lib: account for cwd access from snapshot serialization cb

Functions registered with `addSerializeCallback()` can access and call `process.cwd()`. b7d836e accounted for the fact that it is necessary to reset the cwd cache after the snapshot builder script has run, but did not account for possible accesses from serialization callbacks. To properly account for these, add a deserialization callback as well. As a related drive-by fix, also mention the execution order of callbacks in the documentation. Refs: #49684 PR-URL: #51901 Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Michaël Zasso <[email protected]> Reviewed-By: Marco Ippolito <[email protected]>

Author: addaleax

doc/api/v8.md

@@ -1021,6 +1021,8 @@ get serialized into a snapshot and exit. This can be used to release
 resources that should not or cannot be serialized or to convert user data
 into a form more suitable for serialization.
 
+Callbacks are run in the order in which they are added.
+
 ### `v8.startupSnapshot.addDeserializeCallback(callback[, data])`
 
 <!-- YAML
@@ -1040,6 +1042,8 @@ serialized into the snapshot, they can be used to re-initialize the state
 of the application or to re-acquire resources that the application needs
 when the application is restarted from the snapshot.
 
+Callbacks are run in the order in which they are added.
+
 ### `v8.startupSnapshot.setDeserializeMainFunction(callback[, data])`
 
 <!-- YAML

lib/internal/bootstrap/switches/does_own_process_state.js

@@ -4,6 +4,7 @@ const credentials = internalBinding('credentials');
 constrawMethods=internalBinding('process_methods');
 const{
 namespace: {
+ addDeserializeCallback,
  addSerializeCallback,
  isBuildingSnapshot,
 },
@@ -114,8 +115,13 @@ function wrapPosixCredentialSetters(credentials){
 letcachedCwd='';
 
 if(isBuildingSnapshot()){
+// Reset the cwd on both serialization and deserialization so it's fine
+// for process.cwd() to be accessed inside of serialization callbacks.
 addSerializeCallback(()=>{
 cachedCwd='';
+addDeserializeCallback(()=>{
+cachedCwd='';
+});
 });
 }
 

test/fixtures/snapshot/cwd.js

@@ -1,10 +1,16 @@
 const{
+ addSerializeCallback,
  setDeserializeMainFunction,
 }=require('v8').startupSnapshot;
 
 // To make sure the cwd is present in the cache
 process.cwd();
 
+// Also access it from a serialization callback once
+addSerializeCallback(()=>{
+process.cwd();
+});
+
 setDeserializeMainFunction(()=>{
 console.log(process.cwd());
 });