From 26a18ab863ecb3be87f963233d250814f428bb6f Mon Sep 17 00:00:00 2001
From: Jari Vetoniemi <mailroxas@gmail.com>
Date: Mon, 19 Nov 2018 11:35:32 +0200
Subject: libc: support various _chk functions

---
 src/libc.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/src/libc.c b/src/libc.c
index e3dfa96..96057b7 100644
--- a/src/libc.c
+++ b/src/libc.c
@@ -273,6 +273,69 @@ bionic___stack_chk_fail(void)
    abort();
 }
 
+size_t
+bionic___strlen_chk(const char *s, size_t s_len)
+{
+   const size_t ret = strlen(s);
+   if (__builtin_expect(ret >= s_len, 0)) {
+      fprintf(stderr, "*** strlen read overflow detected ***\n");
+      abort();
+   }
+   return ret;
+}
+
+size_t
+bionic___fwrite_chk(const void * __restrict buf, size_t size, size_t count, FILE * __restrict stream, size_t buf_size)
+{
+   size_t total;
+   if (__builtin_expect(__builtin_mul_overflow(size, count, &total), 0)) {
+      // overflow: trigger the error path in fwrite
+      return fwrite(buf, size, count, stream);
+   }
+
+   if (__builtin_expect(total > buf_size, 0)) {
+      fprintf(stderr, "*** fwrite read overflow detected ***\n");
+      abort();
+   }
+
+   return fwrite(buf, size, count, stream);
+}
+
+char*
+bionic___strchr_chk(const char* p, int ch, size_t s_len)
+{
+   for (;; ++p, s_len--) {
+      if (__builtin_expect(s_len == 0, 0)) {
+         fprintf(stderr, "*** strchr buffer overrun detected ***\n");
+         abort();
+      }
+
+      if (*p == ch)
+         return (char*)p;
+      else if (!*p)
+         return NULL;
+   }
+   assert(0 && "should not happen");
+}
+
+char*
+bionic___strrchr_chk(const char* p, int ch, size_t s_len)
+{
+   const char *save;
+   for (save = NULL;; ++p, s_len--) {
+      if (__builtin_expect(s_len == 0, 0)) {
+         fprintf(stderr, "*** strchr buffer overrun detected ***\n");
+         abort();
+      }
+
+      if (*p == ch)
+         save = p;
+      else if (!*p)
+         return (char*)save;
+   }
+   assert(0 && "should not happen");
+}
+
 static inline int
 bionic_sysconf_to_glibc_sysconf(int name)
 {
-- 
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