bindings/rust/libflashrom: Create fat rust binding

Create a rust library wrapping libflashrom-sys in a more idiomatic rust
API.

BUG=b:230545739
BRANCH=None
TEST=cargo test

Change-Id: Ie3bcfde40dc475f6a9439ccab8e2446967f7d6dd
Signed-off-by: Evan Benn <evanbenn@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/65281
Reviewed-by: Peter Marheine <pmarheine@chromium.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

bindings/rust/libflashrom/.cargo/config.toml

@@ -0,0 +1,2 @@
+[env]
+RUST_TEST_THREADS = "1"

bindings/rust/libflashrom/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "libflashrom"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+libflashrom-sys = { path = "../libflashrom-sys" }
+libc = "0.2.124"
+regex = "1.5.5"
+once_cell = "1.7.2"
+
+[dev-dependencies]
+rusty-fork = "0.3.0"
+gag = "1"
+
+[build-dependencies]
+pkg-config = "0.3.19"
+cc = "1.0.72"

bindings/rust/libflashrom/build.rs

@@ -0,0 +1,17 @@
+extern crate cc;
+
+fn main() {
+    // pkg_config is needed only to pick up the include path for log.c to use.
+    // libflashrom-sys tells cargo how to link to libflashrom.
+    let flashrom = pkg_config::Config::new()
+        .cargo_metadata(false)
+        .probe("flashrom")
+        .unwrap();
+    let mut log_c = cc::Build::new();
+    log_c.file("src/log.c");
+    for p in flashrom.include_paths {
+        log_c.include(p);
+    }
+    log_c.compile("log.o");
+    println!("cargo:rerun-if-changed=src/log.c");
+}

bindings/rust/libflashrom/src/log.c

@@ -0,0 +1,61 @@
+/*
+ * This file is part of the flashrom project.
+ *
+ * Copyright (C) 2022 The Chromium OS Authors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "libflashrom.h"
+
+void log_rust(enum flashrom_log_level level, const char *format);
+
+// LOG_LEVEL = 0 (ERROR) means no messages are printed.
+enum flashrom_log_level current_level = 0;
+
+static int log_c(enum flashrom_log_level level, const char *format, va_list ap)
+{
+	static char *buf = NULL;
+	static int len = 0;
+	if (level >= current_level) {
+		return 0;
+	}
+
+	va_list ap2;
+	va_copy(ap2, ap);
+	// when buf is NULL, len is zero and this will not write to buf
+	int req_len = vsnprintf(buf, len, format, ap2);
+	va_end(ap2);
+
+	if (req_len > len) {
+		char *new_buf = realloc(buf, req_len + 1);
+		if (!new_buf) {
+			return 0;
+		}
+		buf = new_buf;
+		len = req_len + 1;
+		req_len = vsnprintf(buf, len, format, ap);
+	}
+
+	if (req_len > 0) {
+		log_rust(level, buf);
+	}
+	return req_len;
+}
+
+void set_log_callback()
+{
+	flashrom_set_log_callback(log_c);
+}