From fb7eb04f428a09c3b6f3d7ad37d6646c6030c4a1 Mon Sep 17 00:00:00 2001
From: Gabe Black <gabe.black@gmail.com>
Date: Fri, 7 May 2021 15:38:19 -0700
Subject: [PATCH] arch-x86: Fix x86 build.

Variation of fix by Maximilian Stein:

https://gem5-review.googlesource.com/c/public/gem5/+/45185

Placate gcc, which thinks we're doing something wrong when using
strncpy. Also ensure that fixed size buffers for strings are filled
completely, rather than just filling in the part which holds the string
we want.

Change-Id: I59f51f6a56a3a3e2632eb89ecb6db709fbbd165d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/45205
Maintainer: Gabe Black <gabe.black@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
---
 src/arch/x86/bios/acpi.cc | 30 +++++++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/src/arch/x86/bios/acpi.cc b/src/arch/x86/bios/acpi.cc
index 53b6e4dd8e..9a5d32ed17 100644
--- a/src/arch/x86/bios/acpi.cc
+++ b/src/arch/x86/bios/acpi.cc
@@ -37,6 +37,7 @@
 
 #include "arch/x86/bios/acpi.hh"
 
+#include <algorithm>
 #include <cassert>
 #include <cstring>
 
@@ -52,6 +53,26 @@ namespace X86ISA
 namespace ACPI
 {
 
+static void
+fillCopy(void *dest, size_t dest_size, const void *src, size_t src_size)
+{
+    src_size = std::min(src_size, dest_size);
+    const size_t zero_size = dest_size - src_size;
+
+    uint8_t *pos = (uint8_t *)dest;
+
+    std::memcpy(pos, src, src_size);
+    pos += src_size;
+
+    std::memset(pos, 0, zero_size);
+}
+
+static void
+fillCopy(void *dest, size_t dest_size, const std::string &src)
+{
+    fillCopy(dest, dest_size, src.c_str(), src.length());
+}
+
 const char RSDP::signature[] = "RSD PTR ";
 
 static uint8_t
@@ -93,7 +114,7 @@ RSDP::write(PortProxy& phys_proxy, Allocator& alloc) const
     static_assert(sizeof(signature) - 1 == sizeof(data->signature),
             "signature length mismatch");
     std::memcpy(data->signature, signature, sizeof(data->signature));
-    std::strncpy(data->oemID, params().oem_id.c_str(), sizeof(data->oemID));
+    fillCopy(data->oemID, sizeof(data->oemID), params().oem_id);
     data->revision = params().revision;
     data->length = mem.size();
 
@@ -133,12 +154,11 @@ SysDescTable::writeBuf(PortProxy& phys_proxy, Allocator& alloc,
     // Fill in the header.
     auto& p = params();
     Mem* header = (Mem*)mem.data();
-    std::strncpy(header->signature, signature, sizeof(header->signature));
+    fillCopy(header->signature, sizeof(header->signature), signature);
     header->length = mem.size();
     header->revision = revision;
-    std::strncpy(header->oemID, p.oem_id.c_str(), sizeof(header->oemID));
-    std::strncpy(header->oemTableID, p.oem_table_id.c_str(),
-            sizeof(header->oemTableID));
+    fillCopy(header->oemID, sizeof(header->oemID), p.oem_id);
+    fillCopy(header->oemTableID, sizeof(header->oemTableID), p.oem_table_id);
     header->oemRevision = p.oem_revision;
     header->creatorID = p.creator_id;
     header->creatorRevision = p.creator_revision;