1 files changed, 345 insertions, 0 deletions

diff --git a/src/regress/lib/libc/stdio/test_fflush.c b/src/regress/lib/libc/stdio/test_fflush.c
new file mode 100644
index 0000000000..a0586b7d14
--- /dev/null
+++ b/src/regress/lib/libc/stdio/test_fflush.c
@@ -0,0 +1,345 @@
+/*      $OpenBSD: test_fflush.c,v 1.3 2025/06/08 08:53:53 yasuoka Exp $ */
+
+/*
+ * Copyright (c) 2025 YASUOKA Masahiko <yasuoka@yasuoka.net>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <assert.h>
+#include <locale.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wchar.h>
+
+/* we use assert() */
+#undef  NDEBUG
+
+#define TMPFILENAME     "test_fflush.tmp"
+
+void setup(void);
+
+void test_fflush_read0(void);
+void test_fflush_read1(void);
+void test_fflush_read2(void);
+void test_fflush_read3(void);
+void test_fflush_read4(void);
+void setupw(void);
+void test_fflush_read5(void);
+void test_fflush_read6(void);
+
+void
+setup(void)
+{
+        FILE    *fp;
+
+        /* common setup */
+        unlink(TMPFILENAME);
+        fp = fopen(TMPFILENAME, "w+");
+        assert(fp != NULL);
+        fputs("Hello world\n", fp);
+        fclose(fp);
+}
+
+/* fflush work with reading file and seekable */
+void
+test_fflush_read0(void)
+{
+        int      r;
+        char     buf[80];
+        FILE    *fp;
+
+        setup();
+
+        /* In POSIX 2008, fflush() must work with the file object for reading */
+        fp = fopen(TMPFILENAME, "r");
+        assert(fp != NULL);
+        assert(fgetc(fp) == 'H');
+        r = fflush(fp);
+        assert(r == 0);
+
+        /* the position is moved to 1 */
+        assert(ftell(fp) == 1);
+
+        /* can read rest of that */
+        fgets(buf, sizeof(buf), fp);
+        assert(strcmp(buf, "ello world\n") == 0);
+        r = fclose(fp);
+        assert(r == 0);
+}
+
+/* fflush work with reading file and seekable + unget */
+void
+test_fflush_read1(void)
+{
+        int      r;
+        char     buf[80];
+        FILE    *fp;
+
+        setup();
+
+        fp = fopen(TMPFILENAME, "r");
+        assert(fp != NULL);
+        assert(fgetc(fp) == 'H');
+        assert(fgetc(fp) == 'e');
+        assert(fgetc(fp) == 'l');
+        assert(fgetc(fp) == 'l');
+        assert(fgetc(fp) == 'o');
+
+        /* push the 'AAAA' back */
+        ungetc('A', fp);
+        ungetc('A', fp);
+        ungetc('A', fp);
+        ungetc('A', fp);
+
+        /* can read rest of that */
+        fgets(buf, sizeof(buf), fp);
+        assert(strcmp(buf, "AAAA world\n") == 0);
+        r = fclose(fp);
+        assert(r == 0);
+
+        /* do the same thing + fflush */
+
+        fp = fopen(TMPFILENAME, "r");
+        assert(fp != NULL);
+        assert(fgetc(fp) == 'H');
+        assert(fgetc(fp) == 'e');
+        assert(fgetc(fp) == 'l');
+        assert(fgetc(fp) == 'l');
+        assert(fgetc(fp) == 'o');
+
+        /* push 'AAAA' back */
+        ungetc('A', fp);
+        ungetc('A', fp);
+        ungetc('A', fp);
+        ungetc('A', fp);
+
+        /* then fflush */
+        r = fflush(fp);
+        assert(r == 0);
+
+        /* fllush() clears the all pushed back chars */
+
+        /* can read rest of that */
+        fgets(buf, sizeof(buf), fp);
+        assert(strcmp(buf, " world\n") == 0);
+        r = fclose(fp);
+        assert(r == 0);
+}
+
+/* fflush() to reading and non-seekable stream */
+void
+test_fflush_read2(void)
+{
+        int      r;
+        FILE    *fp;
+        char     buf[80];
+
+        /* In POSIX-2008, fflush() must work with the file object for reading */
+        fp = popen("echo Hello world", "r");
+        assert(fp != NULL);
+        assert(fgetc(fp) == 'H');
+        r = fflush(fp);
+        assert(r == 0);
+
+        /*
+         * FILE object for read and NOT seekable.  In that case, fflush does
+         * nothing, but must keep the buffer.
+         */
+
+        /* can read rest of that */
+        fgets(buf, sizeof(buf), fp);
+        assert(strcmp(buf, "ello world\n") == 0);
+        r = pclose(fp);
+        assert(r == 0);
+}
+
+/* fflush() to the file which doesn't have any buffer */
+void
+test_fflush_read3(void)
+{
+        int      r;
+        FILE    *fp;
+
+        setup();
+
+        /* In POSIX-2008, fflush() must work with the file object for reading */
+        fp = fopen(TMPFILENAME, "r");
+        assert(fp != NULL);
+        r = fflush(fp);
+        assert(r == 0);
+        r = fclose(fp);
+        assert(r == 0);
+}
+
+/* freopen() should call fflush() internal */
+void
+test_fflush_read4(void)
+{
+        int      r;
+        FILE    *fp;
+        off_t    pos;
+        char     buf[80];
+
+        setup();
+
+        /* In POSIX-2008, fflush() must work with the file object for reading */
+        fp = fopen(TMPFILENAME, "r");
+        assert(fp != NULL);
+
+        assert(fgetc(fp) == 'H');       /* read 1 */
+
+        pos = lseek(fileno(fp), 0, SEEK_CUR);
+        assert(pos >= 1);
+        assert(pos > 1);        /* this test assume the buffer is used */
+
+        /* freopen() should call fflush() internal */
+        fp = freopen(TMPFILENAME, "r", fp);
+        assert(fp != NULL);
+
+        /* can read rest of that on fp */
+        fgets(buf, sizeof(buf), fp);
+        assert(strcmp(buf, "Hello world\n") == 0);
+
+        r = fclose(fp);
+        assert(r == 0);
+}
+
+void
+setupw(void)
+{
+        FILE    *fp;
+
+        /* common setup */
+        unlink(TMPFILENAME);
+        fp = fopen(TMPFILENAME, "w+");
+        assert(fp != NULL);
+        /* Konnitiwa Sekai(in Kanji) */
+        fputws(L"\u3053\u3093\u306b\u3061\u308f \u4e16\u754c\n", fp);
+        fclose(fp);
+}
+
+/* fflush work with reading file and seekable + ungetwc */
+void
+test_fflush_read5(void)
+{
+        int      r;
+        wchar_t  buf[80];
+        FILE    *fp;
+
+        setupw();
+
+        fp = fopen(TMPFILENAME, "r");
+
+        assert(fp != NULL);
+        assert(fgetwc(fp) == L'\u3053');        /* Ko */
+        assert(fgetwc(fp) == L'\u3093');        /* N  */
+        assert(fgetwc(fp) == L'\u306b');        /* Ni */
+        assert(fgetwc(fp) == L'\u3061');        /* Ti */
+        assert(fgetwc(fp) == L'\u308f');        /* Wa */
+
+        /* push 263A(smile) back */
+        assert(ungetwc(L'\u263a', fp));
+
+        /* we support 1 push back wchar_t */
+        assert(fgetwc(fp) == L'\u263a');
+
+        /* can read reset of that */
+        fgetws(buf, sizeof(buf), fp);
+        assert(wcscmp(buf, L" \u4e16\u754c\n") == 0);
+
+        r = fclose(fp);
+        assert(r == 0);
+
+        /* do the same thing + fflush */
+        fp = fopen(TMPFILENAME, "r");
+
+        assert(fp != NULL);
+        assert(fgetwc(fp) == L'\u3053');        /* Ko */
+        assert(fgetwc(fp) == L'\u3093');        /* N  */
+        assert(fgetwc(fp) == L'\u306b');        /* Ni */
+        assert(fgetwc(fp) == L'\u3061');        /* Ti */
+        assert(fgetwc(fp) == L'\u308f');        /* Wa */
+
+        /* push 263A(smile) back */
+        assert(ungetwc(L'\u263a', fp));
+
+        /* we support 1 push back wchar_t */
+        assert(fgetwc(fp) == L'\u263a');
+
+        /* then fflush */
+        r = fflush(fp);
+        assert(r == 0);
+
+        /* fllush() clears the all pushed back chars */
+
+        /* can read rest of that */
+        fgetws(buf, sizeof(buf), fp);
+        assert(wcscmp(buf, L" \u4e16\u754c\n") == 0);
+        r = fclose(fp);
+        assert(r == 0);
+}
+
+void
+test_fflush_read6(void)
+{
+        int      r, c;
+        FILE    *fp;
+
+        setup();
+        fp = fopen(TMPFILENAME, "r");
+        assert(fp != NULL);
+
+        /*
+         * https://pubs.opengroup.org/onlinepubs/9699919799/functions/fflush.html
+         * .. any characters pushed back onto the stream by ungetc() or ungetwc()
+         * that have not subsequently been read from the stream shall be discarded
+         * (without further changing the file offset).
+         */
+
+        assert(fgetc(fp) == 'H');
+        c = getc(fp);
+        ungetc(c, fp);  /* push back the character has been read */
+        r = fflush(fp);
+        assert(r == 0);
+        assert(getc(fp) == c);
+
+        fseek(fp, 0, SEEK_SET);
+        assert(fgetc(fp) == 'H');
+        c = getc(fp);
+        ungetc('X', fp); /* push back the character has not been read */
+        r = fflush(fp);
+        assert(r == 0);
+        assert(getc(fp) == 'l');
+
+        r = fclose(fp);
+        assert(r == 0);
+}
+
+int
+main(int argc, char *argv[])
+{
+        setlocale(LC_ALL, "C.UTF-8");
+
+        test_fflush_read0();
+        test_fflush_read1();
+        test_fflush_read2();
+        test_fflush_read3();
+        test_fflush_read4();
+        test_fflush_read5();
+        test_fflush_read6();
+
+        exit(0);
+}