sd_bus_message_append_basic(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | NOTES | COLOPHON

SD_BUS_MESSAGE_APPEND_BASIC(3)message_append_basicESSAGE_APPEND_BASIC(3)

NAME         top

       sd_bus_message_append_basic - Attach a single field to a message

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       int sd_bus_message_append_basic(sd_bus_message *m, char type,
                                       const void *p);

DESCRIPTION         top

       sd_bus_message_append_basic() appends a single field to the
       message m. The parameter type determines how the pointer p is
       interpreted.  type must be one of the basic types as defined by
       the Basic Types[1] section of the D-Bus specification, and listed
       in the table below.

       Table 1. Item type specifiers
       ┌──────────┬─────────────────────────┬────────────────┬──────────┬────────────┐
       │Specifier Constant                Description    Size     Expected C │
       │          │                         │                │          │ Type       │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"y"       │ SD_BUS_TYPE_BYTE        │ unsigned       │ 1 byte   │ uint8_t    │
       │          │                         │ integer        │          │            │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"b"       │ SD_BUS_TYPE_BOOLEAN     │ boolean        │ 4 bytes  │ int        │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"n"       │ SD_BUS_TYPE_INT16       │ signed         │ 2 bytes  │ int16_t    │
       │          │                         │ integer        │          │            │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"q"       │ SD_BUS_TYPE_UINT16      │ unsigned       │ 2 bytes  │ uint16_t   │
       │          │                         │ integer        │          │            │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"i"       │ SD_BUS_TYPE_INT32       │ signed         │ 4 bytes  │ int32_t    │
       │          │                         │ integer        │          │            │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"u"       │ SD_BUS_TYPE_UINT32      │ unsigned       │ 4 bytes  │ uint32_t   │
       │          │                         │ integer        │          │            │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"x"       │ SD_BUS_TYPE_INT64       │ signed         │ 8 bytes  │ int64_t    │
       │          │                         │ integer        │          │            │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"t"       │ SD_BUS_TYPE_UINT64      │ unsigned       │ 8 bytes  │ uint64_t   │
       │          │                         │ integer        │          │            │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"d"       │ SD_BUS_TYPE_DOUBLE      │ floating-point │ 8 bytes  │ double     │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"s"       │ SD_BUS_TYPE_STRING      │ Unicode string │ variable │ char[]     │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"o"       │ SD_BUS_TYPE_OBJECT_PATH │ object path    │ variable │ char[]     │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"g"       │ SD_BUS_TYPE_SIGNATURE   │ signature      │ variable │ char[]     │
       ├──────────┼─────────────────────────┼────────────────┼──────────┼────────────┤
       │"h"       │ SD_BUS_TYPE_UNIX_FD     │ UNIX file      │ 4 bytes  │ int        │
       │          │                         │ descriptor     │          │            │
       └──────────┴─────────────────────────┴────────────────┴──────────┴────────────┘

       The value of the parameter is copied into a memory area held by
       the message object, stays in the possession of the caller and may
       hence be freely changed after this call without affecting the bus
       message it has been added to. If type is "h" (UNIX file
       descriptor), the descriptor is duplicated by this call and the
       passed descriptor stays in possession of the caller.

       For types "s", "o", and "g", the parameter p is interpreted as a
       pointer to a NUL-terminated character sequence. As a special
       case, a NULL pointer is interpreted as an empty string. The
       string should be valid Unicode string encoded as UTF-8. In case
       of the two latter types, the additional requirements for a D-Bus
       object path or type signature should be satisfied. Those
       requirements should be verified by the recipient of the message.

RETURN VALUE         top

       On success, this call returns 0 or a positive integer. On
       failure, it returns a negative errno-style error code.

   Errors
       Returned errors may indicate the following problems:

       -EINVAL
           Specified parameter is invalid.

       -EPERM
           Message has been sealed.

       -ESTALE
           Message is in invalid state.

       -ENXIO
           Message cannot be appended to.

       -ENOMEM
           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_message_read_basic(3),
       sd_bus_message_append(3), The D-Bus specification[2]

NOTES         top

        1. Basic Types
           http://dbus.freedesktop.org/doc/dbus-specification.html#basic-types

        2. The D-Bus specification
           http://dbus.freedesktop.org/doc/dbus-specification.html

COLOPHON         top

       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 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-08-27.)  If you discover any rendering
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       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 249                               SD_BUS_MESSAGE_APPEND_BASIC(3)

Pages that refer to this page: sd-bus(3)sd_bus_message_append(3)sd_bus_message_append_array(3)sd_bus_message_append_string_memfd(3)sd_bus_message_append_strv(3)sd_bus_message_read_basic(3)