more error handling

examples/curl.zr

@@ -26,15 +26,9 @@ func main[argc: i64, argv: ptr] : i64
     if i < url_len
         path = str.substr(url, i, url_len - i)
     
-    let addr: i64 = net.resolve(host)
+    let addr: i64 = must(net.resolve?(host))
-    if addr <= 0
-        io.println("ERROR: domain resolution failed")
-        return 1
 
-    let s: i64 = net.connect(addr, 80)
+    let s: i64 = must(net.connect?(addr, 80))
-    if s < 0
-        io.println("ERROR: connection failed")
-        return 1
 
     // TODO: add string builder to std
     let req: str = "GET "

examples/puzzles/aoc2024_01.zr

@@ -15,7 +15,7 @@ func part2[l1: Array, l2: Array] : void
     io.println_i64(out)
 
 func main[] : i64
-    let lines: Array = io.read_file("input.txt") |> str.split("\n")
+    let lines: Array = must(io.read_text_file?("input.txt")) |> str.split("\n")
 
     let l1: Array = []
     let l2: Array = []

examples/puzzles/aoc2024_02.zr

@@ -40,7 +40,7 @@ func part2[data: Array] : void
     io.println_i64(out)
 
 func main[] : i64
-    let lines: Array = io.read_file("input.txt") |> str.split("\n")
+    let lines: Array = must(io.read_text_file?("input.txt")) |> str.split("\n")
 
     let data: Array = []
     for i in 0..lines->size

examples/puzzles/aoc2024_04.zr

@@ -56,7 +56,7 @@ func part2[lines: Array] : void
     io.println_i64(out)
 
 func main[] : i64
-    let lines: Array = io.read_file("input.txt") |> str.split("\n")
+    let lines: Array = must(io.read_text_file?("input.txt")) |> str.split("\n")
 
     part1(lines)
     part2(lines)

examples/puzzles/aoc2024_05.zr

@@ -47,7 +47,7 @@ func part2[updates: Array, rules_left: Array, rules_right: Array] : void
     io.println_i64(out)
 
 func main[] : i64
-    let data: Array = io.read_file("input.txt") |> str.split("\n\n")
+    let data: Array = must(io.read_text_file?("input.txt")) |> str.split("\n\n")
 
     let rules_left: Array = []
     let rules_right: Array = []

examples/puzzles/aoc2024_07.zr

@@ -61,7 +61,7 @@ func part2[equations: Array] : void
     io.println_i64(out)
 
 func main[] : i64
-    let lines: Array = io.read_file("input.txt") |> str.split("\n")
+    let lines: Array = must(io.read_text_file?("input.txt")) |> str.split("\n")
     let equations: Array = []
 
     for i in 0..lines->size

examples/puzzles/aoc2025_01.zr

@@ -47,7 +47,7 @@ func part2[lines: Array] : void
     io.println_i64(password)
 
 func main[] : i64
-    let lines: Array = io.read_file("input.txt") |> str.split("\n")
+    let lines: Array = must(io.read_text_file?("input.txt")) |> str.split("\n")
 
     part1(lines)
     part2(lines)

examples/puzzles/aoc2025_02.zr

@@ -54,7 +54,7 @@ func part2[ranges: Array] : void
     io.println_i64(sum)
 
 func main[] : i64
-    let ranges: Array = io.read_file("input.txt") |> str.split(",")
+    let ranges: Array = must(io.read_text_file?("input.txt")) |> str.split(",")
 
     part1(ranges)
     part2(ranges)

examples/puzzles/aoc2025_03.zr

@@ -45,7 +45,7 @@ func part2[lines: Array] : void
     io.println_i64(sum)
 
 func main[] : i64
-    let lines: Array = io.read_file("input.txt") |> str.split("\n")
+    let lines: Array = must(io.read_text_file?("input.txt")) |> str.split("\n")
 
     part1(lines)
     part2(lines)

examples/tcp_server.zr

@@ -1,7 +1,5 @@
 func main[] : i64
-    let s: i64 = net.listen(net.pack_addr(127, 0, 0, 1), 8000)
+    let s: i64 = must(net.listen?(net.pack_addr(127, 0, 0, 1), 8000))
-    if s < 0
-        panic("failed to bind a socket")
 
     io.println("Listening on port 8000...")
     let resp: str = mem.alloc(60000)

examples/udp_server.zr

@@ -1,7 +1,5 @@
 func main[] : i64
-    let s: i64 = net.udp_listen(net.pack_addr(127, 0, 0, 1), 8000)
+    let s: i64 = must(net.udp_listen?(net.pack_addr(127, 0, 0, 1), 8000))
-    if !s
-        panic("failed to bind a socket")
 
     io.println("Listening on port 8000...")
     while true
@@ -10,5 +8,5 @@ func main[] : i64
             net.UDPPacket.free(pkt)
             continue
 
-        net.udp_send_to(s, pkt->source_addr, pkt->buffer, pkt->size)
+        net.udp_send_to(s, pkt->source_addr, pkt->data, pkt->size)
         net.UDPPacket.free(pkt)

src/analyzer.rs

@@ -17,6 +17,8 @@ impl Analyzer {
             functions: HashMap::from([
                 ("_builtin_heap_head".into(), 0),
                 ("_builtin_heap_tail".into(), 0),
+                ("_builtin_err_code".into(), 0),
+                ("_builtin_err_msg".into(), 0),
                 ("_builtin_read64".into(), 1),
                 ("_builtin_set64".into(), 2),
                 ("_builtin_syscall".into(), -1),

src/codegen_x86_64.rs

@@ -110,6 +110,8 @@ section .bss
     _heap_head: resq 1
     _heap_tail: resq 1
     _environ: resq 1
+    _err_code: resq 1
+    _err_msg: resq 1
 
 section .text._builtin_heap_head
 _builtin_heap_head:
@@ -121,6 +123,16 @@ _builtin_heap_tail:
     lea     rax, [rel _heap_tail]
     ret
 
+section .text._builtin_err_code
+_builtin_err_code:
+    lea     rax, [rel _err_code]
+    ret
+
+section .text._builtin_err_msg
+_builtin_err_msg:
+    lea     rax, [rel _err_msg]
+    ret
+
 section .text._builtin_read64
 _builtin_read64:
     mov rax, qword [rdi]
@@ -734,6 +746,7 @@ _builtin_environ:
             Expr::New(struct_name) => {
                 let struct_fields = &self.analyzer.structs[&struct_name.lexeme];
 
+                // TODO: panic on mem.alloc error
                 let memory_size = struct_fields.len() * 8;
                 emit!(&mut self.output, "    mov rdi, {}", memory_size);
                 emit!(&mut self.output, "    call mem.alloc");

src/std/net.zr

@@ -4,14 +4,17 @@ const SOCK_DGRAM = 2
 const SOL_SOCKET = 1
 const SO_REUSEADDR = 2
 
-func net.listen[packed_host: i64, port: i64] : i64
+func net.listen?[packed_host: i64, port: i64] : i64
+    err.clear()
     let s: i64 = _builtin_syscall(SYS_socket, AF_INET, SOCK_STREAM, 0)
     if s < 0
+        err.set(ERR_SYSCALL_FAILED, "net.listen?: failed to create a socket")
         return -1
     
     let optval = 1
     if _builtin_syscall(SYS_setsockopt, s, SOL_SOCKET, SO_REUSEADDR, ^optval, 8) < 0
         _builtin_syscall(SYS_close, s)
+        err.set(ERR_SYSCALL_FAILED, "net.listen?: setsockopt() failed")
         return -1
 
     let sa: ptr = mem.alloc(16)
@@ -28,19 +31,23 @@ func net.listen[packed_host: i64, port: i64] : i64
     if _builtin_syscall(SYS_bind, s, sa, 16) < 0
         _builtin_syscall(SYS_close, s)
         mem.free(sa)
+        err.set(ERR_SYSCALL_FAILED, "net.listen?: failed to bind")
         return -1
     mem.free(sa)
 
     if _builtin_syscall(SYS_listen, s, 128) < 0
         _builtin_syscall(SYS_close, s)
+        err.set(ERR_SYSCALL_FAILED, "net.listen?: listen() failed")
         return -1
     
     return s
 
 // TODO: resolve DNS
-func net.connect[packed_host: i64, port: i64] : i64
+func net.connect?[packed_host: i64, port: i64] : i64
+    err.clear()
     let s: i64 = _builtin_syscall(SYS_socket, AF_INET, SOCK_STREAM, 0)
     if s < 0
+        err.set(ERR_SYSCALL_FAILED, "net.connect?: failed to create a socket")
         return -1
 
     let sa: ptr = mem.alloc(16)
@@ -57,6 +64,7 @@ func net.connect[packed_host: i64, port: i64] : i64
     if _builtin_syscall(SYS_connect, s, sa, 16) < 0
         mem.free(sa)
         _builtin_syscall(SYS_close, s)
+        err.set(ERR_CONNECTION_FAILED, "net.connect?: connection failed")
         return -1
 
     mem.free(sa)
@@ -86,12 +94,14 @@ struct net.UDPPacket
     source_addr: ptr
     size: i64
 
-func net.create_udp_client[packed_host: i64, port: i64] : net.UDPSocket
+func net.create_udp_client?[packed_host: i64, port: i64] : net.UDPSocket
+    err.clear()
     let s: net.UDPSocket = new net.UDPSocket
 
     s->fd = _builtin_syscall(SYS_socket, AF_INET, SOCK_DGRAM, 0)
     if s->fd < 0
         mem.free(s)
+        err.set(ERR_SYSCALL_FAILED, "net.create_udp_client?: failed to create a socket")
         return 0
 
     s->addr = mem.alloc(16)
@@ -106,13 +116,15 @@ func net.create_udp_client[packed_host: i64, port: i64] : net.UDPSocket
     s->addr[7] = packed_host & 255
     return s
 
-func net.udp_listen[packed_host: i64, port: i64] : net.UDPSocket
+func net.udp_listen?[packed_host: i64, port: i64] : net.UDPSocket
-    let s: net.UDPSocket = net.create_udp_client(packed_host, port)
+    err.clear()
-    if !s
+    let s: net.UDPSocket = net.create_udp_client?(packed_host, port)
+    if err.check()
         return 0
 
     if _builtin_syscall(SYS_bind, s->fd, s->addr, 16) < 0
         net.UDPSocket.close_and_free(s)
+        err.set(ERR_SYSCALL_FAILED, "net.udp_listen?: failed to bind")
         return 0
 
     return s
@@ -146,7 +158,7 @@ const DNS_RECURSION_DESIRED = 256
 
 func net.encode_dns_name[domain: str] : io.Buffer
     let domain_len: i64 = str.len(domain)
-    let buf: io.Buffer = io.Buffer.alloc(domain_len + 2)
+    let buf: io.Buffer = must(io.Buffer.alloc?(domain_len + 2))
     let out_pos: i64 = 0
     let part_start: i64 = 0
     let i: i64 = 0
@@ -165,7 +177,7 @@ func net.encode_dns_name[domain: str] : io.Buffer
 
 func net.build_dns_query[domain_name: str, record_type: i64] : io.Buffer
     let name: io.Buffer = net.encode_dns_name(domain_name)
-    let out: io.Buffer = io.Buffer.alloc(12 + name->size + 4)
+    let out: io.Buffer = must(io.Buffer.alloc?(12 + name->size + 4))
 
     // header
     let id: i64 = math.abs(os.urandom_i64() % 65536)
@@ -184,13 +196,15 @@ func net.build_dns_query[domain_name: str, record_type: i64] : io.Buffer
     io.Buffer.free(name)
     return out
 
-func net.resolve[domain: str] : i64
+// TODO: dont resolve IPs
+func net.resolve?[domain: str] : i64
+    err.clear()
     let query: io.Buffer = net.build_dns_query(domain, DNS_TYPE_A)
 
     // TODO: this probably shouldnt be hardcoded
-    let s: net.UDPSocket = net.create_udp_client(net.pack_addr(8, 8, 8, 8), 53)
+    let s: net.UDPSocket = net.create_udp_client?(net.pack_addr(8, 8, 8, 8), 53)
-    if s == 0
+    if err.check()
-        return 0
+        return -1
 
     net.udp_send_to(s, s->addr, query->data, query->size)
     io.Buffer.free(query)

src/std/std.zr

@@ -1,15 +1,46 @@
+const ERR_NONE              = 0
+const ERR_SYSCALL_FAILED    = 1
+const ERR_OPEN_FAILED       = 2
+const ERR_READ_FAILED       = 3
+const ERR_WRITE_FAILED      = 4
+const ERR_ALLOC_FAILED      = 5
+const ERR_CONNECTION_FAILED = 6
+
+func err.code[] : i64
+    return mem.read64(_builtin_err_code())
+
+func err.msg[] : str
+    return mem.read64(_builtin_err_msg())
+
+func err.check[] : bool
+    return err.code() != 0
+
+func err.clear[] : void
+    err.set(0, 0)
+
+func err.set[code: i64, msg: str] : void
+    mem.write64(_builtin_err_code(), code)
+    mem.write64(_builtin_err_msg(), msg)
+
+func must[x: any] : any
+    if err.check()
+        panic(err.msg())
+    return x
+
 func panic[msg: str] : void
     io.print("PANIC: ")
     io.println(msg)
-    (0 / 0) // crashes program which is kinda better since you get a gdb backtrace
+    // for gdb backtrace
+    _builtin_syscall(SYS_kill, os.getpid(), 6)
     os.exit(1)
 
-const MEM_BLOCK_SIZE = 24
+const MEM_BLOCK_SIZE = 32
 
 struct mem.Block
     size: i64
     free: bool
     next: mem.Block
+    prev: mem.Block
 
 func mem._align[x: i64] : i64
     return (x + 7) & -8
@@ -20,14 +51,19 @@ func mem._split_block[blk: mem.Block, needed: i64] : void
         new_blk->size = blk->size - needed - MEM_BLOCK_SIZE
         new_blk->free = true
         new_blk->next = blk->next
+        new_blk->prev = blk
+
+        if blk->next
+            let next: mem.Block = blk->next
+            next->prev = new_blk
+        else
+            mem.write64(_builtin_heap_tail(), new_blk)
 
         blk->size = needed
         blk->next = new_blk
 
-        if mem.read64(_builtin_heap_tail()) == blk
+func mem._request_space?[size: i64] : mem.Block
-            mem.write64(_builtin_heap_tail(), new_blk)
+    err.clear()
-
-func mem._request_space[size: i64] : mem.Block
     let needed: i64 = size + MEM_BLOCK_SIZE
     let alloc_size: i64 = (needed + 4095) & -4096
 
@@ -36,55 +72,26 @@ func mem._request_space[size: i64] : mem.Block
     // fd = -1, offset = 0
     let blk: mem.Block = _builtin_syscall(SYS_mmap, 0, alloc_size, 3, 34, -1, 0)
     if blk == -1
+        err.set(ERR_ALLOC_FAILED, "mem._request_space: mmap failed")
         return 0
 
     blk->size = alloc_size - MEM_BLOCK_SIZE
     blk->free = false
     blk->next = 0
+    blk->prev = 0
 
     let tail: mem.Block = mem.read64(_builtin_heap_tail())
     if tail
         tail->next = blk
+        blk->prev = tail
 
     mem.write64(_builtin_heap_tail(), blk)
     return blk
 
-func mem._coalesce[] : void
+func mem.alloc?[size: i64] : ptr
-    let cur: mem.Block = mem.read64(_builtin_heap_head())
+    err.clear()
-    let prev: mem.Block = 0
+    if size <= 0
-    
+        err.set(ERR_ALLOC_FAILED, "mem.alloc? called with non-positive size")
-    while cur
-        let next: mem.Block = cur->next
-        let expected_next: mem.Block = cur + MEM_BLOCK_SIZE + cur->size
-        
-        if cur->free && next && next->free && expected_next == next
-            cur->size = cur->size + MEM_BLOCK_SIZE + next->size
-            cur->next = next->next
-            if !cur->next
-                mem.write64(_builtin_heap_tail(), cur)
-            continue
-            
-        let block_total: i64 = cur->size + MEM_BLOCK_SIZE
-        if cur->free && (cur & 4095) == 0 && (block_total & 4095) == 0
-            if prev
-                prev->next = cur->next
-                if !cur->next
-                    mem.write64(_builtin_heap_tail(), prev)
-            else
-                mem.write64(_builtin_heap_head(), cur->next)
-                if !cur->next
-                    mem.write64(_builtin_heap_tail(), 0)
-            
-            let saved_next: mem.Block = cur->next
-            _builtin_syscall(11, cur, block_total)
-            cur = saved_next
-            continue
-            
-        prev = cur
-        cur = cur->next
-
-func mem.alloc[size: i64] : ptr
-    if size == 0
         return 0
 
     size = mem._align(size)
@@ -97,8 +104,8 @@ func mem.alloc[size: i64] : ptr
             return cur + MEM_BLOCK_SIZE
         cur = cur->next
     
-    let blk: mem.Block = mem._request_space(size)
+    let blk: mem.Block = mem._request_space?(size)
-    if !blk
+    if err.check()
         return 0
     
     if !mem.read64(_builtin_heap_head())
@@ -108,17 +115,63 @@ func mem.alloc[size: i64] : ptr
     
     return blk + MEM_BLOCK_SIZE
 
+func mem.alloc[size: i64] : ptr
+    return must(mem.alloc?(size))
+
 func mem.free[x: ptr] : void
     if !x
         return 0
 
     let blk: mem.Block = x - MEM_BLOCK_SIZE
     blk->free = true
-    mem._coalesce()
 
-func mem.realloc[x: ptr, new_size: i64] : ptr
+    let next: mem.Block = blk->next
+    if next && next->free
+        let expected_next: mem.Block = blk + MEM_BLOCK_SIZE + blk->size
+        if expected_next == next
+            blk->size = blk->size + MEM_BLOCK_SIZE + next->size
+            blk->next = next->next
+            if next->next
+                let b: mem.Block = next->next
+                b->prev = blk
+            if mem.read64(_builtin_heap_tail()) == next
+                mem.write64(_builtin_heap_tail(), blk)
+
+    let prev: mem.Block = blk->prev
+    if prev && prev->free
+        let expected_blk: mem.Block = prev + MEM_BLOCK_SIZE + prev->size
+        if expected_blk == blk
+            prev->size = prev->size + MEM_BLOCK_SIZE + blk->size
+            prev->next = blk->next
+            if blk->next
+                let b: mem.Block = blk->next
+                b->prev = prev
+            if mem.read64(_builtin_heap_tail()) == blk
+                mem.write64(_builtin_heap_tail(), prev)
+            blk = prev
+
+    let block_total: i64 = blk->size + MEM_BLOCK_SIZE
+    if (blk & 4095) == 0 && (block_total & 4095) == 0
+        if blk->prev
+            let b: mem.Block = blk->prev
+            b->next = blk->next
+        else
+            mem.write64(_builtin_heap_head(), blk->next)
+        if blk->next
+            let b: mem.Block = blk->next
+            b->prev = blk->prev
+        else
+            mem.write64(_builtin_heap_tail(), blk->prev)
+        _builtin_syscall(SYS_munmap, blk, block_total)
+
+func mem.realloc?[x: ptr, new_size: i64] : ptr
+    err.clear()
     if !x
-        return mem.alloc(new_size)
+        return mem.alloc?(new_size)
+    
+    if new_size < 0
+        err.set(ERR_ALLOC_FAILED, "mem.realloc? called with negative size")
+        return 0
 
     if new_size == 0
         mem.free(x)
@@ -139,17 +192,19 @@ func mem.realloc[x: ptr, new_size: i64] : ptr
         if combined >= new_size
             blk->size = combined
             blk->next = next->next
-            if !blk->next
+            if next->next
+                let b: mem.Block = next->next
+                b->prev = blk
+            if mem.read64(_builtin_heap_tail()) == next
                 mem.write64(_builtin_heap_tail(), blk)
             mem._split_block(blk, new_size)
             return x
 
-    let new_ptr: ptr = mem.alloc(new_size)
+    let new_ptr: ptr = mem.alloc?(new_size)
-    if !new_ptr
+    if err.check()
         return 0
 
     mem.copy(x, new_ptr, math.min(blk->size, new_size))
-
     mem.free(x)
     return new_ptr
 
@@ -162,8 +217,14 @@ func mem.zero[x: ptr, size: i64] : void
         x[i] = 0
 
 func mem.copy[src: ptr, dst: ptr, n: i64] : void
-    for i in 0..n
+    if dst > src
-        dst[i] = src[i]
+        let i: i64 = n - 1
+        while i >= 0
+            dst[i] = src[i]
+            i = i - 1
+    else
+        for i in 0..n
+            dst[i] = src[i]
 
 func mem.read8[x: ptr] : u8
     return x[0]
@@ -270,71 +331,100 @@ func io.read_line[]: str
     let buffer: str = mem.alloc(MAX_SIZE + 1)
     let n: i64 = _builtin_syscall(SYS_read, 0, buffer, MAX_SIZE)
     if n < 0
-        mem.free(buffer)
+        n = 0
-        return ""
-    buffer[n] = 0
-    return buffer
-
-func io.file_exists[path: str] : bool
-    return _builtin_syscall(SYS_faccessat, -100, path, 0, 0) == 0
-
-func io.read_file[path: str] : str
-    let fd: i64 = _builtin_syscall(SYS_openat, -100, path, 0, 0)
-    if fd <= 0
-        panic("failed to open file") // TODO
-
-    let size: i64 = _builtin_syscall(SYS_lseek, fd, 0, 2)
-    _builtin_syscall(SYS_lseek, fd, 0, 0)
-
-    let buffer: str = mem.alloc(size + 1)
-    let n: i64 = _builtin_syscall(SYS_read, fd, buffer, size)
-    _builtin_syscall(SYS_close, fd)
     buffer[n] = 0
+    buffer = must(mem.realloc?(buffer, n + 1))
     return buffer
 
 struct io.Buffer
     data: ptr
     size: i64
 
-func io.Buffer.alloc[size: i64] : io.Buffer
+func io.Buffer.alloc?[size: i64] : io.Buffer
+    err.clear()
     let buffer: io.Buffer = new io.Buffer
     buffer->size = size
-    buffer->data = mem.alloc(size)
+    buffer->data = mem.alloc?(size)
+    if err.check()
+        mem.free(buffer)
+        return 0
     return buffer
 
 func io.Buffer.free[buf: io.Buffer] : void
     mem.free(buf->data)
     mem.free(buf)
 
-func io.read_binary_file[path: str] : io.Buffer
+func io.file_exists[path: str] : bool
+    return _builtin_syscall(SYS_faccessat, -100, path, 0, 0) == 0
+
+func io.read_text_file?[path: str] : str
+    err.clear()
     let fd: i64 = _builtin_syscall(SYS_openat, -100, path, 0, 0)
     if fd < 0
-        panic("failed to open file") // TODO
+        err.set(ERR_OPEN_FAILED, "io.read_text_file?: failed to open file")
+        return 0
 
-    let buffer: io.Buffer = new io.Buffer
+    let size: i64 = _builtin_syscall(SYS_lseek, fd, 0, 2)
-    buffer->size = _builtin_syscall(SYS_lseek, fd, 0, 2)
     _builtin_syscall(SYS_lseek, fd, 0, 0)
 
-    buffer->data = mem.alloc(buffer->size)
+    let buffer: str = mem.alloc?(size + 1)
-    _builtin_syscall(SYS_read, fd, buffer->data, buffer->size)
+    if err.check()
+        _builtin_syscall(SYS_close, fd)
+        return 0
+
+    let n: i64 = _builtin_syscall(SYS_read, fd, buffer, size)
     _builtin_syscall(SYS_close, fd)
+
+    if n != size
+        mem.free(buffer)
+        err.set(ERR_READ_FAILED, "io.read_text_file?: failed to read file")
+        return 0
+
+    buffer[n] = 0
     return buffer
 
-func io.write_file[path: str, content: str] : void
+func io.read_binary_file?[path: str] : io.Buffer
-    let fd: i64 = _builtin_syscall(SYS_openat, -100, path, 0x241, 0o644)
+    err.clear()
+    let fd: i64 = _builtin_syscall(SYS_openat, -100, path, 0, 0)
     if fd < 0
-        panic("failed to open file") // TODO
+        err.set(ERR_OPEN_FAILED, "io.read_binary_file?: failed to open file")
+        return 0
     
-    _builtin_syscall(SYS_write, fd, content, str.len(content))
+    let buf: io.Buffer = new io.Buffer
+    buf->size = _builtin_syscall(SYS_lseek, fd, 0, 2)
+    _builtin_syscall(SYS_lseek, fd, 0, 0)
+
+    buf->data = mem.alloc?(buf->size)
+    if err.check()
+        io.Buffer.free(buf)
+        _builtin_syscall(SYS_close, fd)
+        return 0
+
+    let n: i64 = _builtin_syscall(SYS_read, fd, buf->data, buf->size)
     _builtin_syscall(SYS_close, fd)
 
-func io.write_binary_file[path: str, content: ptr, size: i64] : void
+    if n != buf->size
+        io.Buffer.free(buf)
+        err.set(ERR_READ_FAILED, "io.read_binary_file?: failed to read file")
+        return 0
+
+    return buf
+
+func io.write_file?[path: str, content: str] : void
+    io.write_binary_file?(path, content, str.len(content))
+
+func io.write_binary_file?[path: str, content: ptr, size: i64] : void
+    err.clear()
     let fd: i64 = _builtin_syscall(SYS_openat, -100, path, 0x241, 0o644)
     if fd < 0
-        panic("failed to open file") // TODO
+        err.set(ERR_OPEN_FAILED, "io.write_binary_file?: failed to open file")
+        return 0
 
-    _builtin_syscall(SYS_write, fd, content, size)
+    let n: i64 = _builtin_syscall(SYS_write, fd, content, size)
     _builtin_syscall(SYS_close, fd)
+    if n != size
+        err.set(ERR_WRITE_FAILED, "io.write_binary_file?: failed to write file")
+        return 0
 
 func str.len[s: str] : i64
     let i = 0
@@ -396,6 +486,9 @@ func str.find[haystack: str, needle: str] : i64
     if needle_len == 0
         return 0
     
+    if needle_len > haystack_len
+        return -1
+
     for i in 0..(haystack_len - needle_len + 1)
         let match: bool = true
         for j in 0..needle_len
@@ -418,7 +511,9 @@ func str.substr[s: str, start: i64, length: i64] : str
 func str.trim[s: str] : str
     let len: i64 = str.len(s)
     if len == 0
-        return ""
+        let out: str = mem.alloc(1)
+        out[0] = 0
+        return out
 
     let start = 0
     let end: i64 = len - 1
@@ -472,7 +567,6 @@ func str.reverse[s: str] : str
     out[len] = 0
     return out
 
-// not sure this covers all the wacky edge cases
 func str.from_i64[n: i64] : str
     if n == 0
         let out: str = mem.alloc(2)
@@ -482,19 +576,22 @@ func str.from_i64[n: i64] : str
 
     let neg: bool = n < 0
     if neg
+        // negating MIN_I64 causes overflow
+        if n == -9223372036854775808
+            return str.make_copy("-9223372036854775808")
         n = -n
     let buf: str = mem.alloc(21) // enough to fit -MAX_I64
-    let i = 0
+    let end = 20
+    buf[end] = 0
+    end = end - 1
     while n > 0
-        let d: u8 = n % 10
+        buf[end] = '0' + (n % 10)
-        buf[i] = '0' + d
         n = n / 10
-        i = i + 1
+        end = end - 1
     if neg
-        buf[i] = '-'
+        buf[end] = '-'
-        i = i + 1
+        end = end - 1
-    buf[i] = 0
+    let s: str = str.make_copy(buf + end + 1)
-    let s: str = str.reverse(buf)
     mem.free(buf)
     return s
 
@@ -507,12 +604,13 @@ func str.hex_from_i64[n: i64] : str
         out[1] = 0
         return out
 
+    let mask: i64 = (1 << 60) - 1
     let buf: str = mem.alloc(17)
     let len = 0
 
-    while n > 0
+    while n != 0
         buf[len] = hex_chars[n & 15]
-        n = n >> 4
+        n = (n >> 4) & mask
         len = len + 1
 
     let out: str = mem.alloc(len + 1)
@@ -522,6 +620,7 @@ func str.hex_from_i64[n: i64] : str
         j = j + 1
 
     out[len] = 0
+    mem.free(buf)
     return out
 
 func str.from_char[c: u8] : str
@@ -572,6 +671,9 @@ func str._hex_digit_to_int[d: u8] : i64
 
 func str.hex_decode[s: str] : str
     let s_len: i64 = str.len(s)
+    if s_len % 2 != 0
+        panic("invalid hex string passed to str.hex_decode")
+
     let i = 0
     let j = 0
     let out: str = mem.alloc(s_len / 2 + 1)
@@ -585,6 +687,8 @@ func str.hex_decode[s: str] : str
     return out
 
 func math.gcd[a: i64, b: i64] : i64
+    a = math.abs(a)
+    b = math.abs(b)
     while b != 0
         let tmp: i64 = b
         b = a % b
@@ -602,6 +706,8 @@ func math.max[a: i64, b: i64] : i64
     return b
 
 func math.abs[n: i64] : i64
+    if n == -9223372036854775808
+        panic("MIN_I64 passed to math.abs")
     if n < 0
         return -n
     return n
@@ -615,13 +721,15 @@ func math.sign[n: i64] : i64
         return 0
 
 func math.pow[b: i64, e: i64] : i64
+    if e < 0
+        panic("negative exponent passed to math.pow")
     let out = 1
     for i in 0..e
         out = out * b
     return out
 
 func math.lcm[a: i64, b: i64] : i64
-    return (a * b) / math.gcd(a, b)
+    return (a / math.gcd(a, b)) * b
 
 func math.isqrt[n: i64] : i64
     if n < 0
@@ -661,6 +769,15 @@ struct Array
 func array.new[] : Array
     return new Array
 
+func array.new_with_size_zeroed[size: i64] : Array
+    let xs: Array = new Array
+    if size > 0
+        xs->data = must(mem.realloc?(xs->data, size * 8))
+        mem.zero(xs->data, size * 8)
+        xs->size = size
+        xs->capacity = size
+    return xs
+
 func array.nth[xs: Array, n: i64] : any
     if n < 0 || n >= xs->size
         panic("array.nth out of bounds")
@@ -676,7 +793,7 @@ func array.push[xs: Array, x: any] : void
         let new_capacity = 4
         if xs->capacity != 0
             new_capacity = xs->capacity * 2
-        xs->data = mem.realloc(xs->data, new_capacity * 8)
+        xs->data = must(mem.realloc?(xs->data, new_capacity * 8))
         xs->capacity = new_capacity
 
     mem.write64(xs->data + xs->size * 8, x)
@@ -698,17 +815,17 @@ func array.slice[xs: Array, start: i64, length: i64] : Array
     if start < 0 || length < 0 || start + length > xs->size
         panic("array.slice out of bounds")
 
-    let new_array: Array = []
+    let new_array: Array = array.new_with_size_zeroed(length)
     for i in 0..length
-        array.push(new_array, array.nth(xs, start + i))
+        array.set(new_array, i, array.nth(xs, start + i))
     return new_array
 
 func array.concat[a: Array, b: Array] : Array
-    let new_array: Array = []
+    let new_array: Array = array.new_with_size_zeroed(a->size + b->size)
     for i in 0..a->size
-        array.push(new_array, array.nth(a, i))
+        array.set(new_array, i, array.nth(a, i))
     for i in 0..b->size
-        array.push(new_array, array.nth(b, i))
+        array.set(new_array, a->size + i, array.nth(b, i))
     return new_array
 
 func alg.quicksort[arr: Array] : void
@@ -742,9 +859,9 @@ func alg.count[arr: Array, item: any] : i64
     return count
 
 func alg.map[arr: Array, fn: ptr] : Array
-    let out: Array = []
+    let out: Array = array.new_with_size_zeroed(arr->size)
     for i in 0..arr->size
-        array.push(out, fn(array.nth(arr, i)))
+        array.set(out, i, fn(array.nth(arr, i)))
     return out
 
 func alg.filter[arr: Array, fn: ptr] : Array
@@ -765,26 +882,44 @@ func os.exit[code: i64] : void
 func os.getpid[] : i64
     return _builtin_syscall(SYS_getpid)
 
+struct os.Timespec
+    tv_sec: i64
+    tv_nsec: i64
+
 func os.sleep[ms: i64] : void
     if ms < 0
         panic("negative time passed to os.sleep")
     // TODO: we really shouldnt need a heap allocation to sleep
-    let req: os.Timeval = new os.Timeval
+    let req: os.Timespec = new os.Timespec
     req->tv_sec = ms / 1000
-    // yes, we should have a os.Timespec with tv_nsec but this works for now
+    req->tv_nsec = (ms % 1000) * 1000000
-    req->tv_usec = (ms % 1000) * 1000000
     _builtin_syscall(SYS_nanosleep, req, 0)
     mem.free(req)
 
-func os.urandom[n: i64]: ptr
+func os.urandom?[n: i64]: ptr
+    err.clear()
     let buffer: ptr = mem.alloc(n)
+    if err.check()
+        return 0
+
     let fd: i64 = _builtin_syscall(SYS_openat, -100, "/dev/urandom", 0, 0)
-    _builtin_syscall(SYS_read, fd, buffer, n)
+    if fd < 0
+        mem.free(buffer)
+        err.set(ERR_READ_FAILED, "os.urandom?: failed to open /dev/urandom")
+        return 0
+
+    let bytes_read: i64 = _builtin_syscall(SYS_read, fd, buffer, n)
     _builtin_syscall(SYS_close, fd)
+
+    if n != bytes_read
+        mem.free(buffer)
+        err.set(ERR_READ_FAILED, "os.urandom?: failed to read /dev/urandom")
+        return 0
+    
     return buffer
 
 func os.urandom_i64[]: i64
-    let buffer: ptr = os.urandom(8)
+    let buffer: ptr = must(os.urandom?(8))
     let n: i64 = mem.read64(buffer)
     mem.free(buffer)
     return n
@@ -802,8 +937,13 @@ func os.time[] : i64
     return out
 
 // voodoo magic
-func os.run_shell_command[command: str] : i64
+func os.run_shell_command?[command: str] : i64
+    err.clear()
     let pid: i64 = _builtin_syscall(SYS_fork)
+    if pid < 0
+        err.set(ERR_SYSCALL_FAILED, "os.run_shell_command?: failed to fork")
+        return -1
+
     if pid == 0
         let argv: Array = ["sh", "-c", command, 0] // gets freed after child process exits
         _builtin_syscall(SYS_execve, "/bin/sh", argv->data, _builtin_environ())
@@ -811,7 +951,8 @@ func os.run_shell_command[command: str] : i64
     else
         let status = 0
         let wp: i64 = _builtin_syscall(SYS_wait4, pid, ^status, 0, 0)
-        if wp == -1
+        if wp < 0
+            err.set(ERR_SYSCALL_FAILED, "os.run_shell_command?: wait() failed")
             return -1
         let st: i64 = status & 0xffffffff
         
@@ -820,16 +961,28 @@ func os.run_shell_command[command: str] : i64
         else
             return -(st & 0x7f)
 
-func os.list_directory[path: str] : Array
+func os.list_directory?[path: str] : Array
+    err.clear()
     let fd: i64 = _builtin_syscall(SYS_openat, -100, path, 0, 0)
     if fd < 0
-        return []
+        err.set(ERR_OPEN_FAILED, "os.list_directory?: failed to open dir")
+        return 0
 
     let files: Array = []
     let buf: ptr = mem.alloc(1024)
     while true
         let n: i64 = _builtin_syscall(SYS_getdents64, fd, buf, 1024)
-        if n <= 0
+        if n < 0
+            mem.free(buf)
+
+            for i in 0..files->size
+                mem.free(array.nth(files, i))
+            array.free(files)
+
+            _builtin_syscall(SYS_close, fd)
+            err.set(ERR_SYSCALL_FAILED, "os.list_directory?: getdents64() failed")
+            return 0
+        else if n == 0
             break
 
         let pos = 0

src/tokenizer.rs

@@ -346,7 +346,11 @@ impl Tokenizer {
     }
 
     fn scan_identifier(&mut self) -> Result<(), ZernError> {
-        while self.peek().is_alphanumeric() || self.peek() == '_' || self.peek() == '.' {
+        while self.peek().is_alphanumeric()
+            || self.peek() == '_'
+            || self.peek() == '.'
+            || self.peek() == '?'
+        {
             self.advance();
         }
 

test.zr

@@ -1,6 +1,6 @@
 func run_test[x: str] : void
     let build_blacklist: Array = ["examples/puzzles", "examples/raylib.zr", "examples/chip8.zr", "examples/sqlite_todo.zr"]
-    let run_blacklist: Array = ["/aoc", "guess_number.zr", "tcp_server.zr"]
+    let run_blacklist: Array = ["/aoc", "guess_number.zr", "tcp_server.zr", "udp_server.zr"]
 
     for i in 0..build_blacklist->size
         if str.equal(x, array.nth(build_blacklist, i))
@@ -14,7 +14,7 @@ func run_test[x: str] : void
     io.print("... ")
 
     let build_start_time: i64 = os.time()
-    if os.run_shell_command(str.concat("./target/release/zern ", x)) != 0
+    if must(os.run_shell_command?(str.concat("./target/release/zern ", x))) != 0
         os.exit(1)
     let build_end_time: i64 = os.time()
 
@@ -39,7 +39,7 @@ func run_test[x: str] : void
         run_cmd = str.concat(run_cmd, " test.zr")
 
     let run_start_time: i64 = os.time()
-    if os.run_shell_command(run_cmd) != 0
+    if must(os.run_shell_command?(run_cmd)) != 0
         os.exit(1)
     let run_end_time: i64 = os.time()
 
@@ -50,14 +50,14 @@ func run_test[x: str] : void
     io.println("ms")
 
 func run_directory[dir: str] : void
-    let files: Array = os.list_directory(dir)
+    let files: Array = must(os.list_directory?(dir))
     for i in 0..files->size
         run_test(str.concat(dir, array.nth(files, i)))
     
     array.free(files)
 
 func main[] : i64
-    os.run_shell_command("cargo build --release")
+    must(os.run_shell_command?("cargo build --release"))
 
     run_directory("examples/")
     run_directory("examples/puzzles/")