platform/posix

How an open file may be used: read_only, write_only or read_write.

The process's arguments as its entry gave them: argv after argv[0] and their count. arguments gives the table, which lends what it points to from storage the process keeps, and argument reads it.

An open file's descriptor: a handle the system gives, which names one open file until it is closed. It is a handle and not a number to count with; descriptor(n) and i32(d) convert at a C boundary.

An entry of a directory: its name, lent from the buffer it was read into until the next read, and its kind, unknown_kind where the file system records none.

An open directory stream, POSIX's DIR: a value its caller keeps and passes inout to read_directory, with the same buffer each time. Its fields belong to this module: the directory's descriptor, the C library's stream where there is one, and how much of the buffer the system has filled and the caller has read.

Every failure a POSIX call here reports: the errno it failed with, as an atom, or unlisted. number gives the errno's number on this system and errno_of the atom for a number.

What a file is.

How open_at opens a file: its access, and whether to create it when it is missing, refuse it when it exists (exclusive, with create), truncate it, append every write to its end, or refuse anything that is not a directory with enotdir.

One descriptor for poll to watch and the events asked about, made by watch, and after the call what happened, which happened reads.

Poll events, POSIX's poll bits as a set: a value combines with |, & and ~ and compares with == and <>. poll_input, poll_output and poll_urgent are what an entry can ask about; poll_error, poll_hung_up and poll_invalid are only ever reported. The bits are the same on Linux, Darwin and FreeBSD.

A file's status, POSIX's stat: the device and inode that identify it, what it is and its size in bytes. On Linux the device is the kernel's major number in the upper 32 bits and its minor in the lower, as statx reports them; elsewhere it is the system's st_dev. Two paths name the same file when both identify it alike.

A block device.

A character device.

A directory.

errno E2BIG: Argument list too long.

errno EACCES: Permission denied.

errno EADDRINUSE: Address already in use.

errno EADDRNOTAVAIL: Cannot assign requested address.

errno EADV: Advertise error.

errno EAFNOSUPPORT: Address family not supported by protocol.

errno EAGAIN: Try again.

errno EALREADY: Operation already in progress.

errno EAUTH: Authentication error.

errno EBADARCH: Bad CPU type in executable.

errno EBADE: Invalid exchange.

errno EBADEXEC: Bad executable (or shared library).

errno EBADF: Bad file number.

errno EBADFD: File descriptor in bad state.

errno EBADMACHO: Malformed Mach-o file.

errno EBADMSG: Not a data message.

errno EBADR: Invalid request descriptor.

errno EBADRPC: RPC struct is bad.

errno EBADRQC: Invalid request code.

errno EBADSLT: Invalid slot.

errno EBFONT: Bad font file format.

errno EBUSY: Device or resource busy.

errno ECANCELED: Operation Canceled.

errno ECAPMODE: Not permitted in capability mode.

errno ECHILD: No child processes.

errno ECHRNG: Channel number out of range.

errno ECOMM: Communication error on send.

errno ECONNABORTED: Software caused connection abort.

errno ECONNREFUSED: Connection refused.

errno ECONNRESET: Connection reset by peer.

errno EDEADLK: Resource deadlock would occur.

errno EDESTADDRREQ: Destination address required.

errno EDEVERR: Device error.

errno EDOM: Math argument out of domain of func.

errno EDOOFUS: Programming error.

errno EDOTDOT: RFS specific error.

errno EDQUOT: Quota exceeded.

errno EEXIST: File exists.

errno EFAULT: Bad address.

errno EFBIG: File too large.

errno EFTYPE: Inappropriate file type or format.

errno EHOSTDOWN: Host is down.

errno EHOSTUNREACH: No route to host.

errno EHWPOISON: Memory page has hardware error.

errno EIDRM: Identifier removed.

errno EILSEQ: Illegal byte sequence.

errno EINPROGRESS: Operation now in progress.

errno EINTEGRITY: Integrity check failed.

errno EINTR: Interrupted system call.

errno EINVAL: Invalid argument.

errno EIO: I/O error.

errno EISCONN: Transport endpoint is already connected.

errno EISDIR: Is a directory.

errno EISNAM: Is a named type file.

errno EKEYEXPIRED: Key has expired.

errno EKEYREJECTED: Key was rejected by service.

errno EKEYREVOKED: Key has been revoked.

errno EL2HLT: Level 2 halted.

errno EL2NSYNC: Level 2 not synchronized.

errno EL3HLT: Level 3 halted.

errno EL3RST: Level 3 reset.

errno ELIBACC: Can not access a needed shared library.

errno ELIBBAD: Accessing a corrupted shared library.

errno ELIBEXEC: Cannot exec a shared library directly.

errno ELIBMAX: Attempting to link in too many shared libraries.

errno ELIBSCN: .lib section in a.out corrupted.

errno ELNRNG: Link number out of range.

errno ELOOP: Too many symbolic links encountered.

errno EMEDIUMTYPE: Wrong medium type.

errno EMFILE: Too many open files.

errno EMLINK: Too many links.

errno EMSGSIZE: Message too long.

errno EMULTIHOP: Multihop attempted.

errno ENAMETOOLONG: File name too long.

errno ENAVAIL: No XENIX semaphores available.

errno ENEEDAUTH: Need authenticator.

errno ENETDOWN: Network is down.

errno ENETRESET: Network dropped connection because of reset.

errno ENETUNREACH: Network is unreachable.

errno ENFILE: File table overflow.

errno ENOANO: No anode.

errno ENOATTR: Attribute not found.

errno ENOBUFS: No buffer space available.

errno ENOCSI: No CSI structure available.

errno ENODATA: No data available.

errno ENODEV: No such device.

errno ENOENT: No such file or directory.

errno ENOEXEC: Exec format error.

errno ENOKEY: Required key not available.

errno ENOLCK: No record locks available.

errno ENOLINK: Link has been severed.

errno ENOMEDIUM: No medium found.

errno ENOMEM: Out of memory.

errno ENOMSG: No message of desired type.

errno ENONET: Machine is not on the network.

errno ENOPKG: Package not installed.

errno ENOPOLICY: Policy not found.

errno ENOPROTOOPT: Protocol not available.

errno ENOSPC: No space left on device.

errno ENOSR: Out of streams resources.

errno ENOSTR: Device not a stream.

errno ENOSYS: Invalid system call number.

errno ENOTBLK: Block device required.

errno ENOTCAPABLE: Capabilities insufficient.

errno ENOTCONN: Transport endpoint is not connected.

errno ENOTDIR: Not a directory.

errno ENOTEMPTY: Directory not empty.

errno ENOTNAM: Not a XENIX named type file.

errno ENOTRECOVERABLE: State not recoverable.

errno ENOTSOCK: Socket operation on non-socket.

errno ENOTSUP: Operation not supported.

errno ENOTTY: Not a typewriter.

errno ENOTUNIQ: Name not unique on network.

errno ENXIO: No such device or address.

errno EOPNOTSUPP: Operation not supported on transport endpoint.

errno EOVERFLOW: Value too large for defined data type.

errno EOWNERDEAD: Owner died.

errno EPERM: Operation not permitted.

errno EPFNOSUPPORT: Protocol family not supported.

errno EPIPE: Broken pipe.

errno EPROCLIM: Too many processes.

errno EPROCUNAVAIL: Bad procedure for program.

errno EPROGMISMATCH: Program version wrong.

errno EPROGUNAVAIL: RPC prog. not avail.

errno EPROTO: Protocol error.

errno EPROTONOSUPPORT: Protocol not supported.

errno EPROTOTYPE: Protocol wrong type for socket.

errno EPWROFF: Device power is off.

errno EQFULL: Interface output queue is full.

errno ERANGE: Math result not representable.

errno EREMCHG: Remote address changed.

errno EREMOTE: Object is remote.

errno EREMOTEIO: Remote I/O error.

errno ERESTART: Interrupted system call should be restarted.

errno ERFKILL: Operation not possible due to RF-kill.

errno EROFS: Read-only file system.

errno ERPCMISMATCH: RPC version wrong.

errno ESHLIBVERS: Shared library version mismatch.

errno ESHUTDOWN: Cannot send after transport endpoint shutdown.

errno ESOCKTNOSUPPORT: Socket type not supported.

errno ESPIPE: Illegal seek.

errno ESRCH: No such process.

errno ESRMNT: Srmount error.

errno ESTALE: Stale file handle.

errno ESTRPIPE: Streams pipe error.

errno ETIME: Timer expired.

errno ETIMEDOUT: Connection timed out.

errno ETOOMANYREFS: Too many references: cannot splice.

errno ETXTBSY: Text file busy.

errno EUCLEAN: Structure needs cleaning.

errno EUNATCH: Protocol driver not attached.

errno EUSERS: Too many users.

errno EXDEV: Cross-device link.

errno EXFULL: Exchange full.

A FIFO, a named pipe.

Open for reading only.

Open for reading and writing.

A regular file.

A socket: socket_file, since socket is the name of a call.

A symbolic link, reported as itself when it is not followed.

A kind the system did not say: a directory entry whose file system records none, which status_at then tells.

A failure no errno this module names describes: a number newer than its tables, or a record the system filled that could not be read. Its number is zero.

Open for writing only.

The least a buffer read_directory reads into holds: room for any entry any of the three systems gives, its record and its NUL included.

An error on the file.

The peer has gone.

Data to read, or the end of a file.

A descriptor that is not open.

No event.

Room to write.

Out-of-band data to read.

The options for reading an existing file.

Standard error, descriptor 2.

Standard input, descriptor 0.

Standard output, descriptor 1.

The working directory as the directory an *_at call's relative path is relative to: C's AT_FDCWD, which is no open file.

The working directory as the directory an *_at call's relative path is relative to: C's AT_FDCWD, which is no open file.

The working directory as the directory an *_at call's relative path is relative to: C's AT_FDCWD, which is no open file.

The options for writing a file from its start, creating it when it is missing and truncating it when it is not.

Establish the process's argument root from C's main carriers. The hosted entry calls this with its own argc and argv before its body runs; a C main that drives Landin exports calls it itself, before it reads an argument and before starting a thread that may.

The argument index, from zero, as a host string lending the process's own storage, which nothing copies. An index at or past the table's count traps, as does a null entry, which C promises none below argc is.

The process's arguments, argv[0] not among them. It traps when no argument root has been established: the hosted entry establishes one before main runs, and a C main calls _landin_host_initialize_arguments itself.

Close closing. The descriptor is released even when this fails, so a failed close is never retried: the number may already name another file.

Close the directory stream and its descriptor, which are released even when this fails.

The errno atom for the number value on this system: unlisted for a number it does not define.

End the process with status at once, POSIX's _exit: nothing more of the program runs, and no C stream is flushed.

What happened to an entry's descriptor in the last poll; nothing, before one.

Make the directory path names, relative to at, with the permission bits permissions, which the process umask filters: eexist when the name is taken, enoent when its parent is missing.

Map length bytes of fresh, zeroed memory that this process alone may read and write, POSIX's anonymous private mmap: its first byte, which is aligned to a page, or the errno, enomem when the system has no room.

The number problem has on this system, as C's errno holds it: zero for unlisted and for an errno this system does not define. ENOTSUP is EOPNOTSUPP's number on Linux and FreeBSD.

Open the file path names, relative to the directory open as at (or working_directory), with options; a file it creates gets the permission bits permissions, which the process umask filters. The new descriptor, or the errno: enoent for a missing name, enotdir when a component is not a directory, eacces when refused, eexist for an exclusive name that is taken, eintr when a signal came first.

Open the directory path names, relative to at, for reading: enotdir when it is not a directory, enoent when it is missing. Close it with close_directory, which also closes its descriptor.

The size of the system's pages in bytes, which map aligns to: 16 KiB on Darwin arm64 and 4 KiB on the others. On Linux it is what the kernel told a static executable's entry, and 4096 when the C runtime started the program instead.

Wait until an event happens to one of entries' descriptors, or milliseconds pass, waiting indefinitely when it is negative and not at all when it is zero, POSIX's poll: how many entries had an event, each of which happened reads, zero when the time passed first, or the errno, eintr when a signal came first.

Read at most lenof into bytes from source into into: the count read, zero at the end of a file, or the errno; eintr means nothing was read.

The directory's next entry, read into buffer, which must be the buffer every earlier read of this stream was given and hold at least directory_buffer bytes, or einval. The entry lends its name from buffer until the next read. An entry with an empty name is the end of the directory. Entries come in the system's order, . and .. among them, as POSIX's readdir gives them.

Remove the empty directory path names, relative to at, POSIX's unlinkat with AT_REMOVEDIR: enotempty when it holds anything.

The status of the file path names, relative to the directory open as at (or working_directory), following a final symbolic link when follow is true and reporting the link itself when it is not.

Remove the name path, relative to at, of a file that is not a directory, POSIX's unlinkat.

Give back the length bytes mapped at base, POSIX's munmap.

An entry watching watched for the events wanted asks about; its poll_error, poll_hung_up and poll_invalid are reported whether asked or not.

Write at most lenof bytes bytes of bytes to to: the count accepted, which may be short, or the errno; eintr means nothing was written.