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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * tools/testing/selftests/kvm/lib/io.c4 *5 * Copyright (C) 2018, Google LLC.6 */7 8#include "test_util.h"9 10/* Test Write11 *12 * A wrapper for write(2), that automatically handles the following13 * special conditions:14 *15 * + Interrupted system call (EINTR)16 * + Write of less than requested amount17 * + Non-block return (EAGAIN)18 *19 * For each of the above, an additional write is performed to automatically20 * continue writing the requested data.21 * There are also many cases where write(2) can return an unexpected22 * error (e.g. EIO). Such errors cause a TEST_ASSERT failure.23 *24 * Note, for function signature compatibility with write(2), this function25 * returns the number of bytes written, but that value will always be equal26 * to the number of requested bytes. All other conditions in this and27 * future enhancements to this function either automatically issue another28 * write(2) or cause a TEST_ASSERT failure.29 *30 * Args:31 * fd - Opened file descriptor to file to be written.32 * count - Number of bytes to write.33 *34 * Output:35 * buf - Starting address of data to be written.36 *37 * Return:38 * On success, number of bytes written.39 * On failure, a TEST_ASSERT failure is caused.40 */41ssize_t test_write(int fd, const void *buf, size_t count)42{43 ssize_t rc;44 ssize_t num_written = 0;45 size_t num_left = count;46 const char *ptr = buf;47 48 /* Note: Count of zero is allowed (see "RETURN VALUE" portion of49 * write(2) manpage for details.50 */51 TEST_ASSERT(count >= 0, "Unexpected count, count: %li", count);52 53 do {54 rc = write(fd, ptr, num_left);55 56 switch (rc) {57 case -1:58 TEST_ASSERT(errno == EAGAIN || errno == EINTR,59 "Unexpected write failure,\n"60 " rc: %zi errno: %i", rc, errno);61 continue;62 63 case 0:64 TEST_FAIL("Unexpected EOF,\n"65 " rc: %zi num_written: %zi num_left: %zu",66 rc, num_written, num_left);67 break;68 69 default:70 TEST_ASSERT(rc >= 0, "Unexpected ret from write,\n"71 " rc: %zi errno: %i", rc, errno);72 num_written += rc;73 num_left -= rc;74 ptr += rc;75 break;76 }77 } while (num_written < count);78 79 return num_written;80}81 82/* Test Read83 *84 * A wrapper for read(2), that automatically handles the following85 * special conditions:86 *87 * + Interrupted system call (EINTR)88 * + Read of less than requested amount89 * + Non-block return (EAGAIN)90 *91 * For each of the above, an additional read is performed to automatically92 * continue reading the requested data.93 * There are also many cases where read(2) can return an unexpected94 * error (e.g. EIO). Such errors cause a TEST_ASSERT failure. Note,95 * it is expected that the file opened by fd at the current file position96 * contains at least the number of requested bytes to be read. A TEST_ASSERT97 * failure is produced if an End-Of-File condition occurs, before all the98 * data is read. It is the callers responsibility to assure that sufficient99 * data exists.100 *101 * Note, for function signature compatibility with read(2), this function102 * returns the number of bytes read, but that value will always be equal103 * to the number of requested bytes. All other conditions in this and104 * future enhancements to this function either automatically issue another105 * read(2) or cause a TEST_ASSERT failure.106 *107 * Args:108 * fd - Opened file descriptor to file to be read.109 * count - Number of bytes to read.110 *111 * Output:112 * buf - Starting address of where to write the bytes read.113 *114 * Return:115 * On success, number of bytes read.116 * On failure, a TEST_ASSERT failure is caused.117 */118ssize_t test_read(int fd, void *buf, size_t count)119{120 ssize_t rc;121 ssize_t num_read = 0;122 size_t num_left = count;123 char *ptr = buf;124 125 /* Note: Count of zero is allowed (see "If count is zero" portion of126 * read(2) manpage for details.127 */128 TEST_ASSERT(count >= 0, "Unexpected count, count: %li", count);129 130 do {131 rc = read(fd, ptr, num_left);132 133 switch (rc) {134 case -1:135 TEST_ASSERT(errno == EAGAIN || errno == EINTR,136 "Unexpected read failure,\n"137 " rc: %zi errno: %i", rc, errno);138 break;139 140 case 0:141 TEST_FAIL("Unexpected EOF,\n"142 " rc: %zi num_read: %zi num_left: %zu",143 rc, num_read, num_left);144 break;145 146 default:147 TEST_ASSERT(rc > 0, "Unexpected ret from read,\n"148 " rc: %zi errno: %i", rc, errno);149 num_read += rc;150 num_left -= rc;151 ptr += rc;152 break;153 }154 } while (num_read < count);155 156 return num_read;157}158