failtest: --debugpath= for really hard-to-find bugs.

If children and parents aren't isolated properly (ie. failtest is
buggy) we really want to run gdb on a failing child.  This hack allows that.

diff --git a/ccan/failtest/failtest.c b/ccan/failtest/failtest.c
index 1874d620286d697c9c063319f8435e52dd5823aa..ad7e0feac1ec00be4b161c545e3e5c497a8cd8f6 100644 (file)
--- a/ccan/failtest/failtest.c
+++ b/ccan/failtest/failtest.c
@@ -25,6 +25,7 @@ static int tracefd = -1;
 unsigned int failtest_timeout_ms = 20000;
 
 const char *failpath;
+const char *debugpath;
 
 enum info_type {
        WRITE,
@@ -329,6 +330,29 @@ static bool should_fail(struct failtest_call *call)
                }
        }
 
+       /* Attach debugger if they asked for it. */
+       if (debugpath && history_num == strlen(debugpath)) {
+               unsigned int i;
+
+               for (i = 0; i < history_num; i++) {
+                       char c = info_to_arg[history[i].type];
+                       if (history[i].fail)
+                               c = toupper(c);
+                       if (c != debugpath[i])
+                               break;
+               }
+               if (i == history_num) {
+                       char str[80];
+
+                       /* Don't timeout. */
+                       signal(SIGUSR1, SIG_IGN);
+                       sprintf(str, "xterm -e gdb /proc/%d/exe %d &",
+                               getpid(), getpid());
+                       system(str);
+                       sleep(5);
+               }
+       }
+
        if (!failtest_hook(history, history_num)) {
                call->fail = false;
                return false;
@@ -927,6 +951,9 @@ void failtest_init(int argc, char *argv[])
                } else if (strcmp(argv[i], "--tracepath") == 0) {
                        tracefd = dup(STDERR_FILENO);
                        failtest_timeout_ms = -1;
+               } else if (!strncmp(argv[i], "--debugpath=",
+                                   strlen("--debugpath="))) {
+                       debugpath = argv[i] + strlen("--debugpath=");
                }
        }
        gettimeofday(&start, NULL);