Implement e (execute) command

src/sed/compiler.rs

@@ -1304,6 +1304,104 @@ fn compile_text_command_posix(
     Ok(CommandHandling::Continue)
 }
 
+// Handles e
+// With no argument, the command executes the pattern space as a shell
+// command at runtime. With an argument, the rest of the line is the
+// command to run, following the same escape and backslash-newline
+// continuation rules as the GNU a/c/i text argument.
+fn compile_execute_command(
+    lines: &mut ScriptLineProvider,
+    line: &mut ScriptCharProvider,
+    cmd: &mut Command,
+    context: &mut ProcessingContext,
+) -> UResult<CommandHandling> {
+    if context.posix || context.sandbox {
+        return compilation_error(
+            lines,
+            line,
+            "the 'e' command is not allowed with --posix or --sandbox",
+        );
+    }
+
+    line.advance(); // Skip the command character.
+    line.eat_spaces(); // Skip any leading whitespace.
+
+    if line.eol() {
+        // No argument: execute the pattern space itself at runtime.
+        cmd.data = CommandData::None;
+        return Ok(CommandHandling::Continue);
+    }
+
+    // True after a \ at the end of a line
+    let mut escaped_newline = false;
+
+    // Skip optional \
+    if line.current() == '\\' {
+        line.advance();
+        escaped_newline = line.eol();
+    }
+
+    // Gather the command text. Stop on a non-escaped newline. Unlike most
+    // other commands, ';' does not terminate the argument. The rest of the
+    // (possibly continued) line is consumed unconditionally.
+    let mut text = String::new();
+    // True once a continuation line has actually been pulled in. A dangling
+    // leading backslash with no line to continue into is treated as no
+    // argument at all, matching GNU sed. However once a continuation succeeds,
+    // even into an empty line, we're committed to producing a (possibly empty)
+    // Text argument from then on.
+    let mut continued = false;
+    'text_content: loop {
+        if escaped_newline {
+            match lines.next_line()? {
+                None => {
+                    break 'text_content;
+                }
+                Some(line_string) => {
+                    *line = ScriptCharProvider::new(&line_string);
+                    continued = true;
+                }
+            }
+            escaped_newline = false;
+        }
+
+        // Non-escaped newline
+        if line.eol() {
+            break 'text_content;
+        }
+
+        if line.current() == '\\' {
+            line.advance();
+
+            if line.eol() {
+                escaped_newline = true;
+                text.push('\n');
+                continue 'text_content;
+            }
+
+            if let Some(decoded) = parse_char_escape(line) {
+                text.push(decoded);
+            } else {
+                // Invalid escapes result in the escaped character.
+                text.push(line.current());
+                line.advance();
+            }
+        } else {
+            text.push(line.current());
+            line.advance();
+        }
+    }
+
+    cmd.data = if text.is_empty() && !continued {
+        // A dangling leading backslash with nothing left to continue into.
+        // Treat this the same as no argument at all.
+        CommandData::None
+    } else {
+        CommandData::Text(Rc::from(text))
+    };
+    Ok(CommandHandling::Continue)
+}
+
 // Return the specification for the command letter at the current line position
 // checking for diverse errors.
 fn get_verified_cmd_spec(
@@ -1394,6 +1492,11 @@ fn get_cmd_spec(
             n_addr: 1,
             handler: compile_number_command,
         }),
+        // e is a GNU extension
+        'e' => Ok(CommandSpec {
+            n_addr: 2,
+            handler: compile_execute_command,
+        }),
         'r' => Ok(CommandSpec {
             n_addr: if posix { 1 } else { 2 },
             handler: compile_read_file_command,

src/sed/delimited_parser.rs

@@ -157,7 +157,7 @@ pub fn parse_char_escape(line: &mut ScriptCharProvider) -> Option<char> {
         }
 
         'U' => {
-            // Short Unicode escape \UXXXXXXXX (exactly eight heax digits)
+            // Short Unicode escape \UXXXXXXXX (exactly eight hex digits)
             line.advance(); // move past 'x'
             match parse_numeric_escape(line, |c| c.is_ascii_hexdigit(), 8, 16) {
                 Some(decoded) => Some(decoded),

src/sed/processor.rs

@@ -19,7 +19,7 @@ use crate::sed::named_writer;
 
 use std::borrow::Cow;
 use std::cell::RefCell;
-use std::io::{self, IsTerminal};
+use std::io::{self, IsTerminal, Read};
 use std::path::PathBuf;
 use std::rc::Rc;
 use uucore::display::Quotable;
@@ -215,6 +215,49 @@ fn shell_command(_cmd: &str) -> std::process::Command {
     unimplemented!("the 'e' substitute flag requires a platform shell (/bin/sh or cmd.exe)");
 }
 
+/// Run `cmd` in a shell, returning its standard output. The child's
+/// standard error is left connected to this process's own, matching GNU
+/// sed's behavior of letting shell errors surface directly rather than
+/// being silently captured.
+fn shell_stdout(cmd: &str) -> io::Result<Vec<u8>> {
+    let mut child = shell_command(cmd)
+        .stdout(std::process::Stdio::piped())
+        .spawn()?;
+    let mut stdout = child.stdout.take().expect("stdout was piped");
+    let mut buf = Vec::new();
+    stdout.read_to_end(&mut buf)?;
+    child.wait()?;
+    Ok(buf)
+}
+
+/// Execute the pattern space as a shell command, replacing its contents
+/// with the command's standard output, minus one trailing newline.
+fn execute_pattern_as_shell(
+    pattern: &mut IOChunk,
+    command: &Command,
+    context: &mut ProcessingContext,
+) -> UResult<()> {
+    let cmd_str = pattern.as_str()?.to_string();
+    let stdout_bytes = shell_stdout(&cmd_str).map_err(|e| {
+        input_runtime_error::<()>(
+            &command.location,
+            context,
+            format!("failed to execute shell command: {e}"),
+        )
+        .unwrap_err()
+    })?;
+    let mut shell_out = String::from_utf8_lossy(&stdout_bytes).into_owned();
+    if shell_out.ends_with("\r\n") {
+        // On windows, both return carriage and newline characters are used
+        shell_out.truncate(shell_out.len() - 2);
+    } else if shell_out.ends_with('\n') {
+        // Strip the trailing newline, as GNU sed does
+        shell_out.pop();
+    }
+    pattern.set_to_string(shell_out, pattern.is_newline_terminated());
+    Ok(())
+}
+
 /// Perform the specified RE replacement in the provided pattern space.
 fn substitute(
     pattern: &mut IOChunk,
@@ -328,24 +371,7 @@ fn substitute(
 
         // Execute the pattern space as a shell command if the 'e' flag is set
         if sub.execute {
-            let cmd_str = pattern.as_str()?.to_string();
-            let output_bytes = shell_command(&cmd_str).output().map_err(|e| {
-                input_runtime_error::<()>(
-                    &command.location,
-                    context,
-                    format!("failed to execute shell command: {e}"),
-                )
-                .unwrap_err()
-            })?;
-            let mut shell_out = String::from_utf8_lossy(&output_bytes.stdout).into_owned();
-            if shell_out.ends_with("\r\n") {
-                // On windows, both return carriage and newline characters are used
-                shell_out.truncate(shell_out.len() - 2);
-            } else if shell_out.ends_with('\n') {
-                // Strip the trailing newline, as GNU sed does
-                shell_out.pop();
-            }
-            pattern.set_to_string(shell_out, pattern.is_newline_terminated());
+            execute_pattern_as_shell(pattern, command, context)?;
         }
 
         if sub.print_flag {
@@ -581,6 +607,23 @@ fn process_file(
                     pattern.clear();
                     break;
                 }
+                'e' => match &command.data {
+                    CommandData::None => {
+                        execute_pattern_as_shell(&mut pattern, &command, context)?;
+                    }
+                    CommandData::Text(cmd_str) => {
+                        let stdout_bytes = shell_stdout(cmd_str).map_err(|e| {
+                            input_runtime_error::<()>(
+                                &command.location,
+                                context,
+                                format!("failed to execute shell command: {e}"),
+                            )
+                            .unwrap_err()
+                        })?;
+                        output.write_str(String::from_utf8_lossy(&stdout_bytes).into_owned())?;
+                    }
+                    _ => panic!("invalid 'e' command data"),
+                },
                 'g' => {
                     // Replace pattern with the contents of the hold space.
                     pattern.set_to_string(context.hold.content.clone(), context.hold.has_newline);