+/*
+ * Returns 1 if the i'th line ends in CR/LF (if it is the last line and
+ * has no eol, the preceding line, if any), 0 if it ends in LF-only, and
+ * -1 if the line ending cannot be determined.
+ */
+static int is_eol_crlf(xdfile_t *file, int i)
+{
+ long size;
+
+ if (i < file->nrec - 1)
+ /* All lines before the last *must* end in LF */
+ return (size = file->recs[i]->size) > 1 &&
+ file->recs[i]->ptr[size - 2] == '\r';
+ if (!file->nrec)
+ /* Cannot determine eol style from empty file */
+ return -1;
+ if ((size = file->recs[i]->size) &&
+ file->recs[i]->ptr[size - 1] == '\n')
+ /* Last line; ends in LF; Is it CR/LF? */
+ return size > 1 &&
+ file->recs[i]->ptr[size - 2] == '\r';
+ if (!i)
+ /* The only line has no eol */
+ return -1;
+ /* Determine eol from second-to-last line */
+ return (size = file->recs[i - 1]->size) > 1 &&
+ file->recs[i - 1]->ptr[size - 2] == '\r';
+}
+
+static int is_cr_needed(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m)
+{
+ int needs_cr;
+
+ /* Match post-images' preceding, or first, lines' end-of-line style */
+ needs_cr = is_eol_crlf(&xe1->xdf2, m->i1 ? m->i1 - 1 : 0);
+ if (needs_cr)
+ needs_cr = is_eol_crlf(&xe2->xdf2, m->i2 ? m->i2 - 1 : 0);
+ /* Look at pre-image's first line, unless we already settled on LF */
+ if (needs_cr)
+ needs_cr = is_eol_crlf(&xe1->xdf1, 0);
+ /* If still undecided, use LF-only */
+ return needs_cr < 0 ? 0 : needs_cr;
+}
+