dd: fix GNU test 'dd/skip-seek-past-dev'

src/uu/dd/src/dd.rs

@@ -43,7 +43,7 @@ use std::time;
 use clap::{crate_version, Arg, Command};
 use gcd::Gcd;
 use uucore::display::Quotable;
-use uucore::error::{FromIo, UResult};
+use uucore::error::{set_exit_code, FromIo, UResult};
 use uucore::{format_usage, help_about, help_section, help_usage, show_error};
 
 const ABOUT: &str = help_about!("dd.md");
@@ -143,14 +143,25 @@ impl Source {
                 Err(e) => Err(e),
             },
             #[cfg(unix)]
-            Self::StdinFile(f) => match io::copy(&mut f.take(n), &mut io::sink()) {
-                Ok(m) if m < n => {
-                    show_error!("'standard input': cannot skip to specified offset");
-                    Ok(m)
+            Self::StdinFile(f) => {
+                if let Ok(Some(len)) = try_get_len_of_block_device(f) {
+                    if len < n {
+                        // GNU compatibility:
+                        // this case prints the stats but sets the exit code to 1
+                        show_error!("'standard input': cannot skip: Invalid argument");
+                        set_exit_code(1);
+                        return Ok(len);
+                    }
                 }
-                Ok(m) => Ok(m),
-                Err(e) => Err(e),
-            },
+                match io::copy(&mut f.take(n), &mut io::sink()) {
+                    Ok(m) if m < n => {
+                        show_error!("'standard input': cannot skip to specified offset");
+                        Ok(m)
+                    }
+                    Ok(m) => Ok(m),
+                    Err(e) => Err(e),
+                }
+            }
             Self::File(f) => f.seek(io::SeekFrom::Start(n)),
             #[cfg(unix)]
             Self::Fifo(f) => io::copy(&mut f.take(n), &mut io::sink()),
@@ -426,7 +437,18 @@ impl Dest {
     fn seek(&mut self, n: u64) -> io::Result<u64> {
         match self {
             Self::Stdout(stdout) => io::copy(&mut io::repeat(0).take(n), stdout),
-            Self::File(f, _) => f.seek(io::SeekFrom::Start(n)),
+            Self::File(f, _) => {
+                if let Ok(Some(len)) = try_get_len_of_block_device(f) {
+                    if len < n {
+                        // GNU compatibility:
+                        // this case prints the stats but sets the exit code to 1
+                        show_error!("'standard output': cannot seek: Invalid argument");
+                        set_exit_code(1);
+                        return Ok(len);
+                    }
+                }
+                f.seek(io::SeekFrom::Start(n))
+            }
             #[cfg(unix)]
             Self::Fifo(f) => {
                 // Seeking in a named pipe means *reading* from the pipe.
@@ -925,6 +947,23 @@ fn is_stdout_redirected_to_seekable_file() -> bool {
     }
 }
 
+/// Try to get the len if it is a block device
+fn try_get_len_of_block_device(file: &mut File) -> io::Result<Option<u64>> {
+    #[cfg(not(unix))]
+    return Ok(None);
+
+    let ftype = file.metadata()?.file_type();
+    #[cfg(unix)]
+    if !ftype.is_block_device() {
+        return Ok(None);
+    }
+
+    // FIXME: this can be replaced by file.stream_len() when stable.
+    let len = file.seek(SeekFrom::End(0))?;
+    file.rewind()?;
+    Ok(Some(len))
+}
+
 /// Decide whether the named file is a named pipe, also known as a FIFO.
 #[cfg(unix)]
 fn is_fifo(filename: &str) -> bool {