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Diffstat (limited to 'tools/testing/selftests/kvm/lib/io.c')
-rw-r--r-- | tools/testing/selftests/kvm/lib/io.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/lib/io.c b/tools/testing/selftests/kvm/lib/io.c new file mode 100644 index 000000000000..cff869ffe6ee --- /dev/null +++ b/tools/testing/selftests/kvm/lib/io.c @@ -0,0 +1,158 @@ +/* + * tools/testing/selftests/kvm/lib/io.c + * + * Copyright (C) 2018, Google LLC. + * + * This work is licensed under the terms of the GNU GPL, version 2. + */ + +#include "test_util.h" + +/* Test Write + * + * A wrapper for write(2), that automatically handles the following + * special conditions: + * + * + Interrupted system call (EINTR) + * + Write of less than requested amount + * + Non-block return (EAGAIN) + * + * For each of the above, an additional write is performed to automatically + * continue writing the requested data. + * There are also many cases where write(2) can return an unexpected + * error (e.g. EIO). Such errors cause a TEST_ASSERT failure. + * + * Note, for function signature compatibility with write(2), this function + * returns the number of bytes written, but that value will always be equal + * to the number of requested bytes. All other conditions in this and + * future enhancements to this function either automatically issue another + * write(2) or cause a TEST_ASSERT failure. + * + * Args: + * fd - Opened file descriptor to file to be written. + * count - Number of bytes to write. + * + * Output: + * buf - Starting address of data to be written. + * + * Return: + * On success, number of bytes written. + * On failure, a TEST_ASSERT failure is caused. + */ +ssize_t test_write(int fd, const void *buf, size_t count) +{ + ssize_t rc; + ssize_t num_written = 0; + size_t num_left = count; + const char *ptr = buf; + + /* Note: Count of zero is allowed (see "RETURN VALUE" portion of + * write(2) manpage for details. + */ + TEST_ASSERT(count >= 0, "Unexpected count, count: %li", count); + + do { + rc = write(fd, ptr, num_left); + + switch (rc) { + case -1: + TEST_ASSERT(errno == EAGAIN || errno == EINTR, + "Unexpected write failure,\n" + " rc: %zi errno: %i", rc, errno); + continue; + + case 0: + TEST_ASSERT(false, "Unexpected EOF,\n" + " rc: %zi num_written: %zi num_left: %zu", + rc, num_written, num_left); + break; + + default: + TEST_ASSERT(rc >= 0, "Unexpected ret from write,\n" + " rc: %zi errno: %i", rc, errno); + num_written += rc; + num_left -= rc; + ptr += rc; + break; + } + } while (num_written < count); + + return num_written; +} + +/* Test Read + * + * A wrapper for read(2), that automatically handles the following + * special conditions: + * + * + Interrupted system call (EINTR) + * + Read of less than requested amount + * + Non-block return (EAGAIN) + * + * For each of the above, an additional read is performed to automatically + * continue reading the requested data. + * There are also many cases where read(2) can return an unexpected + * error (e.g. EIO). Such errors cause a TEST_ASSERT failure. Note, + * it is expected that the file opened by fd at the current file position + * contains at least the number of requested bytes to be read. A TEST_ASSERT + * failure is produced if an End-Of-File condition occurs, before all the + * data is read. It is the callers responsibility to assure that sufficient + * data exists. + * + * Note, for function signature compatibility with read(2), this function + * returns the number of bytes read, but that value will always be equal + * to the number of requested bytes. All other conditions in this and + * future enhancements to this function either automatically issue another + * read(2) or cause a TEST_ASSERT failure. + * + * Args: + * fd - Opened file descriptor to file to be read. + * count - Number of bytes to read. + * + * Output: + * buf - Starting address of where to write the bytes read. + * + * Return: + * On success, number of bytes read. + * On failure, a TEST_ASSERT failure is caused. + */ +ssize_t test_read(int fd, void *buf, size_t count) +{ + ssize_t rc; + ssize_t num_read = 0; + size_t num_left = count; + char *ptr = buf; + + /* Note: Count of zero is allowed (see "If count is zero" portion of + * read(2) manpage for details. + */ + TEST_ASSERT(count >= 0, "Unexpected count, count: %li", count); + + do { + rc = read(fd, ptr, num_left); + + switch (rc) { + case -1: + TEST_ASSERT(errno == EAGAIN || errno == EINTR, + "Unexpected read failure,\n" + " rc: %zi errno: %i", rc, errno); + break; + + case 0: + TEST_ASSERT(false, "Unexpected EOF,\n" + " rc: %zi num_read: %zi num_left: %zu", + rc, num_read, num_left); + break; + + default: + TEST_ASSERT(rc > 0, "Unexpected ret from read,\n" + " rc: %zi errno: %i", rc, errno); + num_read += rc; + num_left -= rc; + ptr += rc; + break; + } + } while (num_read < count); + + return num_read; +} |