commit 6239c32aa5b6e0cd533dfd1ffe4ef2e726841e2b
author chihhao.chen <chihhao.chen@mediatek.com> Mon May 20 16:55:55 2019 +0800
committer Hridya Valsaraju <hridya@google.com> Wed May 29 12:41:55 2019 -0700
tree 6109eab335885e1e3481ab2e6e695e4dab63f025
parent e93ebdf9feaa52214c06cc032a64df9875d1351f

Fix non-aio USB read issue for fastbootd

non-aio USB read function was stuck in a loop waiting for more data
because data length parameter is always set 64 for fastbootd commands.
It should be a normal case to get less data than expected
since lengths of these commands are usually less than 64.
Add logic to check this and one more parameter to distinguish
fastbootd from general adbd case.

Bug: 133189029
Test: try various fastbootd commands
Change-Id: I6690324840d78f3f1e04235040301520329976db

adb/daemon/include/adbd/usb.h

diff --git a/adb/daemon/include/adbd/usb.h b/adb/daemon/include/adbd/usb.h
index 3213f69..fca3c58 100644
--- a/adb/daemon/include/adbd/usb.h
+++ b/adb/daemon/include/adbd/usb.h
@@ -43,7 +43,7 @@
     bool open_new_connection = true;
 
     int (*write)(usb_handle* h, const void* data, int len);
-    int (*read)(usb_handle* h, void* data, int len);
+    int (*read)(usb_handle* h, void* data, int len, bool allow_partial);
     void (*kick)(usb_handle* h);
     void (*close)(usb_handle* h);
 

adb/daemon/usb_legacy.cpp

diff --git a/adb/daemon/usb_legacy.cpp b/adb/daemon/usb_legacy.cpp
index b65727a..fe80e7d 100644
--- a/adb/daemon/usb_legacy.cpp
+++ b/adb/daemon/usb_legacy.cpp
@@ -142,11 +142,12 @@
     return orig_len;
 }
 
-static int usb_ffs_read(usb_handle* h, void* data, int len) {
+static int usb_ffs_read(usb_handle* h, void* data, int len, bool allow_partial) {
     D("about to read (fd=%d, len=%d)", h->bulk_out.get(), len);
 
     char* buf = static_cast<char*>(data);
     int orig_len = len;
+    unsigned count = 0;
     while (len > 0) {
         int read_len = std::min(USB_FFS_BULK_SIZE, len);
         int n = adb_read(h->bulk_out, buf, read_len);
@@ -156,6 +157,16 @@
         }
         buf += n;
         len -= n;
+        count += n;
+
+        // For fastbootd command such as "getvar all", len parameter is always set 64.
+        // But what we read is actually less than 64.
+        // For example, length 10 for "getvar all" command.
+        // If we get less data than expected, this means there should be no more data.
+        if (allow_partial && n < read_len) {
+            orig_len = count;
+            break;
+        }
     }
 
     D("[ done fd=%d ]", h->bulk_out.get());
@@ -221,7 +232,7 @@
     }
 }
 
-static int usb_ffs_aio_read(usb_handle* h, void* data, int len) {
+static int usb_ffs_aio_read(usb_handle* h, void* data, int len, bool allow_partial) {
     return usb_ffs_do_aio(h, data, len, true);
 }
 
@@ -299,7 +310,7 @@
 }
 
 int usb_read(usb_handle* h, void* data, int len) {
-    return h->read(h, data, len);
+    return h->read(h, data, len, false /* allow_partial */);
 }
 
 int usb_close(usb_handle* h) {

fastboot/device/usb_client.cpp

diff --git a/fastboot/device/usb_client.cpp b/fastboot/device/usb_client.cpp
index fb51a90..5921df9 100644
--- a/fastboot/device/usb_client.cpp
+++ b/fastboot/device/usb_client.cpp
@@ -255,7 +255,8 @@
     size_t bytes_read_total = 0;
     while (bytes_read_total < len) {
         auto bytes_to_read = std::min(len - bytes_read_total, kFbFfsNumBufs * kFbFfsBufSize);
-        auto bytes_read_now = handle_->read(handle_.get(), char_data, bytes_to_read);
+        auto bytes_read_now =
+                handle_->read(handle_.get(), char_data, bytes_to_read, true /* allow_partial */);
         if (bytes_read_now < 0) {
             return bytes_read_total;
         }