allow empty sources.list entries

coverage.txt

@@ -362,3 +362,5 @@ Variants: essential apt minbase
 Test: apt-patterns
 
 Test: apt-patterns-custom
+
+Test: empty-sources.list

mmdebstrap

@@ -2072,7 +2072,7 @@ sub run_setup() {
     }
 
     # write /etc/apt/sources.list and files in /etc/apt/sources.list.d/
-    {
+    if (scalar @{ $options->{sourceslists} } > 0) {
         my $firstentry = $options->{sourceslists}->[0];
         # if the first sources.list entry is of one-line type and without
         # explicit filename, then write out an actual /etc/apt/sources.list
@@ -2299,6 +2299,9 @@ sub run_update() {
         close $fh;
         if ($indextargets eq '') {
             warning("apt-get indextargets output is empty");
+            if (scalar @{ $options->{sourceslists} } == 0) {
+                warning "no known apt sources.list entry";
+            }
             for my $list (@{ $options->{sourceslists} }) {
                 if (defined $list->{fname}) {
                     info("Filename: $list->{fname}");
@@ -5082,6 +5085,9 @@ sub main() {
                 ## no critic (InputOutput::ProhibitExplicitStdin)
                 <STDIN>;
             };
+            if ($content eq "") {
+                warning "sources.list from standard input is empty";
+            } else {
                 my $type = guess_sources_format($content);
                 if (!defined $type
                     || ($type ne "deb822" and $type ne "one-line")) {
@@ -5093,6 +5099,7 @@ sub main() {
                     fname   => undef,
                     content => $content,
                   };
+            }
         } else {
             my @components = ();
             foreach my $comp (@{ $options->{components} }) {
@@ -5112,9 +5119,11 @@ sub main() {
                 }
             }
             my $compstr = join " ", @components;
-            # if the currently selected apt keyrings do not contain the
-            # necessary key material for the chosen suite, then attempt adding
-            # a signed-by option
+            # From the suite name we can maybe infer which key we need. If we
+            # can infer this information, then we need to check whether the
+            # currently running apt actually trusts this key or not. If it
+            # doesn't, then we need to add a signed-by line to the sources.list
+            # entry.
             my $signedby        = '';
             my %suite_by_vendor = get_suite_by_vendor();
             my $gpgproc         = sub {
@@ -5251,9 +5260,14 @@ sub main() {
                             ## no critic (InputOutput::ProhibitExplicitStdin)
                             <STDIN>;
                         };
+                        if ($content eq "") {
+                            warning
+                              "sources.list from standard input is empty";
+                        } else {
                             my $type = guess_sources_format($content);
                             if (!defined $type
-                            || ($type ne 'deb822' and $type ne 'one-line')) {
+                                || ($type ne 'deb822' and $type ne 'one-line'))
+                            {
                                 error "cannot determine sources.list format";
                             }
                           # if last entry is of same type and without filename,
@@ -5272,6 +5286,7 @@ sub main() {
                                     content => $content,
                                   };
                             }
+                        }
                     } elsif ($arg =~ /^deb(-src)? /) {
                         my $content = "$arg\n";
                         # if last entry is of same type and without filename,
@@ -5315,6 +5330,9 @@ sub main() {
                             $content .= $line;
                         }
                         close $fh;
+                        if ($content eq "") {
+                            warning "$arg is empty";
+                        } else {
                             my $type = undef;
                             if ($arg =~ /\.list$/) {
                                 $type = 'one-line';
@@ -5324,7 +5342,8 @@ sub main() {
                                 $type = guess_sources_format($content);
                             }
                             if (!defined $type
-                            || ($type ne 'deb822' and $type ne 'one-line')) {
+                                || ($type ne 'deb822' and $type ne 'one-line'))
+                            {
                                 error "cannot determine sources.list format";
                             }
                             push @{$sourceslists},
@@ -5333,6 +5352,9 @@ sub main() {
                                 fname   => basename($arg),
                                 content => $content,
                               };
+                        }
+                    } elsif ($arg eq '') {
+                        # empty
                     } else {
                         error "invalid mirror: $arg";
                     }
@@ -5351,7 +5373,7 @@ sub main() {
             }
         }
         if (scalar @{$sourceslists} == 0) {
-            error "empty apt sources.list";
+            warning "empty apt sources.list";
         }
         debug("sources list entries:");
         for my $list (@{$sourceslists}) {

tests/empty-sources.list

@@ -0,0 +1,8 @@
+#!/bin/sh
+set -eu
+export LC_ALL=C.UTF-8
+trap "rm -f /tmp/debian-chroot.tar" EXIT INT TERM
+printf '' | {{ CMD }} --mode={{ MODE }} --variant=apt \
+	--setup-hook='echo "deb {{ MIRROR }} {{ DIST }} main" > "$1"/etc/apt/sources.list' \
+	{{ DIST }} /tmp/debian-chroot.tar -
+tar -tf /tmp/debian-chroot.tar | sort | diff -u tar1.txt -