Fix relative paths for renderer commands.

1 files changed, 36 insertions, 6 deletions

diff --git a/src/renderer/mod.rs b/src/renderer/mod.rs
index f14a9f30..8af2fabc 100644
--- a/src/renderer/mod.rs
+++ b/src/renderer/mod.rs
@@ -20,7 +20,7 @@ mod markdown_renderer;
 use shlex::Shlex;
 use std::fs;
 use std::io::{self, ErrorKind, Read};
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
 
 use crate::book::Book;
@@ -133,14 +133,44 @@ impl CmdRenderer {
         CmdRenderer { name, cmd }
     }
 
-    fn compose_command(&self) -> Result<Command> {
+    fn compose_command(&self, root: &Path, destination: &Path) -> Result<Command> {
         let mut words = Shlex::new(&self.cmd);
-        let executable = match words.next() {
-            Some(e) => e,
+        let exe = match words.next() {
+            Some(e) => PathBuf::from(e),
             None => bail!("Command string was empty"),
         };
 
-        let mut cmd = Command::new(executable);
+        let exe = if exe.components().count() == 1 {
+            // Search PATH for the executable.
+            exe
+        } else {
+            // Relative paths are preferred to be relative to the book root.
+            let abs_exe = root.join(&exe);
+            if abs_exe.exists() {
+                abs_exe
+            } else {
+                // Historically paths were relative to the destination, but
+                // this is not the preferred way.
+                let legacy_path = destination.join(&exe);
+                if legacy_path.exists() {
+                    warn!(
+                        "Renderer command `{}` uses a path relative to the \
+                        renderer output directory `{}`. This was previously \
+                        accepted, but has been deprecated. Relative executable \
+                        paths should be relative to the book root.",
+                        exe.display(),
+                        destination.display()
+                    );
+                    legacy_path
+                } else {
+                    // Let this bubble through to later be handled by
+                    // handle_render_command_error.
+                    abs_exe.to_path_buf()
+                }
+            }
+        };
+
+        let mut cmd = Command::new(exe);
 
         for arg in words {
             cmd.arg(arg);
@@ -195,7 +225,7 @@ impl Renderer for CmdRenderer {
         let _ = fs::create_dir_all(&ctx.destination);
 
         let mut child = match self
-            .compose_command()?
+            .compose_command(&ctx.root, &ctx.destination)?
             .stdin(Stdio::piped())
             .stdout(Stdio::inherit())
             .stderr(Stdio::inherit())