ash,hush: fix corner cases with backslash-newlines in heredocs

function                                             old     new   delta
fetch_heredocs                                       477     485      +8

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

14 files changed, 44 insertions, 5 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 9cacdff64..bfd9aa53e 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -12735,21 +12735,22 @@ checkend: {
 
                 if (striptabs) {
                         while (c == '\t')
-                                c = pgetc();
+                                c = pgetc_eatbnl();  /* dash does pgetc() */
+                                /* (see heredoc_bkslash_newline3a.tests) */
                 }
 
                 markloc = out - (char *)stackblock();
                 for (p = eofmark; STPUTC(c, out), *p; p++) {
                         if (c != *p)
                                 goto more_heredoc;
-                        /* FIXME: fails for backslash-newlined terminator:
+                        /* dash still has this not fixed (as of 2025-08)
                          * cat <<EOF
                          * ...
                          * EO\
                          * F
                          * (see heredoc_bkslash_newline2.tests)
                          */
-                        c = pgetc();
+                        c = pgetc_eatbnl(); /* dash does pgetc() */
                 }
 
                 if (c == '\n' || c == PEOF) {
diff --git a/shell/ash_test/ash-heredoc/heredoc_bkslash_newline2a.right b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline2a.right
new file mode 100644
index 000000000..3d79316d7
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline2a.right
@@ -0,0 +1 @@
+Ok1
diff --git a/shell/ash_test/ash-heredoc/heredoc_bkslash_newline2a.tests b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline2a.tests
new file mode 100755
index 000000000..eb2223031
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline2a.tests
@@ -0,0 +1,4 @@
+cat <<-EOF
+        Ok1
+        EO\
+F
diff --git a/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3.right b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3.right
new file mode 100644
index 000000000..3d79316d7
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3.right
@@ -0,0 +1 @@
+Ok1
diff --git a/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3.tests b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3.tests
new file mode 100755
index 000000000..de21132d1
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3.tests
@@ -0,0 +1,4 @@
+cat <<EOF
+Ok1
+\
+EOF
diff --git a/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3a.right b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3a.right
new file mode 100644
index 000000000..3d79316d7
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3a.right
@@ -0,0 +1 @@
+Ok1
diff --git a/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3a.tests b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3a.tests
new file mode 100755
index 000000000..da3860804
--- /dev/null
+++ b/shell/ash_test/ash-heredoc/heredoc_bkslash_newline3a.tests
@@ -0,0 +1,4 @@
+cat <<-EOF
+Ok1
+        \
+        EOF
diff --git a/shell/hush.c b/shell/hush.c
index 6129a087b..0b8da5e2d 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -4639,7 +4639,15 @@ static char *fetch_till_str(o_string *as_string,
                                         past_EOL = heredoc.length;
                                         /* Get 1st char of next line, possibly skipping leading tabs */
                                         do {
-                                                ch = i_getch(input);
+                                                if (heredoc_flags & HEREDOC_QUOTED)
+                                                        ch = i_getch(input);
+                                                else { /* see heredoc_bkslash_newline3a.tests:
+                                                         * cat <<-EOF
+                                                         * <tab>\
+                                                         * <tab>EOF
+                                                         */
+                                                        ch = i_getch_and_eat_bkslash_nl(input);
+                                                }
                                                 if (ch != EOF)
                                                         nommu_addchr(as_string, ch);
                                         } while ((heredoc_flags & HEREDOC_SKIPTABS) && ch == '\t');
@@ -4665,7 +4673,7 @@ static char *fetch_till_str(o_string *as_string,
                                 prev = 0; /* not '\' */
                                 continue;
                         }
-                }
+                } /* if (\n or EOF) */
                 if (ch == EOF) {
                         o_free(&heredoc);
                         return NULL; /* error */
diff --git a/shell/hush_test/hush-heredoc/heredoc_bkslash_newline2a.right b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline2a.right
new file mode 100644
index 000000000..3d79316d7
--- /dev/null
+++ b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline2a.right
@@ -0,0 +1 @@
+Ok1
diff --git a/shell/hush_test/hush-heredoc/heredoc_bkslash_newline2a.tests b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline2a.tests
new file mode 100755
index 000000000..eb2223031
--- /dev/null
+++ b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline2a.tests
@@ -0,0 +1,4 @@
+cat <<-EOF
+        Ok1
+        EO\
+F
diff --git a/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3.right b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3.right
new file mode 100644
index 000000000..3d79316d7
--- /dev/null
+++ b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3.right
@@ -0,0 +1 @@
+Ok1
diff --git a/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3.tests b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3.tests
new file mode 100755
index 000000000..de21132d1
--- /dev/null
+++ b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3.tests
@@ -0,0 +1,4 @@
+cat <<EOF
+Ok1
+\
+EOF
diff --git a/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3a.right b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3a.right
new file mode 100644
index 000000000..3d79316d7
--- /dev/null
+++ b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3a.right
@@ -0,0 +1 @@
+Ok1
diff --git a/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3a.tests b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3a.tests
new file mode 100755
index 000000000..da3860804
--- /dev/null
+++ b/shell/hush_test/hush-heredoc/heredoc_bkslash_newline3a.tests
@@ -0,0 +1,4 @@
+cat <<-EOF
+Ok1
+        \
+        EOF