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coreutils.32564
coreutils-tail-fix-tailing-sysfs-files-where-PA...
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File coreutils-tail-fix-tailing-sysfs-files-where-PAGE_SIZE-BUFSIZ.patch of Package coreutils.32564
From 73d119f4f8052a9fb6cef13cd9e75d5a4e23311a Mon Sep 17 00:00:00 2001 From: dann frazier <dann.frazier@canonical.com> Date: Wed, 29 Nov 2023 18:32:34 -0700 Subject: [PATCH] tail: fix tailing sysfs files where PAGE_SIZE > BUFSIZ Git-commit: 73d119f4f8052a9fb6cef13cd9e75d5a4e23311a Patch-mainline: v9.5 References: bsc#1219321 * src/tail.c (file_lines): Ensure we use a buffer size >= PAGE_SIZE when searching backwards to avoid seeking within a file, which on sysfs files is accepted but also returns no data. * tests/tail/tail-sysfs.sh: Add a new test. * tests/local.mk: Reference the new test. * NEWS: Mention the bug fix. Fixes https://bugs.gnu.org/67490 Acked-by: Anthony Iliopoulos <ailiop@suse.com> --- NEWS | 4 +++ src/tail.c | 57 +++++++++++++++++++++++++++++----------- tests/local.mk | 1 + tests/tail/tail-sysfs.sh | 34 ++++++++++++++++++++++++ 4 files changed, 81 insertions(+), 15 deletions(-) create mode 100755 tests/tail/tail-sysfs.sh Index: coreutils-8.32/NEWS =================================================================== --- coreutils-8.32.orig/NEWS +++ coreutils-8.32/NEWS @@ -1020,6 +1020,10 @@ GNU coreutils NEWS in locales where character 0xA0 is a blank, numfmt would mishandle it. [bug introduced when numfmt was added in coreutils-8.21] + tail no longer mishandles input from files in /proc and /sys file systems, + on systems with a page size larger than the stdio BUFSIZ. + [This bug was present in "the beginning".] + ptx --format long option parsing no longer falls through into the --help case. [bug introduced in TEXTUTILS-1_22i] Index: coreutils-8.32/src/tail.c =================================================================== --- coreutils-8.32.orig/src/tail.c +++ coreutils-8.32/src/tail.c @@ -210,6 +210,9 @@ static uintmax_t max_n_unchanged_stats_b that is writing to all followed files. */ static pid_t pid; +/* Used to determine the buffer size when scanning backwards in a file. */ +static int page_size; + /* True if we have ever read standard input. */ static bool have_read_stdin; @@ -532,22 +535,40 @@ xlseek (int fd, off_t offset, int whence Return true if successful. */ static bool -file_lines (const char *pretty_filename, int fd, uintmax_t n_lines, - off_t start_pos, off_t end_pos, uintmax_t *read_pos) +file_lines (const char *pretty_filename, int fd, struct stat const *sb, + uintmax_t n_lines, off_t start_pos, off_t end_pos, + uintmax_t *read_pos) { - char buffer[BUFSIZ]; + char *buffer; size_t bytes_read; + blksize_t bufsize = BUFSIZ; off_t pos = end_pos; + bool ok = true; if (n_lines == 0) return true; + /* Be careful with files with sizes that are a multiple of the page size, + as on /proc or /sys file systems these files accept seeking to within + the file, but then return no data when read. So use a buffer that's + at least PAGE_SIZE to avoid seeking within such files. + + We could also indirectly use a large enough buffer through io_blksize() + however this would be less efficient in the common case, as it would + generally pick a larger buffer size, resulting in reading more data + from the end of the file. */ + assume (S_ISREG (sb->st_mode)); + if (sb->st_size % page_size == 0) + bufsize = MAX (BUFSIZ, page_size); + + buffer = xmalloc (bufsize); + /* Set 'bytes_read' to the size of the last, probably partial, buffer; - 0 < 'bytes_read' <= 'BUFSIZ'. */ - bytes_read = (pos - start_pos) % BUFSIZ; + 0 < 'bytes_read' <= 'bufsize'. */ + bytes_read = (pos - start_pos) % bufsize; if (bytes_read == 0) - bytes_read = BUFSIZ; - /* Make 'pos' a multiple of 'BUFSIZ' (0 if the file is short), so that all + bytes_read = bufsize; + /* Make 'pos' a multiple of 'bufsize' (0 if the file is short), so that all reads will be on block boundaries, which might increase efficiency. */ pos -= bytes_read; xlseek (fd, pos, SEEK_SET, pretty_filename); @@ -555,7 +576,8 @@ file_lines (const char *pretty_filename, if (bytes_read == SAFE_READ_ERROR) { error (0, errno, _("error reading %s"), quoteaf (pretty_filename)); - return false; + ok = false; + goto free_buffer; } *read_pos = pos + bytes_read; @@ -583,7 +605,7 @@ file_lines (const char *pretty_filename, xwrite_stdout (nl + 1, bytes_read - (n + 1)); *read_pos += dump_remainder (false, pretty_filename, fd, end_pos - (pos + bytes_read)); - return true; + goto free_buffer; } } @@ -595,23 +617,26 @@ file_lines (const char *pretty_filename, xlseek (fd, start_pos, SEEK_SET, pretty_filename); *read_pos = start_pos + dump_remainder (false, pretty_filename, fd, end_pos); - return true; + goto free_buffer; } - pos -= BUFSIZ; + pos -= bufsize; xlseek (fd, pos, SEEK_SET, pretty_filename); - bytes_read = safe_read (fd, buffer, BUFSIZ); + bytes_read = safe_read (fd, buffer, bufsize); if (bytes_read == SAFE_READ_ERROR) { error (0, errno, _("error reading %s"), quoteaf (pretty_filename)); - return false; + ok = false; + goto free_buffer; } *read_pos = pos + bytes_read; } while (bytes_read > 0); - return true; +free_buffer: + free (buffer); + return ok; } /* Print the last N_LINES lines from the end of the standard input, @@ -1936,7 +1961,7 @@ tail_lines (const char *pretty_filename, { *read_pos = end_pos; if (end_pos != 0 - && ! file_lines (pretty_filename, fd, n_lines, + && ! file_lines (pretty_filename, fd, &stats, n_lines, start_pos, end_pos, read_pos)) return false; } @@ -2355,6 +2380,8 @@ main (int argc, char **argv) atexit (close_stdout); + page_size = getpagesize (); + have_read_stdin = false; count_lines = true; Index: coreutils-8.32/tests/local.mk =================================================================== --- coreutils-8.32.orig/tests/local.mk +++ coreutils-8.32/tests/local.mk @@ -252,6 +252,7 @@ all_tests = \ tests/misc/seq-precision.sh \ tests/misc/head.pl \ tests/misc/head-elide-tail.pl \ + tests/tail/tail-sysfs.sh \ tests/tail-2/tail-n0f.sh \ tests/misc/ls-misc.pl \ tests/misc/date.pl \ Index: coreutils-8.32/tests/tail/tail-sysfs.sh =================================================================== --- /dev/null +++ coreutils-8.32/tests/tail/tail-sysfs.sh @@ -0,0 +1,34 @@ +#!/bin/sh +# sysfs files have weird properties that can be influenced by page size + +# Copyright 2023 Free Software Foundation, Inc. + +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. + +# This program 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 General Public License for more details. + +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <https://www.gnu.org/licenses/>. + +. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src +print_ver_ tail + +file='/sys/kernel/profiling' + +test -r "$file" || skip_ "No $file file" + +cp -f "$file" exp || framework_failure_ + +tail -n1 "$file" > out || fail=1 +compare exp out || fail=1 + +tail -c2 "$file" > out || fail=1 +compare exp out || fail=1 + +Exit $fail
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