src/daemon/common.[ch]: add check_capability() function

This is largely inspired by the capability check done in
src/turbostat.c, so most of the credits go to Vincent Brillault.

diff --git a/src/daemon/common.c b/src/daemon/common.c
index c4dbecb..3e2db15 100644 (file)
--- a/src/daemon/common.c
+++ b/src/daemon/common.c
@@ -60,6 +60,10 @@
 # include <arpa/inet.h>
 #endif
 
+#ifdef HAVE_SYS_CAPABILITY_H
+# include <sys/capability.h>
+#endif
+
 #ifdef HAVE_LIBKSTAT
 extern kstat_ctl_t *kc;
 #endif
@@ -1668,3 +1672,26 @@ void strarray_free (char **array, size_t array_len) /* {{{ */
                sfree (array[i]);
        sfree (array);
 } /* }}} void strarray_free */
+
+#ifdef HAVE_SYS_CAPABILITY_H
+int check_capability (int capability) /* {{{ */
+{
+       struct __user_cap_header_struct cap_header_data;
+       cap_user_header_t cap_header = &cap_header_data;
+       struct __user_cap_data_struct cap_data_data;
+       cap_user_data_t cap_data = &cap_data_data;
+
+       cap_header->pid = getpid();
+       cap_header->version = _LINUX_CAPABILITY_VERSION;
+       if (capget(cap_header, cap_data) < 0)
+       {
+               ERROR("check_capability: capget failed");
+               return (-1);
+       }
+
+       if ((cap_data->effective & (1 << capability)) == 0)
+               return (-1);
+       else
+               return (0);
+} /* }}} int check_capability */
+#endif

diff --git a/src/daemon/common.h b/src/daemon/common.h
index 5ad2b50..720e5f1 100644 (file)
--- a/src/daemon/common.h
+++ b/src/daemon/common.h
@@ -375,4 +375,12 @@ int strtogauge (const char *string, gauge_t *ret_value);
 int strarray_add (char ***ret_array, size_t *ret_array_len, char const *str);
 void strarray_free (char **array, size_t array_len);
 
+#ifdef HAVE_SYS_CAPABILITY_H
+/** Check if the current process benefits from the capability passed in
+ * argument. Returns zero if it does, less than zero if it doesn't or on error.
+ * See capabilities(7) for the list of possible capabilities.
+ * */
+int check_capability (int capability);
+#endif /* HAVE_SYS_CAPABILITY_H */
+
 #endif /* COMMON_H */