From c2077a2fbd856fdee3dfde323369e5e91c2ea860 Mon Sep 17 00:00:00 2001
From: Malavan Sotheeswaran <105669860+msotheeswaran@users.noreply.github.com>
Date: Thu, 2 Mar 2023 13:51:47 -0500
Subject: [PATCH] Fix rdb fd leak (#579)

* close tempfile when done bgsave

* declare getTempFileName

* open close child pipes in correct place

* assert no existing child pipe when opening new child pipe
---
 src/childinfo.cpp | 1 +
 src/rdb.cpp       | 6 +++---
 src/rdb.h         | 1 +
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/childinfo.cpp b/src/childinfo.cpp
index ec3e3c133..f1fba91dd 100644
--- a/src/childinfo.cpp
+++ b/src/childinfo.cpp
@@ -42,6 +42,7 @@ typedef struct {
  * RDB / AOF saving process from the child to the parent (for instance
  * the amount of copy on write memory used) */
 void openChildInfoPipe(void) {
+    serverAssert(g_pserver->child_info_pipe[0] == -1);
     if (pipe(g_pserver->child_info_pipe) == -1) {
         /* On error our two file descriptors should be still set to -1,
          * but we call anyway closeChildInfoPipe() since can't hurt. */
diff --git a/src/rdb.cpp b/src/rdb.cpp
index 593f3c911..7e2c7f125 100644
--- a/src/rdb.cpp
+++ b/src/rdb.cpp
@@ -1490,7 +1490,7 @@ int rdbSaveFile(char *filename, const redisDbPersistentDataSnapshot **rgpdb, rdb
     rio rdb;
     int error = 0;
 
-    snprintf(tmpfile,sizeof(tmpfile),"temp-%d-%d.rdb", getpid(), g_pserver->rdbThreadVars.tmpfileNum);
+    getTempFileName(tmpfile, g_pserver->rdbThreadVars.tmpfileNum);
     fp = fopen(tmpfile,"w");
     if (!fp) {
         char *cwdp = getcwd(cwd,MAXPATHLEN);
@@ -1660,12 +1660,14 @@ int launchRdbSaveThread(pthread_t &child, rdbSaveInfo *rsi)
         pthread_attr_t tattr;
         pthread_attr_init(&tattr);
         pthread_attr_setstacksize(&tattr, 1 << 23); // 8 MB
+        openChildInfoPipe();
         if (pthread_create(&child, &tattr, rdbSaveThread, args)) {
             pthread_attr_destroy(&tattr);
             for (int idb = 0; idb < cserver.dbnum; ++idb)
                 g_pserver->db[idb]->endSnapshot(args->rgpdb[idb]);
             args->~rdbSaveThreadArgs();
             zfree(args);
+            closeChildInfoPipe();
             return C_ERR;
         }
         pthread_attr_destroy(&tattr);
@@ -1683,13 +1685,11 @@ int rdbSaveBackground(rdbSaveInfo *rsi) {
 
     g_pserver->dirty_before_bgsave = g_pserver->dirty;
     g_pserver->lastbgsave_try = time(NULL);
-    openChildInfoPipe();
 
     start = ustime();
     latencyStartMonitor(g_pserver->rdb_save_latency);
 
     if (launchRdbSaveThread(child, rsi) != C_OK) {
-        closeChildInfoPipe();
         g_pserver->lastbgsave_status = C_ERR;
         serverLog(LL_WARNING,"Can't save in background: fork: %s",
             strerror(errno));
diff --git a/src/rdb.h b/src/rdb.h
index 2e017e4e0..68dc7a138 100644
--- a/src/rdb.h
+++ b/src/rdb.h
@@ -151,6 +151,7 @@ int rdbLoad(rdbSaveInfo *rsi, int rdbflags);
 int rdbLoadFile(const char *filename, rdbSaveInfo *rsi, int rdbflags);
 int rdbSaveBackground(rdbSaveInfo *rsi);
 int rdbSaveToSlavesSockets(rdbSaveInfo *rsi);
+void getTempFileName(char tmpfile[], int tmpfileNum);
 void rdbRemoveTempFile(pid_t childpid, int from_signal);
 int rdbSave(const redisDbPersistentDataSnapshot **rgpdb, rdbSaveInfo *rsi);
 int rdbSaveFile(char *filename, const redisDbPersistentDataSnapshot **rgpdb, rdbSaveInfo *rsi);