fix(3p/nix): remove usage of strcpy r/1437

Change-Id: I86125609f433469a8722c780fd758234211d677e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1381
Tested-by: BuildkiteCI
Reviewed-by: Alyssa Ross <hi@alyssa.is>
Reviewed-by: glittershark <grfn@gws.fyi>

2 files changed, 5 insertions, 4 deletions

diff --git a/third_party/nix/src/libstore/build.cc b/third_party/nix/src/libstore/build.cc
index dcc3c7edc7af..da35388d855a 100644
--- a/third_party/nix/src/libstore/build.cc
+++ b/third_party/nix/src/libstore/build.cc
@@ -2833,7 +2833,7 @@ void DerivationGoal::runChild() {
         }
 
         struct ifreq ifr;
-        strcpy(ifr.ifr_name, "lo");
+        strncpy(ifr.ifr_name, "lo", sizeof("lo"));
         ifr.ifr_flags = IFF_UP | IFF_LOOPBACK | IFF_RUNNING;
         if (ioctl(fd.get(), SIOCSIFFLAGS, &ifr) == -1) {
           throw SysError("cannot set loopback interface flags");
diff --git a/third_party/nix/src/libstore/remote-store.cc b/third_party/nix/src/libstore/remote-store.cc
index 7c4f3a138fc0..33a6ec310ac1 100644
--- a/third_party/nix/src/libstore/remote-store.cc
+++ b/third_party/nix/src/libstore/remote-store.cc
@@ -99,12 +99,13 @@ ref<RemoteStore::Connection> UDSRemoteStore::openConnection() {
 
   struct sockaddr_un addr;
   addr.sun_family = AF_UNIX;
-  if (socketPath.size() + 1 >= sizeof(addr.sun_path)) {
+  strncpy(addr.sun_path, socketPath.c_str(), sizeof(addr.sun_path));
+  if (addr.sun_path[sizeof(addr.sun_path) - 1] != '\0') {
     throw Error(format("socket path '%1%' is too long") % socketPath);
   }
-  strcpy(addr.sun_path, socketPath.c_str());
 
-  if (::connect(conn->fd.get(), (struct sockaddr*)&addr, sizeof(addr)) == -1) {
+  if (::connect(conn->fd.get(), reinterpret_cast<struct sockaddr*>(&addr),
+                sizeof(addr)) == -1) {
     throw SysError(format("cannot connect to daemon at '%1%'") % socketPath);
   }