RE: Problem with getenv("HOME")

RE: Problem with getenv("HOME")

[Sergey Okhapkin]

Wolfgang Stuerzlinger wrote:
> By default the environment variable HOME is not set in the GNU-Win32
> environment.
> When getenv is called with ("HOME") as argument the return value is a
> string "(null)" instead of a NULL pointer. Is this a "standard" behaviour 
> or a bug?
>
> Wolfgang Stuerzlinger
>
> P.S.: This breaks commonly used code sequences like:
> 	sprintf(newName,"%s/%s",getenv("HOME"),fileName);

It's a bug in your example. getenv() returns NULL pointer, but sprintf 
formats it as a "(null)" string. You have to check getenv's return value 
before passing it somwhere.

--
Sergey Okhapkin, http://www.lexa.ru/sos
Moscow, Russia
Looking for a job.


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Re: Problem with getenv("HOME")

[marcus]

>When getenv is called with ("HOME") as argument the return value is a
>string "(null)" instead of a NULL pointer. Is this a "standard" behaviour 
>or a bug?

>Wolfgang Stuerzlinger

>P.S.: This breaks commonly used code sequences like:
>	sprintf(newName,"%s/%s",getenv("HOME"),fileName);

Are you sure that this isn't in sprintf?

It is common for printf-like routines to actually print "(null)" when
a NULL pointer is passed for a %s conversion.  Unfortunately, it is
also a rather common implementation for it to blindly use the NULL
pointer and fault or output garbage :-(

Anyhow, I think that getenv() is in fact returning NULL in this case.

Try this:

	if (getenv("HOME") == NULL)
		printf("NULL pointer returned\n");

Or:
	printf("Return of getenv: 0x%x\n", getenv("HOME"));

marcus hall
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Problem with getenv("HOME")

[Wolfgang Stuerzlinger]

By default the environment variable HOME is not set in the GNU-Win32
environment.
When getenv is called with ("HOME") as argument the return value is a
string "(null)" instead of a NULL pointer. Is this a "standard" behaviour 
or a bug?

Wolfgang Stuerzlinger

P.S.: This breaks commonly used code sequences like:
	sprintf(newName,"%s/%s",getenv("HOME"),fileName);
--
Wolfgang Stuerzlinger
Dept. of Computer Science, UNC, Chapel Hill, NC 27599-3175
stuerzl@cs.unc.edu          http://www.cs.unc.edu/~stuerzl



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