When doing the initial open of the proc via procfs, complain if we are

unable to open the /proc/pid/mem file.  Otherwise doing a truss on
a nonexistant pid makes us return success even though no such process
exists.

3 files changed, 14 insertions, 8 deletions

diff --git a/usr.bin/truss/extern.h b/usr.bin/truss/extern.h
index ee977fb..e13f80b 100644
--- a/usr.bin/truss/extern.h
+++ b/usr.bin/truss/extern.h
@@ -32,7 +32,7 @@
  */
 
 extern int setup_and_wait(char **);
-extern int start_tracing(int, int, int);
+extern int start_tracing(int, int, int, int);
 extern void restore_proc(int);
 extern const char *ioctlname(register_t val);
 extern char *strsig(int sig);
diff --git a/usr.bin/truss/main.c b/usr.bin/truss/main.c
index ce61db2..9d289a7 100644
--- a/usr.bin/truss/main.c
+++ b/usr.bin/truss/main.c
@@ -165,12 +165,16 @@ main(int ac, char **av)
 	char **command;
 	struct procfs_status pfs;
 	struct ex_types *funcs;
-	int in_exec = 0;
-	char *fname = NULL;
-	int sigexit = 0;
+	int in_exec, sigexit, initial_open;
+	char *fname;
 	struct trussinfo *trussinfo;
 	char *signame;
 
+	in_exec = 0;
+	sigexit = 0;
+	fname = NULL;
+	initial_open = 1;
+
 	/* Initialize the trussinfo struct */
 	trussinfo = (struct trussinfo *)malloc(sizeof(struct trussinfo));
 	if (trussinfo == NULL)
@@ -246,9 +250,11 @@ main(int ac, char **av)
 
 START_TRACE:
 	Procfd = start_tracing(
-	    trussinfo->pid, S_EXEC | S_SCE | S_SCX | S_CORE | S_EXIT |
+	    trussinfo->pid, initial_open,
+	    S_EXEC | S_SCE | S_SCX | S_CORE | S_EXIT |
 	    ((trussinfo->flags & NOSIGS) ? 0 : S_SIG),
 	    ((trussinfo->flags & FOLLOWFORKS) ? PF_FORK : 0));
+	initial_open = 0;
 	if (Procfd == -1)
 		return (0);
 
diff --git a/usr.bin/truss/setup.c b/usr.bin/truss/setup.c
index fa52dd6..c48370c 100644
--- a/usr.bin/truss/setup.c
+++ b/usr.bin/truss/setup.c
@@ -129,7 +129,7 @@ setup_and_wait(char *command[])
  */
 
 int
-start_tracing(int pid, int eventflags, int flags)
+start_tracing(int pid, int failisfatal, int eventflags, int flags)
 {
 	int fd;
 	char buf[32];
@@ -144,8 +144,8 @@ start_tracing(int pid, int eventflags, int flags)
 		 * happens with SUGID programs.  So we need to see if it still
 		 * exists before we complain bitterly.
 		 */
-		if (kill(pid, 0) == -1)
-			return -1;
+		if (!failisfatal && kill(pid, 0) == -1)
+			return (-1);
 		err(8, "cannot open %s", buf);
 	}