{"id":1801,"date":"2019-01-06T10:05:23","date_gmt":"2019-01-06T02:05:23","guid":{"rendered":"https:\/\/www.yusian.com\/blog\/?p=1801"},"modified":"2020-12-02T10:20:53","modified_gmt":"2020-12-02T02:20:53","slug":"linux%e7%bc%96%e7%a8%8b-%e8%bf%9b%e7%a8%8b%e9%97%b4%e9%80%9a%e8%ae%af","status":"publish","type":"post","link":"https:\/\/www.yusian.com\/blog\/cpp\/2019\/01\/06\/1005231801.html","title":{"rendered":"Linux\u7f16\u7a0b&#8211;\u8fdb\u7a0b\u95f4\u901a\u8baf"},"content":{"rendered":"<p>\u8fdb\u7a0b\u95f4\u901a\u8baf(IPC\uff0c InterProcess communication)<\/p>\n<ul>\n<li>\u7ba1\u9053\uff08\u4f7f\u7528\u6700\u7b80\u5355\uff09<\/li>\n<li>\u4fe1\u53f7\uff08\u5f00\u9500\u6700\u5c0f\uff09<\/li>\n<li>\u5171\u4eab\u6620\u5c04\u533a\uff08\u65e0\u8840\u7f18\u5173\u7cfb\uff09<\/li>\n<li>\u672c\u5730\u5957\u63a5\u5b57\uff08\u6700\u7a33\u5b9a\uff09<\/li>\n<\/ul>\n<h3>1\u3001\u7ba1\u9053<\/h3>\n<ul>\n<li>\u7ba1\u9053\u80fd\u591f\u5b9e\u73b0\u4e24\u4e2a\u8fdb\u7a0b\u95f4\u7684\u901a\u8baf<\/li>\n<li>pipe(int[])\uff0c\u9700\u8981\u4f20\u5165\u4e00\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u6570\u7ec4\uff0c\u957f\u5ea6\u4e3a2\u505a\u4e3a\u7ba1\u9053\u7684\u4e24\u7aef\u64cd\u4f5c<\/li>\n<li>\u51fd\u6570\u7684\u53c2\u6570\u4e3a\u4f20\u51fa\u53c2\u6570\uff0c\u4e24\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u6570\u7ec4\uff0c\u7b2c\u4e00\u4e2a\u4e3a\u5199\uff0c\u7b2c\u4e8c\u4e2a\u4e3a\u8bfb<\/li>\n<li>\u9700\u8981\u901a\u8baf\u7684\u4e24\u4e2a\u8fdb\u7a0b\u53ea\u9700\u8981\u64cd\u4f5c\u76f8\u5bf9\u5e94\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u5373\u53ef\u5b9e\u73b0\u6570\u636e\u7684\u8bfb\u6216\u5199<\/li>\n<li>\u6570\u636e\u81ea\u5df1\u8bfb\u4e0d\u80fd\u81ea\u5df1\u5199<\/li>\n<li>\u6570\u636e\u4e00\u65e6\u88ab\u8bfb\u8d70\uff0c\u4fbf\u4e0d\u5728\u7ba1\u9053\u4e2d\u5b58\u5728\uff0c\u4e0d\u53ef\u53cd\u590d\u8bfb\u53d6<\/li>\n<li>\u7531\u4e8e\u7ba1\u9053\u91c7\u7528\u534a\u53cc\u5de5\u901a\u8baf\u65b9\u5f0f\uff0c\u56e0\u6b64\u6570\u636e\u53ea\u80fd\u5728\u4e00\u4e2a\u65b9\u5411\u4e0a\u6d41\u52a8\uff1b<\/li>\n<li>\u53ea\u80fd\u5728\u6709\u516c\u5171\u7956\u5148\u7684\u8fdb\u7a0b\u95f4\u4f7f\u7528\u7ba1\u9053<\/li>\n<\/ul>\n<pre><code class=\"language-c line-numbers\">#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n#include &lt;unistd.h&gt;\n#include &lt;string.h&gt;\n\nint main(){\n    \/\/ \u5b9a\u4e49\u4e00\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u6570\u7ec4\u505a\u4e3a\u4f20\u51fa\u53c2\u6570\n    int fd[2];\n    \/\/ 1\u3001\u65b0\u5efa\u4e00\u4e2a\u7ba1\u9053\uff0c\u8bfb\u5199\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u5c06\u5199\u5165fd[2]\n    \/\/ \u5176\u4e2dfd[0]\u4e3a\u8bfb\uff0cfd[1]\u4e3a\u5199\n    int ret = pipe(fd);\n    if (ret == -1){\n        perror(\"pipe error\");\n        exit(1);\n    }\n    \/\/ 2\u3001\u65b0\u5efa\u4e00\u4e2a\u8fdb\u7a0b\n    pid_t pid = fork();\n    if (pid == -1){\n        perror(\"fork error\");\n        exit(1);\n    }else if (pid &gt; 0){\n        \/\/ \u7236\u8fdb\u7a0b\u2014-&gt;\u5199\n        close(fd[0]);\n        printf(\"father writing...\\n\");\n        char* txt = \"abc\u201d;\n        \/\/ \u4e0d\u80fd\u5bf9fd[0]\u8fdb\u884c\u5199\u64cd\u4f5c\uff0c\u8fd9\u662f\u534a\u53cc\u5de5\u901a\u8baf\u72b6\u6001\n        int ret = write(fd[1], txt, strlen(txt));\n        if (ret == -1){\n            perror(\"write error:\");\n            exit(1);\n        }\n    }else{\n        \/\/ \u5b50\u8fdb\u7a0b\u2014-&gt;\u8bfb\n        close(fd[1]);\n        printf(\"child reading...\\n\");\n        char buf[512] = {0};\n        \/\/ \u540c\u6837\u4e0d\u80fd\u5bf9fd[1]\u8fdb\u884c\u8bfb\u64cd\u4f5c\n        int ret = read(fd[0], buf, sizeof(buf));\n        if (ret == -1){\n            perror(\"read error:\");\n            exit(1);\n        }\n        \/\/ \u8bfb\u53d6\u5b8c\u6bd5\u540e\u53ef\u76f4\u63a5\u5c06buf\u4e2d\u7684\u5185\u5bb9\u6253\u5370\u51fa\u6765\n        printf(\"child readed:%s\\n\", buf);\n    }\n    return 0;\n}\n<\/code><\/pre>\n<p>\u6267\u884c\u7ed3\u679c<\/p>\n<pre><code class=\"language-cmd line-numbers\">father writing...\nchild reading...\nchild readed:abc\n<\/code><\/pre>\n<h3>2\u3001\u5171\u4eab\u6587\u4ef6\u63cf\u8ff0\u7b26\u901a\u8baf<\/h3>\n<ul>\n<li>\u6253\u5f00\u540c\u4e00\u4e2a\u6587\u4ef6\uff0c\u5728\u5185\u5b58\u4e2d\u6587\u4ef6\u63cf\u8ff0\u7b26\u5bf9\u5e94\u7684\u7ed3\u6784\u4f53\u5b9e\u8d28\u4e3a\u540c\u4e00\u4e2a<\/li>\n<li>\u901a\u8fc7\u5bf9\u540c\u4e00\u4e2a\u6587\u4ef6\u7684\u8bfb\u5199\u64cd\u4f5c\uff0c\u5b9e\u73b0\u8fdb\u7a0b\u95f4\u901a\u8baf<\/li>\n<\/ul>\n<pre><code class=\"language-c line-numbers\">#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n#include &lt;unistd.h&gt;\n#include &lt;fcntl.h&gt;\n#include &lt;string.h&gt;\n#include &lt;sys\/wait.h&gt;\n\nint main(){\n    char* file = \"file.txt\";\n    pid_t pid = fork();\n    if (pid == -1){\n        perror(\"fork error\");\n        exit(1);\n    }else if(pid &gt; 0){\n        \/\/ \u7236\u8fdb\u7a0b\n        printf(\"father writing...\\n\");\n        int fd1 = open(file, O_CREAT | O_RDWR, 0664);\n        char* str = \"I am file for InterProcess communication...\";\n        int ret = write(fd1, str, strlen(str));\n        if (ret == -1){\n            perror(\"write error\");\n            exit(1);\n        }\n        wait(NULL);\n        \/\/ \u5220\u9664\u6587\u4ef6\u76ee\u5f55\u9879\uff0c\u4f7f\u4e4b\u5177\u5907\u88ab\u91ca\u653e\u7684\u6761\u4ef6\uff0c\u6240\u6709\u5360\u7528\u8be5\u6587\u4ef6\u7684\u8fdb\u7a0b\u7ed3\u675f\u540e\uff0c\u8be5\u6587\u4ef6\u88ab\u5f7b\u5e95\u5220\u9664\n        unlink(file);\n        close(fd1);\n    }else {\n        \/\/ \u5b50\u8fdb\u7a0b\n        printf(\"child reading....\\n\");\n        int fd2 = open(file, O_RDWR);\n        char buf[512] = {0};\n        int ret = read(fd2, buf, sizeof(buf));\n        printf(\"child readed:%s\\n\", buf);\n        close(fd2);\n    }\n    return 0;\n}\n<\/code><\/pre>\n<p>\u8fd0\u884c\u7ed3\u679c<\/p>\n<pre><code class=\"language-cmd line-numbers\">parallels@ubuntu:~\/Linux\/process$ .\/a.out\nfather writing...\nchild reading....\nchild readed:I am file for InterProcess communication...\n<\/code><\/pre>\n<h3>3\u3001mmap<\/h3>\n<ul>\n<li>\u5404\u4e2a\u53c2\u6570\u4ecb\u7ecd\n<ul>\n<li>void* addr \u2014> \u6620\u5c04\u5230\u5185\u5b58\u4e2d\u7684\u9996\u5730\u5740\uff0c\u7531\u64cd\u4f5c\u7cfb\u7edf\u63d0\u4f9b\uff0c\u76f4\u63a5\u4f20NULL<\/li>\n<li>size_t length \u2014> \u6620\u5c04\u6587\u4ef6\u7684\u957f\u5ea6\uff1f\uff1f<\/li>\n<li>int prot \u2014> \u5185\u5b58\u4e2d\u7684\u64cd\u4f5c\u6743\u9650\uff0c\u6709PROT_READ\u3001PROT_WRITE\u6216\u8005\u4e24\u8005\u4f4d\u6216<\/li>\n<li>int flags \u2014> \u662f\u5426\u5c06\u53d8\u52a8\u540c\u6b65\u5230\u6587\u4ef6MAP_SHARED\u540c\u6b65\u3001MAP_PRIVATE\u4e0d\u540c\u6b65<\/li>\n<li>int fd \u2014> \u6587\u4ef6\u63cf\u8ff0\u7b26<\/li>\n<li>off_t offset \u2014> \u6620\u5c04\u6587\u4ef6\u7684\u504f\u79fb\u91cf\uff0c\u4ece\u504f\u79fb\u90e8\u5206\u5f00\u59cb\u6620\u5c04\uff08\u90e8\u5206\u6620\u5c04\uff09<\/li>\n<li>\u8fd4\u56de\u503c\u4e3a\u6620\u5c04\u5230\u5185\u5b58\u4e2d\u7684\u9996\u5730\u5740<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<pre><code class=\"language-c line-numbers\">#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n#include &lt;fcntl.h&gt;\n#include &lt;sys\/mman.h&gt;\n#include &lt;unistd.h&gt;\n#include &lt;string.h&gt;\n\nint main(){\n    \/\/ \u6587\u4ef6\u957f\u5ea6\n    int length = 10;\n    \/\/ \u6587\u4ef6\u63cf\u8ff0\u7b26\n    int fd = open(\"mmap.txt\", O_CREAT | O_RDWR, 0644);\n    if (fd &lt; 0){\n        perror(\"open error\");\n        exit(1);\n    }\n    \/\/ \u6269\u5c55\u6587\u4ef6\u957f\u5ea6\n    int ret = ftruncate(fd, length);\n    if (ret &lt; 0){\n        perror(\"ftruncate error\");\n        exit(1);\n    }\n    \/\/ \u6620\u5c04\u6587\u4ef6\u5230\u5185\u5b58\uff0c\u6307\u9488p\n    char* p = mmap(NULL, length, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);\n    if (p == MAP_FAILED){\n        perror(\"mmap error\");\n        exit(1);\n    }\n    \/\/ \u5c06\u5b57\u7b26\u4e32\u62f7\u8d1d\u5230p\uff0c\u4f1a\u540c\u6b65\u5199\u5165\u5230\u6587\u4ef6\n    strcpy(p, \"abcdefg\\n\");\n    \/\/ \u5173\u95edmmap\uff0c\u5173\u95ed\u6587\u4ef6\n    munmap(p, length);\n    close(fd);\n    return 0;\n}\n<\/code><\/pre>\n<ul>\n<li>\u6ce8\u610f\u4e8b\u9879\n<ul>\n<li>\u53ef\u4ee5open\u7684\u65f6\u5019O_CREATE\u4e00\u4e2a\u65b0\u7684\u6587\u4ef6\u6765\u521b\u5efa\u6620\u5c04\u533a\u5417\uff1f<\/li>\n<li>\u53ef\u4ee5\uff0c\u4f46\u6620\u5c04\u533a\u5927\u5c0f\u4e0d\u80fd\u4e3a0\uff1b<\/li>\n<li>\u5982\u679cOpen\u65f6O_RDONLY\uff0cmmap\u65f6PROT\u53c2\u6570\u6307\u5b9aPROT_READ|PRO_WRITE\u4f1a\u600e\u6837\uff1f<\/li>\n<li>\u4f1a\u51fa\u73b0\u6743\u9650\u4e0d\u8db3\uff0copen\u6743\u9650\u5fc5\u987b\u5927\u4e8e\u7b49\u4e8emmap\u6743\u9650\uff0c\u5e76\u4e14\u5fc5\u987b\u5177\u5907read\u6743\u9650<\/li>\n<li>\u6587\u4ef6\u63cf\u8ff0\u7b26\u5148\u5173\u95ed\uff0c\u5bf9mmap\u6620\u5c04\u6709\u6ca1\u6709\u5f71\u54cd\uff1f<\/li>\n<li>\u53ea\u8981\u5b8c\u6210\u4e86mmap\u6620\u5c04\uff0c\u5173\u95ed\u6587\u4ef6\u63cf\u8ff0\u7b26\u662f\u6ca1\u6709\u5f71\u54cd\u7684\uff0c\u56e0\u4e3a\u64cd\u4f5c\u6587\u4ef6\u5df2\u7ecf\u4e0d\u9700\u8981\u5f53\u524d\u6587\u4ef6\u63cf\u8ff0\u7b26<\/li>\n<li>\u5982\u679c\u6587\u4ef6\u504f\u79fb\u91cf\u4e3a1000\u884c\u5417\uff1f<\/li>\n<li>\u4e0d\u884c\uff0c\u5fc5\u987b\u662f4096\u7684\u4f4d\u6570(4K\u662f\u4e00\u9875\u7684\u5927\u5c0f)\uff0cmmu\u5b8c\u6210\u6620\u5c04\uff0cmmu\u6700\u5c0f\u64cd\u4f5c\u5355\u5143\u4e3a4k<\/li>\n<li>\u5bf9mem\u8d8a\u754c\u64cd\u4f5c\u4f1a\u600e\u6837\uff1f<\/li>\n<li>\u4f1a\u62a5\u9519<\/li>\n<li>\u5bf9mem++\uff0cmunmap\u53ef\u5426\u6210\u529f\uff1f<\/li>\n<li>\u4e0d\u53ef\u4ee5\uff0c\u5fc5\u987b\u662f\u539f\u9996\u5730\u5740<\/li>\n<li>mmap\u4ec0\u4e48\u60c5\u51b5\u4e0b\u4f1a\u8c03\u7528\u5931\u8d25\uff1f<\/li>\n<li>\u5982\u679c\u4e0d\u68c0\u6d4bmmap\u8fd4\u56de\u503c\uff0c\u4f1a\u600e\u6837\uff1f<\/li>\n<\/ul>\n<\/li>\n<li>\u603b\u7ed3\uff1a\n<ul>\n<li>\u521b\u5efa\u6620\u5c04\u533a\u8fc7\u7a0b\u4e2d\uff0c\u9690\u542b\u4e86\u4e00\u6b21\u5bf9\u6620\u5c04\u6587\u4ef6\u7684\u8bfb\u53d6\u64cd\u4f5c\uff1b<\/li>\n<li>\u5f53MAP_SHARED\u65f6\uff0c\u8981\u6c42\uff1a\u6620\u5c04\u533a\u7684\u6743\u9650\u5e94 &lt;= \u6587\u4ef6\u64cd\u4f5c\u6743\u9650\uff0c\u800cMAP_PRIVATE\u5219\u65e0\u6240\u8c13\uff0c\u56e0\u4e3ammap\u4e2d\u7684\u6743\u9650\u662f\u5bf9\u5185\u5b58\u7684\u9650\u5236<\/li>\n<li>\u6620\u5c04\u533a\u7684\u91ca\u653e\u4e0e\u6587\u4ef6\u5173\u95ed\u65e0\u5173\uff0c\u53ea\u8981\u6620\u5c04\u5efa\u8bae\u6210\u529f\uff0c\u6587\u4ef6\u53ef\u4ee5\u7acb\u5373\u5173\u95ed\uff1b<\/li>\n<li>\u7279\u522b\u6ce8\u610f\uff0c\u5f53\u6620\u5c04\u6587\u4ef6\u5927\u5c0f\u4e3a0\u65f6\uff0c\u4e0d\u80fd\u521b\u5efa\u6620\u5c04\u533a\u3002\u6240\u4ee5\uff1a\u7528\u4e8e\u6620\u5c04\u7684\u6587\u4ef6\u5fc5\u987b\u6709\u5b9e\u9645\u5927\u5c0f\uff01mmap\u4f7f\u7528\u65f6\u7ecf\u5e38\u4f1a\u51fa\u73b0\u603b\u7ebf\u9519\u8bef\uff0c\u901a\u5e38\u662f\u7531\u4e8e\u5171\u4eab\u6587\u4ef6\u5b58\u50a8\u7a7a\u95f4\u5927\u5c0f\u5f15\u8d77\u7684\u3002<\/li>\n<li>munmap\u4f20\u5165\u7684\u5730\u5740\u4e00\u5b9a\u662fmmap\u7684\u8fd4\u56de\u5730\u5740\uff0c\u675c\u7edd\u8fdb\u884c++\u6216\u2014\u64cd\u4f5c\uff1b<\/li>\n<li>\u6587\u4ef6\u504f\u79fb\u91cf\u5fc5\u987b\u662f4K\u7684\u6574\u6570\u500d\uff1b<\/li>\n<li>mmap\u521b\u5efa\u6620\u5c04\u533a\u51fa\u9519\u7684\u6982\u7387\u975e\u5e38\u9ad8\uff0c\u4e00\u5b9a\u8981\u68c0\u67e5\u8fd4\u56de\u503c\uff0c\u786e\u4fdd\u6620\u5c04\u6210\u529f\u540e\u518d\u8fdb\u884c\u540e\u7eed\u64cd\u4f5c\uff1b<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h3>4\u3001mmap\u5b9e\u73b0\u7236\u5b50\u8fdb\u7a0b\u95f4\u901a\u8baf<\/h3>\n<ul>\n<li>\u521b\u5efa\u4e34\u65f6\u6587\u4ef6\u6620\u5c04<\/li>\n<\/ul>\n<pre><code class=\"language-c line-numbers\">#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n#include &lt;unistd.h&gt;\n#include &lt;sys\/wait.h&gt;\n#include &lt;sys\/mman.h&gt;\n#include &lt;fcntl.h&gt;\n\nint var = 10;\nint main(){\n    \/\/ 1.1\u3001\u51c6\u5907\u4e00\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\n    char* tempfile = \"temp\";\n    int fd = open(tempfile, O_CREAT | O_RDWR, 0664);\n    if (fd == -1){\n        perror(\"open error\");\n        exit(1);\n    }\n    unlink(tempfile);\n    \/\/ 1.2\u3001\u51c6\u5907\u6620\u5c04\u957f\u5ea6\uff0c\u5e76\u62d3\u5c55\u6587\u4ef6\u957f\u5ea6\u81f3\u5c11\u5927\u4e8e\u8be5\u957f\n    int len = 1024;\n    int ret = ftruncate(fd, len);\n    if (ret == -1){\n        perror(\"ltruncate error\");\n        exit(1);\n    }\n    \/\/ 2\u3001\u521b\u5efa\u4e00\u4e2a\u6620\u5c04\u533a\uff0c\u4ee5\u8bfb\u5199\u7684\u65b9\u5f0f\uff0c0\u504f\u79fb\uff0c\u5e76\u68c0\u9a8c\u7ed3\u679c\n    int* mem = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);\n    if (mem == MAP_FAILED){\n        perror(\"mmap error\");\n        exit(1);\n    }\n    \/\/ \u5173\u95ed\u6587\u4ef6\u63cf\u8ff0\u7b26\n    close(fd);\n    \/\/ 3\u3001\u521b\u5efa\u4e00\u4e2a\u5b50\u8fdb\u7a0b\n    ret = fork();\n    if (ret &lt; 0){\n        perror(\"fork error\");\n        exit(1);\n    }else if(ret &gt; 0){\n        \/\/ 3.1\u3001\u7236\u8fdb\u7a0b\u4e2d\u4fee\u6539\u6620\u5c04\u533a\u5185\u5bb9\u4e0e\u5168\u5c40\u53d8\u91cf\u5185\u5bb9\n        *mem = 2000;\n        var = 200;\n        \/\/ 3.1.1\u3001\u6253\u5370\u8f93\u51fa\u7ed3\u679c\n        printf(\"father mem = %d\\nvar = %d\\n\", *mem, var);\n        \/\/ 3.1.2\u3001\u5173\u95ed\u56de\u6536\u6620\u5c04\u533a\uff0c\u56de\u6536\u5b50\u8fdb\u7a0b\n        munmap(mem, len);\n        wait(NULL);\n    }else{\n        \/\/ 3.2\u3001\u5b50\u8fdb\u7a0b\u4e2d\u6253\u5370\u6620\u5c04\u533a\u4e0e\u5168\u5c40\u53d8\u91cf\u5185\u5bb9\uff0c\u9a8c\u8bc1\u8fdb\u7a0b\u95f4\u901a\u8baf\u7ed3\u679c\n        printf(\"child mem = %d\\nvar = %d\\n\", *mem, var);\n    }\n    return 0;\n}\n<\/code><\/pre>\n<p>\u6267\u884c\u7ed3\u679c\uff08\u6620\u5c04\u533a\u6570\u636e\u7236\u5b50\u8fdb\u7a0b\u53ef\u4ee5\u5171\u4eab\uff0c\u5168\u5c40\u53d8\u91cf\u533a\u6570\u636e\u72ec\u4eab\uff09<\/p>\n<pre><code class=\"language-cmd line-numbers\">child mem = 2000\nvar = 10\nfather mem = 2000\nvar = 200\n<\/code><\/pre>\n<ul>\n<li>Linux\u533f\u540d\u6620\u5c04\uff08\u4ec5\u5728Linux\u4e0b\u6709\u6548\uff0c\u56e0\u4e3aMAP_ANONYMOUS\u5b8f\u5728Linux\u4e2d\u7684\u5b9a\u4e49\uff09\n<pre><code class=\"language-c line-numbers\">#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n#include &lt;sys\/mman.h&gt;\n#include &lt;fcntl.h&gt;\n#include &lt;unistd.h&gt;\n#include &lt;sys\/wait.h&gt;\n\nint var = 10;\nint main(){\n  int len = 1024;\n  \/\/ 1\u3001\u521b\u5efa\u533f\u540d\u6620\u5c04\u533a\uff0c\u6587\u4ef6\u63cf\u8ff0\u7b26\u5199-1\uff0cflags\u4e2d\u52a0MAP_ANONYMOUS\n  int* mem = mmap(NULL, len, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0);\n  if (mem == MAP_FAILED){\n      perror(\"mmap error\");\n      exit(1);\n  }\n  \/\/ 2\u3001\u521b\u5efa\u5b50\u8fdb\u7a0b\n  int ret = fork();\n  if (ret &lt; 0){\n      perror(\"fork error\");\n      exit(1);\n  }else if (ret &gt; 0){\n      \/\/ \u7236\u8fdb\u7a0b\n      *mem = 2000;\n      var = 2000;\n      printf(\"father mem = %d, var = %d\\n\", *mem, var);\n      \/\/ \u56de\u6536\u6620\u5c04\u533a\uff0c\u56de\u6536\u5b50\u8fdb\u7a0b\n      munmap(mem, len);\n      wait(NULL);\n  }else{\n      \/\/ \u5b50\u8fdb\u7a0b\n      printf(\"child  mem = %d, var = %d\\n\", *mem, var);\n  }\n  return 0;\n}\n<\/code><\/pre>\n<\/li>\n<li>\u7c7bUnix\u533f\u540d\u6620\u5c04\n<pre><code class=\"language-c line-numbers\">#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n#include &lt;unistd.h&gt;\n#include &lt;sys\/mman.h&gt;\n#include &lt;fcntl.h&gt;\n\nint main(){\n  \/\/ zero\u4e3a\u5b57\u7b26\u6587\u4ef6\uff0c\u8be5\u6587\u4ef6\u8981\u591a\u5927\u6709\u591a\u5927\uff0c\u53ef\u505a\u4e3a\u533f\u540d\u4e34\u65f6\u6587\u4ef6\u4f7f\u7528\n  \/\/ \u7c7b\u4f3c\u7684\u6587\u4ef6\u8fd8\u6709dev\/null\uff0c\u53ef\u4ee5\u65e0\u9650\u5199\n  int fd = open(\"\/dev\/zero\", O_RDWR);\n  if (fd == -1){\n      perror(\"open error\");\n      exit(1);\n  }\n  int len = 1024;\n  int* mem = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);\n  if (mem == MAP_FAILED){\n      perror(\"mmap error\");\n      exit(1);\n  }\n  close(fd);\n  int ret = fork();\n  if (ret &lt; 0){\n      perror(\"fork error\");\n      exit(1);\n  }else if (ret &gt; 0){\n      \/\/ \u7236\u8fdb\u7a0b\n      *mem = 2000;\n      printf(\"father mem = %d\\n\", *mem);\n      munmap(mem, len);\n  }else{\n      printf(\"child  men = %d\\n\", *mem);\n  }\n  return 0;\n}\n<\/code><\/pre>\n<\/li>\n<\/ul>\n<h3>5\u3001mmap\u5b9e\u73b0\u65e0\u8840\u7f18\u5173\u7cfb\u8fdb\u7a0b\u95f4\u901a\u8baf<\/h3>\n<ul>\n<li><code>head.h<\/code>\n<pre><code class=\"language-c line-numbers\">#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n#include &lt;sys\/mman.h&gt;\n#include &lt;fcntl.h&gt;\n#include &lt;string.h&gt;\n#include &lt;unistd.h&gt;\nstruct STU{\n  int no;\n  char name[15];\n  char sex[1];\n};\nvoid sys_err(const char* errstr){\n  perror(errstr);\n  exit(1);\n}\n<\/code><\/pre>\n<\/li>\n<li><code>mmap_w.c<\/code>\n<pre><code class=\"language-c line-numbers\">#include \"head.h\"\n\nstruct STU;\nvoid sys_err(const char*);\nint main(){\n  \/\/ 1\u3001\u51c6\u5907\u4e00\u4e2a\u6620\u5c04\u7684\u6587\u4ef6\uff0c\u4e0d\u80fd\u4f7f\u7528\/dev\/zero\n  int fd = open(\"tempfile\", O_CREAT | O_RDWR, 0644);\n  if (fd &lt; 0) sys_err(\"open error\u201d);\n  int ret = ftruncate(fd, sizeof(struct STU));\n  if (ret &lt; 0) sys_err(\"ftruncase error\");\n  close(fd);\/\/ \u53ef\u4ee5\u5173\u95ed\uff0c\u4f46\u4e0d\u80fd\u5220\u9664\u8be5\u6587\u4ef6\n  \/\/ 2\u3001\u521b\u5efa\u6620\u5c04\u533a\n  struct STU* mem = mmap(NULL, sizeof(struct STU), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);\n  if (mem == MAP_FAILED) sys_err(\"mmap error\u201d);\n  \/\/ 3\u3001\u7ed9\u6620\u5c04\u533a\u5199\u5165\u5185\u5bb9\n  strcpy(mem-&gt;name, \"Jack\");\n  strcpy(mem-&gt;sex, \"m\");\n  mem-&gt;no = 0;\n  while(1){\n      sleep(1);\n      mem-&gt;no++;\n  }\n  return 0;\n}\n<\/code><\/pre>\n<\/li>\n<li><code>mmap_r.c<\/code>\n<pre><code class=\"language-c line-numbers\">#include \"head.h\"\n\nstruct STU;\nvoid sys_err(const char*);\nint main(){\n  \/\/ 1\u3001\u51c6\u5907\u6620\u5c04\u533a\u6587\u4ef6\n  int fd = open(\"tempfile\", O_RDWR);\n  if (fd &lt; 0) sys_err(\"open error\u201d);\n  \/\/ 2\u3001\u521b\u5efa\u6620\u5c04\u533a\n  struct STU* mem = mmap(NULL, sizeof(struct STU), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);\n  if (mem == MAP_FAILED) sys_err(\"mmap error\u201d);\n  \/\/ 3\u3001\u8bfb\u53d6\u6620\u5c04\u533a\u5185\u5bb9\n  while(1){\n      printf(\"name = %s, sex = %s, no = %d\\n\", mem-&gt;name, mem-&gt;sex, mem-&gt;no);\n      sleep(1);\n  }\n  return 0;\n}\n<\/code><\/pre>\n<p>strace \u67e5\u770b\u6587\u4ef6\u64cd\u4f5c\u8bb0\u5f55<\/p>\n<\/li>\n<\/ul>\n<h3>6\u3001\u8fdb\u7a0b\u7ec4\u7684\u51e0\u4e2a\u51fd\u6570getpgrp\u3001getpgid\u3001setpgid<\/h3>\n<ul>\n<li>\u8fdb\u7a0b\u7ec4\u662f\u4e00\u7ec4\u8fdb\u7a0b\u7684\u96c6\u5408\uff0c\u6709\u4e9b\u5730\u65b9\u4e5f\u53eb<strong>\u201c\u4f5c\u4e1a\u201d<\/strong>\uff1b<\/li>\n<\/ul>\n<pre><code class=\"language-c line-numbers\">#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n#include &lt;unistd.h&gt;\n#include &lt;sys\/types.h&gt;\n\nint main(){\n\n    pid_t pid = fork();\n    if (pid &gt; 0){\n        \/\/ \u7236\u8fdb\u7a0b\n        sleep(1);\n        \/\/ \u7236\u8fdb\u7a0b\u4e2d\u8bbe\u7f6e\u5b50\u8fdb\u7a0b\u7684\u7ec4id\n        setpgid(pid, pid);\n        sleep(2);\n        printf(\"father gid %u, pid: %u\\n\", getpgrp(), getpid());\n        \/\/ \u7236\u8fdb\u7a0b\u8bbe\u7f6e\u81ea\u5df1\u7684\u7ec4id\n        int ret = setpgid(getpid(), getppid());\n        if (ret == -1){\n            perror(\"setgpid error\");\n            exit(1);\n        }\n        printf(\"father changed gid %u, pid: %u\\n\", getpgid(0), getpid());\n    }else{\n        \/\/ \u5b50\u8fdb\u7a0b\n        printf(\"child gid: %u, pid: %u\\n\", getpgid(0), getpid());\n        sleep(2);\n        printf(\"child changed gid: %u, pid %u\\n\", getpgid(0), getpid());\n    }\n    return 0;\n}\n<\/code><\/pre>\n<p>\u6267\u884c\u7ed3\u679c\uff1a\u7236\u8fdb\u7a0b\u53ef\u4ee5\u4fee\u6539\u81ea\u5df1\u7684\u7ec4id<\/p>\n<pre><code class=\"language-cmd line-numbers\">child gid: 13190, pid: 13191\nchild changed gid: 13191, pid 13191\nfather gid 13190, pid: 13190\nfather changed gid 1466, pid: 13190\n<\/code><\/pre>\n<h3>7\u3001\u4f1a\u8bdd<\/h3>\n<ul>\n<li>getsid(0) \u83b7\u53d6\u5f53\u524d\u4f1a\u8bddid<\/li>\n<li>setsid( )\u521b\u5efa\u4e00\u4e2a\u4f1a\u8bdd\uff0c\u5e76\u4ee5\u81ea\u5df1\u8fdb\u7a0bid\u4e3a\u4f1a\u8bddid\uff0c\u540c\u65f6\u8fdb\u7a0bid\u4e3a\u65b0\u7684\u7ec4id<\/li>\n<li>\u521b\u5efa\u4f1a\u8bdd\u6ce8\u610f\u4ee5\u4e0b\uff1a\n<ul>\n<li>\u8c03\u7528\u8fdb\u7a0b\u4e0d\u80fd\u662f\u8fdb\u7a0b\u7ec4\u7ec4\u957f\uff1b<\/li>\n<li>\u8be5\u8fdb\u7a0b\u4f1a\u6210\u4e3a\u65b0\u7684\u8fdb\u7a0b\u7ec4\u7ec4\u957f\uff1b<\/li>\n<li>\u9700\u8981root\u6743\u9650\uff08ubuntu\u4e0d\u9700\u8981\uff09\uff1b<\/li>\n<li>\u65b0\u4f1a\u8bdd\u4e22\u5f03\u539f\u6709\u7684\u63a7\u5236\u7ec8\u7aef\uff0c\u8be5\u4f1a\u8bdd\u6ca1\u6709\u63a7\u5236\u7ec8\u7aef\uff1b<\/li>\n<li>\u5efa\u7acb\u65b0\u4f1a\u8bdd\u65f6\uff0c\u5148fork\uff0c\u7236\u8fdb\u7a0b\u7ec8\u6b62\uff0c\u5b50\u8fdb\u7a0b\u8c03\u7528setsid<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<pre><code class=\"language-c line-numbers\">#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n#include &lt;unistd.h&gt;\n\nint main(){\n    \/\/ \u521b\u5efa\u5b50\u8fdb\u7a0b\n    pid_t pid = fork();\n    if (pid == 0){\n        printf(\"pid=%u, gid=%u, sid=%u\\n\", getpid(), getpgid(0), getsid(0));\n        sleep(1);\n        setsid();\n        printf(\"pid=%u, gid=%u, sid=%u\\n\", getpid(), getpgid(0), getsid(0));\n    }else{\n        sleep(2);\n    }\n    return 0;\n}\n<\/code><\/pre>\n<p>\u6267\u884c\u7ed3\u679c\uff1a<\/p>\n<pre><code class=\"language-cmd line-numbers\">pid=16011, gid=16010, sid=1466\npid=16011, gid=16011, sid=16011\n<\/code><\/pre>\n<h3>8\u3001\u5b88\u62a4\u8fdb\u7a0b\uff08daemon\u7cbe\u7075\uff09<\/h3>\n<ul>\n<li>Linux\u7684\u540e\u53f0\u670d\u52a1\u8fdb\u7a0b\uff0c\u901a\u5e38\u72ec\u7acb\u4e8e\u63a7\u5236\u7ec8\u7aef\u5e76\u4e14\u5468\u671f\u6027\u5730\u6267\u884c\u67d0\u79cd\u4efb\u52a1\u6216\u7b49\u5f85\u5904\u7406\u67d0\u4e9b\u53d1\u751f\u7684\u4e8b\u4ef6\uff0c\u4e00\u822c\u91c7\u7528\u4ee5d\u7ed3\u5c3e\u7684\u540d\u5b57<\/li>\n<li>\u4e0d\u80fd\u76f4\u63a5\u548c\u7528\u6237\u4ea4\u4e92\uff0c\u4e0d\u53d7\u7528\u6237\u767b\u5f55\u6ce8\u9500\u7684\u5f71\u54cd\uff0c\u4e00\u76f4\u8fd0\u884c\u7740\uff0c\u5982\uff1ahttpd\u3001sshd\u7b49<\/li>\n<li>\u521b\u5efa\u5b88\u62a4\u8fdb\u7a0b\u6a21\u578b\uff1a\n<ol>\n<li>\u521b\u5efa\u5b50\u8fdb\u7a0b fork<\/li>\n<li>\u5b50\u8fdb\u7a0b\u521b\u5efa\u65b0\u4f1a\u8bdd\uff0c\u4f7f\u5b50\u8fdb\u7a0b\u5b8c\u5168\u72ec\u7acb\u51fa\u6765\uff0c\u8131\u79bb\u63a7\u5236<\/li>\n<li>\u6539\u53d8\u8fdb\u7a0b\u7684\u5de5\u4f5c\u76ee\u5f55 chdir\uff0c\u9632\u6b62\u5360\u7528\u53ef\u5378\u8f7d\u7684\u6587\u4ef6\u7cfb\u7edf\uff0c\u4e00\u822c\u8bbe\u7f6e\u4e3a\u6839\u76ee\u5f55\u6216\u7528\u6237\u4e3b\u76ee\u5f55\uff0c\u6216\u81ea\u5b9a\u4e49\u76ee\u5f55<\/li>\n<li>\u6307\u5b9a\u6587\u4ef6\u9ed8\u8ba4\u63a9\u7801 umask\uff0c\u9632\u6b62\u7ee7\u627f\u7684\u6587\u4ef6\u521b\u5efa\u5c4f\u853d\u5b57\u62d2\u7edd\u67d0\u4e9b\u6743\u9650<\/li>\n<li>\u5c06\u6587\u4ef6\u63cf\u8ff0\u7b260\u30011\u30012\u91cd\u5b9a\u5411\u5230\/dev\/null\uff0c\u7ee7\u627f\u7684\u6253\u5f00\u6587\u4ef6\u4e0d\u4f1a\u7528\u5230\uff0c\u6d6a\u8d39\u7cfb\u7edf\u8d44\u6e90<\/li>\n<li>\u5b88\u62a4\u8fdb\u7a0b\u4e3b\u903b\u8f91\uff0c\u5f00\u542f\u5b88\u62a4\u8fdb\u7a0b\u6838\u5fc3\u5de5\u4f5c<\/li>\n<li>\u9000\u51fa&#8230;<\/li>\n<\/ol>\n<\/li>\n<\/ul>\n<pre><code class=\"language-c line-numbers\">#include &lt;stdio.h&gt;\n#include &lt;stdlib.h&gt;\n#include &lt;unistd.h&gt;\n#include &lt;sys\/stat.h&gt;\n#include &lt;fcntl.h&gt;\n\nint main(){\n    \/\/ 1\u3001\u521b\u5efa\u5b50\u8fdb\u7a0b\n    pid_t pid = fork();\n    if (pid &gt; 0) return 0;\n    \/\/ 2\u3001\u5b50\u8fdb\u7a0b\u521b\u5efa\u65b0\u4f1a\u8bdd\n    pid_t sid = setsid();\n    \/\/ 3\u3001\u6539\u53d8\u8fdb\u7a0b\u5de5\u4f5c\u76ee\u5f55\n    int ret = chdir(\"\/home\/parallels\");\n    if (ret == -1){\n        perror(\"chdir error\");\n        exit(1);\n    }\n    \/\/ 4\u3001\u6307\u5b9a\u6587\u4ef6\u9ed8\u8ba4\u63a9\u7801\n    umask(0002);\n    \/\/ 5\u3001\u4fee\u6539\u9ed8\u8ba4\u6587\u4ef6\u63cf\u8ff0\u7b26\n    close(STDIN_FILENO);\n    open(\"\/dev\/null\", O_RDWR);\n    dup2(0, STDOUT_FILENO);\n    dup2(0, STDERR_FILENO);\n    \/\/ 6\u3001\u5b88\u62a4\u8fdb\u7a0b\u4e3b\u903b\u8f91\n    int fd = open(\"daemon.txt\", O_CREAT | O_RDWR, 0664);\n    while(1){\n        \/\/printf(\"--------\\n\");\n        write(fd, \"0\", 1);\n        sleep(1);\n    }\n    return 0;\n}\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>\u8fdb\u7a0b\u95f4\u901a\u8baf(IPC\uff0c InterProcess communication) \u7ba1\u9053\uff08\u4f7f\u7528\u6700\u7b80\u5355\uff09 \u4fe1\u53f7\uff08\u5f00\u9500\u6700\u5c0f\uff09 \u5171\u4eab\u6620\u5c04\u533a\uff08\u65e0\u8840\u7f18\u5173\u7cfb\uff09 \u672c\u5730\u5957\u63a5\u5b57\uff08\u6700\u7a33\u5b9a\uff09 1\u3001\u7ba1\u9053 \u7ba1\u9053\u80fd\u591f\u5b9e\u73b0\u4e24\u4e2a\u8fdb\u7a0b\u95f4\u7684\u901a\u8baf pipe(int[])\uff0c\u9700\u8981\u4f20\u5165\u4e00\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u6570\u7ec4\uff0c\u957f\u5ea6\u4e3a2\u505a\u4e3a\u7ba1\u9053\u7684\u4e24\u7aef\u64cd\u4f5c \u51fd\u6570\u7684\u53c2\u6570\u4e3a\u4f20\u51fa\u53c2\u6570\uff0c\u4e24\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u6570\u7ec4\uff0c\u7b2c\u4e00\u4e2a\u4e3a\u5199\uff0c\u7b2c\u4e8c\u4e2a\u4e3a\u8bfb \u9700\u8981\u901a\u8baf\u7684\u4e24\u4e2a\u8fdb\u7a0b\u53ea\u9700\u8981\u64cd\u4f5c\u76f8\u5bf9\u5e94\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u5373\u53ef\u5b9e\u73b0\u6570\u636e\u7684\u8bfb\u6216\u5199 \u6570\u636e\u81ea\u5df1\u8bfb\u4e0d\u80fd\u81ea\u5df1\u5199 \u6570\u636e\u4e00\u65e6\u88ab\u8bfb\u8d70\uff0c\u4fbf\u4e0d\u5728\u7ba1\u9053\u4e2d\u5b58\u5728\uff0c\u4e0d\u53ef\u53cd\u590d\u8bfb\u53d6 \u7531\u4e8e\u7ba1\u9053\u91c7\u7528\u534a\u53cc\u5de5\u901a\u8baf\u65b9\u5f0f\uff0c\u56e0\u6b64\u6570\u636e\u53ea\u80fd\u5728\u4e00\u4e2a\u65b9\u5411\u4e0a\u6d41\u52a8\uff1b \u53ea\u80fd\u5728\u6709\u516c\u5171\u7956\u5148\u7684\u8fdb\u7a0b\u95f4\u4f7f\u7528\u7ba1\u9053 #include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; #include &lt;unistd.h&gt; #include &lt;string.h&gt; int main(){ \/\/ \u5b9a\u4e49\u4e00\u4e2a\u6587\u4ef6\u63cf\u8ff0\u7b26\u6570\u7ec4\u505a\u4e3a\u4f20\u51fa\u53c2\u6570 int fd[2]; \/\/ 1\u3001\u65b0\u5efa\u4e00\u4e2a\u7ba1\u9053\uff0c\u8bfb\u5199\u7684\u6587\u4ef6\u63cf\u8ff0\u7b26\u5c06\u5199\u5165fd[2] \/\/ \u5176\u4e2dfd[0]\u4e3a\u8bfb\uff0cfd[1]\u4e3a\u5199 int ret = pipe(fd); if (ret == -1){ perror(&#8220;pipe error&#8221;); exit(1); } \/\/ 2\u3001\u65b0\u5efa\u4e00\u4e2a\u8fdb\u7a0b pid_t pid = fork(); if (pid == [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[88],"tags":[310,314],"class_list":["post-1801","post","type-post","status-publish","format-standard","hentry","category-cpp","tag-linux","tag-314"],"_links":{"self":[{"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/posts\/1801","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/comments?post=1801"}],"version-history":[{"count":0,"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/posts\/1801\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/media?parent=1801"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/categories?post=1801"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.yusian.com\/blog\/wp-json\/wp\/v2\/tags?post=1801"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}