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zig/lib/std/c/dragonfly.zig
mlugg a18fd41064
std: rework/remove ucontext_t 
Our usage of `ucontext_t` in the standard library was kind of
problematic. We unnecessarily mimiced libc-specific structures, and our
`getcontext` implementation was overkill for our use case of stack
tracing.

This commit introduces a new namespace, `std.debug.cpu_context`, which
contains "context" types for various architectures (currently x86,
x86_64, ARM, and AARCH64) containing the general-purpose CPU registers;
the ones needed in practice for stack unwinding. Each implementation has
a function `current` which populates the structure using inline
assembly. The structure is user-overrideable, though that should only be
necessary if the standard library does not have an implementation for
the *architecture*: that is to say, none of this is OS-dependent.

Of course, in POSIX signal handlers, we get a `ucontext_t` from the
kernel. The function `std.debug.cpu_context.fromPosixSignalContext`
converts this to a `std.debug.cpu_context.Native` with a big ol' target
switch.

This functionality is not exposed from `std.c` or `std.posix`, and
neither are `ucontext_t`, `mcontext_t`, or `getcontext`. The rationale
is that these types and functions do not conform to a specific ABI, and
in fact tend to get updated over time based on CPU features and
extensions; in addition, different libcs use different structures which
are "partially compatible" with the kernel structure. Overall, it's a
mess, but all we need is the kernel context, so we can just define a
kernel-compatible structure as long as we don't claim C compatibility by
putting it in `std.c` or `std.posix`.

This change resulted in a few nice `std.debug` simplifications, but
nothing too noteworthy. However, the main benefit of this change is that
DWARF unwinding---sometimes necessary for collecting stack traces
reliably---now requires far less target-specific integration.

Also fix a bug I noticed in `PageAllocator` (I found this due to a bug
in my distro's QEMU distribution; thanks, broken QEMU patch!) and I
think a couple of minor bugs in `std.debug`.

Resolves: #23801
Resolves: #23802
2025-09-30 13:44:54 +01:00

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const std = @import("../std.zig");
const SIG = std.c.SIG;
const caddr_t = std.c.caddr_t;
const gid_t = std.c.gid_t;
const iovec = std.c.iovec;
const pid_t = std.c.pid_t;
const socklen_t = std.c.socklen_t;
const uid_t = std.c.uid_t;
pub extern "c" fn lwp_gettid() c_int;
pub extern "c" fn ptrace(request: c_int, pid: pid_t, addr: caddr_t, data: c_int) c_int;
pub extern "c" fn umtx_sleep(ptr: *const volatile c_int, value: c_int, timeout: c_int) c_int;
pub extern "c" fn umtx_wakeup(ptr: *const volatile c_int, count: c_int) c_int;
pub const E = enum(u16) {
/// No error occurred.
SUCCESS = 0,
PERM = 1,
NOENT = 2,
SRCH = 3,
INTR = 4,
IO = 5,
NXIO = 6,
@"2BIG" = 7,
NOEXEC = 8,
BADF = 9,
CHILD = 10,
DEADLK = 11,
NOMEM = 12,
ACCES = 13,
FAULT = 14,
NOTBLK = 15,
BUSY = 16,
EXIST = 17,
XDEV = 18,
NODEV = 19,
NOTDIR = 20,
ISDIR = 21,
INVAL = 22,
NFILE = 23,
MFILE = 24,
NOTTY = 25,
TXTBSY = 26,
FBIG = 27,
NOSPC = 28,
SPIPE = 29,
ROFS = 30,
MLINK = 31,
PIPE = 32,
DOM = 33,
RANGE = 34,
/// This code is also used for `WOULDBLOCK`.
AGAIN = 35,
INPROGRESS = 36,
ALREADY = 37,
NOTSOCK = 38,
DESTADDRREQ = 39,
MSGSIZE = 40,
PROTOTYPE = 41,
NOPROTOOPT = 42,
PROTONOSUPPORT = 43,
SOCKTNOSUPPORT = 44,
/// This code is also used for `NOTSUP`.
OPNOTSUPP = 45,
PFNOSUPPORT = 46,
AFNOSUPPORT = 47,
ADDRINUSE = 48,
ADDRNOTAVAIL = 49,
NETDOWN = 50,
NETUNREACH = 51,
NETRESET = 52,
CONNABORTED = 53,
CONNRESET = 54,
NOBUFS = 55,
ISCONN = 56,
NOTCONN = 57,
SHUTDOWN = 58,
TOOMANYREFS = 59,
TIMEDOUT = 60,
CONNREFUSED = 61,
LOOP = 62,
NAMETOOLONG = 63,
HOSTDOWN = 64,
HOSTUNREACH = 65,
NOTEMPTY = 66,
PROCLIM = 67,
USERS = 68,
DQUOT = 69,
STALE = 70,
REMOTE = 71,
BADRPC = 72,
RPCMISMATCH = 73,
PROGUNAVAIL = 74,
PROGMISMATCH = 75,
PROCUNAVAIL = 76,
NOLCK = 77,
NOSYS = 78,
FTYPE = 79,
AUTH = 80,
NEEDAUTH = 81,
IDRM = 82,
NOMSG = 83,
OVERFLOW = 84,
CANCELED = 85,
ILSEQ = 86,
NOATTR = 87,
DOOFUS = 88,
BADMSG = 89,
MULTIHOP = 90,
NOLINK = 91,
PROTO = 92,
NOMEDIUM = 93,
ASYNC = 99,
_,
};
pub const BADSIG = SIG.ERR;
pub const sig_t = *const fn (i32) callconv(.c) void;
pub const cmsgcred = extern struct {
pid: pid_t,
uid: uid_t,
euid: uid_t,
gid: gid_t,
ngroups: c_short,
groups: [16]gid_t,
};
pub const sf_hdtr = extern struct {
headers: [*]iovec,
hdr_cnt: c_int,
trailers: [*]iovec,
trl_cnt: c_int,
};
pub const MS_SYNC = 0;
pub const MS_ASYNC = 1;
pub const MS_INVALIDATE = 2;
pub const POSIX_MADV_SEQUENTIAL = 2;
pub const POSIX_MADV_RANDOM = 1;
pub const POSIX_MADV_DONTNEED = 4;
pub const POSIX_MADV_NORMAL = 0;
pub const POSIX_MADV_WILLNEED = 3;
// https://github.com/DragonFlyBSD/DragonFlyBSD/blob/6098912863ed4c7b3f70d7483910ce2956cf4ed3/sys/netinet/ip.h#L94
pub const IP = struct {
pub const OPTIONS = 1;
pub const HDRINCL = 2;
pub const TOS = 3;
pub const TTL = 4;
pub const RECVOPTS = 5;
pub const RECVRETOPTS = 6;
pub const RECVDSTADDR = 7;
pub const SENDSRCADDR = RECVDSTADDR;
pub const RETOPTS = 8;
pub const MULTICAST_IF = 9;
pub const MULTICAST_TTL = 10;
pub const MULTICAST_LOOP = 11;
pub const ADD_MEMBERSHIP = 12;
pub const DROP_MEMBERSHIP = 13;
pub const MULTICAST_VIF = 14;
pub const RSVP_ON = 15;
pub const RSVP_OFF = 16;
pub const RSVP_VIF_ON = 17;
pub const RSVP_VIF_OFF = 18;
pub const PORTRANGE = 19;
pub const RECVIF = 20;
pub const FW_TBL_CREATE = 40;
pub const FW_TBL_DESTROY = 41;
pub const FW_TBL_ADD = 42;
pub const FW_TBL_DEL = 43;
pub const FW_TBL_FLUSH = 44;
pub const FW_TBL_GET = 45;
pub const FW_TBL_ZERO = 46;
pub const FW_TBL_EXPIRE = 47;
pub const FW_X = 49;
pub const FW_ADD = 50;
pub const FW_DEL = 51;
pub const FW_FLUSH = 52;
pub const FW_ZERO = 53;
pub const FW_GET = 54;
pub const FW_RESETLOG = 55;
pub const DUMMYNET_CONFIGURE = 60;
pub const DUMMYNET_DEL = 61;
pub const DUMMYNET_FLUSH = 62;
pub const DUMMYNET_GET = 64;
pub const RECVTTL = 65;
pub const MINTTL = 66;
pub const RECVTOS = 68;
// Same namespace, but these are arguments rather than option names
pub const DEFAULT_MULTICAST_TTL = 1;
pub const DEFAULT_MULTICAST_LOOP = 1;
pub const MAX_MEMBERSHIPS = 20;
pub const PORTRANGE_DEFAULT = 0;
pub const PORTRANGE_HIGH = 1;
pub const PORTRANGE_LOW = 2;
};
// https://github.com/DragonFlyBSD/DragonFlyBSD/blob/6098912863ed4c7b3f70d7483910ce2956cf4ed3/sys/netinet6/in6.h#L448
pub const IPV6 = struct {
pub const UNICAST_HOPS = 4;
pub const MULTICAST_IF = 9;
pub const MULTICAST_HOPS = 10;
pub const MULTICAST_LOOP = 11;
pub const JOIN_GROUP = 12;
pub const LEAVE_GROUP = 13;
pub const PORTRANGE = 14;
pub const @"2292PKTINFO" = 19;
pub const @"2292HOPLIMIT" = 20;
pub const @"2292NEXTHOP" = 21;
pub const @"2292HOPOPTS" = 22;
pub const @"2292DSTOPTS" = 23;
pub const @"2292RTHDR" = 24;
pub const @"2292PKTOPTIONS" = 25;
pub const CHECKSUM = 26;
pub const V6ONLY = 27;
pub const BINDV6ONLY = V6ONLY;
pub const FW_ADD = 30;
pub const FW_DEL = 31;
pub const FW_FLUSH = 32;
pub const FW_ZERO = 33;
pub const FW_GET = 34;
pub const RTHDRDSTOPTS = 35;
pub const RECVPKTINFO = 36;
pub const RECVHOPLIMIT = 37;
pub const RECVRTHDR = 38;
pub const RECVHOPOPTS = 39;
pub const RECVDSTOPTS = 40;
pub const RECVRTHDRDSTOPTS = 41;
pub const USE_MIN_MTU = 42;
pub const RECVPATHMTU = 43;
pub const PATHMTU = 44;
pub const REACHCONF = 45;
pub const PKTINFO = 46;
pub const HOPLIMIT = 47;
pub const NEXTHOP = 48;
pub const HOPOPTS = 49;
pub const DSTOPTS = 50;
pub const RTHDR = 51;
pub const PKTOPTIONS = 52;
pub const RECVTCLASS = 57;
pub const AUTOFLOWLABEL = 59;
pub const TCLASS = 61;
pub const DONTFRAG = 62;
pub const PREFER_TEMPADDR = 63;
pub const MSFILTER = 74;
// Same namespace, but these are arguments rather than option names
pub const RTHDR_LOOSE = 0;
pub const RTHDR_STRICT = 1;
pub const RTHDR_TYPE_0 = 0;
pub const DEFAULT_MULTICAST_HOPS = 1;
pub const DEFAULT_MULTICAST_LOOP = 1;
pub const PORTRANGE_DEFAULT = 0;
pub const PORTRANGE_HIGH = 1;
pub const PORTRANGE_LOW = 2;
};
// https://github.com/DragonFlyBSD/DragonFlyBSD/blob/6098912863ed4c7b3f70d7483910ce2956cf4ed3/sys/netinet/ip.h#L94
pub const IPTOS = struct {
pub const LOWDELAY = 0x10;
pub const THROUGHPUT = 0x08;
pub const RELIABILITY = 0x04;
pub const MINCOST = 0x02;
pub const CE = 0x01;
pub const ECT = 0x02;
pub const PREC_ROUTINE = DSCP_CS0;
pub const PREC_PRIORITY = DSCP_CS1;
pub const PREC_IMMEDIATE = DSCP_CS2;
pub const PREC_FLASH = DSCP_CS3;
pub const PREC_FLASHOVERRIDE = DSCP_CS4;
pub const PREC_CRITIC_ECP = DSCP_CS5;
pub const PREC_INTERNETCONTROL = DSCP_CS6;
pub const PREC_NETCONTROL = DSCP_CS7;
pub const DSCP_CS0 = 0x00;
pub const DSCP_CS1 = 0x20;
pub const DSCP_AF11 = 0x28;
pub const DSCP_AF12 = 0x30;
pub const DSCP_AF13 = 0x38;
pub const DSCP_CS2 = 0x40;
pub const DSCP_AF21 = 0x48;
pub const DSCP_AF22 = 0x50;
pub const DSCP_AF23 = 0x58;
pub const DSCP_CS3 = 0x60;
pub const DSCP_AF31 = 0x68;
pub const DSCP_AF32 = 0x70;
pub const DSCP_AF33 = 0x78;
pub const DSCP_CS4 = 0x80;
pub const DSCP_AF41 = 0x88;
pub const DSCP_AF42 = 0x90;
pub const DSCP_AF43 = 0x98;
pub const DSCP_CS5 = 0xa0;
pub const DSCP_VA = 0xb0;
pub const DSCP_EF = 0xb8;
pub const DSCP_CS6 = 0xc0;
pub const DSCP_CS7 = 0xe0;
pub const ECN_NOTECT = 0x00;
pub const ECN_ECT1 = 0x01;
pub const ECN_ECT0 = 0x02;
pub const ECN_CE = 0x03;
pub const ECN_MASK = 0x03;
};
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