kvisc/ka/usr/cmd-exec.k

; The OS/K Team licenses this file to you under the MIT license.
; See the LICENSE file in the project root for more information.

.try_exec:
    ; try without appending ".com"
    mov rax, Sys.OpenFile
    mov ax0, argv0
    trap 0

    ; we good?
    blte zero, rax, .do_exec

    ; nope, append ".com" and try again
    sub rcx, argbuf.size, 5
    scasb ax0, zero ; find null-term
    mov b[ax0+0], '.' ; ".com"
    mov b[ax0+1], 'c'
    mov b[ax0+2], 'o'
    mov b[ax0+3], 'm'
    nul b[ax0+4]

    ; try again
    mov rax, Sys.OpenFile
    mov ax0, argv0
    trap 0

    ; still no good?
    bltz rax, .exec_not_found

.do_exec:
    ; load file into memory
    mov ax0, rax
    mov ax1, FILE_LOADP
    mov ax2, FILE_MAXSZ
    mov rax, Sys.ReadFile
    trap 0

    ; save load address
    mov rcx, rax

    ; close file
    mov rax, Sys.CloseFile
    trap 0

    ; read anything?
    bltz rcx, .couldnt_read
    jrcxz .empty_file

    ; all good, let's go
    mov rax, Sys.ExecuteInFrame
    mov ax0, FILE_LOADP
    mov ax1, 5
    trap 0

    ; unreachable
    jmp abort