virtualize the 'btime' field of /proc/stat

Currently, the 'btime' of /proc/stat reflects the boot time of the host.
We would like it to reflect when the guest boots, so use the start time of
init.

Signed-off-by: Jason Baron <jbaron@akamai.com>

diff --git a/bindings.c b/bindings.c
index a23c34947c2bba9bb7d4744147c63c0ba41e4d5d..8973df87cec94466d896a6d3cfac4f9c6a1088e4 100644 (file)
--- a/bindings.c
+++ b/bindings.c
@@ -3450,6 +3450,27 @@ err:
        return rv;
 }
 
+static long int getreaperctime(pid_t pid)
+{
+       char fnam[100];
+       struct stat sb;
+       int ret;
+       pid_t qpid;
+
+       qpid = lookup_initpid_in_store(pid);
+       if (qpid <= 0)
+               return 0;
+
+       ret = snprintf(fnam, 100, "/proc/%d", qpid);
+       if (ret < 0 || ret >= 100)
+               return 0;
+
+       if (lstat(fnam, &sb) < 0)
+               return 0;
+
+       return sb.st_ctime;
+}
+
 static int proc_stat_read(char *buf, size_t size, off_t offset,
                struct fuse_file_info *fi)
 {
@@ -3513,7 +3534,10 @@ static int proc_stat_read(char *buf, size_t size, off_t offset,
                        continue;
                if (sscanf(line, "cpu%9[^ ]", cpu_char) != 1) {
                        /* not a ^cpuN line containing a number N, just print it */
-                       l = snprintf(cache, cache_size, "%s", line);
+                       if (strncmp(line, "btime", 5) == 0)
+                               l = snprintf(cache, cache_size, "btime %ld\n", getreaperctime(fc->pid));
+                       else
+                               l = snprintf(cache, cache_size, "%s", line);
                        if (l < 0) {
                                perror("Error writing to cache");
                                rv = 0;
@@ -3603,23 +3627,12 @@ err:
 
 static long int getreaperage(pid_t pid)
 {
-       char fnam[100];
-       struct stat sb;
-       int ret;
-       pid_t qpid;
-
-       qpid = lookup_initpid_in_store(pid);
-       if (qpid <= 0)
-               return 0;
-
-       ret = snprintf(fnam, 100, "/proc/%d", qpid);
-       if (ret < 0 || ret >= 100)
-               return 0;
-
-       if (lstat(fnam, &sb) < 0)
-               return 0;
+       long int ctime;
 
-       return time(NULL) - sb.st_ctime;
+       ctime = getreaperctime(pid);
+       if (ctime)
+               return time(NULL) - ctime;
+       return ctime;
 }
 
 static unsigned long get_reaper_busy(pid_t task)