523afc95f6
Backports: - tests: replace fread by xfread - Fix fflush after ungetc on input file (bug 5994) - Make fclose seek input file to right offset (bug 12724) - Make fflush (NULL) flush input files (bug 32369) - Fix fseek handling for mmap files after ungetc or fflush (bug 32529) - Fix fflush handling for mmap files after ungetc (bug 32535) - Add test of input file flushing / offset issues - libio: Synthesize ESPIPE error if lseek returns 0 after reading bytes Resolves: RHEL-68805
111 lines
3.4 KiB
Diff
111 lines
3.4 KiB
Diff
commit 7b47b3dd214c8ff2c699f13efe5533941be53635
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Tue Apr 8 18:38:38 2025 +0200
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libio: Synthesize ESPIPE error if lseek returns 0 after reading bytes
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This is required so that fclose, when trying to seek to the right
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position after filling the input buffer, does not fail with EINVAL.
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This fclose code path only ignores ESPIPE errors.
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Reported by Petr Pisar on
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<https://bugzilla.redhat.com/show_bug.cgi?id=2358265>.
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Fixes commit be6818be31e756398e45f70e2819d78be0961223 ("Make fclose
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seek input file to right offset (bug 12724)").
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Reviewed-by: Frédéric Bérat <fberat@redhat.com>
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Conflicts:
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stdio-common/Makefile (fixup context)
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diff --git a/libio/fileops.c b/libio/fileops.c
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index 0b35790a9d35bcc5..11303013cb11dbd2 100644
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--- a/libio/fileops.c
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+++ b/libio/fileops.c
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@@ -928,6 +928,16 @@ do_ftell (FILE *fp)
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if (result == EOF)
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return result;
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+ if (result == 0 && offset < 0)
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+ {
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+ /* This happens for some character devices that always report
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+ file offset 0 even after some data has been read (instead of
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+ failing with ESPIPE). The fclose path ignores this
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+ error. */
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+ __set_errno (ESPIPE);
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+ return EOF;
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+ }
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+
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result += offset;
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if (result < 0)
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diff --git a/stdio-common/Makefile b/stdio-common/Makefile
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index fe4a7c4acc3932b2..9a027d41a2e9cc9b 100644
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--- a/stdio-common/Makefile
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+++ b/stdio-common/Makefile
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@@ -218,6 +218,7 @@ tests := \
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tst-bz11319 \
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tst-bz11319-fortify2 \
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tst-cookie \
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+ tst-fclose-devzero \
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tst-fclose-offset \
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tst-fdopen \
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tst-fdopen2 \
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diff --git a/stdio-common/tst-fclose-devzero.c b/stdio-common/tst-fclose-devzero.c
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new file mode 100644
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index 0000000000000000..1c7b39a3e04ba80d
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--- /dev/null
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+++ b/stdio-common/tst-fclose-devzero.c
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@@ -0,0 +1,50 @@
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+/* Test that always-zero lseek does not cause fclose failure after fread.
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+ Copyright (C) 2025 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <errno.h>
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+#include <stdio.h>
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+#include <string.h>
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+
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+#include <support/check.h>
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+#include <support/xstdio.h>
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+
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+int
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+do_test (void)
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+{
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+ for (int do_ftello = 0; do_ftello < 2; ++do_ftello)
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+ {
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+ FILE *fp = xfopen ("/dev/zero", "r");
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+ char buf[17];
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+ memset (buf, 0xcc, sizeof (buf));
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+ xfread (buf, 1, sizeof (buf), fp);
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+ static const char zeros[sizeof (buf)] = { 0 };
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+ TEST_COMPARE_BLOB (buf, sizeof (buf), zeros, sizeof (zeros));
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+ if (do_ftello)
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+ {
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+ errno = 0;
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+ TEST_COMPARE (ftello (fp), -1);
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+ TEST_COMPARE (errno, ESPIPE);
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+ }
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+ /* Do not use xfclose because it flushes first. */
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+ TEST_COMPARE (fclose (fp), 0);
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+ }
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+
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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