Why the macro S_ISDIR in Linux returns all files as directories

Question

I want to recursively browse the directory and find all the text files. For this I use this code

while ((entry = readdir(d)) != NULL) { stat(entry->d_name, &st); if (S_ISREG(st.st_mode)) { printf("%20s\t%d\n", entry->d_name, st.st_size); } if (S_ISDIR(st.st_mode)) { DIR* dir; dir = opendir(entry->d_name); cout << "dir" << entry->d_name << endl; cout << "st "<< st.st_mode << endl; read_dir(dir); } }

but for some reason, when browsing a directory on each file and folder, if (S_ISDIR(st.st_mode)) ,
and if (S_ISREG(st.st_mode)) always false .

Maybe it is not executed at all, and then you look at the same garbage in st.st_mode .
Probably stat () with an error is returned (== - 1, perror ()), for example due to the fact that not the full name is passed or the relative name is not from that directory.
What about other comments (exclude "." , ".." add error checking to all functions)?

Sergey Sergey 6.372 four nineteen · Accepted Answer · 2017-03-03T03:18:30

There are at least three errors in your code:

1) There is no such function in the above text: "read_dir (dir)". There is a "readdir (dir)".

2) You incorrectly form the file name of the current level - there is no top part of the file path. And when processing items that are subdirectories, this error is repeated twice!

3) Well, when analyzing a subdirectory, you are doing something that is not very clear to me - apparently, read_dir (dir) is your function, which should depict repetitive processing? Well, then write it recursively!

I did not bother with the complete alteration of your code to the recursive version, and on the first two points, the code should be like this:

 #include <stdio.h> #include <string.h> #include <stdlib.h> #include <sys/types.h> #include <unistd.h> #include <sys/stat.h> #include <dirent.h> int main(int argc, char *argv[]) { DIR *d; struct dirent *entry; struct stat st; char dir_name[256]; char wrk[256]; int rc; if (argc > 1) { strcpy(dir_name, argv[1]); } else { strcpy(dir_name, "."); } d = opendir(dir_name); if (d == NULL) { printf("Ошибка при открытии директории %s\n", dir_name); exit(-1); } while ((entry = readdir(d)) != NULL) { strcpy(wrk, dir_name); strcat(wrk, "/"); strcat(wrk,entry->d_name); rc = stat(wrk, &st); if (rc != 0 ) { printf("Ошибка при вызове stat('%s')\n", wrk); exit(-1); } if (S_ISREG(st.st_mode)) { printf("%20s\t%ld\n", entry->d_name, st.st_size); } if (S_ISDIR(st.st_mode)) { DIR* dir; dir = opendir(entry->d_name); printf("dir %s\n", entry->d_name); printf("st %x\n", st.st_mode); readdir(dir); } } }

And forgot to write - ALWAYS organize a special processing of the elements "."

Why the macro S_ISDIR in Linux returns all files as directories

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