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f5b2038871
## 开发进展： ## namespace - pid_namespace 基本实现，基于pid_struct等数据结构实现隔离 - mnt_namespace 基本实现，挂载点的隔离通过不同的挂载树来实现 - usernamespace 作为支持性的namespace，目前受限实现全局静态 ## overlayfs - 实现若干个文件系统的叠加，在mount中传入多个路径作为多个fs的mount路径以及最后merge层的fs路径 - copy-up机制的，除最上层外其他层为只读层，满足写时拷贝，需要修改的时候copy到上层修改 - whiteout特殊文件，用于标记在下层需要被删除的文件用来掩盖需要删除的文件 ## cgroups - 目前cgroups还处于框架阶段，之后具体实现具体的内存、CPU等子系统
92 lines
2.2 KiB
C
92 lines
2.2 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mount.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <string.h>
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#include <errno.h>
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// #define LOWERDIR "/tmp/overlayfs/lower"
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// #define UPPERDIR "/tmp/overlayfs/upper"
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// #define WORKDIR "/tmp/overlayfs/work"
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// #define MERGEDDIR "/tmp/overlayfs/merged"
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// void create_directories()
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// {
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// mkdir(LOWERDIR, 0755);
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// mkdir(UPPERDIR, 0755);
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// mkdir(WORKDIR, 0755);
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// mkdir(MERGEDDIR, 0755);
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// }
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#define TMPDIR "/tmp"
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#define OVERLAYFSDIR "/tmp/overlayfs"
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#define LOWERDIR "/tmp/overlayfs/lower"
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#define UPPERDIR "/tmp/overlayfs/upper"
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#define WORKDIR "/tmp/overlayfs/work"
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#define MERGEDDIR "/tmp/overlayfs/merged"
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void create_directories()
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{
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mkdir(TMPDIR, 0755);
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mkdir(OVERLAYFSDIR, 0755);
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mkdir(LOWERDIR, 0755);
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mkdir(UPPERDIR, 0755);
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mkdir(WORKDIR, 0755);
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mkdir(MERGEDDIR, 0755);
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printf("step1 : success\n");
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}
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void create_lower_file()
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{
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char filepath[256];
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snprintf(filepath, sizeof(filepath), "%s/lowerfile.txt", LOWERDIR);
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int fd = open(filepath, O_CREAT | O_WRONLY, 0644);
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if (fd < 0)
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{
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perror("Failed to create file in lowerdir");
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exit(EXIT_FAILURE);
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}
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write(fd, "This is a lower layer file.\n", 28);
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close(fd);
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printf("step2 : success\n");
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}
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void mount_overlayfs()
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{
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char options[1024];
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snprintf(options, sizeof(options),
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"lowerdir=%s,upperdir=%s,workdir=%s",
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LOWERDIR, UPPERDIR, WORKDIR);
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if (mount("overlay", MERGEDDIR, "overlay", 0, options) != 0)
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{
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perror("Mount failed");
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exit(EXIT_FAILURE);
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}
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printf("OverlayFS mounted successfully.\n");
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printf("step3 : success\n");
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}
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void create_directory_in_merged()
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{
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char dirpath[256];
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snprintf(dirpath, sizeof(dirpath), "%s/newdir", UPPERDIR);
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if (mkdir(dirpath, 0755) != 0)
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{
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perror("Failed to create directory in merged dir");
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exit(EXIT_FAILURE);
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}
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printf("Directory created in merged: %s\n", dirpath);
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printf("step4 : success\n");
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}
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int main()
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{
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create_directories();
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mount_overlayfs();
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create_directory_in_merged();
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return 0;
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} |