libc: implement 'readv()'
This patch implements the 'readv()' function in the libc. A lock guard prevents the parallel execution of either or both of the 'readv()' and 'writev()' functions. Fixes #279.
This commit is contained in:
Christian Prochaska
Norman Feske
parent
9124f303f7
commit
dbd1c425bf
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@ -14,7 +14,7 @@ SRC_CC = atexit.cc dummies.cc rlimit.cc sysctl.cc readlink.cc munmap.cc \
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issetugid.cc errno.cc gai_strerror.cc clock_gettime.cc \
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gettimeofday.cc malloc.cc progname.cc fd_alloc.cc file_operations.cc \
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plugin.cc plugin_registry.cc select.cc exit.cc environ.cc nanosleep.cc \
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libc_mem_alloc.cc writev.cc pread_pwrite.cc
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libc_mem_alloc.cc pread_pwrite.cc readv_writev.cc
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#
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# Files from string library that are not included in libc-raw_string because
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@ -0,0 +1,117 @@
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/*
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* \brief 'readv()' and 'writev()' implementations
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* \author Josef Soentgen
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* \author Christian Prochaska
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* \date 2012-04-10
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*/
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/*
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* Copyright (C) 2012 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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/* Genode includes */
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#include <base/lock.h>
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/* libc includes */
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#include <sys/uio.h>
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#include <limits.h>
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#include <unistd.h>
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#include <errno.h>
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#include <stdio.h>
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static Genode::Lock rw_lock;
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struct Read
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{
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ssize_t operator()(int fd, void *buf, size_t count)
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{
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return read(fd, buf, count);
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}
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};
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struct Write
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{
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ssize_t operator()(int fd, const void *buf, size_t count)
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{
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return write(fd, buf, count);
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}
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};
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template <typename Rw_func>
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static ssize_t readv_writev_impl(Rw_func rw_func, int fd, const struct iovec *iov, int iovcnt)
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{
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Genode::Lock_guard<Genode::Lock> rw_lock_guard(rw_lock);
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char *v;
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ssize_t bytes_transfered_total = 0;
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size_t v_len = 0;
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int i;
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if (iovcnt < 1 || iovcnt > IOV_MAX) {
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errno = EINVAL;
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return -1;
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}
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for (i = 0; i < iovcnt; i++)
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v_len += iov->iov_len;
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if (v_len > SSIZE_MAX) {
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errno = EINVAL;
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return -1;
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}
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while (iovcnt > 0) {
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v = static_cast<char *>(iov->iov_base);
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v_len = iov->iov_len;
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while (v_len > 0) {
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ssize_t bytes_transfered = rw_func(fd, v, v_len);
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if (bytes_transfered == -1)
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return -1;
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if (bytes_transfered == 0)
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return bytes_transfered_total;
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v_len -= bytes_transfered;
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v += bytes_transfered;
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bytes_transfered_total += bytes_transfered;
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}
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iov++;
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iovcnt--;
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}
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return bytes_transfered_total;
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}
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extern "C" ssize_t _readv(int fd, const struct iovec *iov, int iovcnt)
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{
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return readv_writev_impl(Read(), fd, iov, iovcnt);
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}
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extern "C" ssize_t readv(int fd, const struct iovec *iov, int iovcnt)
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{
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return _readv(fd, iov, iovcnt);
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}
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extern "C" ssize_t _writev(int fd, const struct iovec *iov, int iovcnt)
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{
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return readv_writev_impl(Write(), fd, iov, iovcnt);
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}
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extern "C" ssize_t writev(int fd, const struct iovec *iov, int iovcnt)
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{
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return _writev(fd, iov, iovcnt);
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}
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@ -1,75 +0,0 @@
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/*
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* \brief Plugin implementation
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* \author Josef Soentgen
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* \date 2012-04-10
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*/
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/*
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* Copyright (C) 2010-2012 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#include <sys/uio.h>
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#include <limits.h>
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#include <unistd.h>
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#include <string.h>
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#include <errno.h>
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#include <stdio.h>
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enum { MAX_BUFFER_LEN = 2048 };
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extern "C" int _writev(int d, const struct iovec *iov, int iovcnt)
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{
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char buffer[MAX_BUFFER_LEN];
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char *v, *b;
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ssize_t written;
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size_t v_len, _len;
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int i;
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if (iovcnt < 1 || iovcnt > IOV_MAX) {
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return -EINVAL;
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}
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for (i = 0; i < iovcnt; i++)
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v_len += iov->iov_len;
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if (v_len > SSIZE_MAX) {
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return -EINVAL;
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}
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b = buffer;
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while (iovcnt) {
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v = static_cast<char *>(iov->iov_base);
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v_len = iov->iov_len;
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while (v_len > 0) {
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if (v_len < sizeof(buffer))
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_len = v_len;
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else
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_len = sizeof(buffer);
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// TODO error check
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memmove(b, v, _len);
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i = write(d, b, _len);
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v += _len;
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v_len -= _len;
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written += i;
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}
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iov++;
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iovcnt--;
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}
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return written;
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}
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extern "C" ssize_t writev(int d, const struct iovec *iov, int iovcnt)
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{
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return _writev(d, iov, iovcnt);
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}
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@ -20,6 +20,7 @@
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#include <fcntl.h>
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#include <stdio.h>
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#include <sys/stat.h>
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#include <sys/uio.h>
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#include <unistd.h>
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#include <string.h>
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#include <errno.h>
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@ -44,6 +45,7 @@ int main(int argc, char *argv[])
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char const *dir_name = "/testdir";
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char const *file_name = "test.tst";
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char const *file_name2 = "test2.tst";
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char const *file_name3 = "test3.tst";
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char const *pattern = "a single line of text";
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size_t pattern_size = strlen(pattern) + 1;
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@ -109,6 +111,35 @@ int main(int argc, char *argv[])
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printf("file content is correct\n");
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}
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/* test 'readv()' and 'writev()' */
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CALL_AND_CHECK(fd, open(file_name3, O_CREAT | O_WRONLY), fd >= 0, "file_name=%s", file_name);
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struct iovec iov[2];
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/* write "a single line" */
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iov[0].iov_base = (void*)pattern;
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iov[0].iov_len = 13;
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/* write " line of text" */
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iov[1].iov_base = (void*)&pattern[8];
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iov[1].iov_len = pattern_size - 8;
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CALL_AND_CHECK(count, writev(fd, iov, 2), (size_t)count == (pattern_size + 5), "");
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CALL_AND_CHECK(ret, close(fd), ret == 0, "");
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CALL_AND_CHECK(fd, open(file_name3, O_RDONLY), fd >= 0, "file_name=%s", file_name);
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memset(buf, 0, sizeof(buf));
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/* read "a single line" */
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iov[0].iov_base = buf;
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iov[0].iov_len = 13;
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/* read " line of text" to offset 8 */
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iov[1].iov_base = &buf[8];
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iov[1].iov_len = pattern_size;
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CALL_AND_CHECK(count, readv(fd, iov, 2), (size_t)count == (pattern_size + 5), "");
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CALL_AND_CHECK(ret, close(fd), ret == 0, "");
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printf("content of buffer: \"%s\"\n", buf);
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if (strcmp(buf, pattern) != 0) {
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printf("unexpected content of file\n");
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return -1;
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} else {
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printf("file content is correct\n");
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}
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/* read directory entries */
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DIR *dir;
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CALL_AND_CHECK(dir, opendir(dir_name), dir, "dir_name=\"%s\"", dir_name);
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