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Add libio test verifying fflush(FILE) and fflush(NULL) semantic equivalence (RHEL-119435)

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Resolves: RHEL-119435
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Frédéric Bérat 2025-10-29 10:01:44 +01:00
parent e594f0dd8e
commit e97a907db2
1 changed files with 249 additions and 0 deletions
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commit 11e188659db264f6b101d8eb65824ffa5bc91a0a
Author: Frédéric Bérat <fberat@redhat.com>
Date: Mon Sep 9 14:43:36 2024 +0200
libio: Add test case for fflush
Since one path uses _IO_SYNC and the other _IO_OVERFLOW, the newly added
test cases verifies that `fflush (FILE)` and `fflush (NULL)` are
semantically equivalent from the FILE perspective.
Reviewed-by: Joseph Myers <josmyers@redhat.com>
diff --git a/libio/Makefile b/libio/Makefile
index efa60525b39331da..e267e6cbd9ac41fa 100644
--- a/libio/Makefile
+++ b/libio/Makefile
@@ -98,6 +98,8 @@ tests = \
tst-fclose-unopened \
tst-fclose-unopened2 \
tst-fdopen-seek-failure \
+ tst-fflush \
+ tst-fflush-NULL \
tst-fgetc-after-eof \
tst-fgetwc \
tst-fgetws \
diff --git a/libio/tst-fflush-NULL.c b/libio/tst-fflush-NULL.c
new file mode 100644
index 0000000000000000..4c8fe7cb87235f34
--- /dev/null
+++ b/libio/tst-fflush-NULL.c
@@ -0,0 +1,24 @@
+/* Test that fflush (FILE) and fflush (NULL) are semantically equivalent.
+ This is the `fflush (NULL)` part.
+
+ Copyright (C) 2024 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#define FILE_FLUSH_TYPE 0
+#define S_FLUSH_TYPE "NULL"
+
+#include "tst-fflush-skeleton.c"
diff --git a/libio/tst-fflush-skeleton.c b/libio/tst-fflush-skeleton.c
new file mode 100644
index 0000000000000000..6341d3d07976eba8
--- /dev/null
+++ b/libio/tst-fflush-skeleton.c
@@ -0,0 +1,158 @@
+/* Test that fflush (FILE) and fflush (NULL) are semantically equivalent.
+
+ Copyright (C) 2024 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+/* A success on this test doesn't imply the effectiveness of fflush as
+ we can't ensure that the file wasn't already in the expected state
+ before the call of the function. It only ensures that, if the test
+ fails, fflush is broken. */
+
+#include <assert.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+#include <support/check.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/test-driver.h>
+#include <support/xstdio.h>
+#include <support/xunistd.h>
+
+#define CONTENT_SZ_MAX 32
+#define TEST_FILE_COUNT 10
+
+struct file_tracking
+{
+ FILE *file;
+ char *name;
+ int fd;
+ char *mfile;
+} files[TEST_FILE_COUNT];
+
+static void
+file_init (int file)
+{
+ int fd = -1;
+
+ assert (file < TEST_FILE_COUNT);
+
+ files[file] = (struct file_tracking) { .fd = -1, };
+
+ xclose (create_temp_file ("tst-fflush", &files[file].name));
+
+ fd = xopen (files[file].name, O_RDONLY, 0);
+ files[file].mfile = xmmap (NULL, CONTENT_SZ_MAX, PROT_READ, MAP_SHARED, fd);
+ xclose (fd);
+}
+
+static void
+file_cleanup (int file)
+{
+ free (files[file].name);
+ xmunmap (files[file].mfile, CONTENT_SZ_MAX);
+ files[file] = (struct file_tracking) { .fd = -1, };
+}
+
+static void
+file_changed (int to_check, const char *mode)
+{
+ struct stat stats = { };
+ char expected[CONTENT_SZ_MAX] = { };
+
+ verbose_printf ("Check that %s (%d) exactly contains the data we put in\n",
+ files[to_check].name, to_check);
+
+ /* File should contain "N:M" where both N and M are one digit exactly. */
+ snprintf (expected, sizeof (expected), "%d:%d", FILE_FLUSH_TYPE, to_check);
+ TEST_COMPARE_BLOB (files[to_check].mfile, sizeof (expected),
+ expected, sizeof (expected));
+
+ TEST_VERIFY (fstat (files[to_check].fd, &stats) >= 0);
+ TEST_VERIFY (stats.st_size == 3);
+ /* In read mode we expect to be at position 1, in write mode at position 3 */
+ TEST_COMPARE (lseek (files[to_check].fd, 0, SEEK_CUR),
+ mode[0] == 'r' ? 1 : 3);
+
+ if (support_record_failure_is_failed ())
+ FAIL_EXIT1 ("exiting due to previous failure");
+
+ /* Not reached if the data doesn't match. */
+}
+
+static void
+file_flush (const char *mode)
+{
+ for (int i = 0; i < TEST_FILE_COUNT; i++)
+ {
+ files[i].file = xfopen (files[i].name, mode);
+ files[i].fd = fileno (files[i].file);
+ }
+
+ /* Print a unique identifier in each file, that is not too long nor contain
+ new line to not trigger _IO_OVERFLOW/_IO_SYNC. */
+ for (int i = 0; i < TEST_FILE_COUNT; i++)
+ {
+ if (mode[0] == 'r')
+ fgetc (files[i].file);
+ else
+ fprintf (files[i].file, "%d:%d", FILE_FLUSH_TYPE, i);
+ }
+
+ if (!FILE_FLUSH_TYPE)
+ TEST_VERIFY (fflush (NULL) == 0);
+ else
+ for (int i = 0; i < TEST_FILE_COUNT; i++)
+ TEST_VERIFY (fflush (files[i].file) == 0);
+
+ for (int i = 0; i < TEST_FILE_COUNT; i++)
+ {
+ verbose_printf ("Check that file %s has been modified after fflush\n",
+ files[i].name);
+ file_changed (i, mode);
+ }
+
+ for (int i = 0; i < TEST_FILE_COUNT; i++)
+ xfclose (files[i].file);
+}
+
+static int
+do_test (void)
+{
+ for (int i = 0; i < TEST_FILE_COUNT; i++)
+ file_init (i);
+
+ verbose_printf ("Checking fflush(" S_FLUSH_TYPE "), WRITE mode\n");
+ file_flush ("w");
+
+ verbose_printf ("Checking fflush(" S_FLUSH_TYPE "), READWRITE mode\n");
+ file_flush ("r+");
+
+ for (int i = 0; i < TEST_FILE_COUNT; i++)
+ file_cleanup (i);
+
+ return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/libio/tst-fflush.c b/libio/tst-fflush.c
new file mode 100644
index 0000000000000000..d3a4b78f4324c7e9
--- /dev/null
+++ b/libio/tst-fflush.c
@@ -0,0 +1,24 @@
+/* Test that fflush (FILE) and fflush (NULL) are semantically equivalent.
+ This is the `fflush (FILE)` part.
+
+ Copyright (C) 2024 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#define FILE_FLUSH_TYPE 1
+#define S_FLUSH_TYPE "FILE"
+
+#include "tst-fflush-skeleton.c"