git_pread() saves the current file offset via lseek(fd, 0,
SEEK_CUR) and later restores it. If the initial lseek fails
(e.g., the fd is a pipe or otherwise non-seekable),
current_offset is -1. This negative value is later passed to
lseek(fd, -1, SEEK_SET) at line 16, which sets the file position
to an unintended location (or fails with EINVAL on some
platforms).
Check the initial lseek return value and return -1 immediately
if it fails, consistent with the error handling for the other
lseek calls in the same function.
Pointed out by Coverity.
Assisted-by: Claude Opus 4.6
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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