACH and waitstop() catching the SIGSTOP.  */
>+		sigprocmask(SIG_BLOCK, &blocked_set, NULL);
> 		if (ptrace(PTRACE_ATTACH, tcp->pid, (char *) 1, 0) < 0) {
> 			perror("attach: ptrace(PTRACE_ATTACH, ...)");
> 			droptcb(tcp);
>-			continue;
>+			tcp = NULL;
>+		} else if (waitstop (tcp->pid) <= 0) {
>+			fprintf (stderr, "Error while attaching to pid %d!\n", tcp->pid);
>+			detach(tcp, 0);
>+			tcp = NULL;
>+		}
>+		sigprocmask(SIG_SETMASK, &empty_set, NULL);
>+		if (interrupted) {
>+			cleanup();
>+			exit(0);
> 		}
>+		if (tcp == NULL)
>+			continue;
> #endif /* !USE_PROCFS */
> 		if (!qflag)
> 			fprintf(stderr,
>@@ -767,43 +890,6 @@ Process %u attached - interrupt to quit\
> 		}
> 	}
> 
>-	sigemptyset(&empty_set);
>-	sigemptyset(&blocked_set);
>-	sa.sa_handler = SIG_IGN;
>-	sigemptyset(&sa.sa_mask);
>-	sa.sa_flags = 0;
>-	sigaction(SIGTTOU, &sa, NULL);
>-	sigaction(SIGTTIN, &sa, NULL);
>-	if (interactive) {
>-		sigaddset(&blocked_set, SIGHUP);
>-		sigaddset(&blocked_set, SIGINT);
>-		sigaddset(&blocked_set, SIGQUIT);
>-		sigaddset(&blocked_set, SIGPIPE);
>-		sigaddset(&blocked_set, SIGTERM);
>-		sa.sa_handler = interrupt;
>-#ifdef SUNOS4
>-		/* POSIX signals on sunos4.1 are a little broken. */
>-		sa.sa_flags = SA_INTERRUPT;
>-#endif /* SUNOS4 */
>-	}
>-	sigaction(SIGHUP, &sa, NULL);
>-	sigaction(SIGINT, &sa, NULL);
>-	sigaction(SIGQUIT, &sa, NULL);
>-	sigaction(SIGPIPE, &sa, NULL);
>-	sigaction(SIGTERM, &sa, NULL);
>-#ifdef USE_PROCFS
>-	sa.sa_handler = reaper;
>-	sigaction(SIGCHLD, &sa, NULL);
>-#else
>-	/* Make sure SIGCHLD has the default action so that waitpid
>-	   definitely works without losing track of children.  The user
>-	   should not have given us a bogus state to inherit, but he might
>-	   have.  Arguably we should detect SIG_IGN here and pass it on
>-	   to children, but probably noone really needs that.  */
>-	sa.sa_handler = SIG_DFL;
>-	sigaction(SIGCHLD, &sa, NULL);
>-#endif /* USE_PROCFS */
>-
> 	if (trace() < 0)
> 		exit(1);
> 	cleanup();
>@@ -1297,7 +1383,7 @@ int sig;
> {
> 	int error = 0;
> #ifdef LINUX
>-	int status, resumed;
>+	int resumed;
> 	struct tcb *zombie = NULL;
> 
> 	/* If the group leader is lingering only because of this other
>@@ -1340,54 +1426,14 @@ int sig;
> 			perror("detach: stopping child");
> 	}
> 	else {
>-		for (;;) {
>-#ifdef __WALL
>-			if (wait4(tcp->pid, &status, __WALL, NULL) < 0) {
>-				if (errno == ECHILD) /* Already gone.  */
>-					break;
>-				if (errno != EINVAL) {
>-					perror("detach: waiting");
>-					break;
>-				}
>-#endif /* __WALL */
>-				/* No __WALL here.  */
>-				if (waitpid(tcp->pid, &status, 0) < 0) {
>-					if (errno != ECHILD) {
>-						perror("detach: waiting");
>-						break;
>-					}
>-#ifdef __WCLONE
>-					/* If no processes, try clones.  */
>-					if (wait4(tcp->pid, &status, __WCLONE,
>-						  NULL) < 0) {
>-						if (errno != ECHILD)
>-							perror("detach: waiting");
>-						break;
>-					}
>-#endif /* __WCLONE */
>-				}
>-#ifdef __WALL
>-			}
>-#endif
>-			if (!WIFSTOPPED(status)) {
>-				/* Au revoir, mon ami. */
>-				break;
>-			}
>-			if (WSTOPSIG(status) == SIGSTOP) {
>-				if ((error = ptrace(PTRACE_DETACH,
>-				    tcp->pid, (char *) 1, sig)) < 0) {
>-					if (errno != ESRCH)
>-						perror("detach: ptrace(PTRACE_DETACH, ...)");
>-					/* I died trying. */
>-				}
>-				break;
>-			}
>-			if ((error = ptrace(PTRACE_CONT, tcp->pid, (char *) 1,
>-			    WSTOPSIG(status) == SIGTRAP ?
>-			    0 : WSTOPSIG(status))) < 0) {
>+		int waitstop_result = waitstop (tcp->pid);
>+		error = waitstop_result < 0;
>+		if (waitstop_result > 0) {
>+			if ((error = ptrace(PTRACE_DETACH, tcp->pid, (char *) 1,
>+					    sig)) < 0) {
> 				if (errno != ESRCH)
>-					perror("detach: ptrace(PTRACE_CONT, ...)");
>-				break;
>+					perror("detach: ptrace(PTRACE_DETACH, ...)");
>+				/* I died trying. */
> 			}
> 		}
> 	}

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Attachments on bug 240986: 155264 | 155446 | 155447 | 156701