1 files changed, 131 insertions, 0 deletions

diff --git a/files/src/android/goldfish/bootconfig.cpp b/files/src/android/goldfish/bootconfig.cpp
new file mode 100644
index 0000000..1efdf6b
--- /dev/null
+++ b/files/src/android/goldfish/bootconfig.cpp
@@ -0,0 +1,131 @@
+#include "android/goldfish/bootconfig.h"
+
+#include <stdio.h>
+
+#include <memory>
+#include <numeric>
+#include <string_view>
+
+#include "aemu/base/logging/Log.h"
+#include "android/base/file/file_io.h"
+
+namespace android::goldfish {
+using namespace std::literals;
+
+constexpr std::string_view kBootconfigMagic = "#BOOTCONFIG\n"sv;
+constexpr uint32_t kBootconfigAlign = 4;
+
+std::pair<int, size_t> copyFile(FILE *src, FILE *dst) {
+  size_t sz = 0;
+  std::vector<char> buf(64 * 1024);
+
+  while (true) {
+    const size_t szR = ::fread(buf.data(), 1, buf.size(), src);
+    if (!szR) {
+      return {::ferror(src), sz};
+    }
+
+    const size_t szW = ::fwrite(buf.data(), 1, szR, dst);
+    if (szR != szW) {
+      return {::ferror(dst), sz};
+    }
+
+    sz += szR;
+  }
+}
+
+void host2le32(const uint32_t v32, void *dst) {
+  auto m8 = static_cast<uint8_t *>(dst);
+  m8[0] = v32;
+  m8[1] = v32 >> 8;
+  m8[2] = v32 >> 16;
+  m8[3] = v32 >> 24;
+}
+
+std::vector<char> flattenBootconfig(
+    const std::vector<std::pair<std::string, std::string>> &bootconfig) {
+  std::vector<char> bits;
+
+  for (const auto &kv : bootconfig) {
+    bits.insert(bits.end(), kv.first.begin(), kv.first.end());
+    bits.push_back('=');
+    bits.push_back('\"');
+    bits.insert(bits.end(), kv.second.begin(), kv.second.end());
+    bits.push_back('\"');
+    bits.push_back('\n');
+  }
+  bits.push_back(0); // it is ASCIIZ
+
+  return bits;
+}
+
+int appendBootconfig(
+    const size_t srcSize,
+    const std::vector<std::pair<std::string, std::string>> &bootconfig,
+    FILE *dst) {
+  const std::vector<char> blob = buildBootconfigBlob(srcSize, bootconfig);
+
+  if (blob.size() != ::fwrite(blob.data(), 1, blob.size(), dst)) {
+    return ::ferror(dst);
+  }
+
+  return 0;
+}
+
+std::vector<char> buildBootconfigBlob(
+    const size_t srcSize,
+    const std::vector<std::pair<std::string, std::string>> &bootconfig) {
+  std::vector<char> blob = flattenBootconfig(bootconfig);
+
+  const size_t unaligend = (srcSize + blob.size()) % kBootconfigAlign;
+  if (unaligend) {
+    blob.insert(blob.end(), kBootconfigAlign - unaligend, '+');
+  }
+
+  const uint32_t csum = std::accumulate(blob.begin(), blob.end(), 0,
+                                        [](const uint32_t z, const char c) {
+                                          return z + static_cast<uint8_t>(c);
+                                        });
+
+  const size_t size = blob.size();
+
+  blob.insert(blob.end(), 8, '+'); // size(u32, LE), csum(u32, LE)
+  host2le32(size, &blob[blob.size() - 8]);
+  host2le32(csum, &blob[blob.size() - 4]);
+
+  blob.insert(blob.end(), kBootconfigMagic.begin(), kBootconfigMagic.end());
+
+  return blob;
+}
+
+int createRamdiskWithBootconfig(
+    const char *srcRamdiskPath, const char *dstRamdiskPath,
+    const std::vector<std::pair<std::string, std::string>> &bootconfig) {
+  struct FILE_deleter {
+    void operator()(FILE *fp) const { ::fclose(fp); }
+  };
+
+  std::unique_ptr<FILE, FILE_deleter> srcRamdisk(
+      android_fopen(srcRamdiskPath, "rb"));
+  if (!srcRamdisk) {
+    derror("%s Can't open '%s' for reading\n", __func__, srcRamdiskPath);
+    return 1;
+  }
+
+  std::unique_ptr<FILE, FILE_deleter> dstRamdisk(
+      android_fopen(dstRamdiskPath, "wb"));
+  if (!dstRamdisk) {
+    derror("%s:  Can't open '%s' for writing", __func__, dstRamdiskPath);
+    return 1;
+  }
+
+  const auto r = copyFile(srcRamdisk.get(), dstRamdisk.get());
+  if (r.first) {
+    derror("%s Error copying '%s' into '%s'\n", __func__, srcRamdiskPath,
+           dstRamdiskPath);
+    return r.first;
+  }
+
+  return appendBootconfig(r.second, bootconfig, dstRamdisk.get());
+}
+} // namespace android::goldfish
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