lxc: fuse: Fix /proc/meminfo size calculation

We virtualize bits of /proc/meminfo by replacing host values with
values specific to the container.

However for calculating the final size of the returned data, we are
using the size of the original file and not the altered copy, which
could give garbelled output.

src/lxc/lxc_fuse.c

@@ -131,7 +131,6 @@ static int lxcProcHostRead(char *path, char *buf, size_t size, off_t offset)
 static int lxcProcReadMeminfo(char *hostpath, virDomainDefPtr def,
                               char *buf, size_t size, off_t offset)
 {
-    int copied = 0;
     int res;
     FILE *fd = NULL;
     char *line = NULL;
@@ -159,7 +158,7 @@ static int lxcProcReadMeminfo(char *hostpath, virDomainDefPtr def,
     }
 
     res = -1;
-    while (copied < size && getline(&line, &n, fd) > 0) {
+    while (getline(&line, &n, fd) > 0) {
         char *ptr = strchr(line, ':');
         if (!ptr)
             continue;
@@ -219,13 +218,11 @@ static int lxcProcReadMeminfo(char *hostpath, virDomainDefPtr def,
             res = -errno;
             goto cleanup;
         }
-
-        copied += strlen(line);
-        if (copied > size)
-            copied = size;
     }
-    res = copied;
-    memcpy(buf, virBufferCurrentContent(new_meminfo), copied);
+    res = strlen(virBufferCurrentContent(new_meminfo));
+    if (res > size)
+        res = size;
+    memcpy(buf, virBufferCurrentContent(new_meminfo), res);
 
  cleanup:
     VIR_FREE(line);