Need help describing these: #define NAMELEN 2048 #define BUFSIZE 1024 #include <sys/types.h> #include <sys/stat.h> #include <time.h> #include <stdio.h> #include <stdlib.h> char *strmode(mode_t mode); // nasty function below this one int main(int argc, char *argv[]) { if (argc != 2) { fprintf(stderr, "Usage: %s <pathname>\n", argv[0]); exit(EXIT_FAILURE); } if(access(argv[1], F_OK)!=0){ // check file exists perror("Couldn't access file"); exit(EXIT_FAILURE); } struct stat sb; if (stat(argv[1], &sb) == -1) { // call to stat(), fills sb, distinguishes symbolic links perror("stat"); exit(EXIT_FAILURE); } printf("Filename: %s\n",argv[1]); printf("File type: "); if(0){} // checks to determine file type else if S_ISBLK (sb.st_mode) { printf("block device\n"); } else if S_ISCHR (sb.st_mode) { printf("character device\n"); } else if S_ISDIR (sb.st_mode) { printf("directory\n"); } else if S_ISFIFO(sb.st_mode) { printf("FIFO/pipe\n"); } else if S_ISLNK (sb.st_mode) { printf("symlink\n"); } else if S_ISREG (sb.st_mode) { printf("regular file\n"); } else if S_ISSOCK(sb.st_mode) { printf("socket\n"); } else{ printf("unknown?\n"); } // Use various fields to display information printf("I-node number: %ld\n" , (long) sb.st_ino); printf("Permissions: %lo (octal)\n" , (unsigned long) sb.st_mode); printf("Link count: %ld\n" , (long) sb.st_nlink); printf("Ownership: UID=%ld GID=%ld\n" , (long) sb.st_uid, (long) sb.st_gid); printf("Preferred I/O block size: %ld bytes\n" , (long) sb.st_blksize); printf("File size: %lld bytes\n" , (long long) sb.st_size); printf("Blocks allocated: %lld\n" , (long long) sb.st_blocks); // Print times of last access printf("Last status change: %s", ctime(&sb.st_ctime)); // formats time as a string printf("Last file access: %s", ctime(&sb.st_atime)); // fields like st_atime are of printf("Last file modification: %s", ctime(&sb.st_mtime)); // type time_t taken by ctime() char *str_mode = strmode(sb.st_mode); // use strmode() form strmode.c to construct permissions string printf("Permissions: %s\n", str_mode); // Optionally report device number // printf("ID of containing device: [%lx,%lx]\n", (long) major(sb.st_dev), (long) minor(sb.st_dev)); exit(EXIT_SUCCESS); } A) What's the best way to describe how the 'access()' system call is used? B) How does `stat()' report the Size of a file? C) `stat()()' report the "kind" of file being queried. How is this information used in `stat_demo.c'? D) Which one of the following is NOT a file "kind" reported by `stat() / lstat()' - ( ) Directory - ( ) Binary - ( ) Socket - ( ) Symbolic Link (symlink) E) What's the difference between ctime and mtime reported by stat()?

Need help describing these: #define NAMELEN 2048 #define BUFSIZE 1024 #include <sys/types.h> #include <sys/stat.h> #include <time.h> #include <stdio.h> #include <stdlib.h> char strmode(mode_t mode); // nasty function below this one int main(int argc, char argv[]) { if (argc != 2) { fprintf(stderr, "Usage: %s <pathname>\n", argv[0]); exit(EXIT_FAILURE); } if(access(argv[1], F_OK)!=0){ // check file exists perror("Couldn't access file"); exit(EXIT_FAILURE); } struct stat sb; if (stat(argv[1], &sb) == -1) { // call to stat(), fills sb, distinguishes symbolic links perror("stat"); exit(EXIT_FAILURE); } printf("Filename: %s\n",argv[1]); printf("File type: "); if(0){} // checks to determine file type else if S_ISBLK (sb.st_mode) { printf("block device\n"); } else if S_ISCHR (sb.st_mode) { printf("character device\n"); } else if S_ISDIR (sb.st_mode) { printf("directory\n"); } else if S_ISFIFO(sb.st_mode) { printf("FIFO/pipe\n"); } else if S_ISLNK (sb.st_mode) { printf("symlink\n"); } else if S_ISREG (sb.st_mode) { printf("regular file\n"); } else if S_ISSOCK(sb.st_mode) { printf("socket\n"); } else{ printf("unknown?\n"); } // Use various fields to display information printf("I-node number: %ld\n" , (long) sb.st_ino); printf("Permissions: %lo (octal)\n" , (unsigned long) sb.st_mode); printf("Link count: %ld\n" , (long) sb.st_nlink); printf("Ownership: UID=%ld GID=%ld\n" , (long) sb.st_uid, (long) sb.st_gid); printf("Preferred I/O block size: %ld bytes\n" , (long) sb.st_blksize); printf("File size: %lld bytes\n" , (long long) sb.st_size); printf("Blocks allocated: %lld\n" , (long long) sb.st_blocks); // Print times of last access printf("Last status change: %s", ctime(&sb.st_ctime)); // formats time as a string printf("Last file access: %s", ctime(&sb.st_atime)); // fields like st_atime are of printf("Last file modification: %s", ctime(&sb.st_mtime)); // type time_t taken by ctime() char *str_mode = strmode(sb.st_mode); // use strmode() form strmode.c to construct permissions string printf("Permissions: %s\n", str_mode); // Optionally report device number // printf("ID of containing device: [%lx,%lx]\n", (long) major(sb.st_dev), (long) minor(sb.st_dev)); exit(EXIT_SUCCESS); } A) What's the best way to describe how the 'access()' system call is used? B) How does `stat()' report the Size of a file? C) `stat()()' report the "kind" of file being queried. How is this information used in `stat_demo.c'? D) Which one of the following is NOT a file "kind" reported by `stat() / lstat()' - ( ) Directory - ( ) Binary - ( ) Socket - ( ) Symbolic Link (symlink) E) What's the difference between ctime and mtime reported by stat()?

Microsoft Visual C#

7th Edition

ISBN:9781337102100

Author:Joyce, Farrell.

Publisher:Joyce, Farrell.

Chapter8: Advanced Method Concepts

Section: Chapter Questions

Problem 7RQ

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Need help describing these:

#define NAMELEN 2048

#define BUFSIZE 1024

#include <sys/types.h>

#include <sys/stat.h>

#include <time.h>

#include <stdio.h>

#include <stdlib.h>

char *strmode(mode_t mode); // nasty function below this one

int main(int argc, char *argv[]) {

if (argc != 2) {

fprintf(stderr, "Usage: %s <pathname>\n", argv[0]);

exit(EXIT_FAILURE);

}

if(access(argv[1], F_OK)!=0){ // check file exists

perror("Couldn't access file");

exit(EXIT_FAILURE);

}

struct stat sb;

if (stat(argv[1], &sb) == -1) { // call to stat(), fills sb, distinguishes symbolic links

perror("stat");

exit(EXIT_FAILURE);

}

printf("Filename: %s\n",argv[1]);

printf("File type: ");

if(0){} // checks to determine file type

else if S_ISBLK (sb.st_mode) { printf("block device\n"); }

else if S_ISCHR (sb.st_mode) { printf("character device\n"); }

else if S_ISDIR (sb.st_mode) { printf("directory\n"); }

else if S_ISFIFO(sb.st_mode) { printf("FIFO/pipe\n"); }

else if S_ISLNK (sb.st_mode) { printf("symlink\n"); }

else if S_ISREG (sb.st_mode) { printf("regular file\n"); }

else if S_ISSOCK(sb.st_mode) { printf("socket\n"); }

else{ printf("unknown?\n"); }

// Use various fields to display information

printf("I-node number: %ld\n" , (long) sb.st_ino);

printf("Permissions: %lo (octal)\n" , (unsigned long) sb.st_mode);

printf("Link count: %ld\n" , (long) sb.st_nlink);

printf("Ownership: UID=%ld GID=%ld\n" , (long) sb.st_uid, (long) sb.st_gid);

printf("Preferred I/O block size: %ld bytes\n" , (long) sb.st_blksize);

printf("File size: %lld bytes\n" , (long long) sb.st_size);

printf("Blocks allocated: %lld\n" , (long long) sb.st_blocks);

// Print times of last access

printf("Last status change: %s", ctime(&sb.st_ctime)); // formats time as a string

printf("Last file access: %s", ctime(&sb.st_atime)); // fields like st_atime are of

printf("Last file modification: %s", ctime(&sb.st_mtime)); // type time_t taken by ctime()

char *str_mode = strmode(sb.st_mode); // use strmode() form strmode.c to construct permissions string

printf("Permissions: %s\n", str_mode);

// Optionally report device number

// printf("ID of containing device: [%lx,%lx]\n", (long) major(sb.st_dev), (long) minor(sb.st_dev));

exit(EXIT_SUCCESS);

}

A) What's the best way to describe how the 'access()' system call is
used?

B) How does `stat()' report the Size of a file?

C) `stat()()' report the "kind" of file being queried. How is this
information used in `stat_demo.c'?

D) Which one of the following is NOT a file "kind" reported by `stat() /
lstat()'
- ( ) Directory
- ( ) Binary
- ( ) Socket
- ( ) Symbolic Link (symlink)

E) What's the difference between ctime and mtime reported by stat()?

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