2 files changed, 27 insertions, 1 deletions

diff --git a/bootloader_message/bootloader_message.cpp b/bootloader_message/bootloader_message.cpp
index 9a5671843..b873d3dc3 100644
--- a/bootloader_message/bootloader_message.cpp
+++ b/bootloader_message/bootloader_message.cpp
@@ -176,6 +176,27 @@ bool write_bootloader_message(const std::vector<std::string>& options, std::stri
   return write_bootloader_message(boot, err);
 }
 
+bool update_bootloader_message(const std::vector<std::string>& options, std::string* err) {
+  bootloader_message boot;
+  if (!read_bootloader_message(&boot, err)) {
+    return false;
+  }
+
+  // Zero out the entire fields.
+  memset(boot.command, 0, sizeof(boot.command));
+  memset(boot.recovery, 0, sizeof(boot.recovery));
+
+  strlcpy(boot.command, "boot-recovery", sizeof(boot.command));
+  strlcpy(boot.recovery, "recovery\n", sizeof(boot.recovery));
+  for (const auto& s : options) {
+    strlcat(boot.recovery, s.c_str(), sizeof(boot.recovery));
+    if (s.back() != '\n') {
+      strlcat(boot.recovery, "\n", sizeof(boot.recovery));
+    }
+  }
+  return write_bootloader_message(boot, err);
+}
+
 bool write_reboot_bootloader(std::string* err) {
   bootloader_message boot;
   if (!read_bootloader_message(&boot, err)) {
diff --git a/bootloader_message/include/bootloader_message/bootloader_message.h b/bootloader_message/include/bootloader_message/bootloader_message.h
index ec47facf6..bc5104ddf 100644
--- a/bootloader_message/include/bootloader_message/bootloader_message.h
+++ b/bootloader_message/include/bootloader_message/bootloader_message.h
@@ -194,9 +194,14 @@ bool write_bootloader_message(const bootloader_message& boot, std::string* err);
 bool write_bootloader_message_to(const bootloader_message& boot,
                                  const std::string& misc_blk_device, std::string* err);
 
-// Write bootloader message (boots into recovery with the options) to BCB.
+// Write bootloader message (boots into recovery with the options) to BCB. Will
+// set the command and recovery fields, and reset the rest.
 bool write_bootloader_message(const std::vector<std::string>& options, std::string* err);
 
+// Update bootloader message (boots into recovery with the options) to BCB. Will
+// only update the command and recovery fields.
+bool update_bootloader_message(const std::vector<std::string>& options, std::string* err);
+
 // Clear BCB.
 bool clear_bootloader_message(std::string* err);