libopenbsd(3): adds pledge(2) and unveil(2) support for Rust; Makefile, include: adds conditional compilation

Makefile

@@ -16,6 +16,9 @@
 DESTDIR ?= dist
 PREFIX ?= /usr/local
 
+# for conditionally compiling OS features
+OS != uname
+
 # normalized prefix
 PREFIX_N != dirname $(PREFIX)/.
 MANDIR != test $(PREFIX_N) = / && printf '/usr/share/man\n' \
@@ -26,8 +29,8 @@ SYSEXITS != printf '\043include <sysexits.h>\n' | cpp -M - | tr ' ' '\n' \
 CC ?= cc
 RUSTC ?= rustc
 RUSTFLAGS += --extern getopt=build/o/libgetopt.rlib \
-	--extern sysexits=build/o/libsysexits.rlib \
-	--extern strerror=build/o/libstrerror.rlib
+	--extern strerror=build/o/libstrerror.rlib \
+	--extern sysexits=build/o/libsysexits.rlib
 CFLAGS += -I$(SYSEXITS)
 
 # testing requires the absolute path to the bin directory set
@@ -74,9 +77,13 @@ docs: docs/ build
 		"s/X\.X\.X/$$(git describe --tags --long | cut -d'-' -f1)/g")"; \
 		sed "s/$$original/$$title/g" <"$$file" >"build/$$file"; done
 
+
+# include OS feature libraries for compilation
+include include/$(OS).mk
+
 .PHONY: rustlibs
-rustlibs: build/o/libsysexits.rlib build/o/libgetopt.rlib \
-	build/o/libstrerror.rlib
+rustlibs: build/o/libgetopt.rlib build/o/libstrerror.rlib \
+	 build/o/libsysexits.rlib $(OSLIB)
 
 build/o/libgetopt.rlib: build src/libgetopt.rs
 	$(RUSTC) $(RUSTFLAGS) --crate-type=lib --crate-name=getopt \

include/FreeBSD.mk

@@ -0,0 +1,6 @@
+# Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
+# SPDX-License-Identifier: FSFAP
+#
+# Copying and distribution of this file, with or without modification, are
+# permitted in any medium without royalty provided the copyright notice and this
+# notice are preserved.  This file is offered as-is, without any warranty.

include/Linux.mk

@@ -0,0 +1,6 @@
+# Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
+# SPDX-License-Identifier: FSFAP
+#
+# Copying and distribution of this file, with or without modification, are
+# permitted in any medium without royalty provided the copyright notice and this
+# notice are preserved.  This file is offered as-is, without any warranty.

include/OpenBSD.mk

@@ -0,0 +1,13 @@
+# Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
+# SPDX-License-Identifier: FSFAP
+#
+# Copying and distribution of this file, with or without modification, are
+# permitted in any medium without royalty provided the copyright notice and this
+# notice are preserved.  This file is offered as-is, without any warranty.
+
+OSLIB = build/o/libopenbsd.rlib
+RUSTFLAGS += --extern openbsd=$(OSLIB)
+
+$(OSLIB): src/libopenbsd.rs
+	$(RUSTC) $(RUSTFLAGS) --crate-type=lib --crate-name=openbsd \
+		-o $@ src/libopenbsd.rs

src/libopenbsd.rs

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 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 Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+use std::{
+	ffi::{ CString, c_int },
+	io::Error,
+	ptr::null,
+};
+
+mod openbsd {
+	use std::ffi::{ c_char, c_int };
+	extern "C" {
+		pub fn pledge(arg1: *const c_char, arg2: *const c_char) -> c_int;
+
+		pub fn unveil(arg1: *const c_char, arg2: *const c_char) -> c_int;
+
+		pub fn __errno() -> *mut c_int;
+	}
+}
+
+pub struct Promises(*const i8);
+
+impl Promises {
+	pub fn new(promises: &str) -> Self {
+		let p = CString::new(promises).unwrap();
+
+		Promises(p.into_raw() as *const i8)
+	}
+}
+
+pub fn pledge(
+	promises: Option<Promises>, execpromises: Option<Promises>
+) -> Result<(), Error> {
+	/* From pledge(2):
+	 *
+	 * Passing NULL to promises or execpromises specifies to not change
+	 * the current value. */
+	let arg1 = promises.unwrap_or(Promises(null())).0;
+	let arg2 = execpromises.unwrap_or(Promises(null())).0;
+
+	unsafe {
+		match openbsd::pledge(arg1, arg2) {
+			-1 => Err(Error::from_raw_os_error(*openbsd::__errno())),
+			0 => Ok(()),
+			_ => panic!(), /* unreachable */
+		}
+	}
+}
+
+pub struct UnveilPerms(CString);
+
+impl UnveilPerms {
+	pub fn new(permissions: Vec<char>) -> Self {
+		if permissions.is_empty() {
+			return UnveilPerms(CString::new("").unwrap());
+		}
+
+		UnveilPerms(
+			CString::new(permissions.iter().collect::<String>()).unwrap()
+		)
+	}
+}
+
+pub fn unveil(path: Option<&str>, permissions: Option<UnveilPerms>) -> c_int {
+	let path_c = path.map(CString::new).map(Result::unwrap);
+	let arg1 = path_c.map(|p| p.into_raw() as *const i8).unwrap_or(null());
+
+	let arg2 = permissions
+		.map(|p| p.0.into_raw() as *const i8)
+		.unwrap_or(null());
+
+	unsafe { openbsd::unveil(arg1, arg2) }
+}