{"id":485,"date":"2011-03-11T00:21:40","date_gmt":"2011-03-10T16:21:40","guid":{"rendered":"http:\/\/www.hawkwithwind.net\/blog\/?p=485"},"modified":"2011-06-09T11:15:09","modified_gmt":"2011-06-09T03:15:09","slug":"linux%e5%86%85%e6%a0%b8%e5%ad%a6%e4%b9%a0-c%e9%a3%8e%e6%a0%bc%e7%9a%84%e9%9d%a2%e5%90%91%e5%af%b9%e8%b1%a1","status":"publish","type":"post","link":"https:\/\/www.hawkwithwind.net\/blog\/2011\/03\/11\/linux%e5%86%85%e6%a0%b8%e5%ad%a6%e4%b9%a0-c%e9%a3%8e%e6%a0%bc%e7%9a%84%e9%9d%a2%e5%90%91%e5%af%b9%e8%b1%a1\/","title":{"rendered":"linux\u5185\u6838\u5b66\u4e60 – C\u98ce\u683c\u7684\u9762\u5411\u5bf9\u8c61"},"content":{"rendered":"

linux\u5185\u6838\u5927\u91cf\u4f7f\u7528\u9762\u5411\u5bf9\u8c61\u7684\u7f16\u7801\u98ce\u683c\u3002\u7136\u800clinux\u5185\u6838\u662f\u5b8c\u5168\u4f7f\u7528C\u5199\u5c31\u3002\u5b66\u4e60\u4ed6\u4eec\u5982\u4f55\u4f7f\u7528C\u6a21\u62df\u9762\u5411\u5bf9\u8c61\u673a\u5236\u5f88\u6709\u610f\u601d\u3002\u8fd9\u79cd\u505a\u6cd5\u5f88\u53ef\u80fd\u88ab\u4eba\u8d2c\u4e3a\u626f\u6de1\uff0c\u4f46\u662f\u7684\u786e\u4f7f\u7528C\u6a21\u62df\u9762\u5411\u5bf9\u8c61\u673a\u5236\uff0c\u4f7f\u5f97\u7a0b\u5e8f\u5458\u5bf9\u7c7b\u578b\u6784\u9020\/\u6790\u6784\uff0c\u62f7\u8d1d\/\u8d4b\u503c\u7b49\u64cd\u4f5c\u6709\u4e86\u7edd\u5bf9\u7684\u63a7\u5236\u6743\uff0c\u53ef\u4ee5\u63d0\u9ad8\u5bf9\u6548\u7387\u7684\u55c5\u89c9\uff0c\u51cf\u5c11\u9519\u8bef\uff0c\u540c\u65f6\u4e5f\u907f\u514d\u4e86\u5bf9C++\u7f16\u8bd1\u5668\u5404\u79cd\u4e0d\u540c\u7c7b\/\u5bf9\u8c61\u5b9e\u73b0\u673a\u5236\u7684\u4f9d\u8d56\u3002<\/p>\n

\u7c7b\u7684\u591a\u6001\u7279\u5f81\u662flinux\u5185\u6838\u7ecf\u5e38\u7528\u5230\u7684\u3002\u4f8b\u5982\u5728\u9a71\u52a8\u4ee3\u7801\u4e2d\u5e38\u5e38\u4f7f\u7528\u51fd\u6570\u6307\u9488\u6765\u5b9a\u4e49\u4e00\u7ec4\u8bbe\u5907\u64cd\u4f5c\u51fd\u6570\uff0c\u4ece\u800c\u6a21\u62df\u4e86\u591a\u6001\u7684\u7279\u70b9\u3002<\/p>\n

\r\nstruct file_operations scull_fops = {\r\n    .owner = THIS_MODULE,\r\n    .llseek = scull_llseek,\r\n    .read = scull_read,\r\n    .write = scull_write,\r\n    .ioctl = scull_ioctl,\r\n    .open = scull_open,\r\n    .release = scull_release,\r\n};\r\n<\/code><\/pre>\n
\u4e0a\u9762\u7684\u4f8b\u5b50\u662fLinux Device Driver\u4e2d\u6284\u6765\u7684\u793a\u4f8b\u4ee3\u7801\u3002\u5f88\u597d\u5730\u5c55\u793a\u4e86file operation\u7ed3\u6784\u4f53\u5982\u4f55\u4f7f\u7528\u8fd9\u79cd\u673a\u5236\u6765\u5b9a\u4e49\u4e00\u7ec4\u6587\u4ef6\u64cd\u4f5c\u7684\u65b9\u5f0f\u3002\u7528\u8fd9\u79cd\u65b9\u5f0f\uff0cLinux\u5f88\u597d\u5730\u8d2f\u5f7b\u4e86\u6240\u6709\u7684\u8bbe\u5907\u90fd\u662f\u6587\u4ef6\u8fd9\u79cd\u6982\u5ff5\u3002\u4e0d\u540c\u7684\u8bbe\u5907\u53ef\u4ee5\u6709\u4e0d\u540c\u7684\u5904\u7406\u51fd\u6570\uff0c\u4f46\u4f7f\u7528\u76f8\u540c\u7684\u63a5\u53e3\uff0c\u8fd9\u6837\u5c31\u628a\u5e95\u5c42\u8bbe\u5907\u7684\u5dee\u5f02\u5728\u6587\u4ef6\u7cfb\u7edf\u8fd9\u4e00\u5c42\u9694\u79bb\u5f00\u6765\u4e86\u3002<\/p>\n
Linux\u5185\u6838\u4e2d\u4e5f\u7ecf\u5e38\u7528\u5230\u7c7b\u7684\u7ee7\u627f\u5173\u7cfb\u3002\u8fd9\u79cd\u5173\u7cfb\u4f7f\u7528C\u4e5f\u5f88\u5bb9\u6613\u6a21\u62df\uff0c\u5c31\u662f\u4f7f\u7528\u7ed3\u6784\u4f53\u5d4c\u5957\u3002\u4f8b\u5982<\/p>\n
\r\nstruct scull_dev {\r\n     struct scull_qset *data;   \r\n     int quantum;               \r\n     int qset;                  \r\n     unsigned long size;    \r\n     unsigned int access_key;  \r\n     struct semaphore sem;     \r\n     struct cdev cdev;      \/\/\u5185\u5d4clinux\u5185\u6838\u5b9a\u4e49\u7684cdev\u7ed3\u6784\u4f53\r\n};\r\n<\/code><\/pre>\n
\u8fd9\u4e2a\u4f8b\u5b50\u540c\u6837\u6765\u81eaLDD\u3002\u6ce8\u610f\u5728\u81ea\u5b9a\u4e49\u7684cdev\u5b57\u7b26\u8bbe\u5907\u7ed3\u6784\u4f53\u4e2d\u5305\u542b\u4e86struct cdev cdev<\/code>\u6210\u5458\u3002\u8fd9\u4e2a\u6210\u5458\u540c\u6837\u662f\u4e00\u4e2a\u7ed3\u6784\u4f53\uff0c\u7531\u5185\u6838\u5b9a\u4e49\uff0c\u662f\u5b57\u7b26\u8bbe\u5907\u63cf\u8ff0\u7b26\u3002\u4f7f\u7528\u8fd9\u79cd\u65b9\u5f0f\uff0c\u53ef\u4ee5\u4e00\u5b9a\u7a0b\u5ea6\u6a21\u62dfC++\u7684\u7ee7\u627f\u673a\u5236\uff0c\u5f53\u7136\u6709\u4ed6\u7684\u5c40\u9650\uff0c\u4f8b\u5982\u4ed6\u4e0d\u80fd\u5982\u540c\u5728C++\u4e2d\u4e00\u6837\u76f4\u63a5\u5f15\u7528cdev\u7684\u6210\u5458\uff0c\u800c\u5fc5\u987b\u901a\u8fc7scull_dev.cdev<\/code>\u6765\u5f15\u7528\u3002<\/p>\n
\u53e6\u4e00\u65b9\u9762\uff0c\u8fd9\u79cd\u65b9\u5f0f\u4e5f\u65e0\u6cd5\u901a\u8fc7\u201c\u57fa\u7c7b\u201d\uff0c\u5373cdev\u7684\u6307\u9488\uff0c\u8bbf\u95ee\u201c\u5b50\u7c7b\u201d\uff0c\u5373scull_dev\u7684\u6210\u5458\u3002\u7cbe\u5f69\u7684\u90e8\u5206\u6765\u4e86\uff0clinux\u901a\u8fc7\u4e00\u7ec4\u5b8f\uff0c\u5de7\u5999\u7684\u5b9e\u73b0\u4e86\u8fd9\u4e00\u70b9\u3002\u5728\u6587\u4ef6\u5904\u7406\u7684\u51fd\u6570\u4e2d\uff0c\u5165\u53c2\u4f1a\u7ed9\u5165inode\u6307\u9488\uff0c\u4ece\u8fd9\u4e2a\u6307\u9488\u53ef\u83b7\u5f97\u5176cdev\u6210\u5458\u3002\u5982\u4f55\u4ece\u8fd9\u4e2acdev\u6210\u5458\u83b7\u53d6\u5305\u542b\u5b83\u7684\u201c\u5b50\u7c7b\u201d\u5bf9\u8c61\uff0cscull_dev\u7684\u6307\u9488\u5462\uff1f
\n <\/code><\/p>\n
container_of(ptr, type, member)\r\n<\/code><\/pre>\n
\u4f7f\u7528\u8fd9\u4e2a\u5b8f\uff0ccontainer_of(inode->i_cdev, struct scull_dev, cdev)<\/code>\u5c31\u53ef\u83b7\u5f97\u5305\u542bcdev\u7684scull_dev\u7684\u5730\u5740\u3002\u8fd9\u4e2a\u5de7\u5999\u7684\u5b8f\u662f\u5982\u4f55\u5b9e\u73b0\u7684\u5462\uff1f
\n <\/code><\/p>\n
#define container_of(ptr, type, member) ({ \\\r\n                const typeof( ((type *)0)->member ) *__mptr = (ptr); \r\n                (type *)( (char *)__mptr - offsetof(type,member) );})\r\n<\/code><\/pre>\n
 <\/code><\/p>\n
\n\u8fd9\u4e2a\u5b8f\u9996\u5148\u5b9a\u4e49\u4e00\u4e2a\u6307\u5411\u7ed3\u6784\u4f53\u6210\u5458\u7684\u6307\u9488__mptr = (ptr)<\/code>\uff0c\u4ed6\u7684\u7c7b\u578b\u662fconst typeof(...)<\/code>\u3002\u8fd9\u91cc\u7528\u5230\u4e86C\u8bed\u8a00\u4e00\u4e2a\u8f83\u65b0\u7684\u5173\u952e\u5b57typeof\uff0c\u53ef\u4ee5\u5728\u7f16\u8bd1\u671f\u83b7\u5f97\u53d8\u91cf\u7684\u7c7b\u578b\u3002\u800c\u8fd9\u4e2a\u7c7b\u578b\u662f((type*)0)->member<\/code>\uff0c\u8fd9\u91cctype\u548cmember\u5206\u522b\u662f\u5b8f\u4f20\u5165\u7684\u53c2\u6570\u3002\u8fd9\u4e00\u884c\u4ee3\u7801\u5c31\u6bd4\u8f83\u6e05\u6670\u4e86\u3002\u5f97\u5230\u8fd9\u4e2a__mptr\u4e4b\u540e\uff0c\u5c06\u4ed6\u5411\u56de\u79fb\u52a8\u4e00\u4e2aoffset\uff0c(char*)__mprt - offsetof(...)<\/code>\uff0c\u800c\u8fd9\u4e2aoffset\u6070\u597d\u4e3amember\u76f8\u5bf9\u4e8etype\u7684\u504f\u79fb\u91cf\uff0coffsetof(type,member)<\/code>\uff0c\u5219\u79fb\u52a8\u5b8c\u6bd5__mptr\u5c31\u6307\u5411type\u7c7b\u578b\u7684\u8d77\u59cb\u5730\u5740\u4e86\uff0c\u53ea\u9700\u5c06\u5176\u8f6c\u6362\u4e3atype*\u7c7b\u578b\u5c31\u53ef\u4ee5\u4e86\uff0c(type*)(...)<\/code>\u3002<\/p>\n
\n\u597d\u4e86\uff0c\u8fd9\u4e2a\u5b8f\u5df2\u7ecf\u770b\u61c2\uff0c\u795e\u5947\u7684\u5730\u65b9\u5c31\u51fa\u5728\u8fd9\u4e2aoffsetof\u5b8f\u4e86\uff0c\u4ed6\u662f\u5982\u4f55\u8ba1\u7b97\u6210\u5458\u76f8\u5bf9\u4e8e\u7ed3\u6784\u4f53\u7684\u504f\u79fb\u91cf\u5462\uff1f\u8fd9\u91cclinux\u5185\u6838hacker\u4eec\u7528\u4e86\u4e00\u4e2a\u5c0f\u5c0ftrick\u3002
\n <\/code><\/p>\n
#define offsetof(s, m)   (size_t)&(((s *)0)->m)\r\n<\/code><\/pre>\n
 <\/code><\/p>\n
\n\u662f\u7684\uff0c\u4ee3\u7801\u975e\u5e38\u7b80\u5355\u3002\u5176\u601d\u60f3\u662f\uff0c\u5047\u5982\u7ed3\u6784\u4f53\u5904\u4e8e0\u5730\u5740\uff0c\u83b7\u53d6\u5176\u6210\u5458\u7684\u5730\u5740\u3002\u8fd9\u4e2a\u5730\u5740\u5c31\u662f\u6210\u5458\u76f8\u5bf9\u4e8e\u7ed3\u6784\u4f53\u521d\u59cb\u5730\u5740\u7684\u504f\u79fb\u91cf\u4e86\u3002\u6ca1\u95190\u5730\u5740\u662f\u4e0d\u80fd\u8fd0\u884c\u65f6\u8bbf\u95ee\u7684\uff0c\u4f46\u8fd9\u53e5\u4ee3\u7801\u53ea\u5728\u7f16\u8bd1\u671f\u4f7f\u7528\u4e860\u5730\u5740\uff0c\u56e0\u6b64\u662f\u5408\u6cd5\u7684\u3002\u5f53\u7136\u5176\u5b9e\u4f7f\u7528\u6210\u5458\u6307\u9488\u548c\u7ed3\u6784\u4f53\u6307\u9488\u76f8\u51cf\u4e5f\u53ef\u505a\u5230\uff0c\u4f46\u7528\u8fd9\u79cd\u65b9\u5f0f\u53ef\u4ee5\u51cf\u5c11\u4e00\u6b21\u8fd0\u7b97\uff0c\u786e\u4fdd\u4e86\u8fd9\u4e2a\u5b8f\u53ef\u4ee5\u5728\u7f16\u8bd1\u671f\u6c42\u51fa\u7ed3\u679c\u3002\u53ef\u8c13\u662f\u7cbe\u76ca\u6c42\u7cbe\u3002<\/p>\n
\n\u6211\u8bf4\u9519\u4e86\u3002\u5373\u4f7f\u4f7f\u7528\u51cf\u6cd5\u4e5f\u53ef\u4ee5\u505a\u5230\u7f16\u8bd1\u671f\u6c42\u503c\uff0c\u56e0\u4e3a\u7ed3\u6784\u4f53\u548c\u6210\u5458\u6307\u9488\u5730\u5740\u90fd\u662f\u53ef\u4ee5\u7f16\u8bd1\u671f\u5f97\u5230\u7684\uff0c\u5e38\u91cf\u6570\u503c\u8ba1\u7b97\u5e94\u8be5\u53ef\u4ee5\u505a\u5230\u7f16\u8bd1\u671f\u4f18\u5316\uff0c\u8ba1\u7b97\u5b8c\u6210\u3002\u8fd9\u79cd\u505a\u6cd5\u5e94\u8be5\u662f
\n&((type*)0)->member - ((type*)0)<\/code>
\n\u8fd9\u6837\u7684\u4ee3\u7801\u7684\u4e00\u4e2a\u76f4\u89c9\u6027\u7684\u4f18\u5316\uff0c\u51cf0\u7684\u8bdd\uff0c\u4f55\u5fc5\u8fd8\u8981\u51cf\u5462\u3002\u4e8b\u5b9e\u4e0a\u4e24\u53e5\u4ee3\u7801\u7684\u8fd0\u884c\u65f6\u95f4\u662f\u4e00\u6837\u7684\uff0c\u4f46\u8fd9\u6837\u505a\u53ef\u4ee5\u51cf\u8f7b\u7f16\u8bd1\u65f6\u95f4\u3002
\n\u5728container_of\u5b8f\u4e2d\uff0c\u4e5f\u6709\u4e00\u53e5\u51cf\u6cd5\u8ba1\u7b97\u3002\u8fd9\u4e2a\u8ba1\u7b97\u5f15\u7528\u4e86\u8fd0\u884c\u65f6\u6c42\u503c\u7684__mptr\uff0c\u6240\u4ee5\u65e0\u6cd5\u505a\u5230\u7f16\u8bd1\u671f\u6c42\u503c\u3002\n<\/p><\/blockquote>\n
\u7c7b\u4f3c\u8fd9\u79cd\u7528\u6cd5\uff0c\u5728linux\u5185\u6838\u4e2d\u7ecf\u5e38\u51fa\u73b0\u3002\u6df1\u6df1\u4f69\u670d\u5927\u725b\u4eec\u7684\u521b\u9020\u529b\uff0c\u5e76\u4e14\u6df1\u6df1\u7684\u610f\u8bc6\u5230\u4e86\u5373\u4f7f\u662fC\u8bed\u8a00\u4e5f\u662f\u5b66\u65e0\u6b62\u5883\u7684\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
linux\u5185\u6838\u5927\u91cf\u4f7f\u7528\u9762\u5411\u5bf9\u8c61\u7684\u7f16\u7801\u98ce\u683c\u3002\u7136\u800clinux\u5185\u6838\u662f\u5b8c\u5168\u4f7f\u7528C\u5199\u5c31\u3002\u5b66\u4e60\u4ed6\u4eec\u5982\u4f55\u4f7f\u7528C\u6a21\u62df\u9762\u5411\u5bf9\u8c61\u673a\u5236\u5f88\u6709\u610f\u601d\u3002\u8fd9\u79cd\u505a\u6cd5\u5f88\u53ef\u80fd\u88ab\u4eba\u8d2c\u4e3a\u626f\u6de1\uff0c\u4f46\u662f\u7684\u786e\u4f7f\u7528C\u6a21\u62df\u9762\u5411\u5bf9\u8c61\u673a\u5236\uff0c\u4f7f\u5f97\u7a0b\u5e8f\u5458\u5bf9\u7c7b\u578b\u6784\u9020\/\u6790\u6784\uff0c\u62f7\u8d1d\/\u8d4b\u503c\u7b49\u64cd\u4f5c\u6709\u4e86\u7edd\u5bf9\u7684\u63a7\u5236\u6743\uff0c\u53ef\u4ee5\u63d0\u9ad8\u5bf9\u6548\u7387\u7684\u55c5\u89c9\uff0c\u51cf\u5c11\u9519\u8bef\uff0c\u540c\u65f6\u4e5f\u907f\u514d\u4e86\u5bf9C++\u7f16\u8bd1\u5668\u5404\u79cd\u4e0d\u540c\u7c7b\/\u5bf9\u8c61\u5b9e\u73b0\u673a\u5236\u7684\u4f9d\u8d56\u3002 \u7c7b\u7684\u591a\u6001\u7279\u5f81\u662flinux\u5185\u6838\u7ecf\u5e38\u7528\u5230\u7684\u3002\u4f8b\u5982\u5728\u9a71\u52a8\u4ee3\u7801\u4e2d\u5e38\u5e38\u4f7f\u7528\u51fd\u6570\u6307\u9488\u6765\u5b9a\u4e49\u4e00\u7ec4\u8bbe\u5907\u64cd\u4f5c\u51fd\u6570\uff0c\u4ece\u800c\u6a21\u62df\u4e86\u591a\u6001\u7684\u7279\u70b9\u3002 struct file_operations scull_fops = { .owner = THIS_MODULE, .llseek = scull_llseek, .read = scull_read, .write = scull_write, .ioctl = scull_ioctl, .open = scull_open, .release = scull_release, }; \u4e0a\u9762\u7684\u4f8b\u5b50\u662fLinux Device Driver\u4e2d\u6284\u6765\u7684\u793a\u4f8b\u4ee3\u7801\u3002\u5f88\u597d\u5730\u5c55\u793a\u4e86file operation\u7ed3\u6784\u4f53\u5982\u4f55\u4f7f\u7528\u8fd9\u79cd\u673a\u5236\u6765\u5b9a\u4e49\u4e00\u7ec4\u6587\u4ef6\u64cd\u4f5c\u7684\u65b9\u5f0f\u3002\u7528\u8fd9\u79cd\u65b9\u5f0f\uff0cLinux\u5f88\u597d\u5730\u8d2f\u5f7b\u4e86\u6240\u6709\u7684\u8bbe\u5907\u90fd\u662f\u6587\u4ef6\u8fd9\u79cd\u6982\u5ff5\u3002\u4e0d\u540c\u7684\u8bbe\u5907\u53ef\u4ee5\u6709\u4e0d\u540c\u7684\u5904\u7406\u51fd\u6570\uff0c\u4f46\u4f7f\u7528\u76f8\u540c\u7684\u63a5\u53e3\uff0c\u8fd9\u6837\u5c31\u628a\u5e95\u5c42\u8bbe\u5907\u7684\u5dee\u5f02\u5728\u6587\u4ef6\u7cfb\u7edf\u8fd9\u4e00\u5c42\u9694\u79bb\u5f00\u6765\u4e86\u3002 Linux\u5185\u6838\u4e2d\u4e5f\u7ecf\u5e38\u7528\u5230\u7c7b\u7684\u7ee7\u627f\u5173\u7cfb\u3002\u8fd9\u79cd\u5173\u7cfb\u4f7f\u7528C\u4e5f\u5f88\u5bb9\u6613\u6a21\u62df\uff0c\u5c31\u662f\u4f7f\u7528\u7ed3\u6784\u4f53\u5d4c\u5957\u3002\u4f8b\u5982 struct scull_dev { struct scull_qset *data; int quantum; int qset; unsigned long size; unsigned int access_key; struct semaphore sem; struct cdev …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[49,35],"class_list":["post-485","post","type-post","status-publish","format-standard","hentry","category-post","tag-linux","tag-35"],"_links":{"self":[{"href":"https:\/\/www.hawkwithwind.net\/blog\/wp-json\/wp\/v2\/posts\/485","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.hawkwithwind.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.hawkwithwind.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.hawkwithwind.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hawkwithwind.net\/blog\/wp-json\/wp\/v2\/comments?post=485"}],"version-history":[{"count":10,"href":"https:\/\/www.hawkwithwind.net\/blog\/wp-json\/wp\/v2\/posts\/485\/revisions"}],"predecessor-version":[{"id":488,"href":"https:\/\/www.hawkwithwind.net\/blog\/wp-json\/wp\/v2\/posts\/485\/revisions\/488"}],"wp:attachment":[{"href":"https:\/\/www.hawkwithwind.net\/blog\/wp-json\/wp\/v2\/media?parent=485"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.hawkwithwind.net\/blog\/wp-json\/wp\/v2\/categories?post=485"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.hawkwithwind.net\/blog\/wp-json\/wp\/v2\/tags?post=485"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}