more robust way of setting IFS to newline (sylabs#1708)

* more robust way of setting IFS to newline

* e2e test for issue 1704

* added bugfix info to changelog

CHANGELOG.md

@@ -57,6 +57,8 @@
 ### Bug Fixes
 
 - Fix interaction between `--workdir` when given relative path and `--scratch`.
+- Fix dropped "n" characters on some platforms in definition file stored as part
+  of SIF metadata.
 
 ## 3.11.3 \[2023-05-04\]
 

cmd/internal/cli/inspect.go

@@ -242,7 +242,8 @@ func newCommand(allData bool, appName string, img *image.Image) *command {
 	cat_file() {
 		echo "%[3]s $1:$2"
 
-		local IFS=$'\n'
+		local IFS="
+"
 		while read -r content; do
 			printf "%%s\n" "$content"
 		done < "$2"

e2e/docker/docker.go

@@ -1037,6 +1037,7 @@ func E2ETests(env e2e.TestEnv) testhelper.Tests {
 		// Regressions
 		"issue 4943": c.issue4943,
 		"issue 5172": c.issue5172,
-		"issue 274":  c.issue274, // https://github.com/sylabs/singularity/issues/274
+		"issue 274":  c.issue274,  // https://github.com/sylabs/singularity/issues/274
+		"issue 1704": c.issue1704, // https://github.com/sylabs/singularity/issues/1704
 	}
 }

e2e/docker/regressions.go

@@ -12,6 +12,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"github.com/sylabs/singularity/e2e/internal/e2e"
@@ -182,6 +183,48 @@ From: continuumio/miniconda3:latest
 	)
 }
 
+// https://github.com/sylabs/singularity/issues/1704 Ensure that trailing "n"s
+// aren't lopped off by the internal sandbox inspect call that is part of the
+// SIF-building process.
+func (c ctx) issue1704(t *testing.T) {
+	tmpDir, cleanup := e2e.MakeTempDir(t, c.env.TestDir, "issue1704-", "")
+	t.Cleanup(func() {
+		if !t.Failed() {
+			cleanup(t)
+		}
+	})
+
+	defPath := filepath.Join("..", "test", "defs", "issue1704.def")
+	sifPath := filepath.Join(tmpDir, "issue1704.sif")
+	bytes, err := os.ReadFile(defPath)
+	if err != nil {
+		t.Fatalf("could not read contents of def file %q: %s", defPath, err)
+	}
+	defFileContents := string(bytes)
+
+	c.env.RunSingularity(
+		t,
+		e2e.AsSubtest("Build"),
+		e2e.WithProfile(e2e.RootProfile),
+		e2e.WithCommand("build"),
+		e2e.WithArgs(sifPath, defPath),
+		e2e.ExpectExit(0),
+	)
+
+	if t.Failed() {
+		return
+	}
+
+	c.env.RunSingularity(
+		t,
+		e2e.AsSubtest("Inspect"),
+		e2e.WithProfile(e2e.UserProfile),
+		e2e.WithCommand("inspect"),
+		e2e.WithArgs("-d", sifPath),
+		e2e.ExpectExit(0, e2e.ExpectOutput(e2e.ContainMatch, strings.TrimSpace(defFileContents))),
+	)
+}
+
 // https://github.com/sylabs/singularity/issues/1286
 // Ensure the bare docker://hello-world image runs in all modes
 func (c ctx) issue1286(t *testing.T) {

test/defs/issue1704.def

@@ -0,0 +1,10 @@
+BootStrap: docker
+From: ubuntu:22.04
+
+%setup
+    #an
+    #abn
+    #nn
+    #ann
+    #nan
+    #anan