libziparchive: fix fallocate failures

The objective of fallocate call seems to be to
make sure that we have enough enough space left
in the disk to house the uncompressed file.
But, fallocate is only supported in the following
file systems:
btrfs, ext4, ocfs2, and xfs

Return error only when fallocate fails due to
lack of space. The immediate ftruncate call is
going to take of the majority of other errors.

Bug: 21561449
Change-Id: I7083f3c7e5d745bd6e8a190ac9020297d638d9d4

libziparchive/zip_archive.cc

@@ -1008,8 +1008,13 @@ class FileWriter : public Writer {
       // entry. Note that the call to ftruncate below will change the file size but
       // will not allocate space on disk and this call to fallocate will not
       // change the file size.
+      // Note: fallocate is only supported by the following filesystems -
+      // btrfs, ext4, ocfs2, and xfs. Therefore fallocate might fail with
+      // EOPNOTSUPP error when issued in other filesystems.
+      // Hence, check for the return error code before concluding that the
+      // disk does not have enough space.
       result = TEMP_FAILURE_RETRY(fallocate(fd, 0, current_offset, declared_length));
-      if (result == -1) {
+      if (result == -1 && errno == ENOSPC) {
         ALOGW("Zip: unable to allocate space for file to %" PRId64 ": %s",
               static_cast<int64_t>(declared_length + current_offset), strerror(errno));
         return std::unique_ptr<FileWriter>(nullptr);