From ca92f1c0aa9cd2461d8834ab26441c60b3ac3def Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=BD=D0=B0=D0=B1?= <nabijaczleweli@nabijaczleweli.xyz>
Date: Mon, 10 Aug 2020 18:01:53 +0200
Subject: [PATCH] Pipe the deliveries and payload into stage 3 instead of
 passing them in argv

Also removes a useless chdir to the cwd in the fork

Closes: ~sircmpwn/git.sr.ht#279
---
 gitsrht-update-hook/post-update.go | 23 +++++++++++++++++------
 gitsrht-update-hook/stage-3.go     | 21 +++++++++++++++++++--
 2 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/gitsrht-update-hook/post-update.go b/gitsrht-update-hook/post-update.go
index 1021efc..8b9c4e9 100644
--- a/gitsrht-update-hook/post-update.go
+++ b/gitsrht-update-hook/post-update.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"strconv"
 	"strings"
 	"syscall"
 
@@ -335,28 +336,38 @@ func postUpdate() {
 		return
 	}
 
-	// Run stage 3 asyncronously - the last few tasks can be done without
+	// Run stage 3 asynchronously - the last few tasks can be done without
 	// blocking the pusher's terminal.
-	wd, err := os.Getwd()
-	if err != nil {
+	var stage3Pipe [2]int
+	if err := syscall.Pipe(stage3Pipe[:]); err != nil {
 		log.Fatalf("Failed to execute stage 3: %v", err)
 	}
+	syscall.CloseOnExec(stage3Pipe[1])
 
 	procAttr := syscall.ProcAttr{
-		Dir:   wd,
-		Files: []uintptr{os.Stdin.Fd(), os.Stdout.Fd(), os.Stderr.Fd()},
+		Dir:   "",
+		Files: []uintptr{uintptr(stage3Pipe[0]), os.Stdout.Fd(), os.Stderr.Fd()},
 		Env:   os.Environ(),
 		Sys: &syscall.SysProcAttr{
 			Foreground: false,
 		},
 	}
 	pid, err := syscall.ForkExec(hook, []string{
-		"hooks/stage-3", string(deliveriesJson), string(payloadBytes),
+		"hooks/stage-3",
+		strconv.Itoa(len(deliveriesJson)), strconv.Itoa(len(payloadBytes)),
 	}, &procAttr)
 	if err != nil {
 		log.Fatalf("Failed to execute stage 3: %v", err)
 	}
 
+	stage3File := os.NewFile(uintptr(stage3Pipe[1]), "stage3 IPC")
+	if _, err = stage3File.Write(deliveriesJson); err != nil {
+		log.Fatalf("Failed to execute stage 3: %v", err)
+	}
+	if _, err = stage3File.Write(payloadBytes); err != nil {
+		log.Fatalf("Failed to execute stage 3: %v", err)
+	}
+
 	logger.Printf("Executing stage 3 to record %d sync deliveries and make "+
 		"%d async deliveries (pid %d)", len(deliveries),
 		len(dbinfo.AsyncWebhooks), pid)
diff --git a/gitsrht-update-hook/stage-3.go b/gitsrht-update-hook/stage-3.go
index b445e37..2c01fbe 100644
--- a/gitsrht-update-hook/stage-3.go
+++ b/gitsrht-update-hook/stage-3.go
@@ -4,6 +4,7 @@ import (
 	"database/sql"
 	"encoding/json"
 	"os"
+	"strconv"
 
 	_ "github.com/lib/pq"
 )
@@ -30,10 +31,26 @@ func stage3() {
 
 	var subscriptions []WebhookSubscription
 	var deliveries []WebhookDelivery
-	if err := json.Unmarshal([]byte(os.Args[1]), &deliveries); err != nil {
+	deliveriesJsonLen, err := strconv.Atoi(os.Args[1])
+	if err != nil {
+		logger.Fatalf("deliveriesJson length \"%v\": %v", string(os.Args[1]), err)
+	}
+	deliveriesJson := make([]byte, deliveriesJsonLen)
+	if read, err := os.Stdin.Read(deliveriesJson); read != len(deliveriesJson) {
+		logger.Fatalf("Failed to read deliveries: %v, %v", read, err)
+	}
+	if err := json.Unmarshal(deliveriesJson, &deliveries); err != nil {
 		logger.Fatalf("Unable to unmarhsal delivery array: %v", err)
 	}
-	payload := []byte(os.Args[2])
+
+	payloadLen, err := strconv.Atoi(os.Args[2])
+	if err != nil {
+		logger.Fatalf("payload length \"%v\": %v", string(os.Args[2]), err)
+	}
+	payload := make([]byte, payloadLen)
+	if read, err := os.Stdin.Read(payload); read != len(payload) {
+		logger.Fatalf("Failed to read payload: %v, %v", read, err)
+	}
 
 	var rows *sql.Rows
 	if rows, err = db.Query(`
-- 
2.38.4