books/apitue/sample-code/03/still-simple-ls.c

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2024-01-20 14:39:54 +00:00
/* This file is part of the sample code and exercises
* used by the class "Advanced Programming in the UNIX
* Environment" taught by Jan Schaumann
* <jschauma@netmeister.org> at Stevens Institute of
* Technology.
*
* This file is in the public domain.
*
* You don't have to, but if you feel like
* acknowledging where you got this code, you may
* reference me by name, email address, or point
* people to the course website:
* https://stevens.netmeister.org/631/
*/
/* This still very simple ls clone illustrates the use of the stat(2)
* family of functions to print out some information about the files in
* the given directory.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
int
main(int argc, char **argv) {
DIR *dp;
struct dirent *dirp;
if (argc != 2) {
fprintf(stderr, "usage: %s dir_name\n", argv[0]);
exit(EXIT_FAILURE);
}
if ((dp = opendir(argv[1])) == NULL ) {
fprintf(stderr, "can't open '%s': %s\n", argv[1], strerror(errno));
exit(EXIT_FAILURE);
}
if (chdir(argv[1]) == -1) {
fprintf(stderr, "can't chdir to '%s': %s\n", argv[1], strerror(errno));
exit(EXIT_FAILURE);
}
while ((dirp = readdir(dp)) != NULL ) {
struct stat sb;
if (stat(dirp->d_name, &sb) == -1) {
fprintf(stderr, "Can't stat %s: %s\n", dirp->d_name,
strerror(errno));
if (lstat(dirp->d_name, &sb) == -1) {
fprintf(stderr,"Can't stat %s: %s\n", dirp->d_name,
strerror(errno));
continue;
}
}
printf("%s: ", dirp->d_name);
if (S_ISREG(sb.st_mode))
printf("regular file");
else if (S_ISDIR(sb.st_mode))
printf("directory");
else if (S_ISCHR(sb.st_mode))
printf("character special");
else if (S_ISBLK(sb.st_mode))
printf("block special");
else if (S_ISFIFO(sb.st_mode))
printf("FIFO");
else if (S_ISLNK(sb.st_mode))
printf("symbolic link");
else if (S_ISSOCK(sb.st_mode))
printf("socket");
else
printf("unknown");
printf(" -- according to stat\n");
if (lstat(dirp->d_name, &sb) == -1) {
fprintf(stderr,"Can't stat %s: %s\n", dirp->d_name,
strerror(errno));
continue;
}
printf("%s: ", dirp->d_name);
if (S_ISREG(sb.st_mode))
printf("regular file");
else if (S_ISDIR(sb.st_mode))
printf("directory");
else if (S_ISCHR(sb.st_mode))
printf("character special");
else if (S_ISBLK(sb.st_mode))
printf("block special");
else if (S_ISFIFO(sb.st_mode))
printf("FIFO");
else if (S_ISLNK(sb.st_mode))
printf("symbolic link");
else if (S_ISSOCK(sb.st_mode))
printf("socket");
else
printf("unknown");
printf(" -- according to lstat\n\n");
}
closedir(dp);
exit(EXIT_SUCCESS);
}