systemd-bootchart: Repair Entropy Graph

Entropy Graph code doesn't handle the error condition if open() of /proc entry
fails. Moreover, the file is only opened once and only first sample will contain
the correct value because the return value of pread() is also not handled
properly and file is not re-opened. Fix both problems.

diff --git a/src/bootchart/store.c b/src/bootchart/store.c
index 8e9a62f91d9f9402cdcf14cab0190982f852833d..fb3dc9ad6e6cb138a2b614f4f41055cc63c46cce 100644 (file)
--- a/src/bootchart/store.c
+++ b/src/bootchart/store.c
@@ -119,7 +119,7 @@ void log_sample(int sample, struct list_sample_data **ptr) {
         int c;
         int p;
         int mod;
-        static int e_fd;
+        static int e_fd = -1;
         ssize_t s;
         ssize_t n;
         struct dirent *ent;
@@ -215,16 +215,21 @@ schedstat_next:
         }
 
         if (arg_entropy) {
-                if (!e_fd) {
+                if (e_fd < 0) {
                         e_fd = openat(procfd, "sys/kernel/random/entropy_avail", O_RDONLY);
+                        if (e_fd == -1) {
+                                log_error_errno(errno, "Failed to open /proc/sys/kernel/random/entropy_avail: %m");
+                                exit(EXIT_FAILURE);
+                        }
                 }
 
-                if (e_fd) {
-                        n = pread(e_fd, buf, sizeof(buf) - 1, 0);
-                        if (n > 0) {
-                                buf[n] = '\0';
-                                sampledata->entropy_avail = atoi(buf);
-                        }
+                n = pread(e_fd, buf, sizeof(buf) - 1, 0);
+                if (n <= 0) {
+                        close(e_fd);
+                        e_fd = -1;
+                } else {
+                        buf[n] = '\0';
+                        sampledata->entropy_avail = atoi(buf);
                 }
         }