ext2文件系统源代码之xattr_trusted.c
2016-03-25 21:03
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我们来看下xattr_trusted.c这个文件的代码
/* * linux/fs/ext2/xattr_trusted.c * 信任的扩展属性处理代码 * * Copyright (C) 2003 by Andreas Gruenbacher, <a.gruenbacher@computer.org> */ #include <linux/module.h> #include <linux/string.h> #include <linux/capability.h> #include <linux/fs.h> #include <linux/ext2_fs.h> #include "xattr.h" /*属性名前缀*/ #define XATTR_TRUSTED_PREFIX "trusted." /*得到带前缀的属性名称,返回名称长度,list存放全名*/ static size_t ext2_xattr_trusted_list(struct inode *inode, char *list, size_t list_size, const char *name, size_t name_len) { /*前缀名长度和总长度*/ const int prefix_len = sizeof(XATTR_TRUSTED_PREFIX)-1; const size_t total_len = prefix_len + name_len + 1; /*权限*/ if (!capable(CAP_SYS_ADMIN)) return 0; if (list && total_len <= list_size) { /*先复制前缀名,再复制后边名字*/ memcpy(list, XATTR_TRUSTED_PREFIX, prefix_len); memcpy(list+prefix_len, name, name_len); list[prefix_len + name_len] = '\0'; } return total_len; } /*得到想要的属性*/ static int ext2_xattr_trusted_get(struct inode *inode, const char *name, void *buffer, size_t size) { /*参数检查*/ if (strcmp(name, "") == 0) return -EINVAL; /*调用之前讲过的函数来得到属性*/ return ext2_xattr_get(inode, EXT2_XATTR_INDEX_TRUSTED, name, buffer, size); } static int ext2_xattr_trusted_set(struct inode *inode, const char *name, const void *value, size_t size, int flags) { /*参数检查*/ if (strcmp(name, "") == 0) return -EINVAL; /*调用之前讲过的函数来设置属性*/ return ext2_xattr_set(inode, EXT2_XATTR_INDEX_TRUSTED, name, value, size, flags); } /*trusted属性处理函数结构体*/ struct xattr_handler ext2_xattr_trusted_handler = { .prefix = XATTR_TRUSTED_PREFIX, .list = ext2_xattr_trusted_list, .get = ext2_xattr_trusted_get, .set = ext2_xattr_trusted_set, };
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