From 8d9fcf658aadb4848038fbcbeb1561f82d21e7c7 Mon Sep 17 00:00:00 2001
From: Thomas Schmitt <scdbackup@gmx.net>
Date: Sun, 1 Sep 2024 18:41:10 +0200
Subject: [PATCH] =?UTF-8?q?Made=20filelist=20weight=20sorting=20determinis?=
 =?UTF-8?q?tic=20with=20different=20qsort=20implementations.=20By=20Henrik?=
 =?UTF-8?q?=20Lindstr=C3=B6m.?=
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---
 libisofs/ecma119.c |  4 ++--
 libisofs/filesrc.c | 13 ++++++++++++-
 libisofs/filesrc.h | 11 +++++++----
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/libisofs/ecma119.c b/libisofs/ecma119.c
index 5c076a9..1db605e 100644
--- a/libisofs/ecma119.c
+++ b/libisofs/ecma119.c
@@ -4633,8 +4633,8 @@ void ecma119_filesrc_array(Ecma119Node *dir,
             } else {
                 if (!child->info.file->taken) {
                     filelist[*size] = child->info.file;
-                    child->info.file->taken = 1;
                     (*size)++;
+                    child->info.file->taken = *size;
                 }
             }
         }
@@ -4658,8 +4658,8 @@ void hidden_filesrc_array(Ecma119Image *t,
         } else {
             if (!item->src->taken) {
                 filelist[*size] = item->src;
-                item->src->taken = 1;
                 (*size)++;
+                item->src->taken = *size;
             }
         }
     }
diff --git a/libisofs/filesrc.c b/libisofs/filesrc.c
index 7213f29..be7c8c6 100644
--- a/libisofs/filesrc.c
+++ b/libisofs/filesrc.c
@@ -218,8 +218,19 @@ static int cmp_by_weight(const void *f1, const void *f2)
 {
     IsoFileSrc *f = *((IsoFileSrc**)f1);
     IsoFileSrc *g = *((IsoFileSrc**)f2);
+    int cmp;
+
     /* higher weighted first */
-    return g->sort_weight - f->sort_weight;
+    cmp = g->sort_weight - f->sort_weight;
+    if (cmp)
+        return cmp;
+    /* Make the result of qsort(3) stable by avoiding return value 0 as good
+       as possible. If not f == g, then their ->taken values are supposed
+       to differ.
+     */
+    if(f->taken == g->taken)
+      return 0;
+    return f->taken < g->taken ? -1 : 1;
 }
 
 static
diff --git a/libisofs/filesrc.h b/libisofs/filesrc.h
index 5dbb742..a89d497 100644
--- a/libisofs/filesrc.h
+++ b/libisofs/filesrc.h
@@ -32,12 +32,15 @@ struct Iso_File_Src
     */
     unsigned int no_write :1;
 
-    /* Is 1 if the object was already put into the filelist array.
-    */
-    unsigned int taken :1;
-
     unsigned int checksum_index :31;
 
+    /* Is > 0 if the object was already put into the filelist array.
+       In this case, the value is the order in which it was inserted,
+       which can be used for stable sorting of the filelist array in
+       case of identical file weights.
+    */
+    size_t taken;
+
     /** File Sections of the file in the image */
     /* Special sections[0].block values while they are relative
        before filesrc_writer_compute_data_blocks().