fastboot: Support larger transfers during flash

Adding methods to queue and download flashable images by fd instead of
by pointer, so that we can deal with sending large (up to 4GB) files
on windows and linux.  This gets past limitations on linux to read
more than 2GB from a file at a time, as well as memory limitations
on win32, in order to download up to 4GB in a single transfer.

Test: fastboot -w
Test: "flash-all" from nexus factory images site (incl. fastboot -w update)
Test: fastboot flash with large and small image, large and small max-download-size
Test: Sanity check flashing on win32, darwin, linux.
Test: Sanity check 3GB image download (with 3GB max-download-size)
      on win32, darwin, linux.

Bug: 36810152
Change-Id: I528d739d344eb080d59d721dadf3b3b34d4b375e

1 files changed, 23 insertions, 10 deletions

diff --git a/fastboot/fastboot.cpp b/fastboot/fastboot.cpp
index cb8e5c026..3b524ac3c 100644
--- a/fastboot/fastboot.cpp
+++ b/fastboot/fastboot.cpp
@@ -55,6 +55,7 @@
 #include <android-base/parsenetaddress.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
+#include <android-base/unique_fd.h>
 #include <sparse/sparse.h>
 #include <ziparchive/zip_archive.h>
 
@@ -67,6 +68,8 @@
 #include "udp.h"
 #include "usb.h"
 
+using android::base::unique_fd;
+
 #ifndef O_BINARY
 #define O_BINARY 0
 #endif
@@ -95,7 +98,7 @@ static unsigned tags_offset    = 0x00000100;
 static const std::string convert_fbe_marker_filename("convert_fbe");
 
 enum fb_buffer_type {
-    FB_BUFFER,
+    FB_BUFFER_FD,
     FB_BUFFER_SPARSE,
 };
 
@@ -103,6 +106,7 @@ struct fastboot_buffer {
     enum fb_buffer_type type;
     void* data;
     int64_t sz;
+    int fd;
 };
 
 static struct {
@@ -826,10 +830,9 @@ static bool load_buf_fd(Transport* transport, int fd, struct fastboot_buffer* bu
         buf->type = FB_BUFFER_SPARSE;
         buf->data = s;
     } else {
-        void* data = load_fd(fd, &sz);
-        if (data == nullptr) return -1;
-        buf->type = FB_BUFFER;
-        buf->data = data;
+        buf->type = FB_BUFFER_FD;
+        buf->data = nullptr;
+        buf->fd = fd;
         buf->sz = sz;
     }
 
@@ -837,11 +840,22 @@ static bool load_buf_fd(Transport* transport, int fd, struct fastboot_buffer* bu
 }
 
 static bool load_buf(Transport* transport, const char* fname, struct fastboot_buffer* buf) {
-    int fd = open(fname, O_RDONLY | O_BINARY);
+    unique_fd fd(TEMP_FAILURE_RETRY(open(fname, O_RDONLY | O_BINARY)));
+
     if (fd == -1) {
         return false;
     }
-    return load_buf_fd(transport, fd, buf);
+
+    struct stat s;
+    if (fstat(fd, &s)) {
+        return false;
+    }
+    if (!S_ISREG(s.st_mode)) {
+        errno = S_ISDIR(s.st_mode) ? EISDIR : EINVAL;
+        return false;
+    }
+
+    return load_buf_fd(transport, fd.release(), buf);
 }
 
 static void flash_buf(const char *pname, struct fastboot_buffer *buf)
@@ -864,9 +878,8 @@ static void flash_buf(const char *pname, struct fastboot_buffer *buf)
             }
             break;
         }
-
-        case FB_BUFFER:
-            fb_queue_flash(pname, buf->data, buf->sz);
+        case FB_BUFFER_FD:
+            fb_queue_flash_fd(pname, buf->fd, buf->sz);
             break;
         default:
             die("unknown buffer type: %d", buf->type);