From 44c8d02e51ff29c94d15855ea82c3d4814f5ec5c Mon Sep 17 00:00:00 2001
From: Sven <skbotnl@disroot.org>
Date: Thu, 9 Apr 2026 19:24:00 +0200
Subject: [PATCH 1/6] Call correct real function in the position0 hook

---
 src/fis_hook.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/fis_hook.c b/src/fis_hook.c
index 2b5c12a..9f6f3ea 100644
--- a/src/fis_hook.c
+++ b/src/fis_hook.c
@@ -168,7 +168,7 @@ jlong JNICALL fis_length0_hook(JNIEnv *env, jobject thiz) {
 
 jlong JNICALL fis_position0_hook(JNIEnv *env, jobject thiz) {
   if (!has_tag(thiz)) {
-    return fis_real_length0(env, thiz);
+    return fis_real_position0(env, thiz);
   }
 
   jclass class = (*env)->GetObjectClass(env, thiz);

From 019c8e58bb7bba02659f346b5a848f4d2cf15f24 Mon Sep 17 00:00:00 2001
From: Sven <skbotnl@disroot.org>
Date: Thu, 9 Apr 2026 19:32:21 +0200
Subject: [PATCH 2/6] Fix possible out of bounds write

---
 src/utils.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/utils.c b/src/utils.c
index d2724a8..185251c 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -59,6 +59,16 @@ void parse_file(char **data_ptr, size_t fsize, const char *filename) {
       if ((c >= 48 && c <= 57) || (c >= 65 && c <= 90) ||
           (c >= 97 && c <= 122) || c == 95) {
         size_t len = strlen(env_var);
+        if (len + 1 >= 4096) {
+          fprintf(stderr,
+                  "\033[0G\e[0;31m[SubstAgent] Failed to expand environment "
+                  "variable \"%s\" in file %s on line %d because it is too "
+                  "big\e[0m\n",
+                  env_var, filename, line_count);
+          begin_env_index = -1;
+          env_var[0] = '\0';
+          continue;
+        }
         env_var[len] = c;
         env_var[len + 1] = '\0';
       } else if (c == '}') {

From 24d5ba8d1212cd334d1682dfc008d73ef4652d2a Mon Sep 17 00:00:00 2001
From: Sven <skbotnl@disroot.org>
Date: Thu, 9 Apr 2026 19:32:35 +0200
Subject: [PATCH 3/6] Fix possible out of bounds read

---
 src/utils.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/utils.c b/src/utils.c
index 185251c..8af5ad4 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -47,7 +47,6 @@ char *substitute(const char *value, int prefix_char_matched_index, size_t i,
 void parse_file(char **data_ptr, size_t fsize, const char *filename) {
   char *data = *data_ptr;
   int line_count = 1;
-  ;
   int begin_env_index = -1;
   char env_var[4096];
   env_var[0] = '\0';
@@ -123,7 +122,7 @@ void parse_file(char **data_ptr, size_t fsize, const char *filename) {
       }
     } else {
       if (c == '^') {
-        if (data[i + 1] == '{') {
+        if (i + 1 < fsize && data[i + 1] == '{') {
           begin_env_index = i;
           i++;
         }

From 5eff59134711384e19d97d743e1cac686a26b61c Mon Sep 17 00:00:00 2001
From: Sven <skbotnl@disroot.org>
Date: Thu, 9 Apr 2026 19:40:44 +0200
Subject: [PATCH 4/6] Improve EOF check

---
 src/fis_hook.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/fis_hook.c b/src/fis_hook.c
index 9f6f3ea..016bd12 100644
--- a/src/fis_hook.c
+++ b/src/fis_hook.c
@@ -139,8 +139,8 @@ jint JNICALL fis_read0_hook(JNIEnv *env, jobject thiz) {
   }
 
   struct fis_file_data *fd = &file->value;
-  char read_byte = fd->data[fd->index++];
-  if (fd->data[fd->index] == '\0') {
+  jint read_byte = (unsigned char)fd->data[fd->index++];
+  if (fd->index >= fd->length) {
     free(fd->data);
     fd->data = NULL;
   }

From 81bdf8b477e1e97df0678287509fc0e5eed1675b Mon Sep 17 00:00:00 2001
From: Sven <skbotnl@disroot.org>
Date: Thu, 9 Apr 2026 19:40:51 +0200
Subject: [PATCH 5/6] Fix tests

---
 tests/Test13.java      | 6 ++++--
 tests/data/test1.txt   | 2 +-
 tests/data/test10.txt  | 2 +-
 tests/data/test11.txt  | 2 +-
 tests/data/test12.txt  | 2 +-
 tests/data/test13.nacf | 2 +-
 tests/data/test2.txt   | 2 +-
 tests/data/test3.txt   | 2 +-
 tests/data/test4.txt   | 2 +-
 tests/data/test5.txt   | 2 +-
 tests/data/test6.txt   | 2 +-
 tests/data/test7.txt   | 2 +-
 tests/data/test8.txt   | 2 +-
 tests/data/test9.txt   | 2 +-
 14 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/tests/Test13.java b/tests/Test13.java
index 4fe9e71..e7c7586 100644
--- a/tests/Test13.java
+++ b/tests/Test13.java
@@ -1,10 +1,12 @@
+
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.util.Arrays;
 
 // Test file that is not a config file
 class Test13 {
-    static String correctString = "This is not a config file so ${SAME_LENGTH_ENV} shouldn't be substituted";
+
+    static String correctString = "This is not a config file so ^{SAME_LENGTH_ENV} shouldn't be substituted";
 
     public static String toHexDump(String s) {
         byte[] bytes = s.getBytes(java.nio.charset.StandardCharsets.UTF_8);
@@ -38,4 +40,4 @@ class Test13 {
             throw e;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/tests/data/test1.txt b/tests/data/test1.txt
index ac896ba..5a70683 100644
--- a/tests/data/test1.txt
+++ b/tests/data/test1.txt
@@ -1 +1 @@
-Hello ${SAME_LENGTH_ENV}
\ No newline at end of file
+Hello ^{SAME_LENGTH_ENV}
\ No newline at end of file
diff --git a/tests/data/test10.txt b/tests/data/test10.txt
index 41e2bea..9f83f57 100644
--- a/tests/data/test10.txt
+++ b/tests/data/test10.txt
@@ -1 +1 @@
-According to all known laws of aviation, there is no way a bee should be able to fly ${SAME_LENGTH_ENV}
\ No newline at end of file
+According to all known laws of aviation, there is no way a bee should be able to fly ^{SAME_LENGTH_ENV}
\ No newline at end of file
diff --git a/tests/data/test11.txt b/tests/data/test11.txt
index 28d934b..0e7e2a4 100644
--- a/tests/data/test11.txt
+++ b/tests/data/test11.txt
@@ -1 +1 @@
-According to all known laws of aviation, there is no way a bee should be able to fly ${SHORTER_ENV}
\ No newline at end of file
+According to all known laws of aviation, there is no way a bee should be able to fly ^{SHORTER_ENV}
\ No newline at end of file
diff --git a/tests/data/test12.txt b/tests/data/test12.txt
index ba48dff..fe09178 100644
--- a/tests/data/test12.txt
+++ b/tests/data/test12.txt
@@ -1 +1 @@
-${SHORTER_ENV}
\ No newline at end of file
+^{SHORTER_ENV}
\ No newline at end of file
diff --git a/tests/data/test13.nacf b/tests/data/test13.nacf
index 75c2861..7cc5b0f 100644
--- a/tests/data/test13.nacf
+++ b/tests/data/test13.nacf
@@ -1 +1 @@
-This is not a config file so ${SAME_LENGTH_ENV} shouldn't be substituted
\ No newline at end of file
+This is not a config file so ^{SAME_LENGTH_ENV} shouldn't be substituted
\ No newline at end of file
diff --git a/tests/data/test2.txt b/tests/data/test2.txt
index c771bec..bb67c8f 100644
--- a/tests/data/test2.txt
+++ b/tests/data/test2.txt
@@ -1 +1 @@
-Hello ${SHORTER_ENV}
\ No newline at end of file
+Hello ^{SHORTER_ENV}
\ No newline at end of file
diff --git a/tests/data/test3.txt b/tests/data/test3.txt
index 16e6ce6..83a5268 100644
--- a/tests/data/test3.txt
+++ b/tests/data/test3.txt
@@ -1 +1 @@
-Hello ${LONGER_ENV}
\ No newline at end of file
+Hello ^{LONGER_ENV}
\ No newline at end of file
diff --git a/tests/data/test4.txt b/tests/data/test4.txt
index 159c530..d8d50b5 100644
--- a/tests/data/test4.txt
+++ b/tests/data/test4.txt
@@ -1 +1 @@
-Hi ${SAME_LENGTH_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
+Hi ^{SAME_LENGTH_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
diff --git a/tests/data/test5.txt b/tests/data/test5.txt
index ddbeee9..9f301eb 100644
--- a/tests/data/test5.txt
+++ b/tests/data/test5.txt
@@ -1 +1 @@
-Hi ${SHORTER_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
+Hi ^{SHORTER_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
diff --git a/tests/data/test6.txt b/tests/data/test6.txt
index 51729d2..8480b64 100644
--- a/tests/data/test6.txt
+++ b/tests/data/test6.txt
@@ -1 +1 @@
-Hi ${LONGER_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
+Hi ^{LONGER_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
diff --git a/tests/data/test7.txt b/tests/data/test7.txt
index 159c530..d8d50b5 100644
--- a/tests/data/test7.txt
+++ b/tests/data/test7.txt
@@ -1 +1 @@
-Hi ${SAME_LENGTH_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
+Hi ^{SAME_LENGTH_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
diff --git a/tests/data/test8.txt b/tests/data/test8.txt
index ddbeee9..9f301eb 100644
--- a/tests/data/test8.txt
+++ b/tests/data/test8.txt
@@ -1 +1 @@
-Hi ${SHORTER_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
+Hi ^{SHORTER_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
diff --git a/tests/data/test9.txt b/tests/data/test9.txt
index 51729d2..8480b64 100644
--- a/tests/data/test9.txt
+++ b/tests/data/test9.txt
@@ -1 +1 @@
-Hi ${LONGER_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file
+Hi ^{LONGER_ENV} According to all known laws of aviation, there is no way a bee should be able to fly
\ No newline at end of file

From 5a6252a24a63eefe5b184882bc7a3ec514e892ee Mon Sep 17 00:00:00 2001
From: Sven <skbotnl@disroot.org>
Date: Thu, 9 Apr 2026 19:53:52 +0200
Subject: [PATCH 6/6] Remove unnecessary return

---
 src/fis_hook.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/fis_hook.c b/src/fis_hook.c
index 016bd12..303c2b4 100644
--- a/src/fis_hook.c
+++ b/src/fis_hook.c
@@ -209,7 +209,6 @@ jlong JNICALL fis_skip0_hook(JNIEnv *env, jobject thiz, jlong n) {
   if (skip == remaining) {
     free(fd->data);
     fd->data = NULL;
-    return skip;
   }
 
   return skip;