Re: [PATCH] Add use of asprintf()

Hi,

I did put some time review the patch, please see my findings below i.e.

1. It seems that you have used strdup() on multiple places in the patch,
e.g. in the below code snippet is it going to lead crash if newp->ident is
NULL because of strdup() failure ?

static EPlan *
> find_plan(char *ident, EPlan **eplan, int *nplans)
> {
> ...
> newp->ident = strdup(ident);
> ...
> }

2. Can we rely on return value of asprintf() instead of recompute length as
strlen(cmdbuf) ?

if (asprintf(&cmdbuf, "COMMENT ON LARGE OBJECT %u IS '", loid) <
> 0)
> return fail_lo_xact("\\lo_import", own_transaction);
> bufptr = cmdbuf + strlen(cmdbuf);

3. There seems naming convention for functions like pfree (that seems
similar to free()), pstrdup etc; but psprintf seems different than sprintf.
Can't we use pg_asprintf instead in the patch, as it seems that both
(psprintf and pg_asprintf) provide almost same functionality ?

4. It seems that "ret < 0" need to be changed to "rc < 0" in the following
code i.e.

int
> pg_asprintf(char **ret, const char *format, ...)
> {
> va_list ap;
> int rc;
> va_start(ap, format);
> rc = vasprintf(ret, format, ap);
> va_end(ap);
> if (ret < 0)
> {
> fprintf(stderr, _("out of memory\n"));
> exit(EXIT_FAILURE);
> }
> return rc;
> }

5. It seems that in the previously implementation, error handling was not
there, is it appropriate here that if there is issue in duplicating
environment, quit the application ? i.e.

/*
> * Handy subroutine for setting an environment variable "var" to "val"
> */
> static void
> doputenv(const char *var, const char *val)
> {
> char *s;
> pg_asprintf(&s, "%s=%s", var, val);
> putenv(s);
> }

Please do let me know if I missed something or more info is required. Thank
you.

Regards,
Muhammad Asif Naeem

On Tue, Sep 17, 2013 at 1:31 AM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>wrote:

> Peter Eisentraut wrote:
>
> > The attached patch should speak for itself.
>
> Yeah, it's a very nice cleanup.
>
> > I have supplied a few variants:
> >
> > - asprintf() is the standard function, supplied by libpgport if
> > necessary.
> >
> > - pg_asprintf() is asprintf() with automatic error handling (like
> > pg_malloc(), etc.)
> >
> > - psprintf() is the same idea but with palloc.
>
> Looks good to me, except that pg_asprintf seems to be checking ret
> instead of rc.
>
> Is there a reason for the API discrepancy of pg_asprintf vs. psprintf?
> I don't see that we use the integer return value anywhere. Callers
> interested in the return value can use asprintf directly (and you have
> already inserted callers that do nonstandard things using direct
> asprintf).
>
> --
> Álvaro Herrera http://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Training & Services
>
>
> --
> Sent via pgsql-hackers mailing list (pgsql-hackers(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-hackers
>