diff --git a/bootloader.cpp b/bootloader.cpp
index 600d238..d80c5e7 100644
--- a/bootloader.cpp
+++ b/bootloader.cpp
@@ -14,28 +14,33 @@
  * limitations under the License.
  */
 
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
 #include <fs_mgr.h>
+
 #include "bootloader.h"
 #include "common.h"
 #include "mtdutils/mtdutils.h"
 #include "roots.h"
+#include "unique_fd.h"
 
-#include <errno.h>
-#include <stdio.h>
-#include <string.h>
-#include <sys/stat.h>
-#include <unistd.h>
+static int get_bootloader_message_mtd(bootloader_message* out, const Volume* v);
+static int set_bootloader_message_mtd(const bootloader_message* in, const Volume* v);
+static int get_bootloader_message_block(bootloader_message* out, const Volume* v);
+static int set_bootloader_message_block(const bootloader_message* in, const Volume* v);
 
-static int get_bootloader_message_mtd(struct bootloader_message *out, const Volume* v);
-static int set_bootloader_message_mtd(const struct bootloader_message *in, const Volume* v);
-static int get_bootloader_message_block(struct bootloader_message *out, const Volume* v);
-static int set_bootloader_message_block(const struct bootloader_message *in, const Volume* v);
-
-int get_bootloader_message(struct bootloader_message *out) {
+int get_bootloader_message(bootloader_message* out) {
     Volume* v = volume_for_path("/misc");
-    if (v == NULL) {
-      LOGE("Cannot load volume /misc!\n");
-      return -1;
+    if (v == nullptr) {
+        LOGE("Cannot load volume /misc!\n");
+        return -1;
     }
     if (strcmp(v->fs_type, "mtd") == 0) {
         return get_bootloader_message_mtd(out, v);
@@ -46,11 +51,11 @@
     return -1;
 }
 
-int set_bootloader_message(const struct bootloader_message *in) {
+int set_bootloader_message(const bootloader_message* in) {
     Volume* v = volume_for_path("/misc");
-    if (v == NULL) {
-      LOGE("Cannot load volume /misc!\n");
-      return -1;
+    if (v == nullptr) {
+        LOGE("Cannot load volume /misc!\n");
+        return -1;
     }
     if (strcmp(v->fs_type, "mtd") == 0) {
         return set_bootloader_message_mtd(in, v);
@@ -68,69 +73,69 @@
 static const int MISC_PAGES = 3;         // number of pages to save
 static const int MISC_COMMAND_PAGE = 1;  // bootloader command is this page
 
-static int get_bootloader_message_mtd(struct bootloader_message *out,
+static int get_bootloader_message_mtd(bootloader_message* out,
                                       const Volume* v) {
     size_t write_size;
     mtd_scan_partitions();
-    const MtdPartition *part = mtd_find_partition_by_name(v->blk_device);
-    if (part == NULL || mtd_partition_info(part, NULL, NULL, &write_size)) {
-        LOGE("Can't find %s\n", v->blk_device);
+    const MtdPartition* part = mtd_find_partition_by_name(v->blk_device);
+    if (part == nullptr || mtd_partition_info(part, nullptr, nullptr, &write_size)) {
+        LOGE("failed to find \"%s\"\n", v->blk_device);
         return -1;
     }
 
-    MtdReadContext *read = mtd_read_partition(part);
-    if (read == NULL) {
-        LOGE("Can't open %s\n(%s)\n", v->blk_device, strerror(errno));
+    MtdReadContext* read = mtd_read_partition(part);
+    if (read == nullptr) {
+        LOGE("failed to open \"%s\": %s\n", v->blk_device, strerror(errno));
         return -1;
     }
 
     const ssize_t size = write_size * MISC_PAGES;
     char data[size];
     ssize_t r = mtd_read_data(read, data, size);
-    if (r != size) LOGE("Can't read %s\n(%s)\n", v->blk_device, strerror(errno));
+    if (r != size) LOGE("failed to read \"%s\": %s\n", v->blk_device, strerror(errno));
     mtd_read_close(read);
     if (r != size) return -1;
 
     memcpy(out, &data[write_size * MISC_COMMAND_PAGE], sizeof(*out));
     return 0;
 }
-static int set_bootloader_message_mtd(const struct bootloader_message *in,
+static int set_bootloader_message_mtd(const bootloader_message* in,
                                       const Volume* v) {
     size_t write_size;
     mtd_scan_partitions();
-    const MtdPartition *part = mtd_find_partition_by_name(v->blk_device);
-    if (part == NULL || mtd_partition_info(part, NULL, NULL, &write_size)) {
-        LOGE("Can't find %s\n", v->blk_device);
+    const MtdPartition* part = mtd_find_partition_by_name(v->blk_device);
+    if (part == nullptr || mtd_partition_info(part, nullptr, nullptr, &write_size)) {
+        LOGE("failed to find \"%s\"\n", v->blk_device);
         return -1;
     }
 
-    MtdReadContext *read = mtd_read_partition(part);
-    if (read == NULL) {
-        LOGE("Can't open %s\n(%s)\n", v->blk_device, strerror(errno));
+    MtdReadContext* read = mtd_read_partition(part);
+    if (read == nullptr) {
+        LOGE("failed to open \"%s\": %s\n", v->blk_device, strerror(errno));
         return -1;
     }
 
     ssize_t size = write_size * MISC_PAGES;
     char data[size];
     ssize_t r = mtd_read_data(read, data, size);
-    if (r != size) LOGE("Can't read %s\n(%s)\n", v->blk_device, strerror(errno));
+    if (r != size) LOGE("failed to read \"%s\": %s\n", v->blk_device, strerror(errno));
     mtd_read_close(read);
     if (r != size) return -1;
 
     memcpy(&data[write_size * MISC_COMMAND_PAGE], in, sizeof(*in));
 
-    MtdWriteContext *write = mtd_write_partition(part);
-    if (write == NULL) {
-        LOGE("Can't open %s\n(%s)\n", v->blk_device, strerror(errno));
+    MtdWriteContext* write = mtd_write_partition(part);
+    if (write == nullptr) {
+        LOGE("failed to open \"%s\": %s\n", v->blk_device, strerror(errno));
         return -1;
     }
     if (mtd_write_data(write, data, size) != size) {
-        LOGE("Can't write %s\n(%s)\n", v->blk_device, strerror(errno));
+        LOGE("failed to write \"%s\": %s\n", v->blk_device, strerror(errno));
         mtd_write_close(write);
         return -1;
     }
     if (mtd_write_close(write)) {
-        LOGE("Can't finish %s\n(%s)\n", v->blk_device, strerror(errno));
+        LOGE("failed to finish \"%s\": %s\n", v->blk_device, strerror(errno));
         return -1;
     }
 
@@ -146,57 +151,67 @@
 static void wait_for_device(const char* fn) {
     int tries = 0;
     int ret;
-    struct stat buf;
     do {
         ++tries;
+        struct stat buf;
         ret = stat(fn, &buf);
-        if (ret) {
-            printf("stat %s try %d: %s\n", fn, tries, strerror(errno));
+        if (ret == -1) {
+            printf("failed to stat \"%s\" try %d: %s\n", fn, tries, strerror(errno));
             sleep(1);
         }
     } while (ret && tries < 10);
+
     if (ret) {
-        printf("failed to stat %s\n", fn);
+        printf("failed to stat \"%s\"\n", fn);
     }
 }
 
-static int get_bootloader_message_block(struct bootloader_message *out,
+static int get_bootloader_message_block(bootloader_message* out,
                                         const Volume* v) {
     wait_for_device(v->blk_device);
     FILE* f = fopen(v->blk_device, "rb");
-    if (f == NULL) {
-        LOGE("Can't open %s\n(%s)\n", v->blk_device, strerror(errno));
+    if (f == nullptr) {
+        LOGE("failed to open \"%s\": %s\n", v->blk_device, strerror(errno));
         return -1;
     }
-    struct bootloader_message temp;
+    bootloader_message temp;
     int count = fread(&temp, sizeof(temp), 1, f);
     if (count != 1) {
-        LOGE("Failed reading %s\n(%s)\n", v->blk_device, strerror(errno));
+        LOGE("failed to read \"%s\": %s\n", v->blk_device, strerror(errno));
         return -1;
     }
     if (fclose(f) != 0) {
-        LOGE("Failed closing %s\n(%s)\n", v->blk_device, strerror(errno));
+        LOGE("failed to close \"%s\": %s\n", v->blk_device, strerror(errno));
         return -1;
     }
     memcpy(out, &temp, sizeof(temp));
     return 0;
 }
 
-static int set_bootloader_message_block(const struct bootloader_message *in,
+static int set_bootloader_message_block(const bootloader_message* in,
                                         const Volume* v) {
     wait_for_device(v->blk_device);
-    FILE* f = fopen(v->blk_device, "wb");
-    if (f == NULL) {
-        LOGE("Can't open %s\n(%s)\n", v->blk_device, strerror(errno));
+    unique_fd fd(open(v->blk_device, O_WRONLY | O_SYNC));
+    if (fd.get() == -1) {
+        LOGE("failed to open \"%s\": %s\n", v->blk_device, strerror(errno));
         return -1;
     }
-    int count = fwrite(in, sizeof(*in), 1, f);
-    if (count != 1) {
-        LOGE("Failed writing %s\n(%s)\n", v->blk_device, strerror(errno));
-        return -1;
+
+    size_t written = 0;
+    const uint8_t* start = reinterpret_cast<const uint8_t*>(in);
+    size_t total = sizeof(*in);
+    while (written < total) {
+        ssize_t wrote = TEMP_FAILURE_RETRY(write(fd.get(), start + written, total - written));
+        if (wrote == -1) {
+            LOGE("failed to write %" PRId64 " bytes: %s\n",
+                 static_cast<off64_t>(written), strerror(errno));
+            return -1;
+        }
+        written += wrote;
     }
-    if (fclose(f) != 0) {
-        LOGE("Failed closing %s\n(%s)\n", v->blk_device, strerror(errno));
+
+    if (fsync(fd.get()) == -1) {
+        LOGE("failed to fsync \"%s\": %s\n", v->blk_device, strerror(errno));
         return -1;
     }
     return 0;