Am 17.04.2013 18:00, schrieb Serge Hallyn:
> Quoting Richard Weinberger (rich...@nod.at):
>> Reimplement mkdir_p() such that it:
>> ...handles relativ paths correctly. (currently it crashes)
>> ...does not rely on dirname().
>> ...is not recursive.
>> ...is shorter. ;-)
>
> Looks good, thanks. Yeah I prefer non-recursive. Three
> comments though,
>
>> Signed-off-by: Richard Weinberger <rich...@nod.at>
>> ---
>> src/lxc/utils.c | 48 +++++++++++++++++-------------------------------
>> 1 file changed, 17 insertions(+), 31 deletions(-)
>>
>> diff --git a/src/lxc/utils.c b/src/lxc/utils.c
>> index e07ca7b..9794553 100644
>> --- a/src/lxc/utils.c
>> +++ b/src/lxc/utils.c
>> @@ -95,39 +95,25 @@ extern int get_u16(unsigned short *val, const char *arg,
>> int base)
>> return 0;
>> }
>>
>> -static int is_all_slashes(char *path)
>> -{
>> - while (*path && *path == '/')
>> - path++;
>> - if (*path)
>> - return 0;
>> - return 1;
>> -}
>> -
>> extern int mkdir_p(char *dir, mode_t mode)
>> {
>> - int ret;
>> - char *d;
>> -
>> - if (is_all_slashes(dir))
>> - return 0;
>> -
>> - d = strdup(dir);
>> - if (!d)
>> - return -1;
>> -
>> - ret = mkdir_p(dirname(d), mode);
>> - free(d);
>> - if (ret)
>> - return -1;
>> -
>> - if (!access(dir, F_OK))
>> - return 0;
>> -
>> - if (mkdir(dir, mode)) {
>> - SYSERROR("failed to create directory '%s'\n", dir);
>> - return -1;
>> - }
>> + char *tmp = dir;
>> + char *orig = dir;
>> + char *makeme;
>> +
>> + do {
>> + dir = tmp + strspn(tmp, "/");
>> + tmp = dir + strcspn(dir, "/");
>> + makeme = strndupa(orig, dir - orig);
>
> strndupa *can* fail and return NULL.
How?
strndupa() uses alloca(), which allocates memory on the stack.
*If* it fails we have already overrun the stack and are on a one-way trip
to lala land. :-)
>
>> + if (*makeme) {
>> + if (!access(makeme, F_OK))
>> + return 0;
>
> did you mean to continue here?
No, if the access() we have to stop.
"mkdir -p /foo/bar" also just exists if it is not allowed to access one parent
directory.
>> + if (mkdir(makeme, mode)) {
>
> As people are starting to want to thread, I think it's worth making sure
> all mkdirs and creats check for errno=-EEXIST even if they've just
> checked with access. Certainly with the cgroup setup a race is possible
> when starting two simultaneous containers first time after boot using
> the api.
Yes, you are right. I'll update my patch to take care of this.
Thanks,
//richard
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