#
# env-test: Tests environment variable syscalls.
#
# 1. Gets CWD (should be "/")
# 2. Sets TEST=hello
# 3. Gets TEST (should be "hello")
# 4. Forks - child gets TEST, verifies it was copied
# 5. Both print results and exit
#

.section .text
.global _start

.equ SYS_EXIT,    0
.equ SYS_WRITE,   1
.equ SYS_FORK,    3
.equ SYS_WAITPID, 6
.equ SYS_GETENV,  8
.equ SYS_SETENV,  9

# Helper: write a string (addr in %ecx, len in %edx) to stdout
.macro WRITE_STR addr, len
    movl $SYS_WRITE, %eax
    movl $1, %ebx
    movl \addr, %ecx
    movl \len, %edx
    int $0x80
.endm

_start:
    # 1. Get CWD env var
    movl $SYS_GETENV, %eax
    movl $key_cwd, %ebx
    movl $buf, %ecx
    movl $128, %edx
    int $0x80

    # Print "CWD="
    WRITE_STR $label_cwd, $4
    # Print the value (length returned in eax)
    movl %eax, %edx         # length
    movl $SYS_WRITE, %eax
    movl $1, %ebx
    movl $buf, %ecx
    int $0x80
    WRITE_STR $newline, $1

    # 2. Set TEST=hello
    movl $SYS_SETENV, %eax
    movl $key_test, %ebx
    movl $val_hello, %ecx
    int $0x80

    # 3. Get TEST
    movl $SYS_GETENV, %eax
    movl $key_test, %ebx
    movl $buf, %ecx
    movl $128, %edx
    int $0x80

    # Print "TEST="
    WRITE_STR $label_test, $5
    movl %eax, %edx
    movl $SYS_WRITE, %eax
    movl $1, %ebx
    movl $buf, %ecx
    int $0x80
    WRITE_STR $newline, $1

    # 4. Fork
    movl $SYS_FORK, %eax
    int $0x80
    testl %eax, %eax
    jz .child

.parent:
    pushl %eax              # save child PID
    WRITE_STR $msg_parent, $15

    # Wait for child
    popl %ebx
    movl $SYS_WAITPID, %eax
    int $0x80

    # Exit
    movl $SYS_EXIT, %eax
    movl $0, %ebx
    int $0x80

.child:
    # Child: get TEST to verify it was inherited
    movl $SYS_GETENV, %eax
    movl $key_test, %ebx
    movl $buf, %ecx
    movl $128, %edx
    int $0x80

    # Print "Child TEST="
    WRITE_STR $label_child_test, $11
    movl %eax, %edx
    movl $SYS_WRITE, %eax
    movl $1, %ebx
    movl $buf, %ecx
    int $0x80
    WRITE_STR $newline, $1

    # Exit
    movl $SYS_EXIT, %eax
    movl $0, %ebx
    int $0x80

.section .rodata
key_cwd:          .asciz "CWD"
key_test:         .asciz "TEST"
val_hello:        .asciz "hello"
label_cwd:        .ascii "CWD="
label_test:       .ascii "TEST="
label_child_test: .ascii "Child TEST="
msg_parent:       .ascii "Parent done!\n\0\0"
newline:          .ascii "\n"

.section .bss
buf: .space 128