From d148b0efdc5ccbfdf2621a908a4ac613dfabe090 Mon Sep 17 00:00:00 2001
From: Dieter Baron <dillo@nih.at>
Date: Wed, 23 Aug 2023 12:38:30 +0200
Subject: [PATCH] Make sure we use and report the modification time
 consistently.

This is important, since it is used for password verification.

Adresses issue #394.
---
 lib/zip_close.c                |  5 +++++
 lib/zip_source_pkware_encode.c | 35 ++++++++++++++++++++++++++++------
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/lib/zip_close.c b/lib/zip_close.c
index 6b33cbf5e..a93e04522 100644
--- a/lib/zip_close.c
+++ b/lib/zip_close.c
@@ -396,6 +396,11 @@ add_data(zip_t *za, zip_source_t *src, zip_dirent_t *de, zip_uint32_t changed) {
     src_final = src;
     zip_source_keep(src_final);
 
+    if (!needs_decrypt && de->encryption_method == ZIP_EM_TRAD_PKWARE && (de->changed & ZIP_DIRENT_LAST_MOD)) {
+        /* PKWare encryption uses the last modification time for password verification, therefore we can't change it without re-encrypting. Ignoring the requested modification time change seems more sensible than failing to close the archive. */
+         de->changed &= ~ZIP_DIRENT_LAST_MOD;
+    }
+
     if (needs_decrypt) {
         zip_encryption_implementation impl;
 
diff --git a/lib/zip_source_pkware_encode.c b/lib/zip_source_pkware_encode.c
index cf2d34c9f..d89b9f4e8 100644
--- a/lib/zip_source_pkware_encode.c
+++ b/lib/zip_source_pkware_encode.c
@@ -42,6 +42,8 @@ struct trad_pkware {
     zip_pkware_keys_t keys;
     zip_buffer_t *buffer;
     bool eof;
+    bool mtime_set;
+    time_t mtime;
     zip_error_t error;
 };
 
@@ -50,7 +52,7 @@ static int encrypt_header(zip_source_t *, struct trad_pkware *);
 static zip_int64_t pkware_encrypt(zip_source_t *, void *, void *, zip_uint64_t, zip_source_cmd_t);
 static void trad_pkware_free(struct trad_pkware *);
 static struct trad_pkware *trad_pkware_new(const char *password, zip_error_t *error);
-
+static void set_mtime(struct trad_pkware* ctx, zip_stat_t* st);
 
 zip_source_t *
 zip_source_pkware_encode(zip_t *za, zip_source_t *src, zip_uint16_t em, int flags, const char *password) {
@@ -81,16 +83,19 @@ zip_source_pkware_encode(zip_t *za, zip_source_t *src, zip_uint16_t em, int flag
 
 static int
 encrypt_header(zip_source_t *src, struct trad_pkware *ctx) {
-    struct zip_stat st;
     unsigned short dostime, dosdate;
     zip_uint8_t *header;
 
-    if (zip_source_stat(src, &st) != 0) {
-        zip_error_set_from_source(&ctx->error, src);
-        return -1;
+    if (!ctx->mtime_set) {
+        struct zip_stat st;
+        if (zip_source_stat(src, &st) != 0) {
+            zip_error_set_from_source(&ctx->error, src);
+            return -1;
+        }
+        set_mtime(ctx, &st);
     }
 
-    _zip_u2d_time(st.mtime, &dostime, &dosdate);
+    _zip_u2d_time(ctx->mtime, &dostime, &dosdate);
 
     if ((ctx->buffer = _zip_buffer_new(NULL, ZIP_CRYPTO_PKWARE_HEADERLEN)) == NULL) {
         zip_error_set(&ctx->error, ZIP_ER_MEMORY, 0);
@@ -182,6 +187,9 @@ pkware_encrypt(zip_source_t *src, void *ud, void *data, zip_uint64_t length, zip
         if (st->valid & ZIP_STAT_COMP_SIZE) {
             st->comp_size += ZIP_CRYPTO_PKWARE_HEADERLEN;
         }
+        set_mtime(ctx, st);
+        st->mtime = ctx->mtime;
+        st->valid |= ZIP_STAT_MTIME;
 
         return 0;
     }
@@ -229,6 +237,8 @@ trad_pkware_new(const char *password, zip_error_t *error) {
         return NULL;
     }
     ctx->buffer = NULL;
+    ctx->mtime_set = false;
+    ctx->mtime = 0;
     zip_error_init(&ctx->error);
 
     return ctx;
@@ -246,3 +256,16 @@ trad_pkware_free(struct trad_pkware *ctx) {
     zip_error_fini(&ctx->error);
     free(ctx);
 }
+
+
+static void set_mtime(struct trad_pkware* ctx, zip_stat_t* st) {
+    if (!ctx->mtime_set) {
+        if (st->valid & ZIP_STAT_MTIME) {
+            ctx->mtime = st->mtime;
+        }
+        else {
+            time(&ctx->mtime);
+        }
+        ctx->mtime_set = true;
+    }
+}