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| -rw-r--r-- | Cargo.toml | 2 | ||||
| -rw-r--r-- | src/error.rs | 97 |
2 files changed, 99 insertions, 0 deletions
diff --git a/Cargo.toml b/Cargo.toml index c9ca1bdaa620..ab5d302156c9 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -4,3 +4,5 @@ version = "0.1.0" authors = ["Vincent Ambo <tazjin@gmail.com>"] [dependencies] +nix = "0.9" +libc = "0.2" diff --git a/src/error.rs b/src/error.rs new file mode 100644 index 000000000000..b288723e5664 --- /dev/null +++ b/src/error.rs @@ -0,0 +1,97 @@ +use nix; +use std::error; +use std::fmt; + +/// This module implements a simple error type to match the errors that can be thrown from the C +/// functions as well as some extra errors resulting from internal validations. +/// +/// As this crate exposes an opinionated API to the POSIX queues certain errors have been +/// ignored: +/// +/// * ETIMEDOUT: The low-level timed functions are not exported and this error can not occur. +/// * EAGAIN: Non-blocking queue calls are not supported. +/// * EINVAL: Same reason as ETIMEDOUT +/// * EMSGSIZE: The message size is immutable after queue creation and this crate checks it. +/// * ENAMETOOLONG: This crate performs name validation +/// +/// If an unexpected error is encountered it will be wrapped appropriately and should be reported +/// as a bug on https://github.com/aprilabank/posix_mq.rs + +#[derive(Debug)] +pub enum Error { + // These errors match what is described in the man pages (from mq_overview(7) onwards). + PermissionDenied(), + InvalidQueueDescriptor(), + QueueCallInterrupted(), + QueueAlreadyExists(), + QueueNotFound(), + InsufficientMemory(), + InsufficientSpace(), + + // These two are (hopefully) unlikely in modern systems + ProcessFileDescriptorLimitReached(), + SystemFileDescriptorLimitReached(), + + // If an unhandled / unknown / unexpected error occurs this error will be used. + // In those cases bug reports would be welcome! + UnknownForeignError(nix::Errno), + + // Some other unexpected / unknown error occured. This is probably an error from + // the nix crate. Bug reports also welcome for this! + UnknownInternalError(Option<nix::Error>), +} + +impl error::Error for Error { + fn description(&self) -> &str { + use Error::*; + match *self { + PermissionDenied() => "permission to the specified queue was denied", + InvalidQueueDescriptor() => "the internal queue descriptor was invalid", + QueueCallInterrupted() => "queue method interrupted by signal", + QueueAlreadyExists() => "the specified queue already exists", + QueueNotFound() => "the specified queue could not be found", + InsufficientMemory() => "insufficient memory to call queue method", + InsufficientSpace() => "insufficient space to call queue method", + ProcessFileDescriptorLimitReached() => "max. number of process file descriptors reached", + SystemFileDescriptorLimitReached() => "max. number of system file descriptors reached", + UnknownForeignError(_) => "unknown foreign error occured: please report a bug!", + UnknownInternalError(_) => "unknown internal error occured: please report a bug!", + } + } +} + +impl fmt::Display for Error { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + // Explicitly import this to gain access to Error::description() + use std::error::Error; + f.write_str(self.description()) + } +} + +/// This from implementation is used to translate errors from the lower-level +/// C-calls into sensible Rust errors. +impl From<nix::Error> for Error { + fn from(e: nix::Error) -> Self { + match e { + nix::Error::Sys(e) => match_errno(e), + _ => Error::UnknownInternalError(Some(e)), + } + } +} + +fn match_errno(err: nix::Errno) -> Error { + use nix::errno::*; + + match err { + EACCES => Error::PermissionDenied(), + EBADF => Error::InvalidQueueDescriptor(), + EINTR => Error::QueueCallInterrupted(), + EEXIST => Error::QueueAlreadyExists(), + EMFILE => Error::ProcessFileDescriptorLimitReached(), + ENFILE => Error::SystemFileDescriptorLimitReached(), + ENOENT => Error::QueueNotFound(), + ENOMEM => Error::InsufficientMemory(), + ENOSPC => Error::InsufficientSpace(), + _ => Error::UnknownForeignError(err), + } +} |