重写C语言中的fgets函数，从文件底部开始读取

抱歉，我作为一名AI语言模型，无法进行实际的编程操作。不过，关于你提到的问题，你可能需要使用 fseek 函数将文件指针定位至文件末尾，再逐行读取文件内容，这样就可以实现从文件底部开始读取的效果。具体代码实现可以参考下面这段示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define BUFFER_SIZE 1024

char* read_lines_from_end(const char* file_path, int count)
{
    char* buffer = (char *) malloc(BUFFER_SIZE * count * sizeof(char));
    
    FILE* fp = fopen(file_path, "r");
    if (fp == NULL)
    {
        printf("Failed to open file!\n");
        return NULL;
    }

    // 移动文件指针到文件末尾
    if (fseek(fp, 0L, SEEK_END) != 0)
    {
        printf("Failed to seek to end of file!\n");
        fclose(fp);
        free(buffer);
        return NULL;
    }
    
    // 获取当前文件指针位置
    long file_offset = ftell(fp);
    printf("File size is %ld bytes.\n", file_offset);

    // 逐行读取文件内容
    int lines_read = 0;
    char line_buffer[BUFFER_SIZE];
    while (lines_read < count)
    {
        // 根据文件指针位置计算行的偏移量
        long line_offset = 0;
        int last_char = '\n';
        while (file_offset > 0 && last_char != '\n')
        {
            if (fseek(fp, --file_offset, SEEK_SET) != 0)
            {
                printf("Failed to seek to offset %ld!\n", file_offset);
                fclose(fp);
                free(buffer);
                return NULL;
            }
            last_char = fgetc(fp);
            line_offset++;
        }

        if (file_offset == 0)
        {
            // 读到文件开头后退出循环
            break;
        }

        // 读取一行文件内容
        if (fgets(line_buffer, BUFFER_SIZE, fp) == NULL)
        {
            printf("Failed to read line at offset %ld!\n", file_offset);
            fclose(fp);
            free(buffer);
            return NULL;
        }

        // 将读取到的文件内容复制到缓冲区中
        int line_length = strlen(line_buffer);
        if (line_length > 0 && line_buffer[line_length - 1] == '\n')
        {
            line_buffer[line_length - 1] = '\0';
        }
        strcat(buffer, line_buffer);
        strcat(buffer, "\n");

        lines_read++;
    }

    // 关闭文件并返回缓冲区指针
    fclose(fp);
    return buffer;
}

int main(int argc, char* argv[])
{
    if (argc < 3)
    {
        printf("Usage: read_lines_from_end <file_path> <count>\n");
        return -1;
    }

    const char* file_path = argv[1];
    int count = atoi(argv[2]);

    char* lines = read_lines_from_end(file_path, count);
    if (lines == NULL)
    {
        printf("Failed to read lines from file.\n");
        return -1;
    }

    printf("Last %d lines from file:\n", count);
    printf("%s", lines);

    free(lines);
    return 0;
}