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Try to avoid ambiguity when sysctl returns ENOMEM additionally

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checking the returned oldlen: when ENOMEM is due to the supplied
buffer being too short the return oldlen is equal to buffer size.

Without this additional check kvm_getprocs() gets stuck in loop if the
returned ENOMEM was due the exceeded memorylocked limit. This is
easily can be observed running `limits -l 1k top'.

Submitted by:	Andrey Zonov <andrey zonov org>
MFC after:	1 week
This commit is contained in:
Mikolaj Golub 2012-02-01 18:02:13 +00:00
parent b34650e320
commit 767993ec97
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=230873
1 changed files with 3 additions and 2 deletions
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5
lib/libkvm/kvm_proc.c
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@ -474,7 +474,7 @@ struct kinfo_proc *
kvm_getprocs(kvm_t *kd, int op, int arg, int *cnt)
{
int mib[4], st, nprocs;
size_t size;
size_t size, osize;
int temp_op;
if (kd->procbase != 0) {
@ -524,10 +524,11 @@ kvm_getprocs(kvm_t *kd, int op, int arg, int *cnt)
_kvm_realloc(kd, kd->procbase, size);
if (kd->procbase == 0)
return (0);
osize = size;
st = sysctl(mib, temp_op == KERN_PROC_ALL ||
temp_op == KERN_PROC_PROC ? 3 : 4,
kd->procbase, &size, NULL, 0);
} while (st == -1 && errno == ENOMEM);
} while (st == -1 && errno == ENOMEM && size == osize);
if (st == -1) {
_kvm_syserr(kd, kd->program, "kvm_getprocs");
return (0);