fio.c

/******************************************************************************
 * Copyright (C) 2014-2018 Zhifeng Gong <gozfree@163.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with libraries; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 ******************************************************************************/
#include "libfile.h"
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>

#define MAX_RETRY_CNT   (3)

static struct file_desc *fio_open(const char *path, file_open_mode_t mode)
{
    struct file_desc *file = (struct file_desc *)calloc(1,
                             sizeof(struct file_desc));
    if (!file) {
        printf("malloc failed:%d %s\n", errno, strerror(errno));
        return NULL;
    }
    const char *flags = NULL;
    switch(mode) {
    case F_RDONLY:
        flags = "r";
        break;
    case F_WRONLY:
        flags = "w";
        break;
    case F_RDWR:
        flags = "r+";
        break;
    case F_CREATE:
        flags = "w+";
        break;
    case F_WRCLEAR:
        flags = "w+";
        break;
    case F_APPEND:
        flags = "a+";
        break;
    default:
        printf("unsupport file mode!\n");
        break;
    }

    file->fp = fopen(path, flags);
    if (!file->fp) {
        printf("fopen %s failed:%d %s\n", path, errno, strerror(errno));
        free(file);
        return NULL;
    }
    file->name = strdup(path);
    return file;
}

static ssize_t fio_read(struct file_desc *file, void *buf, size_t len)
{
    int n;
    char *p = (char *)buf;
    size_t left = len;
    size_t step = 1024*1024;
    int cnt = 0;
    if (file == NULL || buf == NULL || len == 0) {
        printf("%s paraments invalid!\n", __func__);
        return -1;
    }
    FILE *fp = file->fp;
    while (left > 0) {
        if (left < step)
            step = left;
        n = fread((void *)p, 1, step, fp);
        if (n > 0) {
            p += n;
            left -= n;
            continue;
        } else {
            if (0 != feof(fp)) {
                clearerr(fp);
                break;
            } else {
                if (++cnt > MAX_RETRY_CNT)
                    break;
                continue;
            }
        }
    }
    return (len - left);
}

static ssize_t fio_write(struct file_desc *file, const void *buf, size_t len)
{
    ssize_t n;
    char *p = (char *)buf;
    int retry = 0;
    if (file == NULL || buf == NULL || len == 0) {
        printf("%s paraments invalid!\n", __func__);
        return -1;
    }
    FILE *fp = file->fp;
    size_t step = 1024 * 1024;
    size_t left = len;
    while (left > 0) {
        if (left < step)
            step = left;
        n = fwrite((void *)p, 1, step, fp);
        if (n > 0) {
            p += n;
            left -= n;
            continue;
        } else {
            if (errno == EINTR || errno == EAGAIN) {
                if (++retry > MAX_RETRY_CNT) {
                    printf("reach max retry\n");
                    break;
                }
                continue;
            } else {
                printf("write failed:%d %s\n", errno, strerror(errno));
                break;
            }
        }
    }
    return (len - left);
}

static off_t fio_seek(struct file_desc *file, off_t offset, int whence)
{
    if (!file) {
        return -1;
    }
    return fseek(file->fp, offset, whence);
}

static int fio_sync(struct file_desc *file)
{
    if (!file) {
        return -1;
    }
    return fflush(file->fp);
}

static size_t fio_size(struct file_desc *file)
{
    long size;
    if (!file) {
        return 0;
    }
    long tmp = ftell(file->fp);
    fseek(file->fp, 0L, SEEK_END);
    size = ftell(file->fp);
    fseek(file->fp, tmp, SEEK_SET);
    return (size_t)size;
}

static void fio_close(struct file_desc *file)
{
    if (file) {
        fclose(file->fp);
        free(file->name);
        free(file);
    }
}

struct file_ops fio_ops = {
    .open  = fio_open,
    .write = fio_write,
    .read  = fio_read,
    .seek  = fio_seek,
    .sync  = fio_sync,
    .size  = fio_size,
    .close = fio_close,
};