From 44b94875b597458e69b06878cc468a7c3c94f41b Mon Sep 17 00:00:00 2001
From: "Roger A. Light" <roger@atchoo.org>
Date: Thu, 8 Jun 2023 22:45:31 +0100
Subject: [PATCH] mosquitto_passwd uses mkstemp() for backup files.

---
 ChangeLog.txt                            |  3 +++
 apps/mosquitto_passwd/mosquitto_passwd.c | 18 +++++++++++++++---
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/ChangeLog.txt b/ChangeLog.txt
index e382b41c4..2c4e71645 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -29,6 +29,9 @@ Clients:
 - Fix incorrect topic-alias property value in mosquitto_sub json output.
 - Fix confusing message on TLS certificate verification. Closes #2746.
 
+Apps:
+- mosquitto_passwd uses mkstemp() for backup files.
+
 
 2.0.15 - 2022-08-16
 ===================
diff --git a/apps/mosquitto_passwd/mosquitto_passwd.c b/apps/mosquitto_passwd/mosquitto_passwd.c
index 0a5ba722c..262f89cf6 100644
--- a/apps/mosquitto_passwd/mosquitto_passwd.c
+++ b/apps/mosquitto_passwd/mosquitto_passwd.c
@@ -370,15 +370,27 @@ static int copy_contents(FILE *src, FILE *dest)
 	return 0;
 }
 
-static int create_backup(const char *backup_file, FILE *fptr)
+static int create_backup(char *backup_file, FILE *fptr)
 {
 	FILE *fbackup;
 
+#ifdef WIN32
 	fbackup = mosquitto__fopen(backup_file, "wt", true);
+#else
+	int fd;
+	umask(077);
+	fd = mkstemp(backup_file);
+	if(fd < 0){
+		fprintf(stderr, "Error creating backup password file \"%s\", not continuing.\n", backup_file);
+		return 1;
+	}
+	fbackup = fdopen(fd, "wt");
+#endif
 	if(!fbackup){
 		fprintf(stderr, "Error creating backup password file \"%s\", not continuing.\n", backup_file);
 		return 1;
 	}
+
 	if(copy_contents(fptr, fbackup)){
 		fprintf(stderr, "Error copying data to backup password file \"%s\", not continuing.\n", backup_file);
 		fclose(fbackup);
@@ -617,13 +629,13 @@ int main(int argc, char *argv[])
 			return 1;
 		}
 
-		backup_file = malloc((size_t)strlen(password_file)+5);
+		backup_file = malloc((size_t)strlen(password_file)+strlen(".backup.XXXXXX"));
 		if(!backup_file){
 			fprintf(stderr, "Error: Out of memory.\n");
 			free(password_file);
 			return 1;
 		}
-		snprintf(backup_file, strlen(password_file)+5, "%s.tmp", password_file);
+		snprintf(backup_file, strlen(password_file)+5, "%s.backup.XXXXXX", password_file);
 		free(password_file);
 		password_file = NULL;