From b74219aafd6977a99de7e52bc47f956b0b45cb01 Mon Sep 17 00:00:00 2001
From: Martin Pitt <martin@piware.de>
Date: Fri, 27 Aug 2021 09:27:37 +0200
Subject: [PATCH] Implement the rest of c-mounts.c in Rust

Use errno crate for human-readable error formatting.
---
 call-c-from-rust/Cargo.toml  |  1 +
 call-c-from-rust/src/main.rs | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/call-c-from-rust/Cargo.toml b/call-c-from-rust/Cargo.toml
index 535c6b9..b01f48a 100644
--- a/call-c-from-rust/Cargo.toml
+++ b/call-c-from-rust/Cargo.toml
@@ -6,3 +6,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+errno = "*"
diff --git a/call-c-from-rust/src/main.rs b/call-c-from-rust/src/main.rs
index b453d81..ee94586 100644
--- a/call-c-from-rust/src/main.rs
+++ b/call-c-from-rust/src/main.rs
@@ -1,10 +1,39 @@
 mod libmount;
 
 use std::ffi::CStr;
+use std::ptr;
+use std::process;
+
+extern crate errno;
+
+fn check_call(error: i32, msg: &str) {
+    if error < 0 {
+        errno::set_errno(errno::Errno(-error));
+        eprintln!("ERROR: {}: {}", msg, errno::errno());
+        process::exit(1);
+    }
+}
 
 fn main() {
     let fstab_path_cstr: &CStr = unsafe { CStr::from_ptr (libmount::mnt_get_fstab_path()) };
     println!("fstab path C-String: {:?}", fstab_path_cstr);
     let fstab_path = fstab_path_cstr.to_str().unwrap(); // may cause UTF-8 decoding error
     println!("fstab path str: {}", fstab_path);
+
+    let mut version = ptr::null();
+    check_call(unsafe { libmount::mnt_get_library_version(ptr::addr_of_mut!(version)) },
+               "Failed to get lib version");
+    println!("libmount version: {:?}", unsafe { CStr::from_ptr(version) });
+
+    let table = unsafe { libmount::mnt_new_table() };
+    check_call(unsafe {libmount::mnt_table_parse_mtab(table, ptr::null()) },
+               "Failed to parse mtab");
+    let mut fs = ptr::null_mut();
+    check_call(unsafe { libmount::mnt_table_first_fs(table, &mut fs) },
+               "Failed to find first fs");
+
+    println!("first fs type: {:?} source: {:?} target: {:?}",
+             unsafe { CStr::from_ptr (libmount::mnt_fs_get_fstype(fs)) },
+             unsafe { CStr::from_ptr (libmount::mnt_fs_get_source(fs)) },
+             unsafe { CStr::from_ptr (libmount::mnt_fs_get_target(fs)) });
 }
-- 
2.39.5