From 6dc28ff5673c86d8d6042b47538c2f66e7726717 Mon Sep 17 00:00:00 2001
From: Kevin Day <Kevin@kevux.org>
Date: Tue, 3 Mar 2026 22:41:14 -0600
Subject: [PATCH] Bugfix: Invalid seeked value on failure in f_file_seek().

The `lseek()` can return a negative value.

Use a local variable to get the `lseek()` value.
This then allows for the `seeked` to be NULL.

Change the `seeked` parameter to be optional and when set to NULL then it is not assigned.
This neither breaks API nor ABI.

The `seeked` value is only assigned when the result is `-1`.
The POSIX standard is inconsistent about negative return values.
In the case of `lseek()`, only `-1` is technically an error.
---
 level_0/f_file/c/file.c                                  | 7 ++++---
 level_0/f_file/c/file.h                                  | 4 +++-
 level_0/f_file/data/documentation/man/man3/f_file_seek.3 | 1 +
 level_0/f_file/tests/unit/c/test-file-seek.c             | 6 ------
 4 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/level_0/f_file/c/file.c b/level_0/f_file/c/file.c
index cbd55e110..f4fa12b20 100644
--- a/level_0/f_file/c/file.c
+++ b/level_0/f_file/c/file.c
@@ -1823,14 +1823,13 @@ extern "C" {
   f_status_t f_file_seek(const f_file_t file, const int whence, const off_t offset, off_t * const seeked) {
     #ifndef _di_level_0_parameter_checking_
       if (whence < 0) return F_status_set_error(F_parameter);
-      if (!seeked) return F_status_set_error(F_parameter);
     #endif // _di_level_0_parameter_checking_
 
     if (file.id == -1) return F_file_descriptor_not;
 
-    *seeked = lseek(file.id, offset, whence);
+    const int result = lseek(file.id, offset, whence);
 
-    if (*seeked < 0) {
+    if (result == -1) {
       if (errno == EBADF) return F_status_set_error(F_file_descriptor_not);
       if (errno == EINVAL) return F_status_set_error(F_parameter);
       if (errno == ENXIO) return F_status_set_error(F_bound_not);
@@ -1840,6 +1839,8 @@ extern "C" {
       return F_status_set_error(F_failure);
     }
 
+    *seeked = result;
+
     return F_okay;
   }
 #endif // _di_f_file_seek_
diff --git a/level_0/f_file/c/file.h b/level_0/f_file/c/file.h
index 5ca80bc14..151a108b1 100644
--- a/level_0/f_file/c/file.h
+++ b/level_0/f_file/c/file.h
@@ -1964,9 +1964,11 @@ extern "C" {
  * @param offset
  *   The offset to use, based off of whence.
  * @param seeked
- *   This gets update to represent the total amount seeked.
+ *   (optional) This gets update to represent the total amount seeked.
  *   To be compared against offset.
  *
+ *   Set to NULL to not use.
+ *
  * @return
  *   F_okay on success.
  *   F_file_descriptor_not if file.id is -1.
diff --git a/level_0/f_file/data/documentation/man/man3/f_file_seek.3 b/level_0/f_file/data/documentation/man/man3/f_file_seek.3
index e3f0c55e2..e535195da 100644
--- a/level_0/f_file/data/documentation/man/man3/f_file_seek.3
+++ b/level_0/f_file/data/documentation/man/man3/f_file_seek.3
@@ -33,6 +33,7 @@ The offset to use, based off of whence.
 .TP
 .B seeked
 This gets update to represent the total amount seeked. To be compared against offset.
+(optional) This gets update to represent the total amount seeked. To be compared against offset. Set to NULL to not use.
 
 .SH STRUCTURES
 .SS ""
diff --git a/level_0/f_file/tests/unit/c/test-file-seek.c b/level_0/f_file/tests/unit/c/test-file-seek.c
index 024170552..39589a004 100644
--- a/level_0/f_file/tests/unit/c/test-file-seek.c
+++ b/level_0/f_file/tests/unit/c/test-file-seek.c
@@ -56,12 +56,6 @@ void test__f_file_seek__parameter_checking(void **state) {
 
     assert_int_equal(status, F_status_set_error(F_parameter));
   }
-
-  {
-    const f_status_t status = f_file_seek(file, 0, 0, 0);
-
-    assert_int_equal(status, F_status_set_error(F_parameter));
-  }
 }
 
 void test__f_file_seek__returns_file_descriptor_not(void **state) {
-- 
2.47.3