Add function to jump to beginning of current boot

src/lib.rs

@@ -1,4 +1,5 @@
 pub use std::io::{Error, Result};
+use std::mem::MaybeUninit;
 
 use libsystemd_sys as ffi;
 
@@ -34,3 +35,14 @@ pub mod reader;
 
 #[path = "journal_writer.rs"]
 pub mod writer;
+
+pub struct Id(pub(crate) libsystemd_sys::id128::sd_id128_t);
+
+impl Id {
+	pub fn get_boot_id() -> Result<Self> {
+		let mut id = MaybeUninit::uninit();
+
+		unsafe { ffi_result(ffi::id128::sd_id128_get_boot(id.as_mut_ptr())) }?;
+		Ok(Self(unsafe { id.assume_init() }))
+	}
+}

src/reader/mod.rs

@@ -70,6 +70,8 @@ pub enum JournalSeek {
 	Head,
 	Tail,
 	Cursor(String),
+	/// Seek to beginning of the current boot process
+	ThisBoot,
 }
 
 /// Wakeup event types
@@ -270,6 +272,11 @@ impl JournalReader {
 					::std::ffi::CString::new(cur)?.as_ptr(),
 				))?
 			},
+			JournalSeek::ThisBoot => {
+				let boot_id = crate::Id::get_boot_id()?;
+
+				unsafe { ffi_result(ffi::sd_journal_seek_monotonic_usec(self.j, boot_id.0, 0)) }?
+			}
 		};
 
 		Ok(())