split formatted I/O header, unify undefined behavior reporting with UNDEFINED_FMT() macro

1 files changed, 12 insertions, 1 deletions

diff --git a/src/stdio/fgetpos.c b/src/stdio/fgetpos.c
index 8e6d201e..2f105f6a 100644
--- a/src/stdio/fgetpos.c
+++ b/src/stdio/fgetpos.c
@@ -6,10 +6,21 @@
 int fgetpos(FILE * restrict stream, fpos_t * restrict pos)
 {
 	SIGNAL_SAFE(0);
+	ASSERT_STREAM(stream, 0, 0);
+	ASSERT_NONNULL(pos);
 	ASSERT_NOOVERLAP(stream, sizeof(*stream), pos, sizeof(*pos));
 
 	flockfile(stream);
-	*pos = stream->pos;
+	if (!(pos->__impl >= stream->fpos && pos->__impl <= stream->fpos + stream->nfpos)) {
+		struct __fpos_t *tmp = realloc(stream->fpos, sizeof(*stream->fpos) * (stream->nfpos + 1));
+		if (tmp == NULL) {
+			abort();
+		}
+		stream->fpos = tmp;
+		pos->__impl = &(stream->fpos[stream->nfpos++]);
+	}
+
+	pos->__impl->pos = ftell(stream);
 	funlockfile(stream);
 	return 0;
 }