Very Computer

by **Keith Michae** » Wed, 25 Nov 1998 04:00:00

How do I check whether a pointer value will cause a segmentation
violation before using it?

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-------------------------------------------------------------
| Keith R. Michaels Archival Evangelist |
| (425)865-6415 Boeing Archival Service (ufs.boeing.com)|
| Enterprise Servers, Technical Services, SSG. |
-------------------------------------------------------------

by **Marvin Wolftha** » Sat, 28 Nov 1998 04:00:00

Use purify.

> How do I check whether a pointer value will cause a segmentation
> violation before using it?

> --
> -------------------------------------------------------------
> | Keith R. Michaels Archival Evangelist |
> | (425)865-6415 Boeing Archival Service (ufs.boeing.com)|
> | Enterprise Servers, Technical Services, SSG. |
> -------------------------------------------------------------

--
Marvin Wolfthal
Technical Director,
FSJ, Inc.

by **Andrew Gabri** » Sat, 28 Nov 1998 04:00:00

Quote:>How do I check whether a pointer value will cause a segmentation
>violation before using it?

int validaddr(void *addr)
{
static long pagemask = -1;
char c;
if (pagemask == -1)
pagemask = ~(sysconf(_SC_PAGESIZE) - 1); /* initialise */

addr = (void *)((long)addr & pagemask); /* base of page */
if (mincore((char *)addr, 1, &c) == -1 && errno == ENOMEM)
return 0; /* invalid */
else
return 1; /* valid */

Quote:}

.
.
.

if (!validaddr(suspect_pointer))
printf("Duff pointer %p\n", suspect_pointer);
.
.
.

[IIRC, this is based on something Casper posted a while back]

It won't tell you what type of accesses are permitted to the
address though.

--
Andrew Gabriel
Consultant Software Engineer

Very Computer

avoiding segmentation violation

avoiding segmentation violation

avoiding segmentation violation

avoiding segmentation violation