From: Owen W. Taylor Date: Wed, 12 May 2021 20:26:24 +0000 (-0400) Subject: On close, handle short writes from archive_write_callback X-Git-Tag: v3.5.2~15^2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F1530%2Fhead;p=thirdparty%2Flibarchive.git On close, handle short writes from archive_write_callback The archive_write_callback passed to archive_write_open() is documented as: "each call to the write callback function should translate to a single write(2) system call. On success, the write callback should return the number of bytes actually written" And in most places, the code repeatedly calls the write callback, but when flushing the buffer at close, the write callback was called once, assuming it would write everything. This could result in a truncated archive. A test is added to test short writes in different code paths. --- diff --git a/Makefile.am b/Makefile.am index 1ead2813d..e259a33b7 100644 --- a/Makefile.am +++ b/Makefile.am @@ -550,6 +550,7 @@ libarchive_test_SOURCES= \ libarchive/test/test_read_too_many_filters.c \ libarchive/test/test_read_truncated.c \ libarchive/test/test_read_truncated_filter.c \ + libarchive/test/test_short_writes.c \ libarchive/test/test_sparse_basic.c \ libarchive/test/test_tar_filenames.c \ libarchive/test/test_tar_large.c \ diff --git a/libarchive/archive_write.c b/libarchive/archive_write.c index 8d70f51a6..38c14cba7 100644 --- a/libarchive/archive_write.c +++ b/libarchive/archive_write.c @@ -482,6 +482,8 @@ archive_write_client_close(struct archive_write_filter *f) ssize_t block_length; ssize_t target_block_length; ssize_t bytes_written; + size_t to_write; + char *p; int ret = ARCHIVE_OK; /* If there's pending data, pad and write the last block */ @@ -504,9 +506,24 @@ archive_write_client_close(struct archive_write_filter *f) target_block_length - block_length); block_length = target_block_length; } - bytes_written = (a->client_writer)(&a->archive, - a->client_data, state->buffer, block_length); - ret = bytes_written <= 0 ? ARCHIVE_FATAL : ARCHIVE_OK; + p = state->buffer; + to_write = block_length; + while (to_write > 0) { + bytes_written = (a->client_writer)(&a->archive, + a->client_data, p, to_write); + if (bytes_written <= 0) { + ret = ARCHIVE_FATAL; + break; + } + if ((size_t)bytes_written > to_write) { + archive_set_error(&(a->archive), + -1, "write overrun"); + ret = ARCHIVE_FATAL; + break; + } + p += bytes_written; + to_write -= bytes_written; + } } if (a->client_closer) (*a->client_closer)(&a->archive, a->client_data); diff --git a/libarchive/test/CMakeLists.txt b/libarchive/test/CMakeLists.txt index 4be5bf4cd..b26f679cf 100644 --- a/libarchive/test/CMakeLists.txt +++ b/libarchive/test/CMakeLists.txt @@ -199,6 +199,7 @@ IF(ENABLE_TEST) test_read_too_many_filters.c test_read_truncated.c test_read_truncated_filter.c + test_short_writes.c test_sparse_basic.c test_tar_filenames.c test_tar_large.c diff --git a/libarchive/test/test_short_writes.c b/libarchive/test/test_short_writes.c new file mode 100644 index 000000000..afa0206f0 --- /dev/null +++ b/libarchive/test/test_short_writes.c @@ -0,0 +1,216 @@ +/*- + * Copyright (c) 2021 Red Hat, Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +#include "test.h" + +#include +#include +#include + +/* + * This test checks whether things work correctly when the archive_write_callback + * passed to archive_write_open() does a short write and only writes some of the + * data passed in. The way the test works is that two archives are constructed + * in parallel - one with short writes, one with full writes - and the results + * are compared to see if they are identical. + */ + +struct checker { + struct archive *short_archive; + char *shortbuf; + size_t shortbuf_len; + + struct archive *full_archive; + char *fullbuf; + size_t fullbuf_len; +}; + +static ssize_t +short_write_callback(struct archive *a, void *client_data, const void *buffer, size_t length) +{ + (void)a; + + struct checker *checker = client_data; + size_t to_write = length < 100 ? length : 100; + size_t new_len = checker->shortbuf_len + to_write; + char *new_buf = realloc(checker->shortbuf, new_len); + assert(new_buf != NULL); + + checker->shortbuf = new_buf; + memcpy(checker->shortbuf + checker->shortbuf_len, buffer, to_write); + checker->shortbuf_len = new_len; + + return to_write; +} + +static ssize_t +full_write_callback(struct archive *a, void *client_data, const void *buffer, size_t length) +{ + (void)a; + + struct checker *checker = client_data; + size_t to_write = length; + size_t new_len = checker->fullbuf_len + to_write; + char *new_buf = realloc(checker->fullbuf, new_len); + assert(new_buf != NULL); + + checker->fullbuf = new_buf; + memcpy(checker->fullbuf + checker->fullbuf_len, buffer, to_write); + checker->fullbuf_len = new_len; + + return to_write; +} + +static struct archive * +create_archive(struct checker *checker, archive_write_callback write_cb, int buffered) +{ + struct archive *a; + + assert((a = archive_write_new()) != NULL); + + if (!buffered) + assertEqualIntA(a, ARCHIVE_OK, + archive_write_set_bytes_per_block(a, 0)); + + /* With the default value of bytes_in_last_block, the writing code will + * pad out the final write to make it a full block. This causes problems + * for us because the size of the final write can be different depending + * on the size of previous writes, causing the "short" and "full" paths + * to get different amounts of padding. Setting it to 1 results in no + * padding other than that defined by the archive format. */ + assertEqualIntA(a, ARCHIVE_OK, + archive_write_set_bytes_in_last_block(a, 1)); + + /* We write a pax archive, but other formats would work fine too. */ + assertEqualIntA(a, ARCHIVE_OK, + archive_write_set_format_pax(a)); + assertEqualIntA(a, ARCHIVE_OK, + archive_write_add_filter_none(a)); + + assertEqualIntA(a, ARCHIVE_OK, + archive_write_open(a, checker, NULL, write_cb, NULL)); + + return a; +} + +static struct checker * +checker_new(int buffered) +{ + struct checker *checker; + + assert ((checker = calloc(1, sizeof *checker)) != NULL); + + checker->short_archive = create_archive(checker, short_write_callback, buffered); + checker->full_archive = create_archive(checker, full_write_callback, buffered); + + return checker; +} + +static void +checker_add_file(struct checker *checker, const char *name, char *buffer, size_t len) +{ + struct archive_entry *entry; + assert((entry = archive_entry_new()) != NULL); + + archive_entry_set_pathname(entry, name); + archive_entry_set_mode(entry, AE_IFREG | 0755); + archive_entry_set_size(entry, len); + + assertEqualIntA(checker->short_archive, ARCHIVE_OK, + archive_write_header(checker->short_archive, entry)); + assertEqualIntA(checker->short_archive, len, + archive_write_data(checker->short_archive, buffer, len)); + + assertEqualIntA(checker->full_archive, ARCHIVE_OK, + archive_write_header(checker->full_archive, entry)); + assertEqualIntA(checker->full_archive, len, + archive_write_data(checker->full_archive, buffer, len)); + + archive_entry_free(entry); +} + +static void +checker_close(struct checker *checker) +{ + assertEqualIntA(checker->short_archive, ARCHIVE_OK, + archive_write_close(checker->short_archive)); + assertEqualIntA(checker->short_archive, ARCHIVE_OK, + archive_write_close(checker->full_archive)); +} + +static void +checker_check(struct checker *checker) +{ + assertEqualInt(checker->shortbuf_len, checker->fullbuf_len); + assert(memcmp(checker->shortbuf, checker->fullbuf, checker->fullbuf_len) == 0); +} + +static void +checker_free(struct checker *checker) +{ + free(checker->shortbuf); + free(checker->fullbuf); + free(checker); +} + +DEFINE_TEST(test_short_writes) +{ + struct checker *checker; + uint16_t test_data[16384]; + int i; + + for (i = 0; i < 16384; i++) + test_data[i] = i; + + + /* Write a file smaller than the default buffer size (10 * 1024); + * this will be written out at close. + */ + checker = checker_new(1); + checker_add_file(checker, "a", (char *)test_data, 1024); + checker_close(checker); + assert(checker->shortbuf_len > 1024); + checker_check(checker); + checker_free(checker); + + /* Write a file larger larger than twice default buffer size (10 * 1024); + * this both fills the buffer and writes it out, and also exercises + * the "write out full blocks directly" code path. + */ + checker = checker_new(1); + checker_add_file(checker, "a", (char *)test_data, 21 * 1024); + checker_close(checker); + assert(checker->shortbuf_len > 21 * 1024); + checker_check(checker); + checker_free(checker); + + /* Test unbuffered writes - a different code path. + */ + checker = checker_new(0); + checker_add_file(checker, "a", (char *)test_data, 1024); + checker_close(checker); + assert(checker->shortbuf_len > 1024); + checker_check(checker); + checker_free(checker); +}