CHROMIUM: avl_tool: more gracefully handle termination by SIGINT

Since interrupting the test process may be dangerous (leaving the flash
in an inconsistent state), we'll catch SIGINT and print a warning the
first time, also using it as a signal that we should stop at a
convenient time. Any following SIGINT will be handled as normal (killing
the process).

BUG=b:143251344
TEST=Run tool and verify it exits after a test with a single ^C, exits
     immediately given two.
BRANCH=None

Original-Cq-Depend: chromium:2059548
Original-Change-Id: Ib8a7799cba6dbca57dc7f1d3c87521f132c21818
Original-Signed-off-by: Peter Marheine <pmarheine@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/flashrom/+/2050050
Original-Tested-by: Edward O'Callaghan <quasisec@chromium.org>
Original-Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>

Change-Id: If43aea0580fcc7e698daad2ffe085a3c9da5bc41
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/49915
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/util/flashrom_tester/src/main.rs b/util/flashrom_tester/src/main.rs
index 1cc525e6..e589ee1e 100644
--- a/util/flashrom_tester/src/main.rs
+++ b/util/flashrom_tester/src/main.rs
@@ -42,6 +42,7 @@ use clap::{App, Arg};
 use flashrom::FlashChip;
 use flashrom_tester::{tester, tests};
 use std::path::PathBuf;
+use std::sync::atomic::AtomicBool;
 
 pub mod built_info {
     include!(concat!(env!("OUT_DIR"), "/built.rs"));
@@ -136,8 +137,45 @@ fn main() {
         print_layout,
         output_format,
         test_names,
+        Some(handle_sigint()),
     ) {
         eprintln!("Failed to run tests: {:?}", e);
         std::process::exit(1);
     }
 }
+
+/// Catch exactly one SIGINT, printing a message in response and setting a flag.
+///
+/// The returned value is false by default, becoming true after a SIGINT is
+/// trapped.
+///
+/// Once a signal is trapped, the default behavior is restored (terminating
+/// the process) for future signals.
+fn handle_sigint() -> &'static AtomicBool {
+    use nix::libc::c_int;
+    use nix::sys::signal::{self, SigHandler, Signal};
+    use std::sync::atomic::Ordering;
+
+    unsafe {
+        let _ = signal::signal(Signal::SIGINT, SigHandler::Handler(sigint_handler));
+    }
+    static TERMINATE_FLAG: AtomicBool = AtomicBool::new(false);
+
+    extern "C" fn sigint_handler(_: c_int) {
+        const STDERR_FILENO: c_int = 2;
+        static MESSAGE: &[u8] = b"
+WARNING: terminating tests prematurely may leave Flash in an inconsistent state,
+rendering your machine unbootable. Testing will end on completion of the current
+test, or press ^C again to exit immediately (possibly bricking your machine).
+";
+
+        // Use raw write() because signal-safety is a very hard problem
+        let _ = nix::unistd::write(STDERR_FILENO, MESSAGE);
+        unsafe {
+            let _ = signal::signal(Signal::SIGINT, SigHandler::SigDfl);
+        }
+        TERMINATE_FLAG.store(true, Ordering::Release);
+    }
+
+    &TERMINATE_FLAG
+}