From be81e51c171a0cf9b9b5045ee949282b7f36d779 Mon Sep 17 00:00:00 2001
From: Michael Runge <mrunge@google.com>
Date: Wed, 29 Oct 2014 12:42:15 -0700
Subject: Use more aggressive sync writing to applypatch.

We have seen cases where the boot partition is patched, but upon
recovery the partition appears to be corrupted.  Open up all
patched files/partitions with O_SYNC, and do not ignore the
errors from fsync/close operations.

Bug: 18170529
Change-Id: I392ad0a321d937c4ad02eaeea9170be384a4744b
---
 applypatch/applypatch.c | 44 ++++++++++++++++++++++++++++++++++++--------
 1 file changed, 36 insertions(+), 8 deletions(-)

diff --git a/applypatch/applypatch.c b/applypatch/applypatch.c
index bfb9440..2c86e09 100644
--- a/applypatch/applypatch.c
+++ b/applypatch/applypatch.c
@@ -309,7 +309,7 @@ static int LoadPartitionContents(const char* filename, FileContents* file) {
 // Save the contents of the given FileContents object under the given
 // filename.  Return 0 on success.
 int SaveFileContents(const char* filename, const FileContents* file) {
-    int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
+    int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_SYNC, S_IRUSR | S_IWUSR);
     if (fd < 0) {
         printf("failed to open \"%s\" for write: %s\n",
                filename, strerror(errno));
@@ -324,8 +324,14 @@ int SaveFileContents(const char* filename, const FileContents* file) {
         close(fd);
         return -1;
     }
-    fsync(fd);
-    close(fd);
+    if (fsync(fd) != 0) {
+        printf("fsync of \"%s\" failed: %s\n", filename, strerror(errno));
+        return -1;
+    }
+    if (close(fd) != 0) {
+        printf("close of \"%s\" failed: %s\n", filename, strerror(errno));
+        return -1;
+    }
 
     if (chmod(filename, file->st.st_mode) != 0) {
         printf("chmod of \"%s\" failed: %s\n", filename, strerror(errno));
@@ -408,7 +414,7 @@ int WriteToPartition(unsigned char* data, size_t len,
         {
             size_t start = 0;
             int success = 0;
-            int fd = open(partition, O_RDWR);
+            int fd = open(partition, O_RDWR | O_SYNC);
             if (fd < 0) {
                 printf("failed to open %s: %s\n", partition, strerror(errno));
                 return -1;
@@ -433,7 +439,22 @@ int WriteToPartition(unsigned char* data, size_t len,
                     }
                     start += written;
                 }
-                fsync(fd);
+                if (fsync(fd) != 0) {
+                   printf("failed to sync to %s (%s)\n",
+                          partition, strerror(errno));
+                   return -1;
+                }
+                if (close(fd) != 0) {
+                   printf("failed to close %s (%s)\n",
+                          partition, strerror(errno));
+                   return -1;
+                }
+                fd = open(partition, O_RDONLY);
+                if (fd < 0) {
+                   printf("failed to reopen %s for verify (%s)\n",
+                          partition, strerror(errno));
+                   return -1;
+                }
 
                 // drop caches so our subsequent verification read
                 // won't just be reading the cache.
@@ -919,7 +940,8 @@ static int GenerateTarget(FileContents* source_file,
             strcpy(outname, target_filename);
             strcat(outname, ".patch");
 
-            output = open(outname, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
+            output = open(outname, O_WRONLY | O_CREAT | O_TRUNC | O_SYNC,
+                S_IRUSR | S_IWUSR);
             if (output < 0) {
                 printf("failed to open output file %s: %s\n",
                        outname, strerror(errno));
@@ -950,8 +972,14 @@ static int GenerateTarget(FileContents* source_file,
         }
 
         if (output >= 0) {
-            fsync(output);
-            close(output);
+            if (fsync(output) != 0) {
+                printf("failed to fsync file \"%s\" (%s)\n", outname, strerror(errno));
+                result = 1;
+            }
+            if (close(output) != 0) {
+                printf("failed to close file \"%s\" (%s)\n", outname, strerror(errno));
+                result = 1;
+            }
         }
 
         if (result != 0) {
-- 
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