[LTP] [PATCH] lib: add tst_read_meminfo / tst_get_avail_mem

Jan Stancek
2016-06-15T12:51:33Z

On 06/15/2016 09:34 AM, Jan Stancek wrote:
>
>
>
> ----- Original Message -----
>> From: "Li Wang" <liwang@redhat.com>
>> To: "Jan Stancek" <jstancek@redhat.com>
>> Cc: ltp@lists.linux.it
>> Sent: Tuesday, 14 June, 2016 4:37:29 PM
>> Subject: Re: [LTP] [PATCH] lib: add tst_read_meminfo / tst_get_avail_mem
>>
>> It is a good proposal, but the achieved function seems a little bit
>> narrow for ltp-lib.
>
> OK, let me try to come up with something more generic.

How about something like this?

#include <stdio.h>
#include "tst_proc.h"

#define TST_NO_DEFAULT_MAIN
#include "tst_test.h"

static const char *path_meminfo = "/proc/meminfo";

typedef int walk_func(const char *line, void *priv);

/*
* Go through all lines in a text file, calling walk_func() on each
* until it returns 1 or file hits EOF. Returns last return value of
* walk_func().
*
* @filename: name of text file to walk
* @walk_func: function called for each line
* @func_priv: walk_func's specific struct representing in/out data
* */
static int walk_file_lines(const char *filename, walk_func func,
void *func_priv)
{
FILE *fp;
char line[BUFSIZ];

fp = fopen(filename, "r");
if (fp == NULL)
tst_brk(TBROK | TERRNO, "fopen %s", path_meminfo);

while (fgets(line, BUFSIZ, fp) != NULL) {
if (func(line, func_priv) == 1) {
fclose(fp);
return 1;
}
continue;
}
fclose(fp);

return 0;
}

struct colonpair_str_long
{
const char *key;
long value;
};

/*
* Returns 1 if "line" matches pattern: "Key: Value" and
* Key is equal to colonpair_str_long->key, otherwise returns 0.
*
* @line: line searched for pattern
* @priv: pointer to colonpair_str_long struct where
* .key - Key to search for
* .value - stores "Value" if "Key" is found
*/
static int match_colonpair_str_long(const char *line, void *priv)
{
struct colonpair_str_long *s = priv;
char buf[BUFSIZ];
long val;

if (sscanf(line, "%64s %ld", buf, &val) == 2) {
/* strip colon for comparison with key */
buf[strlen(buf) - 1] = '\0';

if (strcmp(buf, s->key) == 0) {
s->value = val;
return 1;
}
}

return 0;
}

static long read_colonpair_str_long(const char *filename, const char *key,
long ret_for_missing)
{
struct colonpair_str_long data = {
.key = key,
};

if (walk_file_lines(filename, match_colonpair_str_long, &data))
return data.value;

return ret_for_missing;
}

/*
* Search for Key: Value pair in /proc/meminfo, if found
* return Value, otherwise return -1.
*/
long tst_get_meminfo(const char *key)
{
return read_colonpair_str_long(path_meminfo, key, -1);
}

long tst_get_avail_mem(void)
{
long mem_available;

mem_available = tst_get_meminfo("MemAvailable");
if (mem_available == -1) {
mem_available = tst_get_meminfo("MemFree");
mem_available += tst_get_meminfo("Cached");
}

return mem_available;
}