fix: better logging behaviour

src/helpers/drop_privileges.c

@@ -0,0 +1,81 @@
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+
+#include <config.h>
+#include <logger.h>
+
+static uid_t
+get_uid_for_user(char *user)
+{
+    if(user == NULL || user[0] == '\0')
+    {
+        return getuid();
+    }
+    struct passwd *pwd = calloc(1, sizeof(struct passwd));
+    size_t buffer_len = sysconf(_SC_GETPW_R_SIZE_MAX) * sizeof(char);
+    char *buffer = malloc(buffer_len);
+    getpwnam_r(user, pwd, buffer, buffer_len, &pwd);
+
+    if(pwd == NULL)
+    {
+        LOGGER_CRIT("couldn't find user to drop privileges\n");
+        exit(1);
+    }
+
+    uid_t result = pwd->pw_uid;
+    free(buffer);
+    free(pwd);
+    return result;
+}
+
+static gid_t
+get_gid_for_group(char *group)
+{
+    if(group == NULL || group[0] == '\0')
+    {
+        return getgid();
+    }
+    struct group *grp = calloc(1, sizeof(struct group));
+    size_t buffer_len = sysconf(_SC_GETPW_R_SIZE_MAX) * sizeof(char);
+    char *buffer = malloc(buffer_len);
+    getgrnam_r(group, grp, buffer, buffer_len, &grp);
+
+    if(grp == NULL)
+    {
+        LOGGER_CRIT("couldn't find group to drop privileges\n");
+        exit(1);
+    }
+
+    gid_t result = grp->gr_gid;
+    free(buffer);
+    free(grp);
+    return result;
+}
+
+int
+helper_drop_privileges()
+{
+    uid_t uid = get_uid_for_user(global_config.user);
+    gid_t gid = get_gid_for_group(global_config.group);
+
+    LOGGER_DEBUG("drop privileges to %lu:%lu\n", uid, gid);
+
+    if (setgid(gid) == -1)
+    {
+        LOGGER_CRIT("failed to drop group privileges\n");
+        exit(1);
+    }
+    if (setuid(uid) == -1)
+    {
+        LOGGER_CRIT("failed to drop user privileges\n");
+        exit(1);
+    }
+
+    return 0;
+}
+
+