feat: build script for controlling filesize cap

Cargo.toml

@@ -1,8 +1,9 @@
 [package]
 name = "sweet"
 description = "simple wayland event encoding text"
-version = "0.2.0"
+version = "0.3.0"
 edition = "2021"
+build = "build.rs"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

build.rs

@@ -0,0 +1,3 @@
+fn main() {
+ println!("cargo:rustc-env=FILESIZE_CAP_MIB=50");
+}

src/lib.rs

@@ -63,8 +63,8 @@ pub enum ConfigReadError {
  ReadingConfig(#[from] std::io::Error),
  #[error("path `{0}` supplied as config is not a regular file")]
  NotRegularFile(PathBuf),
- #[error("the supplied config file {0} size exceeds the 50MiB limit")]
- TooLarge(PathBuf),
+ #[error("the supplied config file {0} size exceeds the {1}MiB limit")]
+ TooLarge(PathBuf, u64),
 }
 
 pub fn read_config<P: AsRef<Path>>(path: P) -> Result<String, ConfigReadError> {
@@ -74,9 +74,11 @@ pub fn read_config<P: AsRef<Path>>(path: P) -> Result<String, ConfigReadError> {
  return Err(ConfigReadError::NotRegularFile(path.to_path_buf()));
  }
  let size = stat.size();
- /* 50MiB size cap */
- if size > (50 << 20) {
- return Err(ConfigReadError::TooLarge(path.to_path_buf()));
+ let mib_cap = std::option_env!("FILESIZE_CAP_MIB")
+ .and_then(|cap| cap.parse().ok())
+ .unwrap_or(50);
+ if size > (mib_cap << 20) {
+ return Err(ConfigReadError::TooLarge(path.to_path_buf(), mib_cap));
  }
  // TODO: Use mmap instead of fs::read_to_string
  Ok(fs::read_to_string(path)?)