Be more defensive in do_test(..)

Shuffle around assertions with `nlines` to the appropriate locations and
initialize `lines[]` to an array of `NULL` pointers to avoid reading
unintialized memory.

Signed-off-by: Enji Cooper <ngie@FreeBSD.org>

Author: ngie-eign

atf-c/detail/sanity_test.c

@@ -85,14 +85,16 @@ do_test_child(void *v)
     exit(EXIT_SUCCESS);
 }
 
+#define	MAX_LINES	3
+
 static
 void
 do_test(enum type t, bool cond)
 {
     atf_process_child_t child;
     atf_process_status_t status;
     int nlines;
-    char *lines[3];
+    char *lines[MAX_LINES] = { 0 };
 
     {
         atf_process_stream_t outsb, errsb;
@@ -106,16 +108,17 @@ do_test(enum type t, bool cond)
     }
 
     nlines = 0;
-    while (nlines < 3 && (lines[nlines] =
+    while (nlines < MAX_LINES && (lines[nlines] =
            atf_utils_readline(atf_process_child_stderr(&child))) != NULL)
         nlines++;
-    ATF_REQUIRE(nlines == 0 || nlines == 3);
 
     RE(atf_process_child_wait(&child, &status));
     if (!cond) {
+        ATF_REQUIRE(nlines == MAX_LINES);
         ATF_REQUIRE(atf_process_status_signaled(&status));
         ATF_REQUIRE(atf_process_status_termsig(&status) == SIGABRT);
     } else {
+        ATF_REQUIRE(nlines == 0);
         ATF_REQUIRE(atf_process_status_exited(&status));
         ATF_REQUIRE(atf_process_status_exitstatus(&status) == EXIT_SUCCESS);
     }