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157 lines
4.3 KiB
157 lines
4.3 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* tools/testing/selftests/kvm/lib/io.c |
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* |
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* Copyright (C) 2018, Google LLC. |
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*/ |
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#include "test_util.h" |
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/* Test Write |
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* |
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* A wrapper for write(2), that automatically handles the following |
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* special conditions: |
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* |
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* + Interrupted system call (EINTR) |
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* + Write of less than requested amount |
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* + Non-block return (EAGAIN) |
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* |
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* For each of the above, an additional write is performed to automatically |
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* continue writing the requested data. |
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* There are also many cases where write(2) can return an unexpected |
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* error (e.g. EIO). Such errors cause a TEST_ASSERT failure. |
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* |
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* Note, for function signature compatibility with write(2), this function |
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* returns the number of bytes written, but that value will always be equal |
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* to the number of requested bytes. All other conditions in this and |
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* future enhancements to this function either automatically issue another |
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* write(2) or cause a TEST_ASSERT failure. |
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* |
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* Args: |
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* fd - Opened file descriptor to file to be written. |
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* count - Number of bytes to write. |
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* |
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* Output: |
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* buf - Starting address of data to be written. |
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* |
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* Return: |
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* On success, number of bytes written. |
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* On failure, a TEST_ASSERT failure is caused. |
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*/ |
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ssize_t test_write(int fd, const void *buf, size_t count) |
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{ |
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ssize_t rc; |
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ssize_t num_written = 0; |
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size_t num_left = count; |
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const char *ptr = buf; |
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/* Note: Count of zero is allowed (see "RETURN VALUE" portion of |
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* write(2) manpage for details. |
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*/ |
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TEST_ASSERT(count >= 0, "Unexpected count, count: %li", count); |
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do { |
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rc = write(fd, ptr, num_left); |
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switch (rc) { |
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case -1: |
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TEST_ASSERT(errno == EAGAIN || errno == EINTR, |
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"Unexpected write failure,\n" |
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" rc: %zi errno: %i", rc, errno); |
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continue; |
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case 0: |
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TEST_FAIL("Unexpected EOF,\n" |
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" rc: %zi num_written: %zi num_left: %zu", |
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rc, num_written, num_left); |
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break; |
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default: |
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TEST_ASSERT(rc >= 0, "Unexpected ret from write,\n" |
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" rc: %zi errno: %i", rc, errno); |
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num_written += rc; |
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num_left -= rc; |
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ptr += rc; |
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break; |
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} |
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} while (num_written < count); |
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return num_written; |
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} |
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/* Test Read |
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* |
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* A wrapper for read(2), that automatically handles the following |
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* special conditions: |
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* |
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* + Interrupted system call (EINTR) |
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* + Read of less than requested amount |
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* + Non-block return (EAGAIN) |
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* |
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* For each of the above, an additional read is performed to automatically |
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* continue reading the requested data. |
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* There are also many cases where read(2) can return an unexpected |
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* error (e.g. EIO). Such errors cause a TEST_ASSERT failure. Note, |
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* it is expected that the file opened by fd at the current file position |
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* contains at least the number of requested bytes to be read. A TEST_ASSERT |
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* failure is produced if an End-Of-File condition occurs, before all the |
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* data is read. It is the callers responsibility to assure that sufficient |
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* data exists. |
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* |
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* Note, for function signature compatibility with read(2), this function |
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* returns the number of bytes read, but that value will always be equal |
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* to the number of requested bytes. All other conditions in this and |
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* future enhancements to this function either automatically issue another |
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* read(2) or cause a TEST_ASSERT failure. |
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* |
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* Args: |
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* fd - Opened file descriptor to file to be read. |
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* count - Number of bytes to read. |
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* |
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* Output: |
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* buf - Starting address of where to write the bytes read. |
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* |
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* Return: |
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* On success, number of bytes read. |
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* On failure, a TEST_ASSERT failure is caused. |
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*/ |
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ssize_t test_read(int fd, void *buf, size_t count) |
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{ |
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ssize_t rc; |
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ssize_t num_read = 0; |
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size_t num_left = count; |
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char *ptr = buf; |
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/* Note: Count of zero is allowed (see "If count is zero" portion of |
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* read(2) manpage for details. |
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*/ |
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TEST_ASSERT(count >= 0, "Unexpected count, count: %li", count); |
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do { |
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rc = read(fd, ptr, num_left); |
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switch (rc) { |
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case -1: |
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TEST_ASSERT(errno == EAGAIN || errno == EINTR, |
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"Unexpected read failure,\n" |
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" rc: %zi errno: %i", rc, errno); |
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break; |
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case 0: |
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TEST_FAIL("Unexpected EOF,\n" |
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" rc: %zi num_read: %zi num_left: %zu", |
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rc, num_read, num_left); |
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break; |
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default: |
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TEST_ASSERT(rc > 0, "Unexpected ret from read,\n" |
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" rc: %zi errno: %i", rc, errno); |
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num_read += rc; |
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num_left -= rc; |
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ptr += rc; |
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break; |
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} |
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} while (num_read < count); |
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return num_read; |
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}
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