[ghex/support-block-devices-part-deux: 4/4] hexbufdir: Add warning in helper function

[Logan Rathbone <larathbone src gnome org>]

commit 78ca3f45cbc941259652c48dd29a58de178a8cfd
Author: Logan Rathbone <poprocks gmail com>
Date:   Sat Jun 11 18:30:11 2022 -0400

    hexbufdir: Add warning in helper function
    
    ie, requesting data beyond the payload is a programmer error. Luckily
    all this reveals is that we're *not* committing that error, but it's a
    good sanity check to have in there.

 src/hex-buffer-direct.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)
---
diff --git a/src/hex-buffer-direct.c b/src/hex-buffer-direct.c
index 23a4ccc..a15ad3a 100644
--- a/src/hex-buffer-direct.c
+++ b/src/hex-buffer-direct.c
@@ -171,6 +171,14 @@ get_file_data (HexBufferDirect *self,
        off_t new_offset;
        ssize_t nread;
 
+       if (offset + len > self->payload)
+       {
+               g_critical ("%s: Programmer error - length is past payload. Reducing. "
+                               "Some garbage may be displayed in the hex widget.", __func__);
+
+               len = self->payload - offset;
+       }
+
        data = g_malloc (len);
        new_offset = lseek (self->fd, offset, SEEK_SET);
 
@@ -179,8 +187,6 @@ get_file_data (HexBufferDirect *self,
        errno = 0;
        nread = read (self->fd, data, len);
 
-       /* FIXME/TODO - test that if nread is less than amount requested, that it
-        * marries up with amount left in payload */
        if (nread == -1)
        {
                set_error (self, _("Failed to read data from file."));