read() can return fewer bytes than requested

Sometimes read returns fewer bytes than requested. read() only read at
most 0x7ffff000 bytes.

Bug: 376247649
Test: manual, make mkbootfs, mkbootfs out/target/product../VENDOR_BOOT
Change-Id: I8cbbae40c5f5c6c54d19bf77e9a801ed3390ed48
1 file changed