[PATCH 09/21] util: Introduce virBitmapShrink

[Martin Kletzander <mkletzan@xxxxxxxxxx>]

Sometimes the size of the bitmap matters and it might not be guessed correctly
when parsing from some type of input.  For example virBitmapNewData() has Byte
granularity, virBitmapNewString() has nibble granularity and so on.
virBitmapParseUnlimited() can be tricked into creating huge bitmap that's not
needed (e.g.: "0-2,^99999999").  This function provides a way to shrink the
bitmap.  It is not supposed to free any memory.

Signed-off-by: Martin Kletzander <mkletzan@xxxxxxxxxx>
---
 src/libvirt_private.syms |  1 +
 src/util/virbitmap.c     | 19 +++++++++++++++++++
 src/util/virbitmap.h     |  2 ++
 3 files changed, 22 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 0b78a0681c5e..3986cc523e39 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1369,6 +1369,7 @@ virBitmapParseUnlimited;
 virBitmapSetAll;
 virBitmapSetBit;
 virBitmapSetBitExpand;
+virBitmapShrink;
 virBitmapSize;
 virBitmapSubtract;
 virBitmapToData;
diff --git a/src/util/virbitmap.c b/src/util/virbitmap.c
index ac6ff4f6d26d..95b1f8656907 100644
--- a/src/util/virbitmap.c
+++ b/src/util/virbitmap.c
@@ -176,6 +176,25 @@ int virBitmapSetBit(virBitmapPtr bitmap, size_t b)
     return 0;
 }
 
+
+/**
+ * virBitmapShrink:
+ * @map: Pointer to bitmap
+ * @b: last bit position to be excluded from bitmap
+ *
+ * Resizes the bitmap so that no more than @b bits will fit into it.  Nothing
+ * will change if the size is already smaller than @b.
+ */
+void virBitmapShrink(virBitmapPtr map, size_t b)
+{
+    if (!map)
+        return;
+
+    if (map->max_bit >= b)
+        map->max_bit = b;
+}
+
+
 /**
  * virBitmapExpand:
  * @map: Pointer to bitmap
diff --git a/src/util/virbitmap.h b/src/util/virbitmap.h
index 7b2bea8b534c..2464814055de 100644
--- a/src/util/virbitmap.h
+++ b/src/util/virbitmap.h
@@ -153,4 +153,6 @@ void virBitmapIntersect(virBitmapPtr a, virBitmapPtr b)
 void virBitmapSubtract(virBitmapPtr a, virBitmapPtr b)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
+void virBitmapShrink(virBitmapPtr map, size_t b);
+
 #endif
-- 
2.15.0

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