@@ -154,6 +154,7 @@ dup203 dup203
dup204 dup204
dup205 dup205
dup206 dup206
+dup207 dup207
dup3_01 dup3_01
dup3_02 dup3_02
@@ -4,3 +4,4 @@
/dup204
/dup205
/dup206
+/dup207
new file mode 100644
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2021 FUJITSU LIMITED. All rights reserved.
+ * Author: Yang Xu <xuyang2018.jy@fujitsu.com>
+ */
+
+/*\
+ * [Description]
+ *
+ * Test whether the file offset are the same for both file descriptors.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include "tst_test.h"
+#include "tst_safe_macros.h"
+
+#define WRITE_STR "abcdefg"
+
+static int ofd = -1, nfd = 10;
+
+static struct tcase {
+ off_t offset;
+ size_t exp_size;
+ /* 0 - change offset before dup2, 1 - change offset after dup2 */
+ int flag;
+ char *exp_data;
+ char *desc;
+} tcases[] = {
+ {1, 6, 0, "bcdefg", "Test offset check when using lseek before dup2"},
+ {2, 5, 1, "cdefg", "Test offset check when using lseek after dup2"},
+};
+
+static void setup(void)
+{
+ char testfile[40];
+
+ sprintf(testfile, "dup207.%d", getpid());
+ ofd = SAFE_OPEN(testfile, O_RDWR | O_CREAT, 0644);
+ SAFE_WRITE(1, ofd, WRITE_STR, sizeof(WRITE_STR) - 1);
+}
+
+static void cleanup(void)
+{
+ if (ofd > 0)
+ SAFE_CLOSE(ofd);
+ close(nfd);
+}
+
+static void run(unsigned int i)
+{
+ struct tcase *tc = tcases + i;
+ char read_buf[20];
+
+ memset(read_buf, 0, sizeof(read_buf));
+ tst_res(TINFO, "%s", tc->desc);
+ if (!tc->flag)
+ SAFE_LSEEK(ofd, tc->offset, SEEK_SET);
+
+ TEST(dup2(ofd, nfd));
+ if (TST_RET == -1) {
+ tst_res(TFAIL | TTERRNO, "call failed unexpectedly");
+ return;
+ }
+ if (tc->flag)
+ SAFE_LSEEK(ofd, tc->offset, SEEK_SET);
+
+ SAFE_READ(1, nfd, read_buf, tc->exp_size);
+ if (strncmp(read_buf, tc->exp_data, tc->exp_size))
+ tst_res(TFAIL, "Expect %s, but get %s.", tc->exp_data, read_buf);
+ else
+ tst_res(TPASS, "Get expected buf %s", read_buf);
+}
+
+static struct tst_test test = {
+ .needs_tmpdir = 1,
+ .tcnt = ARRAY_SIZE(tcases),
+ .test = run,
+ .setup = setup,
+ .cleanup = cleanup,
+};
Since the two file descriptors refer to the same open file description, they share file offset. If the file offset is modified by using lseek(2) on one of the file descriptors, the offset is also changed for the other file descriptor. Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com> --- runtest/syscalls | 1 + testcases/kernel/syscalls/dup2/.gitignore | 1 + testcases/kernel/syscalls/dup2/dup207.c | 82 +++++++++++++++++++++++ 3 files changed, 84 insertions(+) create mode 100644 testcases/kernel/syscalls/dup2/dup207.c