Fix $LESSOPEN tests and behavior

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Features
 
 - Add environment variable `BAT_PAGING`, see #2629 (@einfachIrgendwer0815)
+- Add support for `LESSOPEN` and `LESSCLOSE`. See #1597, #1739, #2444, #2602, and #2662 (@Anomalocaridid)
 
 ## Bugfixes
 
@@ -77,7 +78,6 @@
 
 - Make the default macOS theme depend on Dark Mode. See #2197, #1746 (@Enselic)
 - Support for separate system and user config files. See #668 (@patrickpichler)
-- Add support for $LESSOPEN and $LESSCLOSE. See #1597, #1739, and #2444 (@Anomalocaridid)
 
 ## Bugfixes
 

assets/completions/_bat.ps1.in

@@ -59,7 +59,8 @@ Register-ArgumentCompleter -Native -CommandName '{{PROJECT_EXECUTABLE}}' -Script
             [CompletionResult]::new('--unbuffered', 'unbuffered', [CompletionResultType]::ParameterName, 'unbuffered')
             [CompletionResult]::new('--no-config', 'no-config', [CompletionResultType]::ParameterName, 'Do not use the configuration file')
             [CompletionResult]::new('--no-custom-assets', 'no-custom-assets', [CompletionResultType]::ParameterName, 'Do not load custom assets')
-            [CompletionResult]::new('--no-lessopen', 'no-lessopen', [CompletionResultType]::ParameterName, 'Do not use the $LESSOPEN preprocessor')
+            [CompletionResult]::new('--lessopen', 'lessopen', [CompletionResultType]::ParameterName, 'Enable the $LESSOPEN preprocessor')
+            [CompletionResult]::new('--no-lessopen', 'no-lessopen', [CompletionResultType]::ParameterName, 'Disable the $LESSOPEN preprocessor if enabled (overrides --lessopen)')
             [CompletionResult]::new('--config-file', 'config-file', [CompletionResultType]::ParameterName, 'Show path to the configuration file.')
             [CompletionResult]::new('--generate-config-file', 'generate-config-file', [CompletionResultType]::ParameterName, 'Generates a default configuration file.')
             [CompletionResult]::new('--config-dir', 'config-dir', [CompletionResultType]::ParameterName, 'Show bat''s configuration directory.')

assets/completions/bat.bash.in

@@ -78,6 +78,7 @@ _bat() {
 	--list-themes | \
 	--line-range | \
 	-L | --list-languages | \
+	--lessopen | \
 	--diagnostic | \
 	--acknowledgements | \
 	-h | --help | \
@@ -171,6 +172,7 @@ _bat() {
 			--style
 			--line-range
 			--list-languages
+			--lessopen
 			--diagnostic
 			--acknowledgements
 			--help

assets/completions/bat.fish.in

@@ -163,6 +163,8 @@ complete -c $bat -l italic-text -x -a "$italic_text_opts" -d "When to use italic
 
 complete -c $bat -s l -l language -x -k -a "(__bat_complete_list_languages)" -d "Set the syntax highlighting language" -n __bat_no_excl_args
 
+complete -c $bat -l lessopen -d "Enable the $LESSOPEN preprocessor" -n __fish_is_first_arg
+
 complete -c $bat -s r -l line-range -x -d "Only print lines [M]:[N] (either optional)" -n __bat_no_excl_args
 
 complete -c $bat -l list-languages -f -d "List syntax highlighting languages" -n __fish_is_first_arg

assets/completions/bat.zsh.in

@@ -46,7 +46,8 @@ _{{PROJECT_EXECUTABLE}}_main() {
         '(: --list-themes --list-languages -L)'{-L,--list-languages}'[Display all supported languages]'
         '(: --no-config)'--no-config'[Do not use the configuration file]'
         '(: --no-custom-assets)'--no-custom-assets'[Do not load custom assets]'
-        '(: --no-lessopen)'--no-lessopen'[Do not use the $LESSOPEN preprocessor]'
+        '(: --lessopen)'--lessopen'[Enable the $LESSOPEN preprocessor]'
+        '(: --no-lessopen)'--no-lessopen'[Disable the $LESSOPEN preprocessor if enabled (overrides --lessopen)]'
         '(: --config-dir)'--config-dir'[Show bat'"'"'s configuration directory]'
         '(: --config-file)'--config-file'[Show path to the configuration file]'
         '(: --generate-config-file)'--generate-config-file'[Generates a default configuration file]'

assets/manual/bat.1.in

@@ -248,7 +248,13 @@ These can be installed to `\fB$({{PROJECT_EXECUTABLE}} --config-dir)/themes\fR`,
 Much like less(1) does, {{PROJECT_EXECUTABLE}} supports input preprocessors via the LESSOPEN and LESSCLOSE environment variables.
 In addition, {{PROJECT_EXECUTABLE}} attempts to be as compatible with less's preprocessor implementation as possible.
 
-To run {{PROJECT_EXECUTABLE}} without using the preprocessor, call:
+To use the preprocessor, call:
+
+\fB{{PROJECT_EXECUTABLE}} --lessopen\fR
+
+Alternatively, the preprocessor may be enabled by default by adding the '\-\-lessopen' option to the configuration file. 
+
+To temporarily disable the preprocessor if it is enabled by default, call:
 
 \fB{{PROJECT_EXECUTABLE}} --no-lessopen\fR
 

src/bin/bat/app.rs

@@ -282,7 +282,7 @@ impl App {
                 .unwrap_or_default(),
             use_custom_assets: !self.matches.get_flag("no-custom-assets"),
             #[cfg(feature = "lessopen")]
-            use_lessopen: !self.matches.get_flag("no-lessopen"),
+            use_lessopen: self.matches.get_flag("lessopen"),
         })
     }
 

src/bin/bat/clap_app.rs

@@ -501,13 +501,21 @@ pub fn build_app(interactive_output: bool) -> Command {
 
     #[cfg(feature = "lessopen")]
     {
-        app = app.arg(
-            Arg::new("no-lessopen")
-                .long("no-lessopen")
-                .action(ArgAction::SetTrue)
-                .hide(true)
-                .help("Do not use the $LESSOPEN preprocessor"),
-        )
+        app = app
+            .arg(
+                Arg::new("lessopen")
+                    .long("lessopen")
+                    .action(ArgAction::SetTrue)
+                    .help("Enable the $LESSOPEN preprocessor"),
+            )
+            .arg(
+                Arg::new("no-lessopen")
+                    .long("no-lessopen")
+                    .action(ArgAction::SetTrue)
+                    .overrides_with("lessopen")
+                    .hide(true)
+                    .help("Disable the $LESSOPEN preprocessor if enabled (overrides --lessopen)"),
+            )
     }
 
     app = app

src/lessopen.rs

@@ -12,7 +12,10 @@ use os_str_bytes::RawOsString;
 use run_script::{IoOptions, ScriptOptions};
 
 use crate::error::Result;
-use crate::input::{Input, InputKind, InputReader, OpenedInput, OpenedInputKind};
+use crate::{
+    bat_warning,
+    input::{Input, InputKind, InputReader, OpenedInput, OpenedInputKind},
+};
 
 /// Preprocess files and/or stdin using $LESSOPEN and $LESSCLOSE
 pub(crate) struct LessOpenPreprocessor {
@@ -32,10 +35,18 @@ enum LessOpenKind {
 
 impl LessOpenPreprocessor {
     /// Create a new instance of LessOpenPreprocessor
-    /// Will return Ok if and only if $LESSOPEN is set
+    /// Will return Ok if and only if $LESSOPEN is set and contains exactly one %s
     pub(crate) fn new() -> Result<LessOpenPreprocessor> {
         let lessopen = env::var("LESSOPEN")?;
 
+        // Ignore $LESSOPEN if it does not contains exactly one %s
+        // Note that $LESSCLOSE has no such requirement
+        if lessopen.match_indices("%s").count() != 1 {
+            let error_msg = "LESSOPEN ignored: must contain exactly one %s";
+            bat_warning!("{}", error_msg);
+            return Err(error_msg.into());
+        }
+
         // "||" means pipe directly to bat without making a temporary file
         // Also, if preprocessor output is empty and exit code is zero, use the empty output
         // Otherwise, if output is empty and exit code is nonzero, use original file contents

src/output.rs

@@ -114,6 +114,10 @@ impl OutputType {
                 p.args(args);
             }
             p.env("LESSCHARSET", "UTF-8");
+
+            #[cfg(feature = "lessopen")]
+            // Ensures that 'less' does not preprocess input again if '$LESSOPEN' is set.
+            p.arg("--no-lessopen");
         } else {
             p.args(args);
         };