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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once
#include <stdlib.h>
#include <string.h>
#include "macro.h"
/* strerror(3) says that glibc uses a maximum length of 1024 bytes. */
#define ERRNO_BUF_LEN 1024
/* Note: the lifetime of the compound literal is the immediately surrounding block,
* see C11 §6.5.2.5, and
* https://stackoverflow.com/questions/34880638/compound-literal-lifetime-and-if-blocks
*
* Note that we use the GNU variant of strerror_r() here. */
#define STRERROR(errnum) strerror_r(abs(errnum), (char[ERRNO_BUF_LEN]){}, ERRNO_BUF_LEN)
/* A helper to print an error message or message for functions that return 0 on EOF.
* Note that we can't use ({ … }) to define a temporary variable, so errnum is
* evaluated twice. */
#define STRERROR_OR_EOF(errnum) ((errnum) != 0 ? STRERROR(errnum) : "Unexpected EOF")
static inline void _reset_errno_(int *saved_errno) {
if (*saved_errno < 0) /* Invalidated by UNPROTECT_ERRNO? */
return;
errno = *saved_errno;
}
#define PROTECT_ERRNO \
_cleanup_(_reset_errno_) _unused_ int _saved_errno_ = errno
#define UNPROTECT_ERRNO \
do { \
errno = _saved_errno_; \
_saved_errno_ = -1; \
} while (false)
#define LOCAL_ERRNO(value) \
PROTECT_ERRNO; \
errno = abs(value)
static inline int negative_errno(void) {
/* This helper should be used to shut up gcc if you know 'errno' is
* negative. Instead of "return -errno;", use "return negative_errno();"
* It will suppress bogus gcc warnings in case it assumes 'errno' might
* be 0 and thus the caller's error-handling might not be triggered. */
assert_return(errno > 0, -EINVAL);
return -errno;
}
static inline int RET_NERRNO(int ret) {
/* Helper to wrap system calls in to make them return negative errno errors. This brings system call
* error handling in sync with how we usually handle errors in our own code, i.e. with immediate
* returning of negative errno. Usage is like this:
*
* …
* r = RET_NERRNO(unlink(t));
* …
*
* or
*
* …
* fd = RET_NERRNO(open("/etc/fstab", O_RDONLY|O_CLOEXEC));
* …
*/
if (ret < 0)
return negative_errno();
return ret;
}
static inline int errno_or_else(int fallback) {
/* To be used when invoking library calls where errno handling is not defined clearly: we return
* errno if it is set, and the specified error otherwise. The idea is that the caller initializes
* errno to zero before doing an API call, and then uses this helper to retrieve a somewhat useful
* error code */
if (errno > 0)
return -errno;
return -abs(fallback);
}
/* For send()/recv() or read()/write(). */
static inline bool ERRNO_IS_TRANSIENT(int r) {
return IN_SET(abs(r),
EAGAIN,
EINTR);
}
/* Hint #1: ENETUNREACH happens if we try to connect to "non-existing" special IP addresses, such as ::5.
*
* Hint #2: The kernel sends e.g., EHOSTUNREACH or ENONET to userspace in some ICMP error cases. See the
* icmp_err_convert[] in net/ipv4/icmp.c in the kernel sources.
*
* Hint #3: When asynchronous connect() on TCP fails because the host never acknowledges a single packet,
* kernel tells us that with ETIMEDOUT, see tcp(7). */
static inline bool ERRNO_IS_DISCONNECT(int r) {
return IN_SET(abs(r),
ECONNABORTED,
ECONNREFUSED,
ECONNRESET,
EHOSTDOWN,
EHOSTUNREACH,
ENETDOWN,
ENETRESET,
ENETUNREACH,
ENONET,
ENOPROTOOPT,
ENOTCONN,
EPIPE,
EPROTO,
ESHUTDOWN,
ETIMEDOUT);
}
/* Transient errors we might get on accept() that we should ignore. As per error handling comment in
* the accept(2) man page. */
static inline bool ERRNO_IS_ACCEPT_AGAIN(int r) {
return ERRNO_IS_DISCONNECT(r) ||
ERRNO_IS_TRANSIENT(r) ||
abs(r) == EOPNOTSUPP;
}
/* Resource exhaustion, could be our fault or general system trouble */
static inline bool ERRNO_IS_RESOURCE(int r) {
return IN_SET(abs(r),
EMFILE,
ENFILE,
ENOMEM);
}
/* Seven different errors for "operation/system call/ioctl/socket feature not supported" */
static inline bool ERRNO_IS_NOT_SUPPORTED(int r) {
return IN_SET(abs(r),
EOPNOTSUPP,
ENOTTY,
ENOSYS,
EAFNOSUPPORT,
EPFNOSUPPORT,
EPROTONOSUPPORT,
ESOCKTNOSUPPORT);
}
/* Two different errors for access problems */
static inline bool ERRNO_IS_PRIVILEGE(int r) {
return IN_SET(abs(r),
EACCES,
EPERM);
}
/* Three different errors for "not enough disk space" */
static inline bool ERRNO_IS_DISK_SPACE(int r) {
return IN_SET(abs(r),
ENOSPC,
EDQUOT,
EFBIG);
}
/* Three different errors for "this device does not quite exist" */
static inline bool ERRNO_IS_DEVICE_ABSENT(int r) {
return IN_SET(abs(r),
ENODEV,
ENXIO,
ENOENT);
}
/* Quite often we want to handle cases where the backing FS doesn't support extended attributes at all and
* where it simply doesn't have the requested xattr the same way */
static inline bool ERRNO_IS_XATTR_ABSENT(int r) {
return abs(r) == ENODATA ||
ERRNO_IS_NOT_SUPPORTED(r);
}
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