[INFO] fetching crate ffprobe 0.1.0... [INFO] testing ffprobe-0.1.0 against master#99e3aef02079e9c10583638520cd0c134dc3a01d for pr-85530 [INFO] extracting crate ffprobe 0.1.0 into /workspace/builds/worker-1/source [INFO] validating manifest of crates.io crate ffprobe 0.1.0 on toolchain 99e3aef02079e9c10583638520cd0c134dc3a01d [INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+99e3aef02079e9c10583638520cd0c134dc3a01d" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking crates.io crate ffprobe 0.1.0 [INFO] finished tweaking crates.io crate ffprobe 0.1.0 [INFO] tweaked toml for crates.io crate ffprobe 0.1.0 written to /workspace/builds/worker-1/source/Cargo.toml [INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+99e3aef02079e9c10583638520cd0c134dc3a01d" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }` [INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+99e3aef02079e9c10583638520cd0c134dc3a01d" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+99e3aef02079e9c10583638520cd0c134dc3a01d" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] 8215d4a2b81bd4310d5cf451e44bbbe96a5a300d9e7860af98d75b0f5321aef3 [INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap. [INFO] running `Command { std: "docker" "start" "-a" "8215d4a2b81bd4310d5cf451e44bbbe96a5a300d9e7860af98d75b0f5321aef3", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "8215d4a2b81bd4310d5cf451e44bbbe96a5a300d9e7860af98d75b0f5321aef3", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "8215d4a2b81bd4310d5cf451e44bbbe96a5a300d9e7860af98d75b0f5321aef3", kill_on_drop: false }` [INFO] [stdout] 8215d4a2b81bd4310d5cf451e44bbbe96a5a300d9e7860af98d75b0f5321aef3 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+99e3aef02079e9c10583638520cd0c134dc3a01d" "build" "--frozen" "--message-format=json", kill_on_drop: false }` [INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap. [INFO] [stdout] fe6c557b90c6e2c5160b609413d743cd96aa04fac94cecc92bf3a1c9f827ea94 [INFO] running `Command { std: "docker" "start" "-a" "fe6c557b90c6e2c5160b609413d743cd96aa04fac94cecc92bf3a1c9f827ea94", kill_on_drop: false }` [INFO] [stderr] Compiling ryu v1.0.5 [INFO] [stderr] Compiling serde v1.0.126 [INFO] [stderr] Compiling itoa v0.4.7 [INFO] [stderr] Compiling syn v1.0.72 [INFO] [stderr] Compiling serde_derive v1.0.126 [INFO] [stderr] Compiling serde_json v1.0.64 [INFO] [stderr] Compiling ffprobe v0.1.0 (/opt/rustwide/workdir) [INFO] [stderr] Finished dev [unoptimized + debuginfo] target(s) in 34.02s [INFO] running `Command { std: "docker" "inspect" "fe6c557b90c6e2c5160b609413d743cd96aa04fac94cecc92bf3a1c9f827ea94", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "fe6c557b90c6e2c5160b609413d743cd96aa04fac94cecc92bf3a1c9f827ea94", kill_on_drop: false }` [INFO] [stdout] fe6c557b90c6e2c5160b609413d743cd96aa04fac94cecc92bf3a1c9f827ea94 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+99e3aef02079e9c10583638520cd0c134dc3a01d" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] 9adc4fcd203b03910e356de14a226add15fdd090fd69ade44695bd33404c9d9b [INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap. [INFO] running `Command { std: "docker" "start" "-a" "9adc4fcd203b03910e356de14a226add15fdd090fd69ade44695bd33404c9d9b", kill_on_drop: false }` [INFO] [stderr] Compiling ffprobe v0.1.0 (/opt/rustwide/workdir) [INFO] [stderr] Finished test [unoptimized + debuginfo] target(s) in 2.96s [INFO] running `Command { std: "docker" "inspect" "9adc4fcd203b03910e356de14a226add15fdd090fd69ade44695bd33404c9d9b", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "9adc4fcd203b03910e356de14a226add15fdd090fd69ade44695bd33404c9d9b", kill_on_drop: false }` [INFO] [stdout] 9adc4fcd203b03910e356de14a226add15fdd090fd69ade44695bd33404c9d9b [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+99e3aef02079e9c10583638520cd0c134dc3a01d" "test" "--frozen", kill_on_drop: false }` [INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap. [INFO] [stdout] e216d15da13ed34b6ab9c2dc3dd8eac4357758fd3b15ecad2c373b96f8fd3f4b [INFO] running `Command { std: "docker" "start" "-a" "e216d15da13ed34b6ab9c2dc3dd8eac4357758fd3b15ecad2c373b96f8fd3f4b", kill_on_drop: false }` [INFO] [stderr] Finished test [unoptimized + debuginfo] target(s) in 0.02s [INFO] [stdout] [INFO] [stderr] Running unittests (/opt/rustwide/target/debug/deps/ffprobe-032ca0dab990b690) [INFO] [stdout] running 0 tests [INFO] [stderr] Running tests/verify.rs (/opt/rustwide/target/debug/deps/verify-9e55aea42222af24) [INFO] [stdout] [INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] running 1 test [INFO] [stderr] error: test failed, to rerun pass '--test verify' [INFO] [stdout] test download_and_probe ... FAILED [INFO] [stdout] [INFO] [stdout] failures: [INFO] [stdout] [INFO] [stdout] ---- download_and_probe stdout ---- [INFO] [stdout] Testing url http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/images/BigBuckBunny.jpg [INFO] [stdout] thread 'download_and_probe' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 30, kind: Other, message: "Read-only file system" }', tests/verify.rs:4:35 [INFO] [stdout] stack backtrace: [INFO] [stdout] 0: 0x55556305be50 - std::backtrace_rs::backtrace::libunwind::trace::h1037ca7e6eeef65c [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/../../backtrace/src/backtrace/libunwind.rs:90:5 [INFO] [stdout] 1: 0x55556305be50 - std::backtrace_rs::backtrace::trace_unsynchronized::haaefac1bc3669450 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5 [INFO] [stdout] 2: 0x55556305be50 - std::sys_common::backtrace::_print_fmt::h863a6f5e6d995885 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/sys_common/backtrace.rs:67:5 [INFO] [stdout] 3: 0x55556305be50 - ::fmt::h767e17e1aa7df6a8 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/sys_common/backtrace.rs:46:22 [INFO] [stdout] 4: 0x55556307ea8c - core::fmt::write::h7aa6cd0067dca82a [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/core/src/fmt/mod.rs:1110:17 [INFO] [stdout] 5: 0x555563058aa5 - std::io::Write::write_fmt::h6f1a9b91376a1376 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/io/mod.rs:1584:15 [INFO] [stdout] 6: 0x55556305dfbb - std::sys_common::backtrace::_print::h2769edb26a7eb606 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/sys_common/backtrace.rs:49:5 [INFO] [stdout] 7: 0x55556305dfbb - std::sys_common::backtrace::print::ha71f3549862b4cb6 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/sys_common/backtrace.rs:36:9 [INFO] [stdout] 8: 0x55556305dfbb - std::panicking::default_hook::{{closure}}::h95488a3bade217f6 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panicking.rs:208:50 [INFO] [stdout] 9: 0x55556305dacc - std::panicking::default_hook::h290aa602c0fb11df [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panicking.rs:222:9 [INFO] [stdout] 10: 0x55556305e661 - std::panicking::rust_panic_with_hook::hf32c4fa635e215f2 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panicking.rs:622:17 [INFO] [stdout] 11: 0x55556305e167 - std::panicking::begin_panic_handler::{{closure}}::h95197ccd88846f7a [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panicking.rs:519:13 [INFO] [stdout] 12: 0x55556305c32c - std::sys_common::backtrace::__rust_end_short_backtrace::h7641df9566f7b7d0 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/sys_common/backtrace.rs:141:18 [INFO] [stdout] 13: 0x55556305e0c9 - rust_begin_unwind [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panicking.rs:515:5 [INFO] [stdout] 14: 0x555562fb64b1 - core::panicking::panic_fmt::hbe99dddd3092ba3c [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/core/src/panicking.rs:92:14 [INFO] [stdout] 15: 0x555562fb65a3 - core::result::unwrap_failed::hf79563fef9d11ab8 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/core/src/result.rs:1355:5 [INFO] [stdout] 16: 0x555562ff7807 - core::result::Result::unwrap::h4fb114d7243c7105 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/core/src/result.rs:1037:23 [INFO] [stdout] 17: 0x555562fec6f9 - verify::download::h963f0a199d5f7e0e [INFO] [stdout] at /opt/rustwide/workdir/tests/verify.rs:4:9 [INFO] [stdout] 18: 0x555562feccc1 - verify::check::hef61cf07e457d94c [INFO] [stdout] at /opt/rustwide/workdir/tests/verify.rs:40:16 [INFO] [stdout] 19: 0x555562fecf19 - verify::download_and_probe::ha33253fa38551b38 [INFO] [stdout] at /opt/rustwide/workdir/tests/verify.rs:58:9 [INFO] [stdout] 20: 0x555562fecd3a - verify::download_and_probe::{{closure}}::h23ea7f4ee829698b [INFO] [stdout] at /opt/rustwide/workdir/tests/verify.rs:45:1 [INFO] [stdout] 21: 0x555562ff362e - core::ops::function::FnOnce::call_once::hd9bc06b473d2f3dc [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/core/src/ops/function.rs:227:5 [INFO] [stdout] 22: 0x555563032bc3 - core::ops::function::FnOnce::call_once::h673fbe3f96486fd2 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/core/src/ops/function.rs:227:5 [INFO] [stdout] 23: 0x555563032bc3 - test::__rust_begin_short_backtrace::h8eedc24e104ef6a0 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/test/src/lib.rs:577:5 [INFO] [stdout] 24: 0x555563031670 - as core::ops::function::FnOnce>::call_once::h028d0969d3f94d78 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/alloc/src/boxed.rs:1575:9 [INFO] [stdout] 25: 0x555563031670 - as core::ops::function::FnOnce<()>>::call_once::h7634b01590b1722b [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panic.rs:346:9 [INFO] [stdout] 26: 0x555563031670 - std::panicking::try::do_call::hf74f869706dec63b [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panicking.rs:401:40 [INFO] [stdout] 27: 0x555563031670 - std::panicking::try::hd0b7346ebfaaae44 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panicking.rs:365:19 [INFO] [stdout] 28: 0x555563031670 - std::panic::catch_unwind::hdbf6904f7c253080 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panic.rs:433:14 [INFO] [stdout] 29: 0x555563031670 - test::run_test_in_process::h87e95a014ac91067 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/test/src/lib.rs:600:18 [INFO] [stdout] 30: 0x555563031670 - test::run_test::run_test_inner::{{closure}}::hdd69ae44aaab3470 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/test/src/lib.rs:492:39 [INFO] [stdout] 31: 0x55556300c942 - test::run_test::run_test_inner::{{closure}}::hc159305704d5b68a [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/test/src/lib.rs:519:37 [INFO] [stdout] 32: 0x55556300c942 - std::sys_common::backtrace::__rust_begin_short_backtrace::h33d8a8ad5f788fcc [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/sys_common/backtrace.rs:125:18 [INFO] [stdout] 33: 0x5555630106b8 - std::thread::Builder::spawn_unchecked::{{closure}}::{{closure}}::h6181011ddf4b8353 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/thread/mod.rs:481:17 [INFO] [stdout] 34: 0x5555630106b8 - as core::ops::function::FnOnce<()>>::call_once::hf924ea0a0f25a1c0 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panic.rs:346:9 [INFO] [stdout] 35: 0x5555630106b8 - std::panicking::try::do_call::hd58061792d05fa5c [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panicking.rs:401:40 [INFO] [stdout] 36: 0x5555630106b8 - std::panicking::try::h3080747417e5af37 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panicking.rs:365:19 [INFO] [stdout] 37: 0x5555630106b8 - std::panic::catch_unwind::hfeba515dcf36cb66 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/panic.rs:433:14 [INFO] [stdout] 38: 0x5555630106b8 - std::thread::Builder::spawn_unchecked::{{closure}}::h29d57a62faff749b [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/thread/mod.rs:480:30 [INFO] [stdout] 39: 0x5555630106b8 - core::ops::function::FnOnce::call_once{{vtable.shim}}::h44709d312d2a9c59 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/core/src/ops/function.rs:227:5 [INFO] [stdout] 40: 0x5555630633c7 - as core::ops::function::FnOnce>::call_once::h902e2cf6655e1b0c [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/alloc/src/boxed.rs:1575:9 [INFO] [stdout] 41: 0x5555630633c7 - as core::ops::function::FnOnce>::call_once::h893a5452154309d1 [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/alloc/src/boxed.rs:1575:9 [INFO] [stdout] 42: 0x5555630633c7 - std::sys::unix::thread::Thread::new::thread_start::hdedcb57c96ab37cd [INFO] [stdout] at /rustc/99e3aef02079e9c10583638520cd0c134dc3a01d/library/std/src/sys/unix/thread.rs:71:17 [INFO] [stdout] 43: 0x7f772536f609 - start_thread [INFO] [stdout] 44: 0x7f7725141293 - clone [INFO] [stdout] 45: 0x0 - [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] failures: [INFO] [stdout] download_and_probe [INFO] [stdout] [INFO] [stdout] test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.03s [INFO] [stdout] [INFO] running `Command { std: "docker" "inspect" "e216d15da13ed34b6ab9c2dc3dd8eac4357758fd3b15ecad2c373b96f8fd3f4b", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "e216d15da13ed34b6ab9c2dc3dd8eac4357758fd3b15ecad2c373b96f8fd3f4b", kill_on_drop: false }` [INFO] [stdout] e216d15da13ed34b6ab9c2dc3dd8eac4357758fd3b15ecad2c373b96f8fd3f4b