Fix to swallow BOMs in sourced files

Fixes #1518

4 files changed, 14 insertions, 1 deletions

diff --git a/common.h b/common.h
index 5c462974..4eb17bf0 100644
--- a/common.h
+++ b/common.h
@@ -59,6 +59,9 @@ typedef std::vector<wcstring> wcstring_list_t;
 */
 #define BYTE_MAX 0xffu
 
+/** BOM value */
+#define UTF8_BOM_WCHAR 0xFEFFu
+
 /* Flags for unescape_string functions */
 enum
 {
diff --git a/reader.cpp b/reader.cpp
index ecf42bb3..84c36497 100644
--- a/reader.cpp
+++ b/reader.cpp
@@ -4205,7 +4205,7 @@ static int read_ni(int fd, const io_chain_t &io)
             acc.insert(acc.end(), buff, buff + c);
         }
 
-        const wcstring str = acc.empty() ? wcstring() : str2wcstring(&acc.at(0), acc.size());
+        wcstring str = acc.empty() ? wcstring() : str2wcstring(&acc.at(0), acc.size());
         acc.clear();
 
         if (fclose(in_stream))
@@ -4216,6 +4216,12 @@ static int read_ni(int fd, const io_chain_t &io)
             res = 1;
         }
 
+        /* Swallow a BOM (#1518) */
+        if (! str.empty() && str.at(0) == UTF8_BOM_WCHAR)
+        {
+            str.erase(0, 1);
+        }
+
         parse_error_list_t errors;
         if (! parse_util_detect_errors(str, &errors, false /* do not accept incomplete */))
         {
diff --git a/tests/test9.in b/tests/test9.in
index e5b69485..e85c64b1 100644
--- a/tests/test9.in
+++ b/tests/test9.in
@@ -113,4 +113,7 @@ try_unbalanced_block 'if false'
 "while" false; end
 "wh"'ile' false; "e"nd
 
+# BOM checking (see #1518)
+echo \uFEFF"echo bom_test" | source
+
 false
diff --git a/tests/test9.out b/tests/test9.out
index 2e8e8bc7..9fe347de 100644
--- a/tests/test9.out
+++ b/tests/test9.out
@@ -17,3 +17,4 @@ foo
 bar
 baz
 psub file was deleted
+bom_test