timestamp.c: correctly NUL terminate buffer read from /proc/pid/stat

This solves buf #28.

diff --git a/timestamp.c b/timestamp.c
index 38c89ffcf590c083fbc4a3ce15d2b4b05d0ded1d..75a3af7cbf6572bfa7086d83bf33654b69f5948f 100644 (file)
--- a/timestamp.c
+++ b/timestamp.c
@@ -98,12 +98,12 @@ proc_info(pid_t pid, int *ttynr, unsigned long long *starttime)
        if (n < 0 || n >= (int)sizeof path)
                return -1;
 
-       if ((fd = open(path, O_RDONLY)) == -1) {
+       if ((fd = open(path, O_RDONLY|O_NOFOLLOW)) == -1) {
                warn("failed to open: %s", path);
                return -1;
        }
 
-       while ((n = read(fd, p, buf + sizeof buf - p)) != 0) {
+       while ((n = read(fd, p, buf + (sizeof buf - 1) - p)) != 0) {
                if (n == -1) {
                        if (errno == EAGAIN || errno == EINTR)
                                continue;
@@ -112,15 +112,18 @@ proc_info(pid_t pid, int *ttynr, unsigned long long *starttime)
                        return -1;
                }
                p += n;
-               if (p >= buf + sizeof buf)
+               if (p >= buf + (sizeof buf - 1))
                        break;
        }
        close(fd);
 
        /* error if it contains NULL bytes */
-       if (n != 0 || memchr(buf, '\0', p - buf)) {
+       if (n != 0 || memchr(buf, '\0', p - buf - 1) != NULL) {
                warn("NUL in: %s", path);
                return -1;
+       }
+
+       *p = '\0';
 
        /* Get the 7th field, 5 fields after the last ')',
         * (2th field) because the 5th field 'comm' can include