(re)allow WBMP detection with system libgd

provide getbmi and skipheader not exported functions in gd_compat.

2 files changed, 39 insertions, 0 deletions

diff --git a/ext/gd/libgd/gd_compat.c b/ext/gd/libgd/gd_compat.c
index b56329029e..f3627a1404 100644
--- a/ext/gd/libgd/gd_compat.c
+++ b/ext/gd/libgd/gd_compat.c
@@ -33,6 +33,7 @@ const char * gdPngGetVersionString()
 }
 #endif
 
+/* Not exported by libgd, copied from gdhelpers.h */
 int overflow2(int a, int b)
 {
 	if(a <= 0 || b <= 0) {
@@ -44,3 +45,38 @@ int overflow2(int a, int b)
 	return 0;
 }
 
+/* Not exported by libgd, copied from wbmp.c */
+int
+getmbi (int (*getin) (void *in), void *in)
+{
+  int i, mbi = 0;
+
+  do
+    {
+      i = getin (in);
+      if (i < 0)
+	return (-1);
+      mbi = (mbi << 7) | (i & 0x7f);
+    }
+  while (i & 0x80);
+
+  return (mbi);
+}
+
+/* Not exported by libgd, copied from wbmp.c */
+int
+skipheader (int (*getin) (void *in), void *in)
+{
+  int i;
+
+  do
+    {
+      i = getin (in);
+      if (i < 0)
+	return (-1);
+    }
+  while (i & 0x80);
+
+  return (0);
+}
+
diff --git a/ext/gd/libgd/gd_compat.h b/ext/gd/libgd/gd_compat.h
index 779e709a63..e8fedf80c5 100644
--- a/ext/gd/libgd/gd_compat.h
+++ b/ext/gd/libgd/gd_compat.h
@@ -11,6 +11,9 @@ const char * gdPngGetVersionString();
 const char * gdJpegGetVersionString();
 int gdJpegGetVersionInt();
 int overflow2(int a, int b);
+int getmbi (int (*getin) (void *in), void *in);
+int skipheader (int (*getin) (void *in), void *in);
+
 
 /* filters section
  *