/* spwd.c: a simplified version of pwd * * starts in current directory and recursively * climbs up to root of filesystem, prints top part * then prints current part * * uses readdir() to get info about each thing * * bug: prints an empty string if run from "/" **/ #include #include #include #include ino_t get_inode(char *); void printpathto(ino_t); void inum_to_name(ino_t , char *, int ); int main() { printpathto( get_inode( "." ) ); /* print path to here */ putchar('\n'); /* then add newline */ return 0; } void printpathto( ino_t this_inode ) /* * prints path leading down to an object with this inode * kindof recursive */ { ino_t my_inode ; char its_name[BUFSIZ]; if ( get_inode("..") != this_inode ) { chdir( ".." ); /* up one dir */ inum_to_name(this_inode,its_name,BUFSIZ);/* get its name*/ my_inode = get_inode( "." ); /* print head */ printpathto( my_inode ); /* recursively */ printf("/%s", its_name ); /* now print */ /* name of this */ } } void inum_to_name(ino_t inode_to_find , char *namebuf, int buflen) /* * looks through current directory for a file with this inode * number and copies its name into namebuf */ { DIR *dir_ptr; /* the directory */ struct dirent *direntp; /* each entry */ dir_ptr = opendir( "." ); if ( dir_ptr == NULL ){ perror( "." ); exit(1); } /* * search directory for a file with specified inum */ while ( ( direntp = readdir( dir_ptr ) ) != NULL ) if ( direntp->d_ino == inode_to_find ) { strncpy( namebuf, direntp->d_name, buflen); namebuf[buflen-1] = '\0'; /* just in case */ closedir( dir_ptr ); return; } fprintf(stderr, "error looking for inum %d\n", inode_to_find); exit(1); } ino_t get_inode( char *fname ) /* * returns inode number of the file */ { struct stat info; if ( stat( fname , &info ) == -1 ){ fprintf(stderr, "Cannot stat "); perror(fname); exit(1); } return info.st_ino; }
Fix the spwd code so it works:
/* spwd.c: a simplified version of pwd
*
* starts in current directory and recursively
* climbs up to root of filesystem, prints top part
* then prints current part
*
* uses readdir() to get info about each thing
*
* bug: prints an empty string if run from "/"
**/
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
ino_t get_inode(char *);
void printpathto(ino_t);
void inum_to_name(ino_t , char *, int );
int main()
{
printpathto( get_inode( "." ) ); /* print path to here */
putchar('\n'); /* then add newline */
return 0;
}
void printpathto( ino_t this_inode )
/*
* prints path leading down to an object with this inode
* kindof recursive
*/
{
ino_t my_inode ;
char its_name[BUFSIZ];
if ( get_inode("..") != this_inode )
{
chdir( ".." ); /* up one dir */
inum_to_name(this_inode,its_name,BUFSIZ);/* get its name*/
my_inode = get_inode( "." ); /* print head */
printpathto( my_inode ); /* recursively */
printf("/%s", its_name ); /* now print */
/* name of this */
}
}
void inum_to_name(ino_t inode_to_find , char *namebuf, int buflen)
/*
* looks through current directory for a file with this inode
* number and copies its name into namebuf
*/
{
DIR *dir_ptr; /* the directory */
struct dirent *direntp; /* each entry */
dir_ptr = opendir( "." );
if ( dir_ptr == NULL ){
perror( "." );
exit(1);
}
/*
* search directory for a file with specified inum
*/
while ( ( direntp = readdir( dir_ptr ) ) != NULL )
if ( direntp->d_ino == inode_to_find )
{
strncpy( namebuf, direntp->d_name, buflen);
namebuf[buflen-1] = '\0'; /* just in case */
closedir( dir_ptr );
return;
}
fprintf(stderr, "error looking for inum %d\n", inode_to_find);
exit(1);
}
ino_t get_inode( char *fname )
/*
* returns inode number of the file
*/
{
struct stat info;
if ( stat( fname , &info ) == -1 ){
fprintf(stderr, "Cannot stat ");
perror(fname);
exit(1);
}
return info.st_ino;
}
Trending now
This is a popular solution!
Step by step
Solved in 2 steps
