executor: rework feature setup

Return failure reason from setup functions rather than crash.
This will provide better error messages, but also allow setup
w/o creating subprocesses which will be needed when we combine
fuzzer and executor.

Also close all resources created during setup.
This is also useful for in-process setup, but also should improve
chances of reproducing a bug with C reproducer. Currently leaked
file descriptors may disturb repro execution (e.g. it may act
on a wrong fd).

1 files changed, 14 insertions, 9 deletions

diff --git a/executor/common_bsd.h b/executor/common_bsd.h
index e0beac33f..683e7c140 100644
--- a/executor/common_bsd.h
+++ b/executor/common_bsd.h
@@ -18,11 +18,12 @@
 #endif
 #if SYZ_EXECUTOR || SYZ_USB
 #include <dirent.h>
-static void setup_usb(void)
+
+static const char* setup_usb(void)
 {
 	DIR* dir = opendir("/dev");
 	if (dir == NULL)
-		fail("failed to open /dev");
+		return "failed to open /dev";
 
 	bool have_vhci = false;
 	struct dirent* ent = NULL;
@@ -33,14 +34,14 @@ static void setup_usb(void)
 			continue;
 		char path[1024];
 		snprintf(path, sizeof(path), "/dev/%s", ent->d_name);
-		if (chmod(path, 0666))
-			failmsg("failed to chmod vhci", "path=%s", path);
+		if (chmod(path, 0666)) {
+			closedir(dir);
+			return "failed to chmod /dev/vhci";
+		}
 		have_vhci = true;
 	}
-	if (!have_vhci)
-		fail("don't have any /dev/vhci devices");
-
 	closedir(dir);
+	return have_vhci ? NULL : "don't have any /dev/vhci devices";
 }
 #endif
 
@@ -48,11 +49,14 @@ static void setup_usb(void)
 #include <fcntl.h>
 #include <sys/fault.h>
 #include <sys/stat.h>
-static void setup_fault(void)
+
+static const char* setup_fault(void)
 {
 	if (chmod("/dev/fault", 0666))
-		fail("failed to chmod /dev/fault");
+		return "failed to chmod /dev/fault";
+	return NULL;
 }
+
 static int inject_fault(int nth)
 {
 	struct fault_ioc_enable en;
@@ -71,6 +75,7 @@ static int inject_fault(int nth)
 	return fd;
 }
 #endif
+
 #if SYZ_EXECUTOR
 static int fault_injected(int fd)
 {