Fix for Windows: do not run binaries from CWD

This fixes a bug on Windows where `Command::new` would also run
executables from the current working directory, possibly resulting in
accidental runs of programs called `less`.

Cargo.lock

@@ -1,5 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "adler"
 version = "1.0.2"
@@ -97,6 +99,7 @@ dependencies = [
  "error-chain",
  "git2",
  "globset",
+ "grep-cli",
  "lazy_static",
  "nix",
  "path_abs",
@@ -487,6 +490,23 @@ dependencies = [
  "regex",
 ]
 
+[[package]]
+name = "grep-cli"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2dd110c34bb4460d0de5062413b773e385cbf8a85a63fc535590110a09e79e8a"
+dependencies = [
+ "atty",
+ "bstr",
+ "globset",
+ "lazy_static",
+ "log",
+ "regex",
+ "same-file",
+ "termcolor",
+ "winapi-util",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.9.1"
@@ -1143,6 +1163,15 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "termcolor"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2dfed899f0eb03f32ee8c6a0aabdb8a7949659e3466561fc0adf54e26d88c5f4"
+dependencies = [
+ "winapi-util",
+]
+
 [[package]]
 name = "terminal_size"
 version = "0.1.16"

Cargo.toml

@@ -51,6 +51,7 @@ path_abs = { version = "0.5", default-features = false }
 clircle = "0.3"
 bugreport = "0.4"
 dirs-next = { version = "2.0.0", optional = true }
+grep-cli = "0.1.6"
 
 [dependencies.git2]
 version = "0.13"

src/less.rs

@@ -4,7 +4,9 @@ use std::ffi::OsStr;
 use std::process::Command;
 
 pub fn retrieve_less_version(less_path: &dyn AsRef<OsStr>) -> Option<usize> {
-    let cmd = Command::new(less_path).arg("--version").output().ok()?;
+    let resolved_path = grep_cli::resolve_binary(less_path.as_ref()).ok()?;
+
+    let cmd = Command::new(resolved_path).arg("--version").output().ok()?;
     parse_less_version(&cmd.stdout)
 }
 

src/output.rs

@@ -63,7 +63,14 @@ impl OutputType {
             return Err(ErrorKind::InvalidPagerValueBat.into());
         }
 
-        let mut p = Command::new(&pager.bin);
+        let resolved_path = match grep_cli::resolve_binary(&pager.bin) {
+            Ok(path) => path,
+            Err(_) => {
+                return Ok(OutputType::stdout());
+            }
+        };
+
+        let mut p = Command::new(resolved_path);
         let args = pager.args;
 
         if pager.kind == PagerKind::Less {