I am doing a project in C, and I'm stuck on one thing, i need to check if the directoy "/var/log/PROJECT " exist, if not, my program must create it, the aplication will always run on super user, this is what im doing:
struct stat st = {0};
if (stat("/var/log/project/PROJECT", &st) == -1) {
printf("im creating the folder\n");
mode_t process_mask = umask(0);
int result_code = mkdir("/var/log/project/PROJECT", 0777);
umask(process_mask);
}else{
printf("exist\n");
}
Sorry for asking to "do my homework" but im really stuck...
Well, I'm going to run with my suspicion. If the problem is that the parent directory of the directory you're trying to create does not exist, the solution is to create the parent directory before it. This is not terribly difficult to do with recursion, thankfully. Try this:
#include <errno.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
int create_directory_with_parents(char const *pathname, mode_t modus) {
struct stat st;
if(stat(pathname, &st) == -1) {
// If the directory does not yet exist:
//
// Make sure the parent directory is there. dirname() gives us the name of
// the parent directory, then we call this very function recursively because
// we are, after all, in a function that makes sure directories exist.
char *path_cpy = strdup(pathname);
char *dir = dirname(path_cpy);
int err = create_directory_with_parents(dir, modus);
free(path_cpy);
// If we were able to make sure the parent directory exists,
// make the directory we really want.
if(err == 0) {
mode_t process_mask = umask(0);
int err = mkdir(pathname, modus);
umask(process_mask);
}
// err is 0 if everything went well.
return err;
} else if(!S_ISDIR(st.st_mode)) {
// If the "directory" exists but is not a directory, complain.
errno = ENOTDIR;
return -1;
}
// If the directory exists and is a directory, there's nothing to do and
// nothing to complain about.
return 0;
}
int main(void) {
if(0 != create_directory_with_parents("/var/log/project/PROJECT", 0777)) {
perror("Could not create directory or parent of directory: ");
}
}
The recursion ends when the first parent directory is found that exists; that is with / at the latest.
One limitation of this implementation is that all parent directories will have the same access rights as the leaf directory, which may or may not be what you want. If this is not what you want, you'll have to change the modus parameter in the recursive call to create_directory_with_parents. How to pass several modus parameters for several layers of parent directories that may have to be created is something of a design question that depends on what exactly your needs are, so I cannot give a general answer to it.
Why not just execute the mkdir command anyway, and simply ignore the error it will produce if the directory already exists? This will save you playing around with stat.
Is there a reason you need the file permissions to be 777? If not, you can drop the umask bit too.
