tree fd2e1bc84e6a65fa676adcb59f285dc2f246520d
parent 756138e4755c93265e34704ee95874c0d81425e5
author Patrick Steinhardt <ps@pks.im> 1490688743 +0200
committer Patrick Steinhardt <ps@pks.im> 1491299926 +0200

fileops: do not overwrite correct error message on mmap

When executing `git_futils_mmap_ro_file`, we first try to guess whether
the file is mmapable at all. Part of this check is whether the file is
too large to be mmaped, which can be true on systems with 32 bit
`size_t` types.

The check is performed by first getting the file size wtih
`git_futils_filesize` and then checking whether the returned size can be
represented as `size_t`, returning an error if so. While this test also
catches the case where the function returned an error (as `-1` is not
representable by `size_t`), we will set the misleading error message
"file too large to mmap". But in fact, a negative return value from
`git_futils_filesize` will be caused by the inability to fstat the file.

Fix the error message by handling negative return values separately and
not overwriting the error message in that case.