syscall_fs: diet lseek another 80 bytes or so

diff --git a/Kernel/syscall_fs.c b/Kernel/syscall_fs.c
index 0fe1bf6..aa49f8f 100644 (file)
--- a/Kernel/syscall_fs.c
+++ b/Kernel/syscall_fs.c
@@ -25,10 +25,12 @@ void updoff(void)
    as a 32bit OS might */
 arg_t _lseek(void)
 {
+       static off_t zero;
        inoptr ino;
        struct oft *o;
        off_t p;
        off_t n;
+       off_t *pt;
        
        if (uget(offset, &n, sizeof(n)))
                return -1;
@@ -44,15 +46,21 @@ arg_t _lseek(void)
        o = &of_tab[udata.u_files[file]];
        p = o->o_ptr;
 
+       /* 32bit maths is really messy on some processors and the three cases
+          produce three sets of 32bit maths operations. Instead we take a
+          pointer to what to use as the offset and do the maths once */
+
        if (flag == 0)
-               p = n;
+               pt = &zero;
        else if (flag == 1)
-               p += n;
+               pt = &p;
        else if (flag == 2)
-               p = ino->c_node.i_size + n;
+               pt = &ino->c_node.i_size;
        else
                 goto bad;
 
+       p = *pt + n;
+
        if (p < 0)
                goto bad;