From: Tony Cook <tony@develop-help.com>
Date: Mon, 31 Mar 2014 09:20:07 +0000 (+1100)
Subject: [RT #92738] improve XS for i_io_read()/i_io_raw_read()
X-Git-Tag: v0.99~15
X-Git-Url: http://git.imager.perl.org/imager.git/commitdiff_plain/3e00cb9049373242f21120e9aa3d33796753f83e

[RT #92738] improve XS for i_io_read()/i_io_raw_read()

Previously it would call sv_setpvn() which did all the right things,
but we can avoid the sv_utf8_downgrade() and some of the other work
done by sv_setpvn() with the new code.
---

diff --git a/Imager.xs b/Imager.xs
index ac804344..2b757fed 100644
--- a/Imager.xs
+++ b/Imager.xs
@@ -30,6 +30,10 @@ extern "C" {
 
 #include "imperl.h"
 
+#ifndef SV_COW_DROP_PV
+#define SV_COW_DROP_PV
+#endif
+
 /*
 
 Context object management
@@ -1280,15 +1284,9 @@ i_io_raw_read(ig, buffer_sv, size)
       PPCODE:
         if (size <= 0)
 	  croak("size negative in call to i_io_raw_read()");
-        /* prevent an undefined value warning if they supplied an 
-	   undef buffer.
-           Orginally conditional on !SvOK(), but this will prevent the
-	   downgrade from croaking */
-	sv_setpvn(buffer_sv, "", 0);
-#ifdef SvUTF8
-	if (SvUTF8(buffer_sv))
-          sv_utf8_downgrade(buffer_sv, FALSE);
-#endif
+	if (SvTHINKFIRST(buffer_sv))
+	  sv_force_normal_flags(buffer_sv, SV_COW_DROP_PV);
+	SvUPGRADE(buffer_sv, SVt_PV);
 	buffer = SvGROW(buffer_sv, size+1);
         result = i_io_raw_read(ig, buffer, size);
         if (result >= 0) {
@@ -1411,15 +1409,9 @@ i_io_read(ig, buffer_sv, size)
       PPCODE:
         if (size <= 0)
 	  croak("size negative in call to i_io_read()");
-        /* prevent an undefined value warning if they supplied an 
-	   undef buffer.
-           Orginally conditional on !SvOK(), but this will prevent the
-	   downgrade from croaking */
-	sv_setpvn(buffer_sv, "", 0);
-#ifdef SvUTF8
-	if (SvUTF8(buffer_sv))
-          sv_utf8_downgrade(buffer_sv, FALSE);
-#endif
+	if (SvTHINKFIRST(buffer_sv))
+	  sv_force_normal_flags(buffer_sv, SV_COW_DROP_PV);
+	SvUPGRADE(buffer_sv, SVt_PV);
 	buffer = SvGROW(buffer_sv, size+1);
         result = i_io_read(ig, buffer, size);
         if (result >= 0) {