recovery: write partitions more conservatively
Write and verify partitions using write(2) and read(2) rather than the
stdio functions. Read and write in 4kb blocks. When writing, fsync()
every 1MB.
Bug: 9602014
Change-Id: Ie98ce38e857786fc0f4ebf36bb5ffc93b41bc96f
diff --git a/applypatch/applypatch.c b/applypatch/applypatch.c
index 2f134df..3f67c32 100644
--- a/applypatch/applypatch.c
+++ b/applypatch/applypatch.c
@@ -424,42 +424,50 @@
{
size_t start = 0;
int success = 0;
- FILE* f = fopen(partition, "r+b");
- if (f == NULL) {
+ int fd = open(partition, O_RDWR);
+ if (fd < 0) {
printf("failed to open %s: %s\n", partition, strerror(errno));
return -1;
}
int attempt;
- for (attempt = 0; attempt < 3; ++attempt) {
- printf("write %s attempt %d start at %d\n", partition, attempt+1, start);
- fseek(f, start, SEEK_SET);
+ for (attempt = 0; attempt < 10; ++attempt) {
+ off_t next_sync = start + (1<<20);
+ printf("raw write %s attempt %d start at %d\n", partition, attempt+1, start);
+ lseek(fd, start, SEEK_SET);
while (start < len) {
size_t to_write = len - start;
- if (to_write > (1<<20)) to_write = 1<<20;
+ if (to_write > 4096) to_write = 4096;
- if (fwrite(data+start, 1, to_write, f) != to_write) {
- printf("short write writing to %s (%s)\n",
- partition, strerror(errno));
- return -1;
+ ssize_t written = write(fd, data+start, to_write);
+ if (written < 0) {
+ if (errno == EINTR) {
+ written = 0;
+ } else {
+ printf("failed write writing to %s (%s)\n",
+ partition, strerror(errno));
+ return -1;
+ }
}
- start += to_write;
- if (start < len) {
- usleep(50000); // 50 ms
+ start += written;
+ if (start >= next_sync) {
+ fsync(fd);
+ next_sync = start + (1<<20);
}
}
+ fsync(fd);
// drop caches so our subsequent verification read
// won't just be reading the cache.
sync();
- FILE* dc = fopen("/proc/sys/vm/drop_caches", "w");
- fwrite("3\n", 2, 1, dc);
- fclose(dc);
+ int dc = open("/proc/sys/vm/drop_caches", O_WRONLY);
+ write(dc, "3\n", 2);
+ close(dc);
sleep(1);
printf(" caches dropped\n");
// verify
- fseek(f, 0, SEEK_SET);
+ lseek(fd, 0, SEEK_SET);
unsigned char buffer[4096];
start = len;
size_t p;
@@ -467,11 +475,23 @@
size_t to_read = len - p;
if (to_read > sizeof(buffer)) to_read = sizeof(buffer);
- if (fread(buffer, 1, to_read, f) != to_read) {
- printf("short verify read %s at %d: %s\n",
- partition, p, strerror(errno));
- start = p;
- break;
+ size_t so_far = 0;
+ while (so_far < to_read) {
+ ssize_t read_count = read(fd, buffer+so_far, to_read-so_far);
+ if (read_count < 0) {
+ if (errno == EINTR) {
+ read_count = 0;
+ } else {
+ printf("verify read error %s at %d: %s\n",
+ partition, p, strerror(errno));
+ return -1;
+ }
+ }
+ if (read_count < to_read) {
+ printf("short verify read %s at %d: %d %d %s\n",
+ partition, p, read_count, to_read, strerror(errno));
+ }
+ so_far += read_count;
}
if (memcmp(buffer, data+p, to_read)) {
@@ -486,6 +506,8 @@
success = true;
break;
}
+
+ sleep(2);
}
if (!success) {
@@ -493,7 +515,7 @@
return -1;
}
- if (fclose(f) != 0) {
+ if (close(fd) != 0) {
printf("error closing %s (%s)\n", partition, strerror(errno));
return -1;
}
