Add new fgetwln() function

Man page taken from FreeBSD.

src/Makefile.am

@@ -43,6 +43,7 @@ libbsd_la_SOURCES = \
 	err.c \
 	expand_number.c \
 	fgetln.c \
+	fgetwln.c \
 	flopen.c \
 	fmtcheck.c \
 	fparseln.c \

src/fgetwln.c

@@ -0,0 +1,87 @@
+/*
+ * Copyright © 2012 Guillem Jover <guillem@hadrons.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
+ * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <wchar.h>
+
+struct filewbuf {
+	FILE *fp;
+	wchar_t *wbuf;
+	size_t len;
+};
+
+#define FILEWBUF_INIT_LEN	128
+#define FILEWBUF_POOL_ITEMS	32
+
+static struct filewbuf fb_pool[FILEWBUF_POOL_ITEMS];
+static int fb_pool_cur;
+
+wchar_t *
+fgetwln(FILE *stream, size_t *lenp)
+{
+	struct filewbuf *fb;
+	wint_t wc;
+	size_t wused = 0;
+
+	/* Try to diminish the possibility of several fgetwln() calls being
+	 * used on different streams, by using a pool of buffers per file. */
+	fb = &fb_pool[fb_pool_cur];
+	if (fb->fp != stream && fb->fp != NULL) {
+		fb_pool_cur++;
+		fb_pool_cur %= FILEWBUF_POOL_ITEMS;
+		fb = &fb_pool[fb_pool_cur];
+	}
+	fb->fp = stream;
+
+	while ((wc = fgetwc(stream)) != WEOF) {
+		if (!fb->len || wused > fb->len) {
+			wchar_t *wp;
+
+			if (fb->len)
+				fb->len *= 2;
+			else
+				fb->len = FILEWBUF_INIT_LEN;
+
+			wp = realloc(fb->wbuf, fb->len * sizeof(wchar_t));
+			if (wp == NULL) {
+				wused = 0;
+				break;
+			}
+			fb->wbuf = wp;
+		}
+
+		fb->wbuf[wused++] = wc;
+
+		if (wc == L'\n')
+			break;
+	}
+
+	*lenp = wused;
+	return wused ? fb->wbuf : NULL;
+}

src/libbsd.map

@@ -96,6 +96,7 @@ LIBBSD_0.4 {
 } LIBBSD_0.3;
 
 LIBBSD_0.5 {
+    fgetwln;
     fparseln;
 
     strnstr;