File hg-mpatch-fix04.patch of Package mercurial

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File hg-mpatch-fix04.patch of Package mercurial

# HG changeset patch
# User Augie Fackler <augie@google.com>
# Date 1525140822 14400
# Node ID 1ec4cb8cbc87004ffbeeb1b5d98acef04c38d59a
# Parent  faa924469635512b72868b1552a1866a0f91db20
mpatch: introduce a safeadd() helper to work around UB int overflow

We're about to make extensive use of this. This change duplicates some
stdbool.h portability hacks from cext/util.h. We should probably clean
that up in the future, but we'll skip that for now in order to make
security backports easier.

---
 mercurial/mpatch.c |   28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

--- a/mercurial/mpatch.c
+++ b/mercurial/mpatch.c
@@ -22,11 +22,21 @@
 
 #define PY_SSIZE_T_CLEAN
 #include <Python.h>
+#include <limits.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "util.h"
 
+/* VC9 doesn't include bool and lacks stdbool.h based on cext/util.h */
+#if defined(_MSC_VER) || __STDC_VERSION__ < 199901L
+#define true 1
+#define false 0
+typedef unsigned char bool;
+#else
+#include <stdbool.h>
+#endif
+
 static char mpatch_doc[] = "Efficient binary patching.";
 static PyObject *mpatch_Error;
 
@@ -74,6 +84,24 @@ static Py_ssize_t lsize(struct flist *a)
 	return a->tail - a->head;
 }
 
+/* add helper to add src and *dest iff it won't overflow */
+static inline bool safeadd(int src, int *dest)
+{
+	if ((src > 0) == (*dest > 0)) {
+		if (*dest > 0) {
+			if (src > (INT_MAX - *dest)) {
+				return false;
+			}
+		} else {
+			if (src < (INT_MIN - *dest)) {
+				return false;
+			}
+		}
+	}
+	*dest += src;
+	return true;
+}
+
 /* move hunks in source that are less cut to dest, compensating
    for changes in offset. the last hunk may be split if necessary.
 */

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File hg-mpatch-fix04.patch of Package mercurial

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