Adds rcfile_load(path, runner) to rcfile.c/rcfile.h: reads lines with
getline() (no fixed-size buffer, so a long line like a multi-peer
`set masters ...` can never be silently truncated or split), strips the
trailing newline, invokes the caller-supplied runner once per line, and
stops at the first nonzero runner return, propagating that value. A missing
rc file is a silent no-op; any other open failure prints one stderr warning
and returns 0.
Found during GREEN: fopen() succeeds on a directory path on this platform,
so the EISDIR failure only surfaces on the first getline() call (ferror(f)
set) -- added a post-loop ferror() check to catch it (bug-1716).
5 new unit tests (11 total with task 1.1): ENOENT-silent, per-line-in-order
with newline stripped, stop-on-nonzero with exact propagation, non-ENOENT
open-failure warning, and a >4KB single line proving no truncation/split.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AgYRU3zDTqNGV5Jk8aiKLg
Rongsong Shen
77aba21fb0