https://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html specifies that "If the file size is increased, the extended area shall appear as if it were zero-filled." Many filesystems do not currently do this for the portion of the page after EOF. Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> --- .gitignore | 1 + src/Makefile | 2 +- src/truncate-zero.c | 50 +++++++++++++++++++++++++++++++++++++++++++ tests/generic/707 | 31 +++++++++++++++++++++++++++ tests/generic/707.out | 2 ++ 5 files changed, 85 insertions(+), 1 deletion(-) create mode 100644 src/truncate-zero.c create mode 100755 tests/generic/707 create mode 100644 tests/generic/707.out diff --git a/.gitignore b/.gitignore index a6f433f1..6aa5bca9 100644 --- a/.gitignore +++ b/.gitignore @@ -169,6 +169,7 @@ tags /src/test-nextquota /src/testx /src/trunc +/src/truncate-zero /src/truncfile /src/unwritten_mmap /src/unwritten_sync diff --git a/src/Makefile b/src/Makefile index afdf6b30..83ca11ac 100644 --- a/src/Makefile +++ b/src/Makefile @@ -19,7 +19,7 @@ TARGETS = dirstress fill fill2 getpagesize holes lstat64 \ t_ofd_locks t_mmap_collision mmap-write-concurrent \ t_get_file_time t_create_short_dirs t_create_long_dirs t_enospc \ t_mmap_writev_overlap checkpoint_journal mmap-rw-fault allocstale \ - t_mmap_cow_memory_failure fake-dump-rootino + t_mmap_cow_memory_failure fake-dump-rootino truncate-zero LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \ preallo_rw_pattern_writer ftrunc trunc fs_perms testx looptest \ diff --git a/src/truncate-zero.c b/src/truncate-zero.c new file mode 100644 index 00000000..67f53912 --- /dev/null +++ b/src/truncate-zero.c @@ -0,0 +1,50 @@ +#include <fcntl.h> +#include <stdio.h> +#include <string.h> +#include <sys/mman.h> +#include <unistd.h> + +int main(int argc, char **argv) +{ + char *buf; + int i, fd; + + if (argc != 2) { + fprintf(stderr, "Usage: %s <file>\n", argv[0]); + return 1; + } + + fd = open(argv[1], O_RDWR | O_CREAT, 0644); + if (fd < 0) { + perror(argv[1]); + return 1; + } + + if (ftruncate(fd, 1) < 0) { + perror("ftruncate"); + return 1; + } + + buf = mmap(NULL, 1024, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); + if (buf == MAP_FAILED) { + perror("mmap"); + return 1; + } + + memset(buf, 'a', 10); + + if (ftruncate(fd, 5) < 0) { + perror("ftruncate"); + return 1; + } + + if (memcmp(buf, "a\0\0\0\0", 5) == 0) + return 0; + + fprintf(stderr, "Truncation did not zero new bytes:\n"); + for (i = 0; i < 5; i++) + fprintf(stderr, "%#x ", buf[i]); + fputc('\n', stderr); + + return 2; +} diff --git a/tests/generic/707 b/tests/generic/707 new file mode 100755 index 00000000..ddc82a9a --- /dev/null +++ b/tests/generic/707 @@ -0,0 +1,31 @@ +#! /bin/bash +# SPDX-License-Identifier: GPL-2.0 +# Copyright (c) 2023 Matthew Wilcox for Oracle. All Rights Reserved. +# +# FS QA Test 707 +# +# Test whether we obey this part of POSIX-2017 ftruncate: +# "If the file size is increased, the extended area shall appear as if +# it were zero-filled" +# +. ./common/preamble +_begin_fstest auto quick posix + +_supported_fs generic +_require_test +_require_test_program "truncate-zero" + +test_file=$TEST_DIR/test.$seq + +_cleanup() +{ + cd / + rm -f $test_file +} + +$here/src/truncate-zero $test_file > $seqres.full 2>&1 || + _fail "truncate zero failed!" + +echo "Silence is golden" +status=0 +exit diff --git a/tests/generic/707.out b/tests/generic/707.out new file mode 100644 index 00000000..8e57a1d8 --- /dev/null +++ b/tests/generic/707.out @@ -0,0 +1,2 @@ +QA output created by 707 +Silence is golden -- 2.35.1
