Recursive directory creation

Posted by Nico Golde in hacks & code
Monday, August 22. 2005

For ii I searched for a method to create directories recursive with all parents. There was no standard c function to do this. mkdir(char *path, mode_t mode) only creates one directory, not the whole path tree. This is what we implemented:

static void _mkdir(const char *dir) {
char tmp[256];
char *p = NULL;
size_t len;
snprintf(tmp, sizeof(tmp),"%s",dir);
len = strlen(tmp);
if(tmp[len - 1] == '/')
tmp[len - 1] = 0;
for(p = tmp + 1; *p; p++)
if(*p == '/') {
*p = 0;
mkdir(tmp, S_IRWXU);
*p = '/';
}
mkdir(tmp, S_IRWXU);
}

Now _mkdir ("/home/nion/irc/server/channel"); works. If someone knows a better and maybe shorter variant please let me know.

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mkdir -p /home/nion/irc/server/channel

#1 daniel (Homepage) on 2005-08-22 12:14 (Reply)

And how does "mkdir -p" implement it?

That's the root of the problem, as far as I understand Nico, and his solution is definitely cheaper than calling an external program.

#1.1 foo on 2005-08-22 12:38 (Reply)

bong

Its a C program not a shell script, so no mkdir -p. And I will not use system, exec, ... for such things

#2 nion (Homepage) on 2005-08-22 12:37 (Reply)

did you really test your code?

char *p;
...
p = '/';
-> segfault

you could also check opath[0] for a '/' so it won't try to access and create an empty path.

#3 paul on 2005-08-22 22:59 (Reply)

Yes off course I do.
The code seems to be fucked up because of the html formatting. Fuck, thanks!
See http://nion.modprobe.de/tmp/mkdir.c
for the difference..

It works!
Fucking blog editor.

#4 nion (Homepage) on 2005-08-22 23:29 (Reply)

the comment fucked up the code in the html page grml

#5 nion (Homepage) on 2005-08-22 23:35 (Reply)

hi,
why don't you use strdup?
why don't you use strsep + chdir?

best regards

#6 Anonymous on 2005-08-25 12:46 (Reply)

because of security we work with absoulte paths

#7 nion (Homepage) on 2005-08-25 14:01 (Reply)

Thanks. I made a few edits to make it work in MSoft Visual C, and made it support wchar_t, and both forward and back slash:

void CreateDirectoryAnyDepth(const wchar_t *path)
{
wchar_t opath[MAX_PATH];
wchar_t *p;
size_t len;
wcsncpy_s(opath, path, sizeof(opath));
len = wcslen(opath);
if(opath[len - 1] == L'/')
opath[len - 1] = L'\0';

for(p = opath; *p; p++)
{
if(*p == L'/' || *p == L'\\')
{
*p = L'\0';
if(_waccess(opath, 0))
_wmkdir(opath);
*p = L'\\';
}
}
if(_waccess(opath, 0))
_wmkdir(opath);
}

#8 Mark on 2008-01-24 19:59 (Reply)

This is exactly what I needed. THANKS!

#9 Dustin Howett (Homepage) on 2008-10-08 10:50 (Reply)

awesome

#10 grateful on 2008-11-21 22:48 (Reply)

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