bin: offset should add to skip, not override it

CHANGELOG.md

@@ -1,5 +1,9 @@
 # unreleased
 
+## Changes
+
+- Breaking change (binary): setting the `-o/--display-offset` flag no longer overrides the value set by `--skip` [#115](https://github.com/sharkdp/hexyl/issues/115). The first displayed address is now the sum of the two values - this matches the behaviour of `xxd`.
+
 ## Features
 
 - Allow relative and negative byte offsets (e.g. `hexyl --skip=-1block`), see #99 (@ErichDonGubler)

src/bin/hexyl.rs

@@ -155,7 +155,7 @@ fn run() -> Result<(), AnyhowError> {
         })
         .transpose()?;
 
-    let default_display_offset = if let Some(ByteOffset { kind, value }) = skip_arg {
+    let skip_offset = if let Some(ByteOffset { kind, value }) = skip_arg {
         let value = value.into_inner();
         reader.seek(match kind {
             ByteOffsetKind::ForwardFromBeginning | ByteOffsetKind::ForwardFromLastOffset => {
@@ -203,7 +203,7 @@ fn run() -> Result<(), AnyhowError> {
 
     let squeeze = !matches.is_present("nosqueezing");
 
-    let display_offset = matches
+    let display_offset: u64 = matches
         .value_of("display_offset")
         .map(|s| {
             parse_byte_count(s).context(anyhow!(
@@ -212,14 +212,14 @@ fn run() -> Result<(), AnyhowError> {
             ))
         })
         .transpose()?
-        .unwrap_or(default_display_offset)
+        .unwrap_or(0)
         .into();
 
     let stdout = io::stdout();
     let mut stdout_lock = stdout.lock();
 
     let mut printer = Printer::new(&mut stdout_lock, show_color, border_style, squeeze);
-    printer.display_offset(display_offset);
+    printer.display_offset(skip_offset + display_offset);
     printer.print_all(&mut reader).map_err(|e| anyhow!(e))?;
 
     Ok(())

tests/integration_tests.rs

@@ -94,3 +94,20 @@ fn display_offset() {
              └────────┴─────────────────────────┴─────────────────────────┴────────┴────────┘\n",
         );
 }
+
+#[test]
+fn display_offset_and_skip() {
+    hexyl()
+        .arg("hello_world_elf64")
+        .arg("--color=never")
+        .arg("--display-offset=0x20")
+        .arg("--skip=0x10")
+        .arg("--length=0x10")
+        .assert()
+        .success()
+        .stdout(
+            "┌────────┬─────────────────────────┬─────────────────────────┬────────┬────────┐\n\
+             │00000030│ 02 00 3e 00 01 00 00 00 ┊ 00 10 40 00 00 00 00 00 │•0>0•000┊0•@00000│\n\
+             └────────┴─────────────────────────┴─────────────────────────┴────────┴────────┘\n",
+        );
+}