Use NonZero* where applicable

Cargo.toml

@@ -15,6 +15,7 @@ once_cell = "1.4"
 slog = { version = "2", features = ["max_level_trace", "release_max_level_trace"] }
 slog-term = "2.5"
 slog-async = "2.7"
+nonzero_ext = "0.3.0"
 
 [dev-dependencies]
 tempfile = "3"

src/symbols/tls/key.rs

@@ -1,14 +1,16 @@
 use crate::command_runner::CommandRunner;
 use crate::symbols::Symbol;
 use async_trait::async_trait;
+use nonzero_ext::nonzero;
 use std::error::Error;
+use std::num::NonZeroU32;
 use std::path::Path;
 
 #[derive(Debug)]
 pub struct Key<C, P> {
   file_path: P,
   command_runner: C,
-  bits: u32,
+  bits: NonZeroU32,
 }
 
 impl<C, P> Key<C, P> {
@@ -16,7 +18,7 @@ impl<C, P> Key<C, P> {
     Self {
       file_path,
       command_runner,
-      bits: 4096,
+      bits: nonzero!(4096u32), // FIXME: Policy
     }
   }
 }

src/templates/nginx/server.rs

@@ -1,4 +1,5 @@
 use std::fmt::Display;
+use std::num::NonZeroUsize;
 use std::path::Path;
 
 #[must_use]
@@ -101,11 +102,11 @@ impl<T: AsRef<Path>> SocketSpec for T {
 }
 
 #[derive(Debug)]
-pub struct LocalTcpSocket(usize);
+pub struct LocalTcpSocket(NonZeroUsize);
 
 impl LocalTcpSocket {
   #[must_use]
-  pub const fn new(x: usize) -> Self {
+  pub const fn new(x: NonZeroUsize) -> Self {
     Self(x)
   }
 }

src/templates/php.rs

@@ -1,9 +1,10 @@
 use std::fmt::{Display, Error, Formatter};
+use std::num::NonZeroUsize;
 use std::path::Path;
 
 #[derive(Clone, Debug, PartialEq, Hash, Eq)]
 pub struct FpmPoolConfig {
-  max_children: usize,
+  max_children: NonZeroUsize,
   custom: Option<String>,
 }
 
@@ -19,14 +20,14 @@ impl Display for FpmPoolConfig {
 impl From<usize> for FpmPoolConfig {
   fn from(max_children: usize) -> Self {
     Self {
-      max_children,
+      max_children: NonZeroUsize::try_from(max_children).unwrap(),
       custom: None,
     }
   }
 }
 
 impl FpmPoolConfig {
-  pub fn new(max_children: usize, custom: impl Into<String>) -> Self {
+  pub fn new(max_children: NonZeroUsize, custom: impl Into<String>) -> Self {
     Self {
       max_children,
       custom: Some(custom.into()),