replace strncpy with strlcpy

source/common/common/utility.cc

@@ -51,6 +51,31 @@ void StringUtil::rtrim(std::string& source) {
   }
 }
 
+/**
+ * strlcpy adapted from https://github.com/freebsd/freebsd/blob/20c3c08/sys/libkern/strlcpy.c
+ */
+size_t StringUtil::strlcpy(char* dst, const char* src, size_t siz) {
+  char* d = dst;
+  const char* s = src;
+  size_t n = siz;
+
+  if (n != 0 && --n != 0) {
+    do {
+      if ((*d++ = *s++) == 0)
+        break;
+    } while (--n != 0);
+  }
+
+  if (n == 0) {
+    if (siz != 0)
+      *d = '\0';
+    while (*s++)
+      ;
+  }
+
+  return (s - src - 1);
+}
+
 std::vector<std::string> StringUtil::split(const std::string& source, char split) {
   std::vector<std::string> ret;
   size_t last_index = 0;

source/common/common/utility.h

@@ -68,6 +68,11 @@ class StringUtil {
    */
   static void rtrim(std::string& source);
 
+  /**
+   * Size-bounded string copying and concatenation
+   */
+  static size_t strlcpy(char* dst, const char* src, size_t siz);
+
   /**
    * Split a string.
    * @param source supplies the string to split.

source/common/network/utility.cc

@@ -119,7 +119,7 @@ sockaddr_un Utility::resolveUnixDomainSocket(const std::string& path) {
   sockaddr_un address;
   memset(&address, 0, sizeof(address));
   address.sun_family = AF_UNIX;
-  strncpy(&address.sun_path[0], path.c_str(), sizeof(address.sun_path));
+  StringUtil::strlcpy(&address.sun_path[0], path.c_str(), sizeof(address.sun_path));
   return address;
 }
 

source/common/stats/stats_impl.cc

@@ -1,5 +1,7 @@
 #include "stats_impl.h"
 
+#include "common/common/utility.h"
+
 namespace Stats {
 
 void TimerImpl::TimespanImpl::complete(const std::string& dynamic_name) {
@@ -17,7 +19,7 @@ RawStatData* HeapRawStatDataAllocator::alloc(const std::string& name) {
 void RawStatData::initialize(const std::string& name) {
   ASSERT(!initialized());
   ASSERT(name.size() <= MAX_NAME_SIZE);
-  strncpy(name_, name.substr(0, MAX_NAME_SIZE).c_str(), MAX_NAME_SIZE + 1);
+  StringUtil::strlcpy(name_, name.substr(0, MAX_NAME_SIZE).c_str(), MAX_NAME_SIZE + 1);
 }
 
 bool RawStatData::matches(const std::string& name) {

source/exe/hot_restart.cc

@@ -5,6 +5,8 @@
 #include "envoy/server/instance.h"
 #include "envoy/server/options.h"
 
+#include "common/common/utility.h"
+
 #include <sys/mman.h>
 #include <sys/prctl.h>
 
@@ -119,9 +121,9 @@ sockaddr_un HotRestartImpl::createDomainSocketAddress(uint64_t id) {
   sockaddr_un address;
   memset(&address, 0, sizeof(address));
   address.sun_family = AF_UNIX;
-  strncpy(&address.sun_path[1],
-          fmt::format("envoy_domain_socket_{}", options_.baseId() + id).c_str(),
-          sizeof(address.sun_path) - 1);
+  StringUtil::strlcpy(&address.sun_path[1],
+                      fmt::format("envoy_domain_socket_{}", options_.baseId() + id).c_str(),
+                      sizeof(address.sun_path) - 1);
   address.sun_path[0] = 0;
   return address;
 }

test/common/common/utility_test.cc

@@ -41,6 +41,13 @@ TEST(StringUtil, rtrim) {
   }
 }
 
+TEST(StringUtil, strlcpy) {
+  // TODO: more tests
+  char dest[6];
+  StringUtil::strlcpy(dest, std::string{"hello"}.c_str(), sizeof(dest));
+  EXPECT_STREQ("hello", dest);
+}
+
 TEST(StringUtil, split) {
   EXPECT_EQ(std::vector<std::string>{}, StringUtil::split("", ','));
   EXPECT_EQ(std::vector<std::string>{"a"}, StringUtil::split("a", ','));