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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | REFERENCE OWNERSHIP | NOTES | SEE ALSO | NOTES | COLOPHON |
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SD_BUS_ERROR(3) sd_bus_error SD_BUS_ERROR(3)
sd_bus_error, SD_BUS_ERROR_MAKE_CONST, SD_BUS_ERROR_NULL,
sd_bus_error_free, sd_bus_error_set, sd_bus_error_setf,
sd_bus_error_set_const, sd_bus_error_set_errno,
sd_bus_error_set_errnof, sd_bus_error_set_errnofv,
sd_bus_error_get_errno, sd_bus_error_copy, sd_bus_error_move,
sd_bus_error_is_set, sd_bus_error_has_name,
sd_bus_error_has_names_sentinel, sd_bus_error_has_names - sd-bus
error handling
#include <systemd/sd-bus.h>
typedef struct {
const char *name;
const char *message;
...
} sd_bus_error;
SD_BUS_ERROR_MAKE_CONST(name, message)
SD_BUS_ERROR_NULL
void sd_bus_error_free(sd_bus_error *e);
int sd_bus_error_set(sd_bus_error *e, const char *name,
const char *message);
int sd_bus_error_setf(sd_bus_error *e, const char *name,
const char *format, ...);
int sd_bus_error_set_const(sd_bus_error *e, const char *name,
const char *message);
int sd_bus_error_set_errno(sd_bus_error *e, int error);
int sd_bus_error_set_errnof(sd_bus_error *e, int error,
const char *format, ...);
int sd_bus_error_set_errnofv(sd_bus_error *e, int error,
const char *format, va_list ap);
int sd_bus_error_get_errno(const sd_bus_error *e);
int sd_bus_error_copy(sd_bus_error *dst, const sd_bus_error *e);
int sd_bus_error_move(sd_bus_error *dst, sd_bus_error *e);
int sd_bus_error_is_set(const sd_bus_error *e);
int sd_bus_error_has_name(const sd_bus_error *e,
const char *name);
int sd_bus_error_has_names_sentinel(const sd_bus_error *e, ...);
#define sd_bus_error_has_names(e, ...)
sd_bus_error_has_names_sentinel(e, ..., NULL)
The sd_bus_error structure carries information about a D-Bus
error condition. The functions described below may be used to set
and query fields in this structure. The name field contains a
short identifier of an error. It should follow the rules for
error names described in the D-Bus specification, subsection
Valid Names[1]. A number of common, standardized error names are
described in sd-bus-errors(3), but additional domain-specific
errors may be defined by applications. The message field usually
contains a human-readable string describing the details, but
might be NULL. An unset sd_bus_error structure should have both
fields initialized to NULL. Set an error structure to
SD_BUS_ERROR_NULL in order to reset both fields to NULL. When no
longer necessary, resources held by the sd_bus_error structure
should be destroyed with sd_bus_error_free().
sd_bus_error_set() sets an error structure to the specified name
and message strings. The strings will be copied into internal,
newly allocated memory. It is essential to free the error
structure again when it is not required anymore (see above). The
function will return an errno-like negative value (see errno(3))
determined from the specified error name. Various well-known
D-Bus errors are converted to well-known errno counterparts, and
the other ones to -EIO. See sd-bus-errors(3) for a list of
well-known error names. Additional error mappings may be defined
with sd_bus_error_add_map(3). If e is NULL, no error structure is
initialized, but the error is still converted into an errno-style
error. If name is NULL, it is assumed that no error occurred, and
0 is returned. This means that this function may be conveniently
used in a return statement. If message is NULL, no message is
set. This call can fail if no memory may be allocated for the
name and message strings, in which case an SD_BUS_ERROR_NO_MEMORY
error might be set instead and -ENOMEM be returned. Do not use
this call on error structures that are already initialized. If
you intend to reuse an error structure, free the old data stored
in it with sd_bus_error_free() first.
sd_bus_error_setf() is similar to sd_bus_error_set(), but takes a
printf(3) format string and corresponding arguments to generate
the message field.
sd_bus_error_set_const() is similar to sd_bus_error_set(), but
the string parameters are not copied internally, and must hence
remain constant and valid for the lifetime of e. Use this call to
avoid memory allocations when setting error structures. Since
this call does not allocate memory, it will not fail with an
out-of-memory condition as sd_bus_error_set() can, as described
above. Alternatively, the SD_BUS_ERROR_MAKE_CONST() macro may be
used to generate a literal, constant bus error structure
on-the-fly.
sd_bus_error_set_errno() will set name from an errno-like value
that is converted to a D-Bus error. strerror_r(3) will be used
to set message. Well-known D-Bus error names will be used for
name if applicable, otherwise a name in the "System.Error."
namespace will be generated. The sign of the specified error
number is ignored. The absolute value is used implicitly. The
call always returns a negative value, for convenient usage in
return statements. This call might fail due to lack of memory, in
which case an SD_BUS_ERROR_NO_MEMORY error is set instead, and
-ENOMEM is returned.
sd_bus_error_set_errnof() is similar to sd_bus_error_set_errno(),
but in addition to error, takes a printf(3) format string and
corresponding arguments. The message field will be generated from
format and the arguments.
sd_bus_error_set_errnofv() is similar to
sd_bus_error_set_errnof(), but takes the format string parameters
as va_arg(3) parameter list.
sd_bus_error_get_errno() converts the name field of an error
structure to an errno-like (positive) value using the same rules
as sd_bus_error_set(). If e is NULL, 0 will be returned.
sd_bus_error_copy() will initialize dst using the values in e. If
the strings in e were set using sd_bus_error_set_const(), they
will be shared. Otherwise, they will be copied. Returns a
converted errno-like, negative error code.
sd_bus_error_move() is similar to sd_bus_error_copy(), but will
move any error information from e into dst, resetting the former.
This function cannot fail, as no new memory is allocated. Note
that if e is not set (or NULL) dst is initializated to
SD_BUS_ERROR_NULL. Moreover, if dst is NULL no operation is
executed on it and and resources held by e are freed and reset.
Returns a converted errno-like, negative error code.
sd_bus_error_is_set() will return a non-zero value if e is
non-NULL and an error has been set, false otherwise.
sd_bus_error_has_name() will return a non-zero value if e is
non-NULL and an error with the same name has been set, false
otherwise.
sd_bus_error_has_names_sentinel() is similar to
sd_bus_error_has_name(), but takes multiple names to check
against. The list must be terminated with NULL.
sd_bus_error_has_names() is a macro wrapper around
sd_bus_error_has_names_sentinel() that adds the NULL sentinel
automatically.
sd_bus_error_free() will destroy resources held by e. The
parameter itself will not be deallocated, and must be free(3)d by
the caller if necessary. The function may also be called safely
on unset errors (error structures with both fields set to NULL),
in which case it performs no operation. This call will reset the
error structure after freeing the data, so that all fields are
set to NULL. The structure may be reused afterwards.
The functions sd_bus_error_set(), sd_bus_error_setf(), and
sd_bus_error_set_const(), when successful, return the negative
errno value corresponding to the name parameter. The functions
sd_bus_error_set_errno(), sd_bus_error_set_errnof() and
sd_bus_error_set_errnofv(), when successful, return the negative
value of the error parameter. If an error occurs, one of the
negative error values listed below will be returned.
sd_bus_error_get_errno() returns false when e is NULL, and a
positive errno value mapped from e->name otherwise.
sd_bus_error_copy() and sd_bus_error_move() return 0 or a
positive integer on success, and a negative error value converted
from the error name otherwise.
sd_bus_error_is_set() returns a non-zero value when e and the
name field are non-NULL, zero otherwise.
sd_bus_error_has_name(), sd_bus_error_has_names(), and
sd_bus_error_has_names_sentinel() return a non-zero value when e
is non-NULL and the name field is equal to one of the given
names, zero otherwise.
sd_bus_error is not reference counted. Users should destroy
resources held by it by calling sd_bus_error_free(). Usually,
error structures are allocated on the stack or passed in as
function parameters, but they may also be allocated dynamically,
in which case it is the duty of the caller to free(3) the memory
held by the structure itself after freeing its contents with
sd_bus_error_free().
Errors
Returned errors may indicate the following problems:
-EINVAL
Error was already set in sd_bus_error structure when one the
error-setting functions was called.
-ENOMEM
Memory allocation failed.
These APIs are implemented as a shared library, which can be
compiled and linked to with the libsystemd pkg-config(1) file.
systemd(1), sd-bus(3), sd-bus-errors(3), sd_bus_error_add_map(3),
errno(3), strerror_r(3)
1. Valid Names
http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have
a bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2020-12-18. (At that
time, the date of the most recent commit that was found in the
repository was 2020-12-18.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 247 SD_BUS_ERROR(3)
Pages that refer to this page: sd-bus(3), sd_bus_add_object(3), sd_bus_call(3), sd_bus_error_add_map(3), sd-bus-errors(3), sd_bus_message_new_method_error(3), sd_bus_reply_method_error(3), systemd.directives(7), systemd.index(7)
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