fix: bug that caused the fmt to overwrite the input source file wit…

…h empty content.

When the input file was syntactically incorrect, `yr fmt` was overwriting the input file with empty content.

yara-x-cli/src/commands/fmt.rs

@@ -1,29 +1,45 @@
 use std::fs;
 use std::fs::File;
-use std::io::{stdin, stdout};
+use std::io::{stdin, stdout, Cursor, Seek, Write};
 use std::path::PathBuf;
 
 use clap::{arg, value_parser, ArgAction, ArgMatches, Command};
 use yara_x_fmt::Formatter;
 
 pub fn fmt() -> Command {
-    super::command("fmt").about("Format source files").arg(
-        arg!(<RULES_PATH>)
-            .help("Path to YARA source file or directory")
+    super::command("fmt").about("Format YARA source files")
+        .arg(
+            arg!(<FILE>)
+            .help("Path to YARA source file")
             .value_parser(value_parser!(PathBuf))
             .action(ArgAction::Append),
-    )
+        )
+        .arg(
+            arg!(-w  --write ... "Write output to source file instead of stdout")
+                .action(ArgAction::SetTrue),
+        )
 }
 
 pub fn exec_fmt(args: &ArgMatches) -> anyhow::Result<()> {
-    let rules_path = args.get_many::<PathBuf>("RULES_PATH");
+    let files = args.get_many::<PathBuf>("FILE");
+    let write = args.get_one::<bool>("write");
+
     let formatter = Formatter::new();
 
-    if let Some(files) = rules_path {
+    if let Some(files) = files {
         for file in files {
             let input = fs::read(file.as_path())?;
-            let output = File::create(file.as_path())?;
-            formatter.format(input.as_slice(), output)?;
+            if *write.unwrap() {
+                let mut formatted = Cursor::new(Vec::new());
+
+                formatter.format(input.as_slice(), &mut formatted)?;
+                formatted.rewind()?;
+
+                File::create(file.as_path())?
+                    .write_all(formatted.into_inner().as_slice())?;
+            } else {
+                formatter.format(input.as_slice(), stdout())?;
+            };
         }
     } else {
         formatter.format(stdin(), stdout())?;