implement error::unexpected, use it everywhere

This is an improved form of the previous `error::Unexpected` type, now
with more capabilities and generally better naming.

TODO

@@ -1,3 +1 @@
-- expect statements (pretend it's "expected", not "expect")
-- map_unexpected annotation string
 - clean up main a lot

src/domain/acme/manager.rs

@@ -1,18 +1,17 @@
 use std::{future, pin, sync, time};
 
 use crate::domain::{self, acme};
-use crate::error;
+use crate::error::unexpected::{self, Intoable, Mappable};
-use crate::error::{MapUnexpected, ToUnexpected};
 
 const LETS_ENCRYPT_URL: &str = "https://acme-v02.api.letsencrypt.org/directory";
 
 pub type GetHttp01ChallengeKeyError = acme::store::GetHttp01ChallengeKeyError;
 
 #[mockall::automock(
-    type SyncDomainFuture=future::Ready<Result<(), error::Unexpected>>;
+    type SyncDomainFuture=future::Ready<Result<(), unexpected::Error>>;
 )]
 pub trait Manager {
-    type SyncDomainFuture<'mgr>: future::Future<Output = Result<(), error::Unexpected>>
+    type SyncDomainFuture<'mgr>: future::Future<Output = Result<(), unexpected::Error>>
         + Send
         + Unpin
         + 'mgr
@@ -37,14 +36,14 @@ where
 pub async fn new<Store>(
     store: Store,
     contact_email: &str,
-) -> Result<impl BoxedManager, error::Unexpected>
+) -> Result<impl BoxedManager, unexpected::Error>
 where
     Store: acme::store::BoxedStore,
 {
     let dir = acme2::DirectoryBuilder::new(LETS_ENCRYPT_URL.to_string())
         .build()
         .await
-        .map_unexpected()?;
+        .or_unexpected_while("creating acme2 directory builder")?;
 
     let mut contact = String::from("mailto:");
     contact.push_str(contact_email);
@@ -55,17 +54,29 @@ where
 
     match store.get_account_key() {
         Ok(account_key) => {
-            builder.private_key((&account_key).try_into().map_unexpected()?);
+            builder.private_key(
+                (&account_key)
+                    .try_into()
+                    .or_unexpected_while("parsing private key")?,
+            );
         }
         Err(acme::store::GetAccountKeyError::NotFound) => (),
-        Err(acme::store::GetAccountKeyError::Unexpected(err)) => return Err(err.to_unexpected()),
+        Err(acme::store::GetAccountKeyError::Unexpected(err)) => return Err(err.into_unexpected()),
     }
 
-    let account = builder.build().await.map_unexpected()?;
+    let account = builder
-    let account_key: acme::PrivateKey =
+        .build()
-        account.private_key().as_ref().try_into().map_unexpected()?;
+        .await
+        .or_unexpected_while("building account")?;
+    let account_key: acme::PrivateKey = account
+        .private_key()
+        .as_ref()
+        .try_into()
+        .or_unexpected_while("parsing private key back out")?;
 
-    store.set_account_key(&account_key).map_unexpected()?;
+    store
+        .set_account_key(&account_key)
+        .or_unexpected_while("storing account key")?;
 
     Ok(sync::Arc::new(ManagerImpl { store, account }))
 }
@@ -76,7 +87,7 @@ impl<Store> Manager for sync::Arc<ManagerImpl<Store>>
 where
     Store: acme::store::BoxedStore,
 {
-    type SyncDomainFuture<'mgr> = pin::Pin<Box<dyn future::Future<Output = Result<(), error::Unexpected>> + Send + 'mgr>>
+    type SyncDomainFuture<'mgr> = pin::Pin<Box<dyn future::Future<Output = Result<(), unexpected::Error>> + Send + 'mgr>>
         where Self: 'mgr;
 
     fn sync_domain(&self, domain: domain::Name) -> Self::SyncDomainFuture<'_> {
@@ -92,10 +103,10 @@ where
                     .into_iter()
                     .map(|cert| openssl::x509::X509::try_from(&cert))
                     .try_collect::<Vec<openssl::x509::X509>>()
-                    .map_unexpected()?
+                    .or_unexpected_while("parsing x509 certs")?
                     .into_iter()
                     .reduce(|a, b| if a.not_after() < b.not_after() { a } else { b })
-                    .ok_or(error::Unexpected::from(
+                    .ok_or(unexpected::Error::from(
                         "expected there to be more than one cert",
                     ))?;
 
@@ -107,28 +118,34 @@ where
             log::info!("Fetching a new certificate for domain {}", domain.as_str());
             let mut builder = acme2::OrderBuilder::new(self.account.clone());
             builder.add_dns_identifier(domain.as_str().to_string());
-            let order = builder.build().await.map_unexpected()?;
+            let order = builder
+                .build()
+                .await
+                .or_unexpected_while("building order")?;
 
-            let authorizations = order.authorizations().await.map_unexpected()?;
+            let authorizations = order
+                .authorizations()
+                .await
+                .or_unexpected_while("fetching authorizations")?;
 
             for auth in authorizations {
                 let challenge = auth
                     .get_challenge("http-01")
-                    .ok_or(error::Unexpected::from("expected http-01 challenge"))?;
+                    .ok_or(unexpected::Error::from("expected http-01 challenge"))?;
 
                 let challenge_token = challenge
                     .token
                     .as_ref()
-                    .ok_or(error::Unexpected::from("expected challenge to have token"))?;
+                    .ok_or(unexpected::Error::from("expected challenge to have token"))?;
 
                 let challenge_key = challenge
                     .key_authorization()
-                    .map_unexpected()?
+                    .or_unexpected_while("getting challenge key from authorization")?
-                    .ok_or(error::Unexpected::from("expected challenge to have key"))?;
+                    .ok_or(unexpected::Error::from("expected challenge to have key"))?;
 
                 self.store
                     .set_http01_challenge_key(challenge_token, &challenge_key)
-                    .map_unexpected()?;
+                    .or_unexpected_while("storing challenge token")?;
 
                 // At this point the manager is prepared to serve the challenge key via the
                 // `get_http01_challenge_key` method. It is expected that there is some http
@@ -141,7 +158,10 @@ where
                     "Waiting for ACME challenge to be validated for domain {}",
                     domain.as_str(),
                 );
-                let challenge = challenge.validate().await.map_unexpected()?;
+                let challenge = challenge
+                    .validate()
+                    .await
+                    .or_unexpected_while("initiating challenge validation")?;
 
                 // Poll the challenge every 5 seconds until it is in either the
                 // `valid` or `invalid` state.
@@ -150,12 +170,12 @@ where
                 // no matter what the result is, clean up the challenge key
                 self.store
                     .del_http01_challenge_key(challenge_token)
-                    .map_unexpected()?;
+                    .or_unexpected_while("deleting challenge token")?;
 
-                let challenge = challenge_res.map_unexpected()?;
+                let challenge = challenge_res.or_unexpected_while("getting challenge status")?;
 
                 if challenge.status != acme2::ChallengeStatus::Valid {
-                    return Err(error::Unexpected::from(
+                    return Err(unexpected::Error::from(
                         format!(
                             "expected challenge status to be valid, instead it was {:?}",
                             challenge.status
@@ -174,10 +194,10 @@ where
                 let authorization = auth
                     .wait_done(time::Duration::from_secs(5), 3)
                     .await
-                    .map_unexpected()?;
+                    .or_unexpected_while("waiting for authorization status")?;
 
                 if authorization.status != acme2::AuthorizationStatus::Valid {
-                    return Err(error::Unexpected::from(
+                    return Err(unexpected::Error::from(
                         format!(
                             "expected authorization status to be valid, instead it was {:?}",
                             authorization.status,
@@ -197,10 +217,10 @@ where
             let order = order
                 .wait_ready(time::Duration::from_secs(5), 3)
                 .await
-                .map_unexpected()?;
+                .or_unexpected_while("waiting for order to be ready")?;
 
             if order.status != acme2::OrderStatus::Ready {
-                return Err(error::Unexpected::from(
+                return Err(unexpected::Error::from(
                     format!(
                         "expected order status to be ready, instead it was {:?}",
                         order.status,
@@ -212,14 +232,16 @@ where
             // Generate an RSA private key for the certificate.
             let pkey = acme::PrivateKey::new();
 
-            let acme2_pkey = (&pkey).try_into().map_unexpected()?;
+            let acme2_pkey = (&pkey)
+                .try_into()
+                .or_unexpected_while("parsing new private key")?;
 
             // Create a certificate signing request for the order, and request
             // the certificate.
             let order = order
                 .finalize(acme2::Csr::Automatic(acme2_pkey))
                 .await
-                .map_unexpected()?;
+                .or_unexpected_while("finalizing order")?;
 
             // Poll the order every 5 seconds until it is in either the
             // `valid` or `invalid` state. Valid means that the certificate
@@ -231,10 +253,10 @@ where
             let order = order
                 .wait_done(time::Duration::from_secs(5), 3)
                 .await
-                .map_unexpected()?;
+                .or_unexpected_while("waiting for order to be validated")?;
 
             if order.status != acme2::OrderStatus::Valid {
-                return Err(error::Unexpected::from(
+                return Err(unexpected::Error::from(
                     format!(
                         "expected order status to be valid, instead it was {:?}",
                         order.status,
@@ -248,17 +270,17 @@ where
             let cert = order
                 .certificate()
                 .await
-                .map_unexpected()?
+                .or_unexpected_while("fetching certificate")?
-                .ok_or(error::Unexpected::from(
+                .ok_or(unexpected::Error::from(
                     "expected the order to return a certificate",
                 ))?
                 .into_iter()
                 .map(|cert| acme::Certificate::try_from(cert.as_ref()))
                 .try_collect::<Vec<acme::Certificate>>()
-                .map_unexpected()?;
+                .or_unexpected_while("parsing certificate")?;
 
             if cert.len() <= 1 {
-                return Err(error::Unexpected::from(
+                return Err(unexpected::Error::from(
                     format!(
                         "expected more than one certificate to be returned, instead got {}",
                         cert.len(),
@@ -270,7 +292,7 @@ where
             log::info!("Certificate for {} successfully retrieved", domain.as_str());
             self.store
                 .set_certificate(domain.as_str(), pkey, cert)
-                .map_unexpected()?;
+                .or_unexpected_while("storing new cert")?;
 
             Ok(())
         })

src/domain/acme/store.rs

@@ -1,10 +1,10 @@
 use std::io::{Read, Write};
 use std::str::FromStr;
-use std::{fs, io, path, sync};
+use std::{fs, path, sync};
 
 use crate::domain::acme::{Certificate, PrivateKey};
-use crate::error;
+use crate::error::unexpected::{self, Mappable};
-use crate::error::{MapUnexpected, ToUnexpected};
+use crate::util;
 
 use hex::ToHex;
 use serde::{Deserialize, Serialize};
@@ -16,7 +16,7 @@ pub enum GetAccountKeyError {
     NotFound,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 #[derive(thiserror::Error, Debug)]
@@ -25,7 +25,7 @@ pub enum GetHttp01ChallengeKeyError {
     NotFound,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 #[derive(thiserror::Error, Debug)]
@@ -34,24 +34,24 @@ pub enum GetCertificateError {
     NotFound,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 #[mockall::automock]
 pub trait Store {
-    fn set_account_key(&self, k: &PrivateKey) -> Result<(), error::Unexpected>;
+    fn set_account_key(&self, k: &PrivateKey) -> Result<(), unexpected::Error>;
     fn get_account_key(&self) -> Result<PrivateKey, GetAccountKeyError>;
 
-    fn set_http01_challenge_key(&self, token: &str, key: &str) -> Result<(), error::Unexpected>;
+    fn set_http01_challenge_key(&self, token: &str, key: &str) -> Result<(), unexpected::Error>;
     fn get_http01_challenge_key(&self, token: &str) -> Result<String, GetHttp01ChallengeKeyError>;
-    fn del_http01_challenge_key(&self, token: &str) -> Result<(), error::Unexpected>;
+    fn del_http01_challenge_key(&self, token: &str) -> Result<(), unexpected::Error>;
 
     fn set_certificate(
         &self,
         domain: &str,
         key: PrivateKey,
         cert: Vec<Certificate>,
-    ) -> Result<(), error::Unexpected>;
+    ) -> Result<(), unexpected::Error>;
 
     /// Returned vec is guaranteed to have len > 0
     fn get_certificate(
@@ -77,10 +77,17 @@ struct BoxedFSStore(sync::Arc<FSStore>);
 
 pub fn new(
     dir_path: &path::Path,
-) -> Result<impl BoxedStore + rustls::server::ResolvesServerCert, error::Unexpected> {
+) -> Result<impl BoxedStore + rustls::server::ResolvesServerCert, unexpected::Error> {
-    fs::create_dir_all(dir_path).map_unexpected()?;
+    vec![
-    fs::create_dir_all(dir_path.join("http01_challenge_keys")).map_unexpected()?;
+        dir_path,
-    fs::create_dir_all(dir_path.join("certificates")).map_unexpected()?;
+        dir_path.join("http01_challenge_keys").as_ref(),
+        dir_path.join("certificates").as_ref(),
+    ]
+    .iter()
+    .map(|dir| {
+        fs::create_dir_all(dir).map_unexpected_while(|| format!("creating dir {}", dir.display()))
+    })
+    .try_collect()?;
 
     Ok(BoxedFSStore(sync::Arc::new(FSStore {
         dir_path: dir_path.into(),
@@ -113,47 +120,72 @@ impl BoxedFSStore {
 impl BoxedStore for BoxedFSStore {}
 
 impl Store for BoxedFSStore {
-    fn set_account_key(&self, k: &PrivateKey) -> Result<(), error::Unexpected> {
+    fn set_account_key(&self, k: &PrivateKey) -> Result<(), unexpected::Error> {
-        let mut file = fs::File::create(self.account_key_path()).map_unexpected()?;
+        let path = self.account_key_path();
-        file.write_all(k.to_string().as_bytes()).map_unexpected()?;
+        {
+            let mut file = fs::File::create(&path).or_unexpected_while("creating file")?;
+            file.write_all(k.to_string().as_bytes())
+                .or_unexpected_while("writing file")
+        }
+        .map_unexpected_while(|| format!("path is {}", path.display()))?;
         Ok(())
     }
 
     fn get_account_key(&self) -> Result<PrivateKey, GetAccountKeyError> {
-        let mut file = fs::File::open(self.account_key_path()).map_err(|e| match e.kind() {
+        let path = self.account_key_path();
-            io::ErrorKind::NotFound => GetAccountKeyError::NotFound,
+        {
-            _ => e.to_unexpected().into(),
+            let mut file =
-        })?;
+                match util::open_file(path.as_path()).or_unexpected_while("opening_file")? {
+                    Some(file) => file,
+                    None => return Err(GetAccountKeyError::NotFound),
+                };
 
-        let mut key = String::new();
+            let mut key = String::new();
-        file.read_to_string(&mut key).map_unexpected()?;
+            file.read_to_string(&mut key)
+                .or_unexpected_while("reading file")?;
 
-        let key = PrivateKey::from_str(&key).map_unexpected()?;
+            let key = PrivateKey::from_str(&key).or_unexpected_while("parsing private key")?;
-        Ok(key)
+
+            Ok::<PrivateKey, unexpected::Error>(key)
+        }
+        .map_unexpected_while(|| format!("path is {}", path.display()))
+        .map_err(|err| err.into())
     }
 
-    fn set_http01_challenge_key(&self, token: &str, key: &str) -> Result<(), error::Unexpected> {
+    fn set_http01_challenge_key(&self, token: &str, key: &str) -> Result<(), unexpected::Error> {
-        let mut file = fs::File::create(self.http01_challenge_key_path(token)).map_unexpected()?;
+        let path = self.http01_challenge_key_path(token);
-        file.write_all(key.as_bytes()).map_unexpected()?;
+        {
+            let mut file = fs::File::create(path.as_path()).or_unexpected_while("creating file")?;
+            file.write_all(key.as_bytes())
+                .or_unexpected_while("writing file")
+        }
+        .map_unexpected_while(|| format!("path is {}", path.display()))?;
         Ok(())
     }
 
     fn get_http01_challenge_key(&self, token: &str) -> Result<String, GetHttp01ChallengeKeyError> {
-        let mut file =
+        let path = self.http01_challenge_key_path(token);
-            fs::File::open(self.http01_challenge_key_path(token)).map_err(|e| match e.kind() {
+        {
-                io::ErrorKind::NotFound => GetHttp01ChallengeKeyError::NotFound,
+            let mut file =
-                _ => e.to_unexpected().into(),
+                match util::open_file(path.as_path()).or_unexpected_while("opening_file")? {
-            })?;
+                    Some(file) => file,
+                    None => return Err(GetHttp01ChallengeKeyError::NotFound),
+                };
 
-        let mut key = String::new();
+            let mut key = String::new();
-        file.read_to_string(&mut key).map_unexpected()?;
+            file.read_to_string(&mut key)
+                .or_unexpected_while("reading file")?;
 
-        Ok(key)
+            Ok::<String, unexpected::Error>(key)
+        }
+        .map_unexpected_while(|| format!("path is {}", path.display()))
+        .map_err(|err| err.into())
     }
 
-    fn del_http01_challenge_key(&self, token: &str) -> Result<(), error::Unexpected> {
+    fn del_http01_challenge_key(&self, token: &str) -> Result<(), unexpected::Error> {
-        fs::remove_file(self.http01_challenge_key_path(token)).map_unexpected()?;
+        let path = self.http01_challenge_key_path(token);
-        Ok(())
+        fs::remove_file(path.as_path())
+            .map_unexpected_while(|| format!("path is {}", path.display()))
     }
 
     fn set_certificate(
@@ -161,31 +193,42 @@ impl Store for BoxedFSStore {
         domain: &str,
         key: PrivateKey,
         cert: Vec<Certificate>,
-    ) -> Result<(), error::Unexpected> {
+    ) -> Result<(), unexpected::Error> {
         let to_store = StoredPKeyCert {
             private_key: key,
             cert,
         };
 
-        let cert_file = fs::File::create(self.certificate_path(domain)).map_unexpected()?;
+        let path = self.certificate_path(domain);
-
+        {
-        serde_json::to_writer(cert_file, &to_store).map_unexpected()?;
+            let cert_file =
-
+                fs::File::create(path.as_path()).or_unexpected_while("creating file")?;
-        Ok(())
+            serde_json::to_writer(cert_file, &to_store).or_unexpected_while("writing cert to file")
+        }
+        .map_unexpected_while(|| format!("path is {}", path.display()))
     }
 
     fn get_certificate(
         &self,
         domain: &str,
     ) -> Result<(PrivateKey, Vec<Certificate>), GetCertificateError> {
-        let file = fs::File::open(self.certificate_path(domain)).map_err(|e| match e.kind() {
+        let path = self.certificate_path(domain);
-            io::ErrorKind::NotFound => GetCertificateError::NotFound,
+        {
-            _ => e.to_unexpected().into(),
+            let file = match util::open_file(path.as_path()).or_unexpected_while("opening_file")? {
-        })?;
+                Some(file) => file,
+                None => return Err(GetCertificateError::NotFound),
+            };
 
-        let stored: StoredPKeyCert = serde_json::from_reader(file).map_unexpected()?;
+            let stored: StoredPKeyCert =
+                serde_json::from_reader(file).or_unexpected_while("parsing json")?;
 
-        Ok((stored.private_key, stored.cert))
+            Ok::<(PrivateKey, Vec<Certificate>), unexpected::Error>((
+                stored.private_key,
+                stored.cert,
+            ))
+        }
+        .map_unexpected_while(|| format!("path is {}", path.display()))
+        .map_err(|err| err.into())
     }
 }
 
@@ -203,7 +246,7 @@ impl rustls::server::ResolvesServerCert for BoxedFSStore {
             }
             Err(GetCertificateError::Unexpected(err)) => Err(err),
             Ok((key, cert)) => {
-                match rustls::sign::any_supported_type(&key.into()).map_unexpected() {
+                match rustls::sign::any_supported_type(&key.into()).or_unexpected() {
                     Err(err) => Err(err),
                     Ok(key) => Ok(Some(sync::Arc::new(rustls::sign::CertifiedKey {
                         cert: cert.into_iter().map(|cert| cert.into()).collect(),

src/domain/checker.rs

@@ -1,8 +1,8 @@
 use std::net;
 use std::str::FromStr;
 
-use crate::error::MapUnexpected;
+use crate::domain;
-use crate::{domain, error};
+use crate::error::unexpected::{self, Mappable};
 
 use trust_dns_client::client::{AsyncClient, ClientHandle};
 use trust_dns_client::rr::{DNSClass, Name, RData, RecordType};
@@ -14,7 +14,7 @@ pub enum NewDNSCheckerError {
     InvalidResolverAddress,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 #[derive(thiserror::Error, Debug)]
@@ -26,7 +26,7 @@ pub enum CheckDomainError {
     ChallengeTokenNotSet,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 pub struct DNSChecker {
@@ -46,7 +46,7 @@ pub async fn new(
 
     let stream = udp::UdpClientStream::<tokio::net::UdpSocket>::new(resolver_addr);
 
-    let (client, bg) = AsyncClient::connect(stream).await.map_unexpected()?;
+    let (client, bg) = AsyncClient::connect(stream).await.or_unexpected()?;
 
     tokio::spawn(bg);
 
@@ -72,7 +72,7 @@ impl DNSChecker {
                 .await
                 .query(domain.clone(), DNSClass::IN, RecordType::A)
                 .await
-                .map_unexpected()?;
+                .or_unexpected_while("querying A record")?;
 
             let records = response.answers();
 
@@ -91,9 +91,9 @@ impl DNSChecker {
         // check that the TXT record with the challenge token is correctly installed on the domain
         {
             let domain = Name::from_str("_domiply_challenge")
-                .map_unexpected()?
+                .or_unexpected_while("parsing TXT name")?
                 .append_domain(domain)
-                .map_unexpected()?;
+                .or_unexpected_while("appending domain to TXT")?;
 
             let response = self
                 .client
@@ -101,7 +101,7 @@ impl DNSChecker {
                 .await
                 .query(domain, DNSClass::IN, RecordType::TXT)
                 .await
-                .map_unexpected()?;
+                .or_unexpected_while("querying TXT record")?;
 
             let records = response.answers();
 

src/domain/config.rs

@@ -2,8 +2,8 @@ use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use std::{fs, io, sync};
 
-use crate::error::{MapUnexpected, ToUnexpected};
+use crate::error::unexpected::{self, Intoable, Mappable};
-use crate::{domain, error, origin};
+use crate::{domain, origin};
 
 use hex::ToHex;
 use serde::{Deserialize, Serialize};
@@ -16,9 +16,9 @@ pub struct Config {
 }
 
 impl Config {
-    pub fn hash(&self) -> Result<String, error::Unexpected> {
+    pub fn hash(&self) -> Result<String, unexpected::Error> {
         let mut h = Sha256::new();
-        serde_json::to_writer(&mut h, self).map_unexpected()?;
+        serde_json::to_writer(&mut h, self).or_unexpected()?;
         Ok(h.finalize().encode_hex::<String>())
     }
 }
@@ -29,17 +29,17 @@ pub enum GetError {
     NotFound,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 #[derive(thiserror::Error, Debug)]
 pub enum SetError {
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 /// Used in the return from all_domains from Store.
-pub type AllDomainsResult<T> = Result<T, error::Unexpected>;
+pub type AllDomainsResult<T> = Result<T, unexpected::Error>;
 
 #[mockall::automock]
 pub trait Store {
@@ -75,37 +75,46 @@ impl BoxedStore for sync::Arc<FSStore> {}
 
 impl Store for sync::Arc<FSStore> {
     fn get(&self, domain: &domain::Name) -> Result<Config, GetError> {
-        let config_file =
+        let path = self.config_file_path(domain);
-            fs::File::open(self.config_file_path(domain)).map_err(|e| match e.kind() {
+        let config_file = fs::File::open(path.as_path()).map_err(|e| match e.kind() {
-                io::ErrorKind::NotFound => GetError::NotFound,
+            io::ErrorKind::NotFound => GetError::NotFound,
-                _ => e.to_unexpected().into(),
+            _ => e
-            })?;
+                .into_unexpected_while(format!("opening {}", path.display()))
+                .into(),
+        })?;
 
-        let config = serde_json::from_reader(config_file).map_unexpected()?;
+        let config = serde_json::from_reader(config_file)
+            .map_unexpected_while(|| format!("json parsing {}", path.display()))?;
         Ok(config)
     }
 
     fn set(&self, domain: &domain::Name, config: &Config) -> Result<(), SetError> {
-        fs::create_dir_all(self.config_dir_path(domain)).map_unexpected()?;
+        let dir_path = self.config_dir_path(domain);
+        fs::create_dir_all(dir_path.as_path())
+            .map_unexpected_while(|| format!("creating dir {}", dir_path.display()))?;
 
-        let config_file = fs::File::create(self.config_file_path(domain)).map_unexpected()?;
+        let file_path = self.config_file_path(domain);
+        let config_file = fs::File::create(file_path.as_path())
+            .map_unexpected_while(|| format!("creating file {}", file_path.display()))?;
 
-        serde_json::to_writer(config_file, config).map_unexpected()?;
+        serde_json::to_writer(config_file, config)
+            .map_unexpected_while(|| format!("writing config to {}", file_path.display()))?;
 
         Ok(())
     }
 
     fn all_domains(&self) -> AllDomainsResult<Vec<AllDomainsResult<domain::Name>>> {
         Ok(fs::read_dir(&self.dir_path)
-            .map_unexpected()?
+            .or_unexpected()?
             .map(
                 |dir_entry_res: io::Result<fs::DirEntry>| -> AllDomainsResult<domain::Name> {
-                    let domain = dir_entry_res.map_unexpected()?.file_name();
+                    let domain = dir_entry_res.or_unexpected()?.file_name();
-                    let domain = domain.to_str().ok_or_else(|| {
+                    let domain = domain.to_str().ok_or(unexpected::Error::from(
-                        error::Unexpected::from("couldn't convert os string to &str")
+                        "couldn't convert os string to &str",
-                    })?;
+                    ))?;
 
-                    domain::Name::from_str(domain).map_unexpected()
+                    domain::Name::from_str(domain)
+                        .map_unexpected_while(|| format!("parsing {domain} as domain name"))
                 },
             )
             .collect())

src/domain/manager.rs

@@ -1,6 +1,6 @@
 use crate::domain::{self, acme, checker, config};
-use crate::error::{MapUnexpected, ToUnexpected};
+use crate::error::unexpected::{self, Intoable, Mappable};
-use crate::{error, origin};
+use crate::origin;
 
 use std::{future, pin, sync};
 
@@ -10,7 +10,7 @@ pub enum GetConfigError {
     NotFound,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 impl From<config::GetError> for GetConfigError {
@@ -28,7 +28,7 @@ pub enum GetOriginError {
     NotFound,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 impl From<config::GetError> for GetOriginError {
@@ -49,7 +49,7 @@ pub enum SyncError {
     AlreadyInProgress,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 impl From<config::GetError> for SyncError {
@@ -79,7 +79,7 @@ pub enum SyncWithConfigError {
     ChallengeTokenNotSet,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 impl From<origin::store::SyncError> for SyncWithConfigError {
@@ -120,7 +120,7 @@ pub type AllDomainsResult<T> = config::AllDomainsResult<T>;
 #[mockall::automock(
     type Origin=origin::MockOrigin;
     type SyncWithConfigFuture=future::Ready<Result<(), SyncWithConfigError>>;
-    type SyncAllOriginsErrorsIter=Vec<(Option<origin::Descr>,error::Unexpected)>;
+    type SyncAllOriginsErrorsIter=Vec<unexpected::Error>;
 )]
 pub trait Manager {
     type Origin<'mgr>: origin::Origin + 'mgr
@@ -134,8 +134,7 @@ pub trait Manager {
     where
         Self: 'mgr;
 
-    type SyncAllOriginsErrorsIter<'mgr>: IntoIterator<Item = (Option<origin::Descr>, error::Unexpected)>
+    type SyncAllOriginsErrorsIter<'mgr>: IntoIterator<Item = unexpected::Error> + 'mgr
-        + 'mgr
     where
         Self: 'mgr;
 
@@ -149,7 +148,7 @@ pub trait Manager {
         config: config::Config,
     ) -> Self::SyncWithConfigFuture<'_>;
 
-    fn sync_all_origins(&self) -> Result<Self::SyncAllOriginsErrorsIter<'_>, error::Unexpected>;
+    fn sync_all_origins(&self) -> Result<Self::SyncAllOriginsErrorsIter<'_>, unexpected::Error>;
 
     fn get_acme_http01_challenge_key(
         &self,
@@ -214,7 +213,7 @@ where
     type SyncWithConfigFuture<'mgr> = pin::Pin<Box<dyn future::Future<Output = Result<(), SyncWithConfigError>> + Send + 'mgr>>
         where Self: 'mgr;
 
-    type SyncAllOriginsErrorsIter<'mgr> = Box<dyn Iterator<Item = (Option<origin::Descr>, error::Unexpected)> + 'mgr>
+    type SyncAllOriginsErrorsIter<'mgr> = Box<dyn Iterator<Item = unexpected::Error> + 'mgr>
         where Self: 'mgr;
 
     fn get_config(&self, domain: &domain::Name) -> Result<config::Config, GetConfigError> {
@@ -227,7 +226,7 @@ where
             .origin_store
             .get(config.origin_descr)
             // if there's a config there should be an origin, any error here is unexpected
-            .map_unexpected()?;
+            .or_unexpected()?;
         Ok(origin)
     }
 
@@ -237,7 +236,9 @@ where
         config: config::Config,
     ) -> Self::SyncWithConfigFuture<'_> {
         Box::pin(async move {
-            let config_hash = config.hash().map_unexpected()?;
+            let config_hash = config
+                .hash()
+                .or_unexpected_while("calculating config hash")?;
 
             self.domain_checker
                 .check_domain(&domain, &config_hash)
@@ -256,12 +257,16 @@ where
         })
     }
 
-    fn sync_all_origins(&self) -> Result<Self::SyncAllOriginsErrorsIter<'_>, error::Unexpected> {
+    fn sync_all_origins(&self) -> Result<Self::SyncAllOriginsErrorsIter<'_>, unexpected::Error> {
-        let iter = self.origin_store.all_descrs().map_unexpected()?.into_iter();
+        let iter = self
+            .origin_store
+            .all_descrs()
+            .or_unexpected_while("fetching all origin descrs")?
+            .into_iter();
 
         Ok(Box::from(iter.filter_map(|descr| {
             if let Err(err) = descr {
-                return Some((None, err.to_unexpected()));
+                return Some(err.into_unexpected());
             }
 
             let descr = descr.unwrap();
@@ -270,7 +275,7 @@ where
                 .origin_store
                 .sync(descr.clone(), origin::store::Limits {})
             {
-                return Some((Some(descr), err.to_unexpected()));
+                return Some(err.into_unexpected_while(format!("syncing store {:?}", descr)));
             }
 
             None

src/error.rs

@@ -1,56 +1 @@
-use std::error;
+pub mod unexpected;
-use std::fmt;
-use std::fmt::Write;
-
-#[derive(Debug, Clone)]
-/// Unexpected is a String which implements the Error trait. It is intended to be used in
-/// situations where the caller is being given an error they can't really handle, except to pass it
-/// along or log it.
-///
-/// The error is intended to also implement Send + Sync + Clone, such that it is easy to use in
-/// async situations.
-pub struct Unexpected(String);
-
-impl fmt::Display for Unexpected {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "Unexpected error occurred: {}", self.0)
-    }
-}
-
-impl error::Error for Unexpected {}
-
-impl From<&str> for Unexpected {
-    fn from(s: &str) -> Self {
-        Unexpected(s.to_string())
-    }
-}
-
-pub trait ToUnexpected {
-    fn to_unexpected(&self) -> Unexpected;
-}
-
-impl<E: error::Error> ToUnexpected for E {
-    fn to_unexpected(&self) -> Unexpected {
-        let mut w = String::new();
-        write!(w, "{}", self.to_string()).expect("underlying error formatted correctly");
-
-        if let Some(src) = self.source() {
-            write!(w, " [{src}]").expect("underyling source formatted correctly");
-        }
-
-        Unexpected(w.to_string())
-    }
-}
-
-pub trait MapUnexpected<T> {
-    fn map_unexpected(self) -> Result<T, Unexpected>;
-}
-
-impl<T, E: ToUnexpected> MapUnexpected<T> for Result<T, E> {
-    fn map_unexpected(self) -> Result<T, Unexpected> {
-        match self {
-            Ok(t) => Ok(t),
-            Err(err) => Err(err.to_unexpected()),
-        }
-    }
-}

src/error/unexpected.rs

@@ -0,0 +1,128 @@
+use std::fmt::Write;
+use std::{error, fmt};
+
+#[derive(Debug, Clone)]
+/// Error is a String which implements the Error trait. It is intended to be used in
+/// situations where the caller is being given an error they can't really handle, except to pass it
+/// along or log it.
+///
+/// The error is intended to also implement Send + Sync + Clone, such that it is easy to use in
+/// async situations.
+pub struct Error(String);
+
+impl Error {
+    fn from_displays<D1, D2, D3>(prefix: Option<D1>, body: &D2, source: Option<D3>) -> Error
+    where
+        D1: fmt::Display,
+        D2: fmt::Display + ?Sized,
+        D3: fmt::Display,
+    {
+        let mut w = String::new();
+
+        if let Some(prefix) = prefix {
+            write!(w, "{prefix}").expect("error writing prefix");
+        }
+
+        write!(w, "{body}").expect("error formatting body");
+
+        if let Some(source) = source {
+            write!(w, " [{source}]").expect("error formatting source");
+        }
+
+        Error(w.to_string())
+    }
+
+    fn from_err<E, D>(prefix: Option<D>, e: E) -> Error
+    where
+        E: error::Error,
+        D: fmt::Display,
+    {
+        return Error::from_displays(prefix, &e, e.source());
+    }
+
+    pub fn from(s: &str) -> Error {
+        Error::from_displays(None::<String>, s, None::<String>)
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Unexpected error occurred: {}", self.0)
+    }
+}
+
+impl error::Error for Error {}
+
+pub trait Mappable<T> {
+    /// or_unexpected returns an Err(Error) wrapping self's Err, or the Ok value of self.
+    fn or_unexpected(self) -> Result<T, Error>;
+
+    /// or_unexpected_while is like or_unexpected, but will prefix the error message. The prefix
+    /// should be worded as if it started with the word "while", e.g.: `opening file {path}`.
+    fn or_unexpected_while<D: fmt::Display>(self, prefix: D) -> Result<T, Error>;
+
+    /// map_unexpected_while is like or_unexpected_while, but uses a closure to produce the error
+    /// prefix.
+    fn map_unexpected_while<F, D>(self, f: F) -> Result<T, Error>
+    where
+        F: FnOnce() -> D,
+        D: fmt::Display;
+}
+
+fn map_unexpected_maybe_while<T, E, F, D>(
+    res: Result<T, E>,
+    prefix_fn: Option<F>,
+) -> Result<T, Error>
+where
+    E: error::Error,
+    F: FnOnce() -> D,
+    D: std::fmt::Display,
+{
+    match res {
+        Ok(res) => Ok(res),
+        Err(err) => Err(Error::from_err(prefix_fn.map(|prefix_fn| prefix_fn()), err)),
+    }
+}
+
+impl<T, E: error::Error> Mappable<T> for Result<T, E> {
+    fn or_unexpected(self) -> Result<T, Error> {
+        let no_fn = None::<Box<dyn FnOnce() -> Box<dyn fmt::Display>>>; // lol, good job rust
+        map_unexpected_maybe_while(self, no_fn)
+    }
+
+    fn or_unexpected_while<D: fmt::Display>(self, prefix: D) -> Result<T, Error> {
+        map_unexpected_maybe_while(self, Some(|| prefix))
+    }
+
+    fn map_unexpected_while<F, D>(self, f: F) -> Result<T, Error>
+    where
+        F: FnOnce() -> D,
+        D: fmt::Display,
+    {
+        map_unexpected_maybe_while(self, Some(f))
+    }
+}
+
+pub trait Intoable {
+    fn into_unexpected(self) -> Error;
+
+    /// into_unexpected_while is like to_unexpected, but will prefix the Error error. The
+    /// prefix should be worded as if it started with the word "while", e.g.: `opening file
+    /// {path}`.
+    fn into_unexpected_while<D>(self, prefix: D) -> Error
+    where
+        D: fmt::Display;
+}
+
+impl<E: error::Error> Intoable for E {
+    fn into_unexpected(self) -> Error {
+        Error::from_err(None::<String>, self)
+    }
+
+    fn into_unexpected_while<D>(self, prefix: D) -> Error
+    where
+        D: fmt::Display,
+    {
+        Error::from_err(Some(prefix), self)
+    }
+}

src/lib.rs

@@ -4,3 +4,4 @@ pub mod domain;
 pub mod error;
 pub mod origin;
 pub mod service;
+pub mod util;

src/main.rs

@@ -98,8 +98,8 @@ async fn main() {
         let canceller = canceller.clone();
 
         tokio::spawn(async move {
-            let mut signals =
+            let mut signals = Signals::new(signal_hook::consts::TERM_SIGNALS)
-                Signals::new(signal_hook::consts::TERM_SIGNALS).expect("initialized signals");
+                .expect("initializing signals failed");
 
             if (signals.next().await).is_some() {
                 log::info!("Gracefully shutting down...");
@@ -114,23 +114,23 @@ async fn main() {
     }
 
     let origin_store = domiply::origin::store::git::new(config.origin_store_git_dir_path)
-        .expect("git origin store initialized");
+        .expect("git origin store initialization failed");
 
     let domain_checker = domiply::domain::checker::new(
         config.domain_checker_target_a,
         &config.domain_checker_resolver_addr,
     )
     .await
-    .expect("domain checker initialized");
+    .expect("domain checker initialization failed");
 
     let domain_config_store = domiply::domain::config::new(&config.domain_config_store_dir_path)
-        .expect("domain config store initialized");
+        .expect("domain config store initialization failed");
 
     let https_params = if let Some(https_listen_addr) = config.https_listen_addr {
         let domain_acme_store_dir_path = config.domain_acme_store_dir_path.unwrap();
 
         let domain_acme_store = domiply::domain::acme::store::new(&domain_acme_store_dir_path)
-            .expect("domain acme store initialized");
+            .expect("domain acme store initialization failed");
 
         // if https_listen_addr is set then domain_acme_contact_email is required, see the Cli/clap
         // settings.
@@ -141,7 +141,7 @@ async fn main() {
             &domain_acme_contact_email,
         )
         .await
-        .expect("domain acme manager initialized");
+        .expect("domain acme manager initialization failed");
 
         Some(HTTPSParams {
             https_listen_addr,
@@ -182,10 +182,7 @@ async fn main() {
                 errors_iter
                     .unwrap()
                     .into_iter()
-                    .for_each(|(descr, err)| match descr {
+                    .for_each(|err| log::error!("syncing failed: {err}"));
-                        None => log::error!("Error while syncing unknown descr: {err}"),
-                        Some(descr) => log::error!("Failed to sync {descr:?}: {err}"),
-                    });
             }
         })
     });
@@ -323,7 +320,7 @@ async fn main() {
 
                 let addr = https_params.https_listen_addr;
                 let addr_incoming = hyper::server::conn::AddrIncoming::bind(&addr)
-                    .expect("https listen socket created");
+                    .expect("https listen socket creation failed");
 
                 let incoming =
                     tls_listener::TlsListener::new(server_config, addr_incoming).filter(|conn| {

src/origin.rs

@@ -1,4 +1,4 @@
-use crate::error;
+use crate::error::unexpected;
 
 mod descr;
 pub use self::descr::Descr;
@@ -10,7 +10,7 @@ pub enum ReadFileIntoError {
     FileNotFound,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 #[mockall::automock]

src/origin/store.rs

@@ -1,4 +1,5 @@
-use crate::{error, origin};
+use crate::error::unexpected;
+use crate::origin;
 
 pub mod git;
 
@@ -19,7 +20,7 @@ pub enum SyncError {
     AlreadyInProgress,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 #[derive(thiserror::Error, Debug)]
@@ -28,13 +29,13 @@ pub enum GetError {
     NotFound,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 #[derive(thiserror::Error, Debug)]
 pub enum AllDescrsError {
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 /// Used in the return from all_descrs from Store.

src/origin/store/git.rs

@@ -1,6 +1,5 @@
-use crate::error::{MapUnexpected, ToUnexpected};
+use crate::error::unexpected::{self, Intoable, Mappable};
-use crate::origin::store;
+use crate::origin::{self, store};
-use crate::{error, origin};
 
 use std::path::{Path, PathBuf};
 use std::{collections, fs, io, sync};
@@ -28,16 +27,23 @@ impl origin::Origin for sync::Arc<Origin> {
 
         let file_object = repo
             .find_object(self.tree_object_id)
-            .map_unexpected()?
+            .map_unexpected_while(|| format!("finding tree object {}", self.tree_object_id))?
             .peel_to_tree()
-            .map_unexpected()?
+            .map_unexpected_while(|| format!("peeling tree object {}", self.tree_object_id))?
             .lookup_entry_by_path(clean_path)
-            .map_unexpected()?
+            .map_unexpected_while(|| {
+                format!(
+                    "looking up {} in tree object {}",
+                    clean_path.display(),
+                    self.tree_object_id
+                )
+            })?
             .ok_or(origin::ReadFileIntoError::FileNotFound)?
             .object()
-            .map_unexpected()?;
+            .or_unexpected()?;
 
-        into.write_all(file_object.data.as_ref()).map_unexpected()?;
+        into.write_all(file_object.data.as_ref())
+            .or_unexpected_while("copying out file")?;
 
         Ok(())
     }
@@ -49,7 +55,7 @@ enum GetOriginError {
     InvalidBranchName,
 
     #[error(transparent)]
-    Unexpected(#[from] error::Unexpected),
+    Unexpected(#[from] unexpected::Error),
 }
 
 /// git::Store implements the Store trait for any Descr::Git based Origins. If any non-git
@@ -95,19 +101,21 @@ impl Store {
             ref branch_name, ..
         } = descr;
 
+        let branch_ref = self.branch_ref(branch_name);
+
         let commit_object_id = repo
-            .try_find_reference(&self.branch_ref(branch_name))
+            .try_find_reference(&branch_ref)
-            .map_unexpected()?
+            .map_unexpected_while(|| format!("finding branch ref {branch_ref}"))?
             .ok_or(GetOriginError::InvalidBranchName)?
             .peel_to_id_in_place()
-            .map_unexpected()?
+            .or_unexpected_while("peeling id in place")?
             .detach();
 
         let tree_object_id = repo
             .find_object(commit_object_id)
-            .map_unexpected()?
+            .map_unexpected_while(|| format!("finding commit object {commit_object_id}"))?
             .try_to_commit_ref()
-            .map_unexpected()?
+            .map_unexpected_while(|| format!("parsing {commit_object_id} as commit"))?
             .tree();
 
         Ok(sync::Arc::from(Origin {
@@ -131,7 +139,8 @@ impl Store {
         // if the path doesn't exist then use the gix clone feature to clone it into the
         // directory.
         if fs::read_dir(repo_path).is_err() {
-            fs::create_dir_all(repo_path).map_unexpected()?;
+            fs::create_dir_all(repo_path)
+                .map_unexpected_while(|| format!("creating {}", repo_path.display()))?;
 
             let origin::Descr::Git {
                 ref url,
@@ -146,43 +155,53 @@ impl Store {
                     gixCloneErr::UrlParse(_) | gixCloneErr::CanonicalizeUrl { .. } => {
                         store::SyncError::InvalidURL
                     }
-                    _ => e.to_unexpected().into(),
+                    _ => e
+                        .into_unexpected_while(format!(
+                            "cloning {} into {}",
+                            url,
+                            repo_path.display()
+                        ))
+                        .into(),
                 })?
                 .fetch_only(Discard, should_interrupt)
                 .map_err(|_| store::SyncError::InvalidURL)?;
 
             // Check to make sure the branch name exists
             // TODO if this fails we should delete repo_path
-            repo.try_find_reference(&self.branch_ref(branch_name))
+            let branch_ref = self.branch_ref(branch_name);
-                .map_unexpected()?
+            repo.try_find_reference(&branch_ref)
+                .map_unexpected_while(|| format!("finding branch ref {branch_ref}"))?
                 .ok_or(store::SyncError::InvalidBranchName)?;
 
             // Add the descr to the repo directory, so we can know the actual descr later
             // TODO if this fails we should delete repo_path
-            let descr_file =
+            let file_path = self.descr_file_path(descr.id().as_ref());
-                fs::File::create(self.descr_file_path(descr.id().as_ref())).map_unexpected()?;
+            let descr_file = fs::File::create(&file_path)
+                .map_unexpected_while(|| format!("creating {}", file_path.display()))?;
 
-            serde_json::to_writer(descr_file, &descr).map_unexpected()?;
+            serde_json::to_writer(descr_file, &descr)
+                .map_unexpected_while(|| format!("writing descr to {}", file_path.display()))?;
 
             return Ok(repo);
         }
 
         let direction = gix::remote::Direction::Fetch;
 
-        let repo = gix::open(repo_path).map_unexpected()?;
+        let repo = gix::open(repo_path)
+            .map_unexpected_while(|| format!("opening repo at {}", repo_path.display()))?;
 
         let remote = repo
             .find_default_remote(direction)
-            .ok_or_else(|| error::Unexpected::from("no default configured"))?
+            .ok_or_else(|| unexpected::Error::from("no default configured"))?
-            .map_unexpected()?;
+            .or_unexpected_while("finding default remote for fetching")?;
 
         remote
             .connect(direction)
-            .map_unexpected()?
+            .or_unexpected_while("connecting to remote")?
             .prepare_fetch(Discard, Default::default())
-            .map_unexpected()?
+            .or_unexpected_while("preparing fetch")?
             .receive(Discard, should_interrupt)
-            .map_unexpected()?;
+            .or_unexpected_while("fetching from remote")?;
 
         Ok(repo)
     }
@@ -253,15 +272,18 @@ impl super::Store for sync::Arc<Store> {
 
         fs::read_dir(&repo_path).map_err(|e| match e.kind() {
             io::ErrorKind::NotFound => store::GetError::NotFound,
-            _ => e.to_unexpected().into(),
+            _ => e
+                .into_unexpected_while(format!("checking if {} exists", repo_path.display()))
+                .into(),
         })?;
 
-        let repo = gix::open(&repo_path).map_unexpected()?;
+        let repo = gix::open(&repo_path)
+            .map_unexpected_while(|| format!("opening {} as git repo", repo_path.display()))?;
 
         let origin = self.get_origin(repo, descr.clone()).map_err(|e| match e {
             // it's not expected that the branch name is invalid at this point, it must have
             // existed for sync to have been successful.
-            GetOriginError::InvalidBranchName => e.to_unexpected().into(),
+            GetOriginError::InvalidBranchName => e.into_unexpected().into(),
             GetOriginError::Unexpected(e) => store::GetError::Unexpected(e),
         })?;
 
@@ -273,14 +295,14 @@ impl super::Store for sync::Arc<Store> {
 
     fn all_descrs(&self) -> store::AllDescrsResult<Self::AllDescrsIter<'_>> {
         Ok(Box::from(
-            fs::read_dir(&self.dir_path).map_unexpected()?.map(
+            fs::read_dir(&self.dir_path).or_unexpected()?.map(
                 |dir_entry_res: io::Result<fs::DirEntry>| -> store::AllDescrsResult<origin::Descr> {
                     let descr_id: String = dir_entry_res
-                        .map_unexpected()?
+                        .or_unexpected()?
                         .file_name()
                         .to_str()
                         .ok_or_else(|| {
-                            error::Unexpected::from("couldn't convert os string to &str")
+                            unexpected::Error::from("couldn't convert os string to &str")
                         })?
                         .into();
 
@@ -289,9 +311,14 @@ impl super::Store for sync::Arc<Store> {
                     // TODO it's possible that opening the file will fail if syncing is
                     // still ongoing, as writing the descr file is the last step after
                     // initial sync has succeeded.
-                    let descr_file = fs::File::open(descr_file_path).map_unexpected()?;
+                    let descr_file = fs::File::open(descr_file_path.as_path())
+                        .map_unexpected_while(|| {
+                            format!("opening descr file {}", descr_file_path.display())
+                        })?;
 
-                    let descr = serde_json::from_reader(descr_file).map_unexpected()?;
+                    let descr = serde_json::from_reader(descr_file).map_unexpected_while(|| {
+                        format!("reading descr file {}", descr_file_path.display())
+                    })?;
 
                     Ok(descr)
                 },

src/util.rs

@@ -0,0 +1,11 @@
+use std::{fs, io, path};
+
+pub fn open_file(path: &path::Path) -> io::Result<Option<fs::File>> {
+    match fs::File::open(path) {
+        Ok(file) => Ok(Some(file)),
+        Err(err) => match err.kind() {
+            io::ErrorKind::NotFound => Ok(None),
+            _ => Err(err),
+        },
+    }
+}