Linux C gets the file name through a filename descriptor

Each file that is opened in Linux is recorded in the/proc/self/fd/directory, where the file (/proc/self/fd/file description symbol; This file is a symbol file) is the file that corresponds to the file descriptor.
and Readlink can get the file that the symbolic connection refers to
Function Prototypes:

ssize_t readlink(constcharchar *buf, size_t bufsiz);

Function Description:

readlink()会将参数path的符号连接内容存到参数buf所指的内存空间，返回的内容不是以NULL作字符串结尾，但会将字符串的字符数返回。若参数bufsiz小于符号连接的内容长度，过长的内容会被截断。返回值 执行成功则传符号连接所指的文件路径字符串，失败则返回-1I/O 存取错误。ELOOP 欲打开的文件有过多符号连接问题。ENAMETOOLONG 参数path的路径名称太长ENOENT 参数path所指定的文件不存在ENOMEM 核心内存不足ENOTDIR 参数path路径中的目录存在但却非真正的目录。

Get the filename by file descriptor source code:

#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <errno.h>#include <string.h>Const Char*file_name ="A.txt";intMain () {intFdif(FD = open (file_name, o_rdonly)) = =-1){fprintf(stderr,'%s Open:%s\n ', Flow_rx_file, Strerror (errno));return-1; }Charbuf[1024x768] = {' + '};Charfile_path[1024x768] = {' + '};snprintf(BUF,sizeof(BUF),"/proc/self/fd/%d", FD); Readlink (Buf,file_path,sizeof(File_path)-1);printf("%s\n", File_path);return 0;}

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Linux C gets the file name through a filename descriptor