refactor: one helper each for the repeated blocks

src/commands/postgres.rs

@@ -16,7 +16,7 @@ use crate::cmd::{
 };
 use crate::ctx::Ctx;
 use crate::fsops::{create_private_new, suffixed};
-use crate::output::{note, warning};
+use crate::output::{note, plural, warning};
 
 // unique per run: docker cp will not copy a directory over an existing path, and
 // quietly leaves whatever was there for pg_restore to read instead
@@ -36,6 +36,13 @@ fn partial_path(file: &Path) -> PathBuf {
     suffixed(file, &format!(".{}.partial", std::process::id()))
 }
 
+// the database was dropped before the restore was attempted, so a restore that
+// failed leaves nothing behind: said the same way wherever it happens, since
+// what the user has to do about it does not depend on which tool it was
+fn left_empty(tool: &str) -> anyhow::Error {
+    anyhow::anyhow!("{tool} failed, the database is left empty")
+}
+
 // pg_dumpall recreates roles the cluster already has, so this is the expected
 // complaint rather than a failure
 fn is_existing_role_error(line: &str) -> bool {
@@ -75,17 +82,17 @@ fn restore_cluster(ctx: &Ctx, db: &Database, restore: &dyn Cmd, file: &Path) ->
         note!(
             ctx,
             "left {existing} existing role{} alone",
-            if existing == 1 { "" } else { "s" }
+            plural(existing)
         );
     }
 
     if !out.status.success() {
-        bail!("psql failed, the database is left empty");
+        return Err(left_empty("psql"));
     }
     if failed > 0 {
         bail!(
             "psql reported {failed} error{}, so the cluster restored only in part",
-            if failed == 1 { "" } else { "s" }
+            plural(failed)
         );
     }
 
@@ -99,7 +106,7 @@ fn gzip_kind(ctx: &Ctx, db: &Database, file: &Path) -> Result<Kind> {
     wait_until_ready(ctx, db)?;
 
     let out = Gunzip
-        .pipe(&Head::bytes(HEADER_LEN))
+        .pipe(&Head::bytes(HEADER_LEN))?
         // head closes the pipe once it has its bytes, which kills gunzip
         .allow_early_close()
         .in_container(&db.container)
@@ -257,14 +264,14 @@ fn restore_dump(
             .status(ctx)?;
 
         if !status.success() {
-            bail!("{tool} failed, the database is left empty");
+            return Err(left_empty(tool));
         }
 
         return Ok(());
     }
 
     let restore: Box<dyn Cmd> = match dump {
-        Dump::Gzip => Box::new(Gunzip.pipe(&*restore)),
+        Dump::Gzip => Box::new(Gunzip.pipe(&*restore)?),
         _ => restore,
     };
 
@@ -280,7 +287,7 @@ fn restore_dump(
         .stdin_from(ctx, file)?;
 
     if !status.success() {
-        bail!("{tool} failed, the database is left empty");
+        return Err(left_empty(tool));
     }
 
     Ok(())
@@ -328,7 +335,7 @@ pub fn dump(ctx: &Ctx, args: &cli::Dump) -> Result<()> {
 
     let dumped = if gzip {
         dumping
-            .pipe(&Gzip)
+            .pipe(&Gzip)?
             .in_container(&db.container)
             .stream_to(ctx, stdout)
     } else {