I'm trying to show what folder contains as an output. When I run this program in my harddisk after 1-2 minutes it crashes, beside of crashing part it works just fine. I dont know how I can prevent this. Can anyone help me ?
#include <string.h>
#include <stdio.h>
#include <dirent.h>
void showingFiles(DIR *, char *);
int main(void) {
DIR *folder;
char path[350];
sprintf(path, ".");
folder = opendir(path);
showingFiles(folder, path);
closedir(folder);
printf("\n\nEnter a key to close this program ");
getch();
return 0;
}
void showingFiles(DIR *currentFolder, char *path){
struct dirent *nextFile;
DIR *subFolder;
char copyPath[350];
strcpy(copyPath, path);
while ((nextFile = readdir(currentFolder)) != NULL) {
sprintf(copyPath, "%s//%s", path, nextFile->d_name);
printf("%s\n", (*nextFile).d_name);
if ((strcmp(nextFile->d_name, "..")) &&
strcmp(nextFile->d_name ,".") &&
(subFolder = opendir(copyPath)) != NULL) {
deletingFiles(subFolder, copyPath);
}
}
closedir(currentFolder);
}
There are at least 3 problems in your code that can explain the crash:
the buffers used to store the complete pathnames pay be too short and you use an unsafe sprintf to construct them, potentially causing buffer overflows.
you never close the subFolder directory handles that you open in the recursive function showingFiles, potentially running out of system handles.
you do close the directory handle currentFolder in the function showingFiles(), but is is also closed in the main() function. This causes undefined behavior. As a rule of thumb, always close the handle in the function that opened it and only there.
Less important but issues:
To name showingFiles a function that performs a recursive removal of a complete directory tree is a bit misleading.
separating directory and pathnames with double slashes // is useless and not portable. You may have been thinking of \\ and converted this Windows specific directory separator into // for Unix portability, but be aware that single forward slashes are supported by the Windows file system handlers, to you should always use / as a directory separator for programs aimed for both Unix and Windows.
Here is a modified version:
#include <dirent.h>
#include <stdio.h>
#include <string.h>
void deleteTree(DIR *, const char *);
int main(void) {
char path[350] = ".";
DIR *folder = opendir(path);
if (folder != NULL) {
deleteTree(folder, path);
closedir(folder);
}
printf("\n\nEnter a key to close this program ");
getch();
return 0;
}
void deleteTree(DIR *currentFolder, const char *path) {
char copyPath[1024];
struct dirent *nextFile;
DIR *subFolder;
while ((nextFile = readdir(currentFolder)) != NULL) {
snprintf(copyPath, sizeof(copyPath), "%s/%s", path, nextFile->d_name);
printf("%s\n", nextFile->d_name);
if (strcmp(nextFile->d_name,"..")
&& strcmp(nextFile->d_name,".")
&& (subFolder = opendir(copyPath)) != NULL) {
deletingFiles(subFolder, copyPath);
closedir(subFolder);
}
}
}
Related
How to delete a non empty directory in C or C++? Is there any function? rmdir only deletes empty directory. Please provide a way without using any external library.
Also tell me how to delete a file in C or C++?
You want to write a function (a recursive function is easiest, but can easily run out of stack space on deep directories) that will enumerate the children of a directory. If you find a child that is a directory, you recurse on that. Otherwise, you delete the files inside. When you are done, the directory is empty and you can remove it via the syscall.
To enumerate directories on Unix, you can use opendir(), readdir(), and closedir(). To remove you use rmdir() on an empty directory (i.e. at the end of your function, after deleting the children) and unlink() on a file. Note that on many systems the d_type member in struct dirent is not supported; on these platforms, you will have to use stat() and S_ISDIR(stat.st_mode) to determine if a given path is a directory.
On Windows, you will use FindFirstFile()/FindNextFile() to enumerate, RemoveDirectory() on empty directories, and DeleteFile() to remove files.
Here's an example that might work on Unix (completely untested):
int remove_directory(const char *path) {
DIR *d = opendir(path);
size_t path_len = strlen(path);
int r = -1;
if (d) {
struct dirent *p;
r = 0;
while (!r && (p=readdir(d))) {
int r2 = -1;
char *buf;
size_t len;
/* Skip the names "." and ".." as we don't want to recurse on them. */
if (!strcmp(p->d_name, ".") || !strcmp(p->d_name, ".."))
continue;
len = path_len + strlen(p->d_name) + 2;
buf = malloc(len);
if (buf) {
struct stat statbuf;
snprintf(buf, len, "%s/%s", path, p->d_name);
if (!stat(buf, &statbuf)) {
if (S_ISDIR(statbuf.st_mode))
r2 = remove_directory(buf);
else
r2 = unlink(buf);
}
free(buf);
}
r = r2;
}
closedir(d);
}
if (!r)
r = rmdir(path);
return r;
}
Many unix-like systems (Linux, the BSDs, and OS X, at the very least) have the fts functions for directory traversal.
To recursively delete a directory, perform a depth-first traversal (without following symlinks) and remove every visited file:
int recursive_delete(const char *dir)
{
int ret = 0;
FTS *ftsp = NULL;
FTSENT *curr;
// Cast needed (in C) because fts_open() takes a "char * const *", instead
// of a "const char * const *", which is only allowed in C++. fts_open()
// does not modify the argument.
char *files[] = { (char *) dir, NULL };
// FTS_NOCHDIR - Avoid changing cwd, which could cause unexpected behavior
// in multithreaded programs
// FTS_PHYSICAL - Don't follow symlinks. Prevents deletion of files outside
// of the specified directory
// FTS_XDEV - Don't cross filesystem boundaries
ftsp = fts_open(files, FTS_NOCHDIR | FTS_PHYSICAL | FTS_XDEV, NULL);
if (!ftsp) {
fprintf(stderr, "%s: fts_open failed: %s\n", dir, strerror(errno));
ret = -1;
goto finish;
}
while ((curr = fts_read(ftsp))) {
switch (curr->fts_info) {
case FTS_NS:
case FTS_DNR:
case FTS_ERR:
fprintf(stderr, "%s: fts_read error: %s\n",
curr->fts_accpath, strerror(curr->fts_errno));
break;
case FTS_DC:
case FTS_DOT:
case FTS_NSOK:
// Not reached unless FTS_LOGICAL, FTS_SEEDOT, or FTS_NOSTAT were
// passed to fts_open()
break;
case FTS_D:
// Do nothing. Need depth-first search, so directories are deleted
// in FTS_DP
break;
case FTS_DP:
case FTS_F:
case FTS_SL:
case FTS_SLNONE:
case FTS_DEFAULT:
if (remove(curr->fts_accpath) < 0) {
fprintf(stderr, "%s: Failed to remove: %s\n",
curr->fts_path, strerror(curr->fts_errno));
ret = -1;
}
break;
}
}
finish:
if (ftsp) {
fts_close(ftsp);
}
return ret;
}
If you are using a POSIX compliant OS, you could use nftw() for file tree traversal and remove (removes files or directories). If you are in C++ and your project uses boost, it is not a bad idea to use the Boost.Filesystem as suggested by Manuel.
In the code example below I decided not to traverse symbolic links and mount points (just to avoid a grand removal:) ):
#include <stdio.h>
#include <stdlib.h>
#include <ftw.h>
static int rmFiles(const char *pathname, const struct stat *sbuf, int type, struct FTW *ftwb)
{
if(remove(pathname) < 0)
{
perror("ERROR: remove");
return -1;
}
return 0;
}
int main(int argc, char *argv[])
{
if (argc != 2)
{
fprintf(stderr,"usage: %s path\n",argv[0]);
exit(1);
}
// Delete the directory and its contents by traversing the tree in reverse order, without crossing mount boundaries and symbolic links
if (nftw(argv[1], rmFiles,10, FTW_DEPTH|FTW_MOUNT|FTW_PHYS) < 0)
{
perror("ERROR: ntfw");
exit(1);
}
return 0;
}
The easiest way to do this is with remove_all function of the Boost.Filesystem library. Besides, the resulting code will be portable.
If you want to write something specific for Unix (rmdir) or for Windows (RemoveDirectory) then you'll have to write a function that deletes are subfiles and subfolders recursively.
EDIT
Looks like this question was already asked, in fact someone already recommended Boost's remove_all. So please don't upvote my answer.
C++17 has <experimental\filesystem> which is based on the boost version.
Use std::experimental::filesystem::remove_all to remove recursively.
If you need more control, try std::experimental::filesystem::recursive_directory_iterator.
You can also write your own recursion with the non-resursive version of the iterator.
namespace fs = std::experimental::filesystem;
void IterateRecursively(fs::path path)
{
if (fs::is_directory(path))
{
for (auto & child : fs::directory_iterator(path))
IterateRecursively(child.path());
}
std::cout << path << std::endl;
}
You can use opendir and readdir to read directory entries and unlink to delete them.
//======================================================
// Recursely Delete files using:
// Gnome-Glib & C++11
//======================================================
#include <iostream>
#include <string>
#include <glib.h>
#include <glib/gstdio.h>
using namespace std;
int DirDelete(const string& path)
{
const gchar* p;
GError* gerr;
GDir* d;
int r;
string ps;
string path_i;
cout << "open:" << path << "\n";
d = g_dir_open(path.c_str(), 0, &gerr);
r = -1;
if (d) {
r = 0;
while (!r && (p=g_dir_read_name(d))) {
ps = string{p};
if (ps == "." || ps == "..") {
continue;
}
path_i = path + string{"/"} + p;
if (g_file_test(path_i.c_str(), G_FILE_TEST_IS_DIR) != 0) {
cout << "recurse:" << path_i << "\n";
r = DirDelete(path_i);
}
else {
cout << "unlink:" << path_i << "\n";
r = g_unlink(path_i.c_str());
}
}
g_dir_close(d);
}
if (r == 0) {
r = g_rmdir(path.c_str());
cout << "rmdir:" << path << "\n";
}
return r;
}
How to delete a non empty folder using unlinkat() in c?
Here is my work on it:
/*
* Program to erase the files/subfolders in a directory given as an input
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
void remove_dir_content(const char *path)
{
struct dirent *de;
char fname[300];
DIR *dr = opendir(path);
if(dr == NULL)
{
printf("No file or directory found\n");
return;
}
while((de = readdir(dr)) != NULL)
{
int ret = -1;
struct stat statbuf;
sprintf(fname,"%s/%s",path,de->d_name);
if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
continue;
if(!stat(fname, &statbuf))
{
if(S_ISDIR(statbuf.st_mode))
{
printf("Is dir: %s\n",fname);
printf("Err: %d\n",ret = unlinkat(dirfd(dr),fname,AT_REMOVEDIR));
if(ret != 0)
{
remove_dir_content(fname);
printf("Err: %d\n",ret = unlinkat(dirfd(dr),fname,AT_REMOVEDIR));
}
}
else
{
printf("Is file: %s\n",fname);
printf("Err: %d\n",unlink(fname));
}
}
}
closedir(dr);
}
void main()
{
char str[10],str1[20] = "../",fname[300]; // Use str,str1 as your directory path where it's files & subfolders will be deleted.
printf("Enter the dirctory name: ");
scanf("%s",str);
strcat(str1,str);
printf("str1: %s\n",str1);
remove_dir_content(str1); //str1 indicates the directory path
}
This code will open particular directory and iterate over all files and delete them which are under that directory. After that it will delete empty directory at the end.
/**
* #file RemoveDir.c
* #author Om Patel (ompatel1861#gmail.com)
* #brief This program will remove non empty directory.
* #version 0.1
* #date 2022-05-31
*
* #copyright Copyright (c) 2022
*
*/
#include<stdio.h>
#include<string.h>
#include<dirent.h>
#include <unistd.h>
int main()
{
DIR* dir = opendir("OUTPUT/Aakash");
struct dirent* entity;
entity = readdir(dir);
while(entity != NULL){
char path[30] ="OUTPUT/Aakash/";
printf("%s\n",entity->d_name);
strcat(path,entity->d_name);
printf("PAth: %s\n",path);
remove(path);
entity = readdir(dir);
}
char path1[30] ="OUTPUT/Aakash";
rmdir(path1);
closedir(dir);
char out[20]="OUTPUT/";
char fol_file[30];
sprintf(fol_file,"%s\\",out);
printf("%s",fol_file);
return 0;
}
So im trying to write a program in C that works like the ls command from Linux,
for the moment i've been capable of listing the files and directories inside my Current working directory, but i don't seem to be capable of doing the same for directories that are not my CWD, do i need to change it before i start listing it? or does the function opendir() work for any directory?
It has to work like ls -li from Linux but i got the printing stuff handled.
In general my program looks like this (obvsly it has more things):
void function(char *directory_to_list){
DIR *d;
struct dirent *dirp;
struct stat filestat;
if ( (d = opendir(directory_to_list)) == NULL){
//print error
}
while ( ( dirp = readdir(d) ) != NULL){
//here i call the stat() function for every entry to get various information
if (stat(dirp->d_name, &filestat) == -1){
continue;
}
//various prints
}
closedir(d);
}
EDIT: The command would be -> ls -li [-dir] so if you dont get any dir you just list your CWD.
EDIT2: No error is being returned it just does nothing, it opens the directory just fine but doenst list anything so i guess the stat call is not being done well, also added the line for how i call stat().
Here is a working version. Pay special attention that you do not overflow the buffer. you'll have to do some significant error checking to make this secure:
#include <stdio.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
int function(char *);
int main(void)
{
function("/tmp");
return 0;
}
int function(char *path)
{
DIR *dir;
struct dirent *dentry;
struct stat filestat;
char *giantbuffer = malloc(sizeof(char) * ((PATH_MAX * 2 ) + 1) );
if ( ( dir = opendir(path) ) )
{
dentry = readdir(dir);
while ( dentry )
{
sprintf(giantbuffer, "%s/%s", path, dentry->d_name);
printf("%s ", giantbuffer);
if (stat(giantbuffer, &filestat) == 0)
printf("%zu\n", filestat.st_size);
dentry = readdir(dir);
}
closedir(dir);
}
else
return -1;
return 0;
}
I will go ahead and say this is a homework assignment for an intro to Linux class. I would not be posting it without extensive attempts on my own, and seeing as I am a distance student this semester, I cannot make it to campus for tutoring. I need some help finding out what the issue is.
Essentially the assignment asks us to make a program that serves the same basic function as the pwd command in POSIX, to show the absolute path for the current directory. We are to use three functions along with main. We are not to use the getcwd command as well. I'll list them and their purpose
inum_to_filename: Accepts three arguments (inode number to translate, a pointer to a buffer where the name is written, and the size of the buffer). Returns nothing. It is to:
Open the current directory,
Read the first directory entry,
If the inode of the current directory matches the one passed in, copy name to buffer and return.
Otherwise read the next directory entry and repeat the previous step.
filename_to_inum: Accepts one argument (a char * representing the filename). It returns the corresponding inode number. It is to:
Read the information from the files inode into a structure in memory.
If there is any problem, display the appropriate error.
Return the inode number from the structure.
display_path: Accepts one argument (inode from the current working directory). It returns nothing. It is to:
Create an array of characters to use as a buffer for the name of the directory.
Get the inode for the parent directory using filename_to_inode.
If the parent inode is equal to the current inode, we have reached root and can return.
Otherwise, change to the parent directory and use inum_to_filename to find the name for the inode that was passed into the function. Use the buffer from step 1 to store it.
Recursively call display_path to display the absolute path.
Here is the code:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <dirent.h>
#include <sys/stat.h>
void inum_to_filename (int inode_arg, char *pathBuffer, int size_arg) {
DIR *dir_ptr = opendir(".");
struct dirent *dirent_ptr = readdir(dir_ptr);
int counter = 0;
while (counter != 1) {
if (inode_arg == dirent_ptr->d_ino) {
strcat(pathBuffer, "/");
strcat(pathBuffer, dirent_ptr->d_name);
counter = counter + 1;
return;
} else {
dirent_ptr = readdir(dir_ptr);
}
}
closedir(dir_ptr);
}
int filename_to_inum (char *src) {
int res = 0;
struct stat info;
int result = stat(src, &info);
if (result != 0) {
fprintf(stderr, "Cannot stat ");
perror(src);
exit(EXIT_FAILURE);
} else {
res = info.st_ino;
}
return res;
}
void display_path (int ino_src) {
int bufSize = 4096;
char pathBuffer[bufSize];
int ino_prnt = filename_to_inum("..");
if (ino_src == ino_prnt) {
//print for test
inum_to_filename(ino_src, pathBuffer, bufSize);
printf("%s", pathBuffer);
return;
} else {
//print for test
chdir("..");
inum_to_filename(ino_src, pathBuffer, bufSize);
display_path(ino_prnt);
printf("%s", pathBuffer);
}
}
int main (int argc, char *argv[]) {
int c_ino = filename_to_inum(".");
display_path(c_ino);
printf("\n");
}
As of right now it is displaying "/./MyName" with MyName being my personal named directory on the server. It is the directory I am running the program from. When using pwd I return "/home/MyName". I'm not really sure what my next step to getting the absolute path correct is.
The code is mostly set up to print one name at a time in the correct order, so the primary problem is the use of strcat() rather than strcpy(). Also, detecting when you're in the root directory at the start is important; if you don't, you can end up with /. or something similar (depending on exactly how you coordinate the printing) when the current directory is the root directory.
This version of your code has:
Squished the loop in inum_to_filename(), but also added error reporting. Remember, a process can be run in a directory which it does not have permission to get to (it requires a setuid program, usually — although permissions could be changed after the program is launched). In that case, it may fail to open .. (or .).
Lost variable count; it wasn't serving a useful purpose. Using the assign-and-test idiom allows the code to contain a single call to readdir().
Use strcpy() instead of strcat().
Use type ino_t to store inode numbers. Use size_t for sizes.
Reduce number of intermediate variables in filename_to_inum().
Note that the code in the if (ino_src == ino_prnt) statement body is for the root directory; in the absence of the testing print, it would do nothing.
Note that the printing in the else part is a major part of the operations, not just test printing.
Error check chdir("..");
Detect root in main().
Observe that this code is not directly suitable for rewriting into a function because it changes the process's current directory to / when it succeeds.
Revised code:
#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
static void inum_to_filename(ino_t inode_arg, char *pathBuffer, size_t size_arg)
{
assert(size_arg > 0);
DIR *dir_ptr = opendir(".");
if (dir_ptr == 0)
{
fprintf(stderr, "Failed to open directory '.' (%d: %s)\n", errno, strerror(errno));
exit(EXIT_FAILURE);
}
struct dirent *dirent_ptr;
while ((dirent_ptr = readdir(dir_ptr)) != 0)
{
if (inode_arg == dirent_ptr->d_ino)
{
if (strlen(dirent_ptr->d_name) >= size_arg)
{
fprintf(stderr, "File name %s too long (%zu vs %zu max)\n",
dirent_ptr->d_name, strlen(dirent_ptr->d_name), size_arg);
exit(EXIT_FAILURE);
}
strcpy(pathBuffer, dirent_ptr->d_name);
break;
}
}
closedir(dir_ptr);
}
static ino_t filename_to_inum(char *src)
{
struct stat info;
if (stat(src, &info) != 0)
{
fprintf(stderr, "Cannot stat ");
perror(src);
exit(EXIT_FAILURE);
}
return info.st_ino;
}
static void display_path(ino_t ino_src)
{
size_t bufSize = 4096;
char pathBuffer[bufSize];
ino_t ino_prnt = filename_to_inum("..");
if (ino_src == ino_prnt)
{
// print for test
inum_to_filename(ino_src, pathBuffer, bufSize);
printf("%s", "(root): /\n");
}
else
{
// print for real
if (chdir("..") != 0)
{
fprintf(stderr, "Failed to chdir to .. (%d: %s)\n",
errno, strerror(errno));
}
inum_to_filename(ino_src, pathBuffer, bufSize);
display_path(ino_prnt);
printf("/%s", pathBuffer);
}
}
int main(void)
{
ino_t c_ino = filename_to_inum(".");
ino_t r_ino = filename_to_inum("/");
if (r_ino == c_ino)
putchar('/');
else
display_path(c_ino);
printf("\n");
}
There are undoubtedly other ways to fix this.
Caveat: this is giving me some grief when working in /Volumes/CRUZER/Sub-Directory which is a memory stick. It fails to find the inode (1, which is surprising) when scanning /Volumes, and I've not worked out why. One of my programs — a getpwd implementation — is working fine; another is having a different problem. I expect I'll get to the bottom of it all. Testing on Mac OS X 10.10.5 with GCC 5.1.0.
this is really nice assignment :).
I read and tried your code, and it is almost correct. There were two small issues which were causing the incorrect behaviour.
First issue
When display_path reaches the root folder you don't need to call inum_to_filename and print the name of the folder because you have already printed the first folder of the path in the previous iteration. This prevents your code from showing a "./" in the beginning of the path.
That is, the if condition becomes:
if (ino_src == ino_prnt) {
return;
} else {
chdir("..");
inum_to_filename(ino_src, pathBuffer, bufSize);
display_path(ino_prnt);
printf("%s", pathBuffer);
}
Second Issue:
You're not initializing propertly the buffer where you save the name of the directory. This causes random values to be displayed. To solve this issue you can just set the initial value of the buffer to zero by using memset.
void inum_to_filename (int inode_arg, char *pathBuffer, int size_arg) {
DIR *dir_ptr = opendir(".");
struct dirent *dirent_ptr = readdir(dir_ptr);
int counter = 0;
memset(pathBuffer, 0, size_arg);
while (counter != 1) {
...
}
closedir(dir_ptr);
}
Full code working :
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <dirent.h>
#include <sys/stat.h>
void inum_to_filename (int inode_arg, char *pathBuffer, int size_arg) {
DIR *dir_ptr = opendir(".");
struct dirent *dirent_ptr = readdir(dir_ptr);
int counter = 0;
memset(pathBuffer, 0, size_arg);
while (counter != 1) {
if (inode_arg == dirent_ptr->d_ino) {
strcat(pathBuffer, "/");
strcat(pathBuffer, dirent_ptr->d_name);
counter = counter + 1;
return;
} else {
dirent_ptr = readdir(dir_ptr);
}
}
closedir(dir_ptr);
}
int filename_to_inum (char *src) {
int res = 0;
struct stat info;
int result = stat(src, &info);
if (result != 0) {
fprintf(stderr, "Cannot stat ");
perror(src);
exit(EXIT_FAILURE);
} else {
res = info.st_ino;
}
return res;
}
/*
- Create an array of characters to use as a buffer for the name of the directory.
- Get the inode for the parent directory using filename_to_inode.
- If the parent inode is equal to the current inode, we have reached root and can return.
- Otherwise, change to the parent directory and use inum_to_filename to find the name for
the inode that was passed into the function. Use the buffer from step 1 to store it.
- Recursively call display_path to display the absolute path.
*/
void display_path (int ino_src) {
int bufSize = 4096;
char pathBuffer[bufSize];
int ino_prnt = filename_to_inum("..");
if (ino_src == ino_prnt) {
return;
} else {
chdir("..");
inum_to_filename(ino_src, pathBuffer, bufSize);
display_path(ino_prnt);
printf("%s", pathBuffer);
}
}
int main (int argc, char *argv[]) {
int c_ino = filename_to_inum(".");
display_path(c_ino);
printf("\n");
}
Output :
ubuntu#ubuntu-VirtualBox:~/dev$ vi pwd.c
ubuntu#ubuntu-VirtualBox:~/dev$ gcc pwd.c
ubuntu#ubuntu-VirtualBox:~/dev$ ./a.out
/home/ubuntu/dev
ubuntu#ubuntu-VirtualBox:~/dev$ pwd
/home/ubuntu/dev
ubuntu#ubuntu-VirtualBox:~/dev$
I am completing cs50x (the edX (free) version of the Harvard cs50) course and am trying to be a bit tricky/lazy/test myself.
I am trying to use a C program to create all the directories I will need for my psets.
I have looked online and found that <sys/stat.h> includes the mkdir() function and therefore tried creating some nested loops to create all the necessary folders by doing something similar to mkdir {pset1,pset1/{standard,hacker},pset2,pset2{standard... to give me a directory structure like this:
pset1/Standard
pset1/Hacker
pset2/Standard
etc...
I came up with this:
#include <cs50.h>
#include <stdio.h>
#include <sys/stat.h>
int main(int argc, string argv[])
{
for(int i = 1; i <=8; i++)
{
string dir = argv[1];
sprintf(dir,"%s%i", argv[1], i);
mkdir(dir, 0777);
for(int j = 0; j<2; j++)
{
string subDir[] = {"Standard","Hacker"};
sprintf(dir,"%s%i/%s", argv[1], i, subDir[j]);
mkdir(dir, 0777);
}
}
}
However, the program only creates pset1 and completes, there are no subfolders, no pset2 etc.
Yes, you're being lazy since you seem to have very little knowledge of C, yet try to program in it. :)
C is not Python, there is no string interpolation/formatting operator. You have to call a function, specificially snprintf(). Read that manual page.
Also, you can't create a bunch of nested directories with a single call to mkdir(). Read the manual page.
To create nested directories, you're either going to have to build each's absolute path (i.e. each successive time you call mkdir() the path will be longer than the previous time), or actually enter each directory as you create it, and go from there.
To create a full path you can call mkdir() recursivly like this:
#include <limits.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
int mkdirr(const char * path, const mode_t mode, const int fail_on_exist)
{
int result = 0;
char * dir = NULL;
do
{
if (NULL == path)
{
errno = EINVAL;
result = -1;
break;
}
if ((dir = strrchr(path, '/')))
{
*dir = '\0';
result = mkdirr(path, mode, fail_on_exist);
*dir = '/';
if (result)
{
break;
}
}
if (strlen(path))
{
if ((result = mkdir(path, mode)))
{
char s[PATH_MAX];
sprintf(s, "mkdir() failed for '%s'", path);
perror(s);
if ((EEXIST == result) && (0 == fail_on_exist))
{
result = 0;
}
else
{
break;
}
}
}
} while (0);
return result;
}
And then call mkdirr() like this;
int main(void)
{
char p[] = "test/1/2/3";
if (-1 == mkdirr(p, 0777, 0))
{
perror("mkdirr() failed()");
}
return 0;
}
I am working on a POSIX C learning exercise that involves recursively listing files/folders in a specified directory. The program takes in as arguments of one or more directories. I can list the contents of the initial directory fine but having a problem with the recursion. Is something wrong with the way I am passing in the argument for the recursive function call?
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <dirent.h>
#include <errno.h>
#include <string.h>
void listdir(char *argv[])
{
DIR *mydirhandle;
struct dirent *mydirent;
struct stat statinfo;
int n = 1;
while(argv[n] != NULL)
{
if((mydirhandle = opendir(argv[n])) == NULL)
{
perror("opendir");
exit(1);
}
printf("%s/\n", argv[n]);
while((mydirent = readdir(mydirhandle)) != NULL)
{
if((strcmp(mydirent->d_name, ".") == 0) || (strcmp(mydirent->d_name, "..") == 0))
{
continue;
}
else
{
printf("\t%s\n", mydirent->d_name);
//check if next entry is a directory
if(mydirent->d_type == DT_DIR)
{
//is current directory being passed correctly here?
listdir(mydirent->d_name);
}
}
}
n++;
closedir(mydirhandle);
}
}
int main(int argc, char *argv[])
{
if(argc < 2)
{
printf("usage: %s <directory>\n", argv[0]);
return 0;
}
listdir(argv);
return 0;
}
The d_name member of struct dirent is the basename of the item in question. So, if you're going through a directory like this:
.
..
where-is/
pancakes/
.
..
house
Once you're in where-is, you'll try to listdir("pancakes") but that won't work because you need to listdir("where-is/pancakes").
You need to combine that with the name of the directory that you're looking before you have something that you can pass to the next listdir call.
You'll want to replace things like this:
listdir(mydirent->d_name);
with things like this:
char *next_dir = malloc(strlen(argv[n]) + strlen(mydirent->d_name) + 1 + 1);
sprintf(next_dir, "%s/%s", argv[n], mydirent->d_name);
listdir(next_dir);
free(next_dir);
Alternatively, you could chdir into the directories as you enter them and then chdir back up when you're done.
Turning on warnings will show that you're passing the wrong type when making the recursive function call. I would simply make listdir take a char * argument rather than char **, and then use a for loop in main to loop over multiple arguments if you need to.
You should use ftw for this, it calls a given callback on every item of the subtree. This way, you avoid using explicit recursion yourself, and your code will get much shorter.