From 053bd55d37a1fa1400644a0b3a7721530abd65d3 Mon Sep 17 00:00:00 2001
From: Donald Buczek <buczek@molgen.mpg.de>
Date: Mon, 29 Mar 2021 18:49:17 +0200
Subject: [PATCH] mxqd: Add option --prerequisites

---
 mxq_daemon.h |  1 +
 mxqd.c       | 33 +++++++++++++++++++++++++++++++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/mxq_daemon.h b/mxq_daemon.h
index c1069f46..65474982 100644
--- a/mxq_daemon.h
+++ b/mxq_daemon.h
@@ -49,6 +49,7 @@ struct mxq_daemon {
 
     int daemon_flags;
     char *tags;
+    char *prerequisites;
 };
 
 void mxq_daemon_free_content(struct mxq_daemon *daemon);
diff --git a/mxqd.c b/mxqd.c
index 40160bb9..3941912f 100644
--- a/mxqd.c
+++ b/mxqd.c
@@ -44,6 +44,7 @@
 
 #include "mxqd_control.h"
 #include "keywordset.h"
+#include "parser.tab.h"
 
 #ifndef MXQ_INITIAL_PATH
 #  define MXQ_INITIAL_PATH      "/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin"
@@ -79,8 +80,8 @@ static void print_usage(void)
     "options:\n"
     "  -j, --slots     <slots>           default: depends on number of cores\n"
     "  -m, --memory    <totalmemory>     default: 2G\n"
-    "  -t, --max-time  <minutes>         default: 0 (unlimited)"
-    "\n"
+    "  -t, --max-time  <minutes>         default: 0 (unlimited)\n"
+    "      --prerequisites <expr>        default: ''\n"
     "  -x, --max-memory-per-slot-soft <softlimit>\n"
     "                         root user: default: <totalmemory>/<slots>\n"
     "                     non-root user: default: <totalmemory>\n"
@@ -424,6 +425,22 @@ static void read_cpufeatures(struct keywordset *kws) {
     fclose(proc_cpuinfo);
 }
 
+static int expression_is_valid(char *expr) {
+    struct keywordset *tags = keywordset_new(NULL);
+    struct parser_context parser_context = {
+        .input = expr,
+        .tags = tags,
+        .pos = 0,
+        .result = 0,
+    };
+    int sts = yyparse(&parser_context);
+    keywordset_free(tags);
+    if (sts)
+        return 0;
+    else
+        return 1;
+}
+
 int server_init(struct mxq_server *server, int argc, char *argv[])
 {
     assert(server);
@@ -438,6 +455,7 @@ int server_init(struct mxq_server *server, int argc, char *argv[])
     char *arg_logdir = NULL;
     char *arg_initial_path;
     char *arg_initial_tmpdir;
+    char *arg_prerequisites = "";
     char arg_daemonize = 0;
     char arg_nolog = 0;
     char arg_recoveronly = 0;
@@ -478,6 +496,7 @@ int server_init(struct mxq_server *server, int argc, char *argv[])
                 MX_OPTION_OPTIONAL_ARG("mysql-default-file",  'M'),
                 MX_OPTION_OPTIONAL_ARG("mysql-default-group", 'S'),
                 MX_OPTION_OPTIONAL_ARG("max-time",      't'),
+                MX_OPTION_OPTIONAL_ARG("prerequisites",  11),
                 MX_OPTION_END
     };
 
@@ -631,6 +650,10 @@ int server_init(struct mxq_server *server, int argc, char *argv[])
                     return -EX_USAGE;
                 }
                 break;
+
+            case 11:
+                arg_prerequisites = optctl.optarg;
+                break;
         }
     }
 
@@ -662,6 +685,11 @@ int server_init(struct mxq_server *server, int argc, char *argv[])
     server->initial_tmpdir = arg_initial_tmpdir;
     server->recoveronly = arg_recoveronly;
 
+    if (*arg_prerequisites != 0 && !expression_is_valid(arg_prerequisites)) {
+            mx_log_err("syntax error in --prerequisites expression \"%s\"", arg_prerequisites);
+            return -EX_UNAVAILABLE;
+    }
+
     server->flock = mx_flock(LOCK_EX, "/dev/shm/mxqd.%s.%s.lck", server->hostname, server->daemon_name);
     if (!server->flock) {
         mx_log_err("mx_flock(/dev/shm/mxqd.%s.%s.lck) failed: %m", server->hostname, server->daemon_name);
@@ -812,6 +840,7 @@ int server_init(struct mxq_server *server, int argc, char *argv[])
     daemon->daemon_maxtime = server->maxtime;
     daemon->daemon_memory_limit_slot_soft = server->memory_limit_slot_soft;
     daemon->daemon_memory_limit_slot_hard = server->memory_limit_slot_hard;
+    daemon->prerequisites = arg_prerequisites;
 
     server->tags=keywordset_new("true");
     keywordset_add(server->tags, server->hostname);