Re: [PATCH] getcwd: Set errno to EINVAL when size == 0

[Jens Gustedt <jens.gustedt@inria.fr>]

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Hello,

Am Sonntag, den 06.10.2013, 23:08 -0700 schrieb Michael Forney:
> According to POSIX,
> 
>     The getcwd() function shall fail if:
> 
>     [EINVAL]
>     The size argument is 0.
>     [ERANGE]
>     The size argument is greater than 0, but is smaller than the length
>     of the string +1.
> ---
>  src/unistd/getcwd.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/src/unistd/getcwd.c b/src/unistd/getcwd.c
> index 2e540cd..0238fa7 100644
> --- a/src/unistd/getcwd.c
> +++ b/src/unistd/getcwd.c
> @@ -8,6 +8,10 @@ char *getcwd(char *buf, size_t size)
>  {
>  	char tmp[PATH_MAX];
>  	if (!buf) buf = tmp, size = PATH_MAX;
> +	else if (size == 0) {
> +		errno = EINVAL;
> +		return 0;
> +	}
>  	if (syscall(SYS_getcwd, buf, size) < 0) return 0;

Is the new error check really necessary?  I would have expected the
error path to have triggered before when buf is !0 and size is 0 on
entry.

>  	return buf == tmp ? strdup(buf) : buf;

This in turn doesn't seem to be consistent with the extension that
glibc offers. It says

> In  this case, the allocated buffer has the length size 

So I would think that strdup(buf) should be replaced by something like

strcpy(malloc(size), buf)

Jens

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