Integrate change #8586 from maint-5.6/perl.

make the BOM detection code not call tell() until it has to
(meant to fix esoteric compatibility issues where PL_rsfp
is overridden)

p4raw-link: @8586 on //depot/maint-5.6/perl: 7b18f0b9fd425b568b9ff49e195709c84e549b71

p4raw-id: //depot/perl@8589
p4raw-integrated: from //depot/maint-5.6/perl@8588 'merge in' toke.c
	(@8579..)

diff --git a/toke.c b/toke.c
index a85a725..a1f521d 100644 (file)
--- a/toke.c
+++ b/toke.c
@@ -2572,7 +2572,32 @@ Perl_yylex(pTHX)
        }
        do {
            bof = PL_rsfp ? TRUE : FALSE;
-           if (bof) {
+           if ((s = filter_gets(PL_linestr, PL_rsfp, 0)) == Nullch) {
+             fake_eof:
+               if (PL_rsfp) {
+                   if (PL_preprocess && !PL_in_eval)
+                       (void)PerlProc_pclose(PL_rsfp);
+                   else if ((PerlIO *)PL_rsfp == PerlIO_stdin())
+                       PerlIO_clearerr(PL_rsfp);
+                   else
+                       (void)PerlIO_close(PL_rsfp);
+                   PL_rsfp = Nullfp;
+                   PL_doextract = FALSE;
+               }
+               if (!PL_in_eval && (PL_minus_n || PL_minus_p)) {
+                   sv_setpv(PL_linestr,PL_minus_p ? ";}continue{print" : "");
+                   sv_catpv(PL_linestr,";}");
+                   PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
+                   PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
+                   PL_minus_n = PL_minus_p = 0;
+                   goto retry;
+               }
+               PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
+               sv_setpv(PL_linestr,"");
+               TOKEN(';');     /* not infinite loop because rsfp is NULL now */
+           }
+           /* if it looks like the start of a BOM, check if it in fact is */
+           else if (bof && (!*s || *(U8*)s == 0xEF || *(U8*)s >= 0xFE)) {
 #ifdef PERLIO_IS_STDIO
 #  ifdef __GNU_LIBRARY__
 #    if __GNU_LIBRARY__ == 1 /* Linux glibc5 */
@@ -2592,38 +2617,14 @@ Perl_yylex(pTHX)
                 * Workaround?  Maybe attach some extra state to PL_rsfp?
                 */
                if (!PL_preprocess)
-                   bof = PerlIO_tell(PL_rsfp) == 0;
+                   bof = PerlIO_tell(PL_rsfp) == SvCUR(PL_linestr);
 #else
-               bof = PerlIO_tell(PL_rsfp) == 0;
+               bof = PerlIO_tell(PL_rsfp) == SvCUR(PL_linestr);
 #endif
-           }
-           s = filter_gets(PL_linestr, PL_rsfp, 0);
-           if (s == Nullch) {
-             fake_eof:
-               if (PL_rsfp) {
-                   if (PL_preprocess && !PL_in_eval)
-                       (void)PerlProc_pclose(PL_rsfp);
-                   else if ((PerlIO *)PL_rsfp == PerlIO_stdin())
-                       PerlIO_clearerr(PL_rsfp);
-                   else
-                       (void)PerlIO_close(PL_rsfp);
-                   PL_rsfp = Nullfp;
-                   PL_doextract = FALSE;
-               }
-               if (!PL_in_eval && (PL_minus_n || PL_minus_p)) {
-                   sv_setpv(PL_linestr,PL_minus_p ? ";}continue{print" : "");
-                   sv_catpv(PL_linestr,";}");
-                   PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
+               if (bof) {
                    PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-                   PL_minus_n = PL_minus_p = 0;
-                   goto retry;
+                   s = swallow_bom((U8*)s);
                }
-               PL_oldoldbufptr = PL_oldbufptr = s = PL_linestart = SvPVX(PL_linestr);
-               sv_setpv(PL_linestr,"");
-               TOKEN(';');     /* not infinite loop because rsfp is NULL now */
-           } else if (bof) {
-               PL_bufend = SvPVX(PL_linestr) + SvCUR(PL_linestr);
-               s = swallow_bom((U8*)s);
            }
            if (PL_doextract) {
                if (*s == '#' && s[1] == '!' && instr(s,"perl"))