From a64e35b336dbca32aa16228b09670ff8f83029d2 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Sat, 28 Mar 2015 20:21:03 -0500
Subject: Fix sed bug David Halls hit trying to compile libiconv.

---
 tests/sed.test   |  5 ++++-
 toys/posix/sed.c | 42 ++++++++++++++++++++++++------------------
 2 files changed, 28 insertions(+), 19 deletions(-)

diff --git a/tests/sed.test b/tests/sed.test
index dfc76023..9f2956f8 100644
--- a/tests/sed.test
+++ b/tests/sed.test
@@ -4,7 +4,7 @@
 
 testing 'sed as cat' 'sed ""' "one\ntwo\nthree" "" "one\ntwo\nthree"
 # This segfaults ubuntu 12.04's sed. No really.
-testing 'sed - - twice' 'sed "" - -' "hello\n" "" "hello\n"
+SKIP_HOST=1 testing 'sed - - twice' 'sed "" - -' "hello\n" "" "hello\n"
 testing 'sed -n' 'sed -n ""' "" "" "one\ntwo\nthree"
 testing 'sed -n p' 'sed -n p' "one\ntwo\nthree" "" "one\ntwo\nthree"
 testing 'sed explicit pattern' 'sed -e p -n' "one\ntwo\nthree" "" \
@@ -132,6 +132,9 @@ hello'" "merp\nhello\n" "" "merp"
 #echo merp | sed/sed "1a\\
 #hello"
 
+testing "sed bonus backslashes" \
+  "sed -e 'a \l \x\' -e \"\$(echo -e 'ab\\\nc')\"" \
+  "hello\nl x\nab\nc\n" "" "hello\n"
 # -i with $ last line test
 
 exit $FAILCOUNT
diff --git a/toys/posix/sed.c b/toys/posix/sed.c
index 705ea7bc..20975320 100644
--- a/toys/posix/sed.c
+++ b/toys/posix/sed.c
@@ -4,7 +4,7 @@
  *
  * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html
  *
- * TODO: lines > 2G could signed int wrap length counters. Not just getline()
+ * TODO: lines > 2G could wrap signed int length counters. Not just getline()
  * but N and s///
 
 USE_SED(NEWTOY(sed, "(version)e*f*inEr[+Er]", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_LOCALE))
@@ -967,29 +967,35 @@ resume_a:
       }
 
       // Extend allocation to include new string. We use offsets instead of
-      // pointers so realloc() moving stuff doesn't break things. Do it
-      // here instead of toybuf so there's no maximum size.
+      // pointers so realloc() moving stuff doesn't break things. Ok to write
+      // \n over NUL terminator because call to extend_string() adds it back.
       if (!corwin->arg1) corwin->arg1 = reg - (char*)corwin;
       else if ((corwin+1) != (void *)reg) *(reg++) = '\n';
       reg = extend_string((void *)&corwin, line, reg - (char *)corwin, end);
 
-      line += end;
-
-      // Line continuation? (Two slightly different input methods, -e with
-      // embedded newline vs -f line by line. Must parse both correctly.)
-      if (!strchr("btT:", c) && line[-1] == '\\') {
-        // backslash only matters if we have an odd number of them
-        for (i = 0; i<end; i++) if (line[-i-1] != '\\') break;
-        if (i&1) {
-          // reg is next available space, so reg[-1] is the null terminator
-          reg[-2] = 0;
-          if (*line && line[1]) {
-            reg -= 2;
+      // Recopy data to remove escape sequences and handle line continuation.
+      if (strchr("aci", c)) {
+        reg -= end+1;
+        for (i = end; i; i--) {
+          if ((*reg++ = *line++)=='\\') {
+
+            // escape at end of line: resume if -e escaped literal newline,
+            // else request callback and resume with next line
+            if (!--i) {
+              *--reg = 0;
+              if (*line) {
+                line++;
+                goto resume_a;
+              }
+              corwin->hit = 256;
+              break;
+            }
+            if (!(reg[-1] = unescape(*line))) reg[-1] = *line;
             line++;
-            goto resume_a;
-          } else corwin->hit = 256;
+          }
         }
-      }
+        *reg = 0;
+      } else line += end;
 
     // Commands that take no arguments
     } else if (!strchr("{dDgGhHlnNpPqx=", c)) break;
-- 
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