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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | NOTES | SEE ALSO | NOTES | COLOPHON |
SD_BUS_MESSAGE_APPEND_BASIC(3)s_message_append_basic_MESSAGE_APPEND_BASIC(3)
sd_bus_message_append_basic - Attach a single field to a message
#include <systemd/sd-bus.h>
int sd_bus_message_append_basic(sd_bus_message *m, char type,
const void *p);
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.
On success, this call returns 0 or a positive integer. On failure, it
returns a negative errno-style error code.
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.
The sd_bus_append_basic() function described here is available 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_message_append(3), The D-Bus
specification[2]
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
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
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⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
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COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
systemd 234 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), systemd.directives(7), systemd.index(7)