How to realize the functions related to soft links in linux
This article mainly introduces "linux how to achieve soft link-related functions", in daily operation, I believe many people in linux how to achieve soft link-related functions on the question of doubt, small make up access to all kinds of information, sorting out simple and easy to use operation methods, hope to answer "linux how to achieve soft link-related functions" doubts helpful! Next, please follow the small series to learn together!
/* * linux/fs/minix/symlink.c * * Copyright (C) 1991, 1992 Linus Torvalds * * minix symlink handling code */
#ifdef MODULE#include #endif
#include
#include #include #include #include #include
static int minix_readlink(struct inode *, char *, int);static int minix_follow_link(struct inode *, struct inode *, int, int, struct inode **);
/* * symlinks can't do much... *///Function set for operating soft link files, assign to inode struct inode_operations minix_symlink_inode_operations = { NULL, /* no file-operations */ NULL, /* create */ NULL, /* lookup */ NULL, /* link */ NULL, /* unlink */ NULL, /* symlink */ NULL, /* mkdir */ NULL, /* rmdir */ NULL, /* mknod */ NULL, /* rename */ minix_readlink, /* readlink */ minix_follow_link, /* follow_link */ NULL, /* bmap */ NULL, /* truncate */ NULL /* permission */};//Open the file corresponding to the soft chain static int minix_follow_link(struct inode * dir, struct inode * inode, int flag, int mode, struct inode ** res_inode){ int error; struct buffer_head * bh;
*res_inode = NULL; if (! dir) { dir = current->fs->root; dir->i_count++; } if (! inode) { iput(dir); return -ENOENT; } if (! S_ISLNK(inode->i_mode)) { iput(dir); *res_inode = inode; return 0; } if (current->link_count > 5) { iput(inode); iput(dir); return -ELOOP; } //Read the first block of the file if (! (bh = minix_bread(inode, 0, 0))) { iput(inode); iput(dir); return -EIO;} iput(inode); current->link_count++; //Open the file corresponding to the saved filename in b_data error = open_namei(bh->b_data,flag,mode,res_inode,dir); current->link_count--; brelse(bh); return error;}//Read the contents of the soft chain file, i.e. the file path static int minix_readlink(struct inode * inode, char * buffer, int bufflen){ struct buffer_head * bh; int i; char c;
if (! S_ISLNK(inode->i_mode)) { iput(inode); return -EINVAL; } if (buflen > 1023) buflen = 1023; bh = minix_bread(inode, 0, 0); iput(inode); if (! bh) return 0; i = 0; while (ib_data[i])) { i++; put_fs_byte(c,buffer++); } brelse(bh); return i;}
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