Am 17.04.2013 22:49, schrieb Serge Hallyn:
> Quoting Richard Weinberger (rich...@nod.at):
>> 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?
>
> I was hoping that smart libc on embedded would return NULL if it sees
> there isn't enough space. I misread the strndupa manpage to say it
> returns NULL on failure - I see there is no such promise.
>
>> 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.
> =========
>
> If the access() does what? access("/var", F_OK) should immediately
> return 0, so you're saying mkdir_p("/var/lib/lxc/c1") should immediately
> fail? It's entirely possible I'm not thinking right, but...
Please let me dig into mkdir(1) to copy the exact semantics. :-)
Thanks,
//richard
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