From 7e6f8dd36c55d3ed8b57cab8ee0dd9a45a8f87c9 Mon Sep 17 00:00:00 2001
From: bth <git@bth.moi>
Date: Wed, 21 Jan 2026 12:31:47 -0800
Subject: [PATCH] pipe : FileListSplit and better errors

---
 pipe/pipe.go | 28 ++++++++++++++++++++++++++++
 sort/sort.go | 29 ++++++++---------------------
 2 files changed, 36 insertions(+), 21 deletions(-)

diff --git a/pipe/pipe.go b/pipe/pipe.go
index 2629823..930b650 100644
--- a/pipe/pipe.go
+++ b/pipe/pipe.go
@@ -2,6 +2,7 @@ package pipe
 
 import (
 	"errors"
+	"fmt"
 	"io"
 	"log"
 	"os"
@@ -27,3 +28,30 @@ func GetStdin() ([]string, error) {
 	s, _ := strings.CutSuffix(string(data), Newline)
 	return strings.Split(s, Newline), nil
 }
+
+// reads files from stdin if present, otherwise from the filename:
+func FileListSplitMaybeStdin(f string) ([]string, error) {
+	filelist, err := GetStdin()
+	if err != nil {
+		// BORK: don't see a neater way of wrapping these two when we depend on the non-nil in this block:
+		// if i just return FileListSplit(), we lose the first err
+		filelist, err2 := FileListSplit(f)
+		if err2 != nil {
+			return nil, fmt.Errorf("%w: %w", err, err2)
+		}
+		return filelist, nil
+	}
+	return filelist, nil
+}
+
+// opens the given filename and splits into lines:
+func FileListSplit(f string) ([]string, error) {
+	if f == "" {
+		return nil, errors.New("filename is empty")
+	}
+	dat, err := os.ReadFile(f)
+	if err != nil {
+		return nil, fmt.Errorf("error opening file: %w", err)
+	}
+	return strings.Split(string(dat), Newline), nil
+}
diff --git a/sort/sort.go b/sort/sort.go
index 8af6718..919900b 100644
--- a/sort/sort.go
+++ b/sort/sort.go
@@ -33,25 +33,6 @@ func initOpts() options {
 	}
 }
 
-// reads files from stdin if present, otherwise from the filename:
-func fileListSplitMaybeStdin(f string) []string {
-	filelist, err := pipe.GetStdin()
-	if err != nil {
-		filelist = fileListSplit(f)
-	}
-	return filelist
-}
-
-// opens the given filename and splits into lines:
-func fileListSplit(f string) []string {
-	dat, err := os.ReadFile(f)
-	if err != nil {
-		// if this fails all is lost. just exit.
-		log.Fatalf("um %s: error opening file: %s\n%s", CMD, f, err)
-	}
-	return strings.Split(string(dat), pipe.Newline)
-}
-
 // record the order of the given filelist.
 func kMap(kslice []string) map[string]int {
 	m := make(map[string]int, 0)
@@ -95,8 +76,14 @@ func Sort(args []string) {
 		flags.Help(CMD, SUMMARY, opts)
 	}
 
-	sslice := fileListSplitMaybeStdin(opts.Source.Val)
-	kslice := fileListSplit(opts.Key.Val)
+	sslice, err := pipe.FileListSplitMaybeStdin(opts.Source.Val)
+	if err != nil {
+		log.Fatalf("um %s: %s", CMD, err)
+	}
+	kslice, err := pipe.FileListSplit(opts.Key.Val)
+	if err != nil {
+		log.Fatalf("um %s: %s", CMD, err)
+	}
 	kmap := kMap(kslice)
 	out := sort(sslice, kmap)
 	if opts.Write.IsSet() {