when no target is specified, show an extra warning and just build an index.

with this, you can use rembackup on the `target` server to generate a new index if,
for some reason, your local index gets messed up and has to be regenerated

src/apply_indexchanges.rs

@@ -1,4 +1,7 @@
-use std::{fs, io, path::Path};
+use std::{
+    fs, io,
+    path::{Path, PathBuf},
+};
 
 use crate::{indexchanges::IndexChange, repr_file::ReprFile};
 
@@ -8,7 +11,7 @@ use crate::{indexchanges::IndexChange, repr_file::ReprFile};
 pub fn apply_indexchanges(
     source: &Path,
     index: &Path,
-    target: &Path,
+    target: &Option<PathBuf>,
     changes: &Vec<IndexChange>,
 ) -> io::Result<()> {
     let o = apply_indexchanges_int(source, index, target, changes);
@@ -18,7 +21,7 @@ pub fn apply_indexchanges(
 pub fn apply_indexchanges_int(
     source: &Path,
     index: &Path,
-    target: &Path,
+    target: &Option<PathBuf>,
     changes: &Vec<IndexChange>,
 ) -> io::Result<()> {
     let len_width = changes.len().to_string().len();
@@ -32,6 +35,7 @@ pub fn apply_indexchanges_int(
     for (i, change) in changes.iter().enumerate() {
         match change {
             IndexChange::AddDir(dir) => {
+                let ok = if let Some(target) = target {
                     let t = target.join(dir);
                     if let Some(e) = fs::create_dir(&t).err().and_then(|e| {
                         if matches!(e.kind(), io::ErrorKind::AlreadyExists) {
@@ -41,33 +45,65 @@ pub fn apply_indexchanges_int(
                         }
                     }) {
                         eprintln!("\n[warn] couldn't create directory {t:?}: {e}");
+                        false
                     } else {
+                        true
+                    }
+                } else {
+                    true
+                };
+                if ok {
                     fs::create_dir(&index.join(dir))?;
                 }
             }
             IndexChange::AddFile(file, index_file) => {
+                let ok = if let Some(target) = target {
                     let s = source.join(file);
                     let t = target.join(file);
                     if let Err(e) = fs::copy(&s, &t) {
                         eprintln!("\n[warn] couldn't copy file from {s:?} to {t:?}: {e}");
+                        false
+                    } else {
+                        true
                     }
+                } else {
+                    true
+                };
+                if ok {
                     fs::write(&index.join(file), index_file.save())?;
                 }
+            }
             IndexChange::RemoveFile(file) => {
                 let i = index.join(file);
+                let ok = if let Some(target) = target {
                     let t = target.join(file);
                     if let Err(e) = fs::remove_file(&t) {
                         eprintln!("\n[warn] couldn't remove file {t:?}, keeping index file {i:?}: {e:?}\n     If this error keeps appearing, check if the file was deleted on the target system but still exists in the index. if yes, consider manually deleting it.");
+                        false
                     } else {
+                        true
+                    }
+                } else {
+                    true
+                };
+                if ok {
                     fs::remove_file(i)?;
                 }
             }
             IndexChange::RemoveDir(dir) => {
                 let i = index.join(dir);
+                let ok = if let Some(target) = target {
                     let t = target.join(dir);
                     if let Err(e) = fs::remove_dir_all(&t) {
                         eprintln!("\n[warn] couldn't remove directory {t:?}, keeping index files under {i:?}: {e:?}\n     If this error keeps appearing, check if the directory was deleted on the target system but still exists in the index. if yes, consider manually deleting it.");
+                        false
                     } else {
+                        true
+                    }
+                } else {
+                    true
+                };
+                if ok {
                     fs::remove_dir_all(i)?;
                 }
             }

src/args.rs

@@ -5,10 +5,13 @@ use clap::Parser;
 #[derive(Parser)]
 #[command(author, version)]
 pub struct Args {
+    /// the data to be backed up
     #[arg()]
     pub source: PathBuf,
+    /// the index used to determine which files have been modified
     #[arg()]
     pub index: PathBuf,
+    /// where your backup will be stored
     #[arg()]
-    pub target: PathBuf,
+    pub target: Option<PathBuf>,
 }

src/main.rs

@@ -45,6 +45,9 @@ fn main() {
         eprintln!("  -  remove file");
         eprintln!(" [-] remove directory (and all contents!)");
         eprintln!("Press Enter to to apply these actions.");
+        if args.target.is_none() {
+            eprintln!("[WARN] You didn't set a `target` directory!\n[WARN] Be careful not to update your index without actually applying the changes to the `target` filesystem!");
+        }
         // apply changes
         if std::io::stdin().read_line(&mut String::new()).is_ok() {
             match apply_indexchanges(&args.source, &args.index, &args.target, &changes) {