sd_bus_error(3) — Linux manual page


SD_BUS_ERROR(3)               sd_bus_error               SD_BUS_ERROR(3)

NAME         top

       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

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       typedef struct {
               const char *name;
               const char *message;
       } sd_bus_error;

       SD_BUS_ERROR_MAKE_CONST(name, message)


       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)

DESCRIPTION         top

       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

       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

       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

       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.

RETURN VALUE         top

       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

       Returned errors may indicate the following problems:

           Error was already set in sd_bus_error structure when one the
           error-setting functions was called.

           Memory allocation failed.

NOTES         top

       These APIs are implemented as a shared library, which can be
       compiled and linked to with the libsystemd pkg-config(1) file.

SEE ALSO         top

       systemd(1), sd-bus(3), sd-bus-errors(3), sd_bus_error_add_map(3),
       errno(3), strerror_r(3)

NOTES         top

        1. Valid Names

COLOPHON         top

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       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-12-18.  (At that
       time, the date of the most recent commit that was found in the
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       (which is not part of the original manual page), send a mail to

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)