first draft of working user deletion

TODO:
  * remove user group
  * remove shadow entry

src/bin/delete_user.rs

@@ -1,14 +1,31 @@
+use std::path::PathBuf;
+
 extern crate adduser;
 
 extern crate env_logger;
+#[allow(unused_imports)]
+use log::{debug, error, info, trace, warn};
 
 fn main() {
     env_logger::init();
 
     use adduser::api::UserDBWrite;
+    use adduser::api::UserRead;
 
-    let mut db = adduser::UserDBLocal::load_files(adduser::Files::default());
+    let mf = adduser::Files {
+        passwd: Some(PathBuf::from("./passwd")),
+        shadow: Some(PathBuf::from("./shadow")),
+        group: Some(PathBuf::from("./group")),
+    };
 
-    let user = db.delete_user("teste").expect("failed to delete the user");
-    println!("The user {} has been deleted!", user);
+    let mut db = adduser::UserDBLocal::load_files(mf);
+
+    let user_res: Result<adduser::User, adduser::UserLibError> = db.delete_user("teste");
+    match user_res {
+        Ok(u) => info!(
+            "The user <{}> has been deleted! ",
+            u.get_username().unwrap()
+        ),
+        Err(e) => error!("Failed to delete the user: {}", e),
+    }
 }

src/user/mod.rs

@@ -4,6 +4,8 @@ pub mod passwd_fields;
 pub mod shadow_fields;
 
 use crate::userlib::NewFromString;
+#[allow(unused_imports)]
+use log::{debug, error, info, trace, warn};
 use std::convert::TryFrom;
 use std::fmt::{self, Display};
 
@@ -22,6 +24,31 @@ pub struct User {
 }
 
 impl User {
+    /*fn get_nth_line(content: &str, n: u32) -> (String, u64) {
+        use std::io::BufRead;
+        let mut cursor = std::io::Cursor::new(content);
+
+        let mut offset: u64 = 0;
+        let mut tmp = String::new();
+        for _ in 0..n + 1 {
+            tmp = String::new();
+            offset += cursor.read_line(&mut tmp).expect("failed to read line") as u64;
+            //trace!("reading user{}: {}", i, &tmp);
+        }
+        (tmp.trim().to_owned(), offset)
+    }
+    pub(crate) fn is_unchanged_in(&self, content: &str) -> (u64, usize, bool) {
+        let (line, offset) = Self::get_nth_line(content, self.pos);
+        trace!("Olduser:\n\t{}\nNewuser\n\t{}", &self.source, &line);
+        (offset, line.len(), line == self.source)
+    }*/
+    pub fn remove_in(&self, content: &str) -> String {
+        content
+            .split(&self.source)
+            .map(|x| x.trim())
+            .collect::<Vec<&str>>()
+            .join("\n")
+    }
     pub fn username(&mut self, name: String) -> &mut Self {
         self.username = crate::Username {
             username: name.into(),

src/userlib.rs

@@ -9,7 +9,7 @@
 
 use crate::api::GroupRead;
 use crate::api::UserRead;
-use log::{debug, error, info, warn};
+use log::{debug, error, info, trace, warn};
 use std::fs::File;
 use std::io::{BufReader, Read};
 use std::ops::Deref;
@@ -18,14 +18,15 @@ use std::{collections::HashMap, io::Write};
 
 pub struct UserDBLocal {
     source_files: Files,
+    source_hashes: Hashes, // to detect changes
     pub users: HashMap<String, crate::User>,
     pub groups: Vec<crate::Group>,
 }
 
 pub struct Files {
-    passwd: Option<PathBuf>,
-    shadow: Option<PathBuf>,
-    group: Option<PathBuf>,
+    pub passwd: Option<PathBuf>,
+    pub shadow: Option<PathBuf>,
+    pub group: Option<PathBuf>,
 }
 
 impl Default for Files {
@@ -62,6 +63,7 @@ impl Files {
 
 pub struct LockedFileGuard {
     lockfile: PathBuf,
+    path: PathBuf,
     pub(crate) file: File,
 }
 
@@ -69,11 +71,26 @@ impl LockedFileGuard {
     pub fn new(path: &PathBuf) -> Result<Self, crate::userlib_error::UserLibError> {
         let locked = Self::try_to_lock_file(path);
         match locked {
-            Ok((lockfile, file)) => Ok(Self { lockfile, file }),
+            Ok((lockfile, file)) => Ok(Self {
+                lockfile,
+                path: path.to_owned(),
+                file,
+            }),
             Err(e) => Err(e),
         }
     }
 
+    pub fn replace_contents(
+        &mut self,
+        new_content: String,
+    ) -> Result<(), crate::userlib_error::UserLibError> {
+        self.file = File::create(&self.path).expect("Failed to truncate file.");
+        self.file
+            .write_all(&new_content.into_bytes())
+            .expect("Failed to write all users.");
+        Ok(())
+    }
+
     /// This function tries to lock a file in the way other passwd locking mechanisms work.
     ///
     /// * get the pid
@@ -246,6 +263,7 @@ impl UserDBLocal {
             },
             users,
             groups,
+            source_hashes: Hashes::new(&passwd_content, &shadow_content, &group_content),
         };
         res
     }
@@ -272,17 +290,40 @@ impl UserDBLocal {
             source_files: files,
             users,
             groups: string_to(&my_group_lines),
+            source_hashes: Hashes::new(&my_passwd_lines, &my_shadow_lines, &my_group_lines),
         }
     }
 }
 
 use crate::api::UserDBWrite;
 impl UserDBWrite for UserDBLocal {
-    fn delete_user(&mut self, user: &str) -> Result<crate::User, crate::UserLibError> {
-        let res = self.users.remove(user);
-        match res {
-            Some(user) => Ok(user),
-            None => Err(format!("Failed to delete the user {}", user).into()),
+    fn delete_user(&mut self, username: &str) -> Result<crate::User, crate::UserLibError> {
+        let opened = self.source_files.lock_all_get();
+        let (mut locked_p, locked_s, locked_g) = opened.expect("failed to lock files!");
+        // read the files to strings
+        let p = file_to_string(&locked_p.file);
+        let _s = file_to_string(&locked_s.file);
+        let _g = file_to_string(&locked_g.file);
+        {
+            let user_opt = self.users.get(username);
+            let user = match user_opt {
+                Some(user) => user,
+                None => {
+                    return Err(crate::UserLibError::NotFound);
+                }
+            };
+            if self.source_hashes.passwd.has_changed(&p) {
+                error!("The source file has changed. Deleting the user could corrupt the userdatabase. Aborting!");
+            } else {
+                // create the new content of passwd
+                let modified = user.remove_in(&p);
+                // write the new content to the file.
+                locked_p
+                    .replace_contents(modified)
+                    .expect("Error during write to the database. Please doublecheck as the userdatabase could be corrupted");
+                return Ok(user.clone());
+            }
+            Err(format!("The user has been changed {}", username).into())
         }
     }
 
@@ -412,12 +453,39 @@ impl UserDBValidation for UserDBLocal {
     }
 }
 
-fn get_nth_line(path: &File, n: u32) -> String {
-    let lines = file_to_string(path);
-    let line = lines.lines().nth(n as usize);
-    match line {
-        Some(line) => line.to_owned(),
-        None => "".to_owned(),
+pub struct SourceHash {
+    hashvalue: String,
+}
+
+impl SourceHash {
+    pub fn new(src: &str) -> Self {
+        Self {
+            hashvalue: src.to_owned(),
+        }
+    }
+    pub fn has_changed(&self, new: &str) -> bool {
+        trace!(
+            "Old and new lengths: {}, {}",
+            self.hashvalue.len(),
+            new.len()
+        );
+        !self.hashvalue.eq(new)
+    }
+}
+
+pub struct Hashes {
+    pub passwd: SourceHash,
+    pub shadow: SourceHash,
+    pub group: SourceHash,
+}
+
+impl Hashes {
+    pub fn new(passwd: &str, shadow: &str, group: &str) -> Self {
+        Self {
+            passwd: SourceHash::new(passwd),
+            shadow: SourceHash::new(shadow),
+            group: SourceHash::new(group),
+        }
     }
 }