dlopen

.github/workflows/rust.yml

@@ -4,6 +4,9 @@ name: Continuous integration
 
 jobs:
   check:
+    strategy:
+      matrix:
+        features: [ libsystemd-sys, open ]
     name: Check
     runs-on: ubuntu-latest
     steps:
@@ -20,8 +23,12 @@ jobs:
       - uses: actions-rs/cargo@v1
         with:
           command: check
+          args: --no-default-features --features ${{ matrix.features }}
 
   test:
+    strategy:
+      matrix:
+        features: [ libsystemd-sys, open ]
     name: Test Suite
     runs-on: ubuntu-latest
     steps:
@@ -38,6 +45,7 @@ jobs:
       - uses: actions-rs/cargo@v1
         with:
           command: test
+          args: --no-default-features --features ${{ matrix.features }}
         timeout-minutes: 6
 
   fmt:

Cargo.toml

@@ -9,15 +9,20 @@ documentation = "https://docs.rs/journald"
 edition = "2018"
 
 [features]
-default = []
-systemd_v245 = [ "libsystemd-sys/systemd_v245" ]
+default = [ "libsystemd-sys" ]
+systemd_v245 = [ "libsystemd-sys", "libsystemd-sys/systemd_v245" ]
+dl_namespace = [ "open" ]
+open = [ "dlopen", "dlopen_derive" ]
+
 
 [dependencies]
 cstr-argument = "~0.0"
 libc = "~0.2"
-libsystemd-sys = "0.9"
 log = "~0.4"
 utf8-cstr = "~0.1"
+libsystemd-sys = { version = "0.9", optional = true }
+dlopen = { version = "0.1", optional = true }
+dlopen_derive = { version = "0.1", optional = true }
 
 [dependencies.serde]
 package = "serde"

src/journal_writer.rs

@@ -1,5 +1,6 @@
-use libc::c_int;
-use libsystemd_sys::{c_void, const_iovec, journal as ffi, size_t};
+use libc::{c_int, c_void, size_t};
+#[cfg(feature = "libsystemd-sys")]
+use libsystemd_sys::{const_iovec, journal as ffi};
 
 use super::{JournalEntry, Result};
 use crate::ffi_result;
@@ -13,12 +14,18 @@ pub fn submit(entry: &JournalEntry) -> Result<()> {
 
 	let fields_iovec = array_to_iovecs(&fields.iter().map(|v| v.as_str()).collect::<Vec<&str>>());
 
-	unsafe {
-		ffi_result(ffi::sd_journal_sendv(
-			fields_iovec.as_ptr(),
-			fields_iovec.len() as c_int,
-		))?
-	};
+	ffi_result(unsafe {
+		#[cfg(feature = "libsystemd-sys")]
+		{
+			ffi::sd_journal_sendv(fields_iovec.as_ptr(), fields_iovec.len() as c_int)
+		}
+
+		#[cfg(feature = "open")]
+		{
+			crate::open_systemd()?
+				.sd_journal_sendv(fields_iovec.as_ptr(), fields_iovec.len() as c_int)
+		}
+	})?;
 
 	Ok(())
 }
@@ -31,3 +38,34 @@ pub fn array_to_iovecs(args: &[&str]) -> Vec<const_iovec> {
 		})
 		.collect()
 }
+
+// START COPY FROM LIBSYSTEMD_SYS
+/// Helper type to mark functions systemd functions that promise not to modify the underying iovec
+/// data.  There is no corresponding type in libc, so their function signatures take *const iovec,
+/// which technically allow iov_base to be modified.  However, const_iovec provides the same ABI, so
+/// it can be used to make the function interface easier to work with.
+#[cfg(feature = "open")]
+#[repr(C)]
+pub struct const_iovec {
+	pub iov_base: *const c_void,
+	pub iov_len: size_t,
+}
+
+#[cfg(feature = "open")]
+impl const_iovec {
+	///
+	/// # Safety
+	///
+	/// Lifetime of `arg` must be long enough to cover future dereferences of the internal
+	/// `Self::iov_base` pointer.
+	pub unsafe fn from_str<T>(arg: T) -> Self
+	where
+		T: AsRef<str>,
+	{
+		const_iovec {
+			iov_base: arg.as_ref().as_ptr() as *const c_void,
+			iov_len: arg.as_ref().len() as size_t,
+		}
+	}
+}
+// END COPY FROM LIBSYSTEMD_SYS