[perl #88420] BOM support on Windows broken in 5.13.11

When Perl reads the script in text mode, then the tell() position
on the script handle may include stripped carriage return characters.
Therefore the file position after reading the first line of the
script may be one larger than the length of the input buffer.

3 files changed, 22 insertions, 1 deletions

diff --git a/MANIFEST b/MANIFEST
index 0e02719f9a..a28ada3fdb 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -4683,6 +4683,7 @@ time64_config.h			64 bit clean time.h (configuration)
 time64.h			64 bit clean time.h (header)
 t/io/argv.t			See if ARGV stuff works
 t/io/binmode.t			See if binmode() works
+t/io/bom.t			See if scripts can start with a byte order mark
 t/io/crlf.t			See if :crlf works
 t/io/crlf_through.t		See if pipe passes data intact with :crlf
 t/io/data.t			See if DATA works
diff --git a/t/io/bom.t b/t/io/bom.t
new file mode 100644
index 0000000000..dd1be6541e
--- /dev/null
+++ b/t/io/bom.t
@@ -0,0 +1,14 @@
+#!./perl
+
+BEGIN {
+    chdir 't' if -d 't';
+    @INC = '../lib';
+}
+
+BEGIN { require "./test.pl"; }
+
+plan(tests => 1);
+
+# It is important that the script contains at least one newline character
+# that can be expanded to \r\n on DOSish systems.
+fresh_perl_is("\xEF\xBB\xBFprint 1;\nprint 2", "12", {}, "script starts with a BOM" );
diff --git a/toke.c b/toke.c
index c4cda7b324..0f08d42ab4 100644
--- a/toke.c
+++ b/toke.c
@@ -4792,7 +4792,13 @@ Perl_yylex(pTHX)
 		      *(U8*)s == 0xEF ||
 		      *(U8*)s >= 0xFE ||
 		      s[1] == 0)) {
-		bof = PerlIO_tell(PL_rsfp) == (Off_t)SvCUR(PL_linestr);
+		IV offset = (IV)PerlIO_tell(PL_rsfp);
+		bof = (offset == SvCUR(PL_linestr));
+#if defined(PERLIO_USING_CRLF) && defined(PERL_TEXTMODE_SCRIPTS)
+		/* offset may include swallowed CR */
+		if (!bof)
+		    bof = (offset == SvCUR(PL_linestr)+1);
+#endif
 		if (bof) {
 		    PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
 		    s = swallow_bom((U8*)s);