Date: 17 Jul 1999 14:42:43 +0200 From: Dag-Erling Smorgrav <des@flood.ping.uio.no> To: hackers@freebsd.org Subject: Determining the return address Message-ID: <xzpwvvzo3b0.fsf@flood.ping.uio.no>
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Is there any (evidently non-portable) way of determining a function
instance's return address? I have an idea or two that involves the
return address and dladdr(). The code I currently use looks like this:
int
log_print(log_t *log, char *fmt, ...)
{
char date[32], str[MAX_LOG_LINE];
struct iovec iov[10];
Dl_info info;
size_t len;
va_list ap;
int n;
len = log_makedate(date, sizeof date);
iov[n=0].iov_base = date;
iov[n].iov_len = len;
if (dladdr(*(((void**)&log)-1), &info) == 0)
iov[++n].iov_base = "(unknown)";
else
iov[++n].iov_base = (char *)info.dli_sname;
iov[n].iov_len = strlen(iov[n].iov_base);
iov[++n].iov_base = ": ";
iov[n].iov_len = 2;
va_start(ap, fmt);
len = lvformat(str, sizeof str, fmt, ap);
va_end(ap);
while (len > 0 && isspace(str[len-1]))
--len;
iov[++n].iov_base = str;
iov[n].iov_len = len;
iov[++n].iov_base = "\n";
iov[n].iov_len = 1;
return writev(log->fd, iov, ++n);
}
Is it correct? (empirical evidence suggests it is) Is there any better
way to do it? Will it work on the Alpha?
BTW, is dladdr() signal-safe?
DES
--
Dag-Erling Smorgrav - des@flood.ping.uio.no
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