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Systems with lots of geom providers can end up with a kern.geom.confxml

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value too large for the buffer allocated. Work around this by retrying
a few times with larger buffer sizes.

Submitted by:	Scott Ferris <scott.ferris@isilon.com>
Reviewed by:	mlaier, ngie
Sponsored by:	EMC Isilon Storage Division
This commit is contained in:
Benno Rice 2014-09-04 03:31:48 +00:00
parent f214250a17
commit 39a8d9f3f0
1 changed files with 34 additions and 7 deletions
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41
lib/libgeom/geom_getxml.c
View File

@ -31,10 +31,23 @@
#include <sys/types.h>
#include <sys/sysctl.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include "libgeom.h"
/*
* Amount of extra space we allocate to try and anticipate the size of
* confxml.
*/
#define GEOM_GETXML_SLACK 4096
/*
* Number of times to retry in the face of the size of confxml exceeding
* that of our buffer.
*/
#define GEOM_GETXML_RETRIES 4
char *
geom_getxml(void)
{
@ -42,19 +55,33 @@ geom_getxml(void)
size_t l = 0;
int mib[3];
size_t sizep;
int retries;
sizep = sizeof(mib) / sizeof(*mib);
if (sysctlnametomib("kern.geom.confxml", mib, &sizep) != 0)
return (NULL);
if (sysctl(mib, sizep, NULL, &l, NULL, 0) != 0)
return (NULL);
l += 4096;
p = malloc(l);
if (p == NULL)
return (NULL);
if (sysctl(mib, sizep, p, &l, NULL, 0) != 0) {
l += GEOM_GETXML_SLACK;
for (retries = 0; retries < GEOM_GETXML_RETRIES; retries++) {
p = malloc(l);
if (p == NULL)
return (NULL);
if (sysctl(mib, sizep, p, &l, NULL, 0) == 0)
return (reallocf(p, strlen(p) + 1));
free(p);
return (NULL);
if (errno != ENOMEM)
return (NULL);
/*
* Our buffer wasn't big enough. Make it bigger and
* try again.
*/
l *= 2;
}
return (reallocf(p, strlen(p) + 1));
return (NULL);
}