[OpenWrt-Devel] [PATCH v2] procd: Add cached and available to memory table

[Zachary Cook]

This should allow Luci to show a better measure of system memory usage
Cached memory will be used to add a new progress bar
MemAvailable is the kernel's estimate of memory that is useable
by userspace without swapping, and is more accurate than the current
memory.free + memory.buffered calculation for total memory available

Changes in v2:
reorganized code to not leak a file descriptor if early return
stay consistent with current comment style
use atoll instead of atol to better match the data size

Signed-off-by: Zachary Cook <zachcook1991 at gmail.com>
---
 system.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/system.c b/system.c
index 8ed3f93..79f0ca8 100644
--- a/system.c
+++ b/system.c
@@ -228,9 +228,36 @@ static int system_info(struct ubus_context *ctx, struct ubus_object *obj,
 #ifdef linux
 	struct sysinfo info;
 	void *c;
+	char line[256];
+	char *key, *val;
+	unsigned long long available, cached;
+	FILE *f;
 
 	if (sysinfo(&info))
 		return UBUS_STATUS_UNKNOWN_ERROR;
+
+	if ((f = fopen("/proc/meminfo", "r")) == NULL)
+		return UBUS_STATUS_UNKNOWN_ERROR;
+	
+	/* if linux < 3.14 MemAvailable is not in meminfo */
+	available = 0;
+	cached = 0;
+
+	while(fgets(line, sizeof(line), f))
+	{
+		key = strtok(line, " :");
+		val = strtok(NULL, " ");
+
+		if (!key || !val)
+			continue;
+
+		if (!strcasecmp(key, "MemAvailable"))
+			available = 1024 * atoll(val);
+		else if (!strcasecmp(key, "Cached"))
+			cached =    1024 * atoll(val);
+	}
+
+	fclose(f);
 #endif
 
 	now = time(NULL);
@@ -256,6 +283,8 @@ static int system_info(struct ubus_context *ctx, struct ubus_object *obj,
 	blobmsg_add_u64(&b, "free",     info.mem_unit * info.freeram);
 	blobmsg_add_u64(&b, "shared",   info.mem_unit * info.sharedram);
 	blobmsg_add_u64(&b, "buffered", info.mem_unit * info.bufferram);
+	blobmsg_add_u64(&b, "available",available);
+	blobmsg_add_u64(&b, "cached",   cached);
 	blobmsg_close_table(&b, c);
 
 	c = blobmsg_open_table(&b, "swap");
-- 
2.20.1


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