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procps/proc/meminfo.c
Jim Warner b8c688fb36 library: meminfo redesigned to use 'stack' vs. 'chain' 
In addition to that text shown below the line which is
common to several commit messages, this patch contains
the following additional change without an API impact:

. The #include header files are ordered alphabetically
now, with all those <sys/??> types separately grouped.

------------------------------------------------------
. The former 'chains' have now become 'stacks' without
the 'next' pointer in each result struct. The pointers
initially seemed to offer some flexibility with memory
allocations and benefits for the library access logic.
However, user access was always via displacement and a
a statically allocated chain was cumbersome to define.

. An enumerator ending in '_noop' will no longer serve
as a fencepost delimiter. Rather, it has become a much
more important and flexible user oriented tool. Adding
one or more such 'items' in any items list passed into
the library becomes the means of extending the 'stack'
to also include user (not just library) data. Any such
data is guaranteed to never be altered by the library.

. Anticipating PID support, where many different types
must be represented in a result structure, we'll adopt
a common naming standard. And, while not every results
structure currently needs to reflect disparate types a
union will be employed so the same dot qualifier ('.')
can be used consistently when accessing all such data.

Signed-off-by: Jim Warner <james.warner@comcast.net>
2015-07-23 22:31:24 +10:00

568 lines
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/*
* meminfo - Memory statistics part of procps
*
* Copyright (C) 1992-1998 by Michael K. Johnson <johnsonm@redhat.com>
* Copyright (C) 1998-2003 Albert Cahalan
* Copyright (C) 2015 Craig Small <csmall@enc.com.au>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <proc/meminfo.h>
#include "procps-private.h"
#define MEMINFO_FILE "/proc/meminfo"
struct meminfo_data {
unsigned long active;
unsigned long inactive;
unsigned long high_free;
unsigned long high_total;
unsigned long low_free;
unsigned long low_total;
unsigned long available;
unsigned long buffers;
unsigned long cached;
unsigned long free;
unsigned long shared;
unsigned long total;
unsigned long used;
unsigned long slab;
unsigned long swap_free;
unsigned long swap_total;
unsigned long swap_used;
};
struct procps_meminfo {
int refcount;
int meminfo_fd;
struct meminfo_data data;
struct stacks_anchor *stacked;
};
struct stack_vectors {
struct stacks_anchor *owner;
struct meminfo_stack **heads;
};
struct stacks_anchor {
int depth;
int header_size;
struct stack_vectors *vectors;
struct stacks_anchor *self;
struct stacks_anchor *next;
};
/*
* procps_meminfo_new():
*
* Create a new container to hold the meminfo information
*
* The initial refcount is 1, and needs to be decremented
* to release the resources of the structure.
*
* Returns: a new meminfo info container
*/
PROCPS_EXPORT int procps_meminfo_new (
struct procps_meminfo **info)
{
struct procps_meminfo *m;
m = calloc(1, sizeof(struct procps_meminfo));
if (!m)
return -ENOMEM;
m->refcount = 1;
m->meminfo_fd = -1;
*info = m;
return 0;
}
/*
* procps_meminfo_read():
*
* Read the data out of /proc/meminfo putting the information
* into the supplied info structure
*/
PROCPS_EXPORT int procps_meminfo_read (
struct procps_meminfo *info)
{
char buf[8192];
char *head, *tail;
int size;
unsigned long *valptr;
signed long mem_used;
if (info == NULL)
return -1;
memset(&(info->data), 0, sizeof(struct meminfo_data));
/* read in the data */
if (-1 == info->meminfo_fd && (info->meminfo_fd = open(MEMINFO_FILE, O_RDONLY)) == -1) {
return -errno;
}
if (lseek(info->meminfo_fd, 0L, SEEK_SET) == -1) {
return -errno;
}
for (;;) {
if ((size = read(info->meminfo_fd, buf, sizeof(buf)-1)) < 0) {
if (errno == EINTR || errno == EAGAIN)
continue;
return -errno;
}
break;
}
if (size == 0)
return 0;
buf[size] = '\0';
/* Scan the file */
head = buf;
do {
tail = strchr(head, ' ');
if (!tail)
break;
*tail = '\0';
valptr = NULL;
switch (*head) {
case 'A':
if (0 == strcmp(head, "Active:"))
valptr = &(info->data.active);
break;
case 'B':
if (0 == strcmp(head, "Buffers:"))
valptr = &(info->data.buffers);
break;
case 'C':
if (0 == strcmp(head, "Cached:"))
valptr = &(info->data.cached);
break;
case 'H':
if (0 == strcmp(head, "HighFree:"))
valptr = &(info->data.high_free);
else if (0 == strcmp(head, "HighTotal:"))
valptr = &(info->data.high_total);
break;
case 'I':
if (0 == strcmp(head, "Inactive:"))
valptr = &(info->data.inactive);
break;
case 'L':
if (0 == strcmp(head, "LowFree:"))
valptr = &(info->data.low_free);
else if (0 == strcmp(head, "LowTotal:"))
valptr = &(info->data.low_total);
break;
case 'M':
if (0 == strcmp(head, "MemAvailable:"))
valptr = &(info->data.available);
else if (0 == strcmp(head, "MemFree:"))
valptr = &(info->data.free);
else if (0 == strcmp(head, "MemTotal:"))
valptr = &(info->data.total);
break;
case 'S':
if (0 == strcmp(head, "Slab:"))
valptr = &(info->data.slab);
else if (0 == strcmp(head, "SwapFree:"))
valptr = &(info->data.swap_free);
else if (0 == strcmp(head, "SwapTotal:"))
valptr = &(info->data.swap_total);
else if (0 == strcmp(head, "Shmem:"))
valptr = &(info->data.shared);
break;
default:
break;
}
head = tail+1;
if (valptr) {
*valptr = strtoul(head, &tail, 10);
}
tail = strchr(head, '\n');
if (!tail)
break;
head = tail + 1;
} while(tail);
if (0 == info->data.low_total) {
info->data.low_total = info->data.total;
info->data.low_free = info->data.free;
}
if (0 == info->data.available) {
info->data.available = info->data.free;
}
info->data.cached += info->data.slab;
info->data.swap_used = info->data.swap_total - info->data.swap_free;
/* if 'available' is greater than 'total' or our calculation of mem_used
overflows, that's symptomatic of running within a lxc container where
such values will be dramatically distorted over those of the host. */
if (info->data.available > info->data.total)
info->data.available = info->data.free;
mem_used = info->data.total - info->data.free - info->data.cached - info->data.buffers;
if (mem_used < 0)
mem_used = info->data.total - info->data.free;
info->data.used = (unsigned long)mem_used;
return 0;
}
PROCPS_EXPORT int procps_meminfo_ref (
struct procps_meminfo *info)
{
if (info == NULL)
return -EINVAL;
info->refcount++;
return info->refcount;
}
PROCPS_EXPORT int procps_meminfo_unref (
struct procps_meminfo **info)
{
if (info == NULL || *info == NULL)
return -EINVAL;
(*info)->refcount--;
if ((*info)->refcount == 0) {
if ((*info)->stacked) {
do {
struct stacks_anchor *p = (*info)->stacked;
(*info)->stacked = (*info)->stacked->next;
free(p);
} while((*info)->stacked);
}
free(*info);
*info = NULL;
return 0;
}
return (*info)->refcount;
}
/*
* Accessor functions
*/
PROCPS_EXPORT unsigned long procps_meminfo_get (
struct procps_meminfo *info,
enum meminfo_item item)
{
switch (item) {
case PROCPS_MEM_ACTIVE:
return info->data.active;
case PROCPS_MEM_INACTIVE:
return info->data.inactive;
case PROCPS_MEMHI_FREE:
return info->data.high_free;
case PROCPS_MEMHI_TOTAL:
return info->data.high_total;
case PROCPS_MEMHI_USED:
if (info->data.high_free > info->data.high_total)
return 0;
return info->data.high_total - info->data.high_free;
case PROCPS_MEMLO_FREE:
return info->data.low_free;
case PROCPS_MEMLO_TOTAL:
return info->data.low_total;
case PROCPS_MEMLO_USED:
if (info->data.low_free > info->data.low_total)
return 0;
return info->data.low_total - info->data.low_free;
case PROCPS_MEM_AVAILABLE:
return info->data.available;
case PROCPS_MEM_BUFFERS:
return info->data.buffers;
case PROCPS_MEM_CACHED:
return info->data.cached;
case PROCPS_MEM_FREE:
return info->data.free;
case PROCPS_MEM_SHARED:
return info->data.shared;
case PROCPS_MEM_TOTAL:
return info->data.total;
case PROCPS_MEM_USED:
return info->data.used;
case PROCPS_SWAP_FREE:
return info->data.swap_free;
case PROCPS_SWAP_TOTAL:
return info->data.swap_total;
case PROCPS_SWAP_USED:
if (info->data.swap_free > info->data.swap_total)
return 0;
return info->data.swap_total - info->data.swap_free;
default:
return 0;
}
}
PROCPS_EXPORT int procps_meminfo_getstack (
struct procps_meminfo *info,
struct meminfo_result *these)
{
if (info == NULL || these == NULL)
return -EINVAL;
for (;;) {
switch (these->item) {
case PROCPS_MEM_ACTIVE:
these->result.ul_int = info->data.active;
break;
case PROCPS_MEM_INACTIVE:
these->result.ul_int = info->data.inactive;
break;
case PROCPS_MEMHI_FREE:
these->result.ul_int = info->data.high_free;
break;
case PROCPS_MEMHI_TOTAL:
these->result.ul_int = info->data.high_total;
break;
case PROCPS_MEMHI_USED:
if (info->data.high_free > info->data.high_total)
these->result.ul_int = 0;
else
these->result.ul_int = info->data.high_total - info->data.high_free;
break;
case PROCPS_MEMLO_FREE:
these->result.ul_int = info->data.low_free;
break;
case PROCPS_MEMLO_TOTAL:
these->result.ul_int = info->data.low_total;
break;
case PROCPS_MEMLO_USED:
if (info->data.low_free > info->data.low_total)
these->result.ul_int = 0;
else
these->result.ul_int = info->data.low_total - info->data.low_free;
break;
case PROCPS_MEM_AVAILABLE:
these->result.ul_int = info->data.available;
break;
case PROCPS_MEM_BUFFERS:
these->result.ul_int = info->data.buffers;
break;
case PROCPS_MEM_CACHED:
these->result.ul_int = info->data.cached;
break;
case PROCPS_MEM_FREE:
these->result.ul_int = info->data.free;
break;
case PROCPS_MEM_SHARED:
these->result.ul_int = info->data.shared;
break;
case PROCPS_MEM_TOTAL:
these->result.ul_int = info->data.total;
break;
case PROCPS_MEM_USED:
these->result.ul_int = info->data.used;
break;
case PROCPS_SWAP_FREE:
these->result.ul_int = info->data.swap_free;
break;
case PROCPS_SWAP_TOTAL:
these->result.ul_int = info->data.swap_total;
break;
case PROCPS_SWAP_USED:
if (info->data.swap_free > info->data.swap_total)
these->result.ul_int = 0;
else
these->result.ul_int = info->data.swap_total - info->data.swap_free;
break;
case PROCPS_MEM_noop:
// don't disturb potential user data in the result struct
break;
case PROCPS_MEM_stack_end:
return 0;
default:
return -EINVAL;
}
++these;
}
}
PROCPS_EXPORT int procps_meminfo_stack_fill (
struct procps_meminfo *info,
struct meminfo_stack *stack)
{
int rc;
if (info == NULL || stack == NULL || stack->head == NULL)
return -EINVAL;
if ((rc == procps_meminfo_read(info)) < 0)
return rc;
return procps_meminfo_getstack(info, stack->head);
}
static void stacks_validate (struct meminfo_stack **v, const char *who)
{
#if 0
#include <stdio.h>
int i, t, x, n = 0;
struct stack_vectors *p = (struct stack_vectors *)v - 1;
fprintf(stderr, "%s: called by '%s'\n", __func__, who);
fprintf(stderr, "%s: owned by %p (whose self = %p)\n", __func__, p->owner, p->owner->self);
for (x = 0; v[x]; x++) {
struct meminfo_stack *h = v[x];
struct meminfo_result *r = h->head;
fprintf(stderr, "%s: vector[%02d] = %p", __func__, x, h);
i = 0;
for (i = 0; r->item < PROCPS_MEM_stack_end; i++, r++)
;
t = i + 1;
fprintf(stderr, ", stack %d found %d elements\n", n, i);
++n;
}
fprintf(stderr, "%s: found %d stack(s), each %d bytes (including eos)\n", __func__, x, (int)sizeof(struct meminfo_result) * t);
fprintf(stderr, "%s: this header size = %2d\n", __func__, (int)p->owner->header_size);
fprintf(stderr, "%s: sizeof(struct meminfo_stack) = %2d\n", __func__, (int)sizeof(struct meminfo_stack));
fprintf(stderr, "%s: sizeof(struct meminfo_result) = %2d\n", __func__, (int)sizeof(struct meminfo_result));
fputc('\n', stderr);
return;
#endif
}
static struct meminfo_result *stack_make (
struct meminfo_result *p,
int maxitems,
enum meminfo_item *items)
{
struct meminfo_result *p_sav = p;
int i;
for (i = 0; i < maxitems; i++) {
p->item = items[i];
// note: we rely on calloc to initialize actual result
++p;
}
return p_sav;
}
static int stack_items_valid (
int maxitems,
enum meminfo_item *items)
{
int i;
for (i = 0; i < maxitems; i++) {
if (items[i] < PROCPS_MEMHI_FREE)
return 0;
if (items[i] > PROCPS_MEM_stack_end)
return 0;
}
if (items[maxitems -1] != PROCPS_MEM_stack_end)
return 0;
return 1;
}
/*
* procps_meminfo_stacks_alloc():
*
* A local copy of code borrowed from slab.c to support the public version
* representing a single stack. Currently there is no conceivable need
* for multiple stacks in the 'memory' arena.
*/
static struct meminfo_stack **procps_meminfo_stacks_alloc (
struct procps_meminfo *info,
int maxstacks,
int stack_extra,
int maxitems,
enum meminfo_item *items)
{
struct stacks_anchor *p_blob;
struct stack_vectors *p_vect;
struct meminfo_stack *p_head;
size_t vect_size, head_size, list_size, blob_size;
void *v_head, *v_list;
int i;
if (info == NULL || items == NULL)
return NULL;
if (maxstacks < 1 || maxitems < 1)
return NULL;
if (!stack_items_valid(maxitems, items))
return NULL;
vect_size = sizeof(struct stack_vectors); // address vector struct
vect_size += sizeof(void *) * maxstacks; // plus vectors themselves
vect_size += sizeof(void *); // plus NULL delimiter
head_size = sizeof(struct meminfo_stack) + stack_extra; // a head struct + user stuff
list_size = sizeof(struct meminfo_result) * maxitems; // a results stack
blob_size = sizeof(struct stacks_anchor); // the anchor itself
blob_size += vect_size; // all vectors + delims
blob_size += head_size * maxstacks; // all head structs + user stuff
blob_size += list_size * maxstacks; // all results stacks
/* note: all memory is allocated in a single blob, facilitating a later free().
as a minimum, it's important that the result structures themselves always be
contiguous for any given stack (just as they are when defined statically). */
if (NULL == (p_blob = calloc(1, blob_size)))
return NULL;
p_blob->next = info->stacked;
info->stacked = p_blob;
p_blob->self = p_blob;
p_blob->header_size = head_size;
p_blob->vectors = (void *)p_blob + sizeof(struct stacks_anchor);
p_vect = p_blob->vectors;
p_vect->owner = p_blob->self;
p_vect->heads = (void *)p_vect + sizeof(struct stack_vectors);
v_head = (void *)p_vect + vect_size;
v_list = v_head + (head_size * maxstacks);
for (i = 0; i < maxstacks; i++) {
p_head = (struct meminfo_stack *)v_head;
p_head->head = stack_make((struct meminfo_result *)v_list, maxitems, items);
p_blob->vectors->heads[i] = p_head;
v_list += list_size;
v_head += head_size;
}
p_blob->depth = maxstacks;
stacks_validate(p_blob->vectors->heads, __func__);
return p_blob->vectors->heads;
}
/*
* procps_meminfo_stack_alloc():
*
* Allocate and initialize a single result stack under a simplified interface.
*
* Such a stack will will have its result structures properly primed with
* 'items', while the result itself will be zeroed.
*
*/
PROCPS_EXPORT struct meminfo_stack *procps_meminfo_stack_alloc (
struct procps_meminfo *info,
int maxitems,
enum meminfo_item *items)
{
struct meminfo_stack **v;
v = procps_meminfo_stacks_alloc(info, 1, 0, maxitems, items);
if (!v)
return NULL;
stacks_validate(v, __func__);
return v[0];
}
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