1SD_BUS_ERROR(3) sd_bus_error SD_BUS_ERROR(3)
2
6 sd_bus_error, SD_BUS_ERROR_MAKE_CONST, SD_BUS_ERROR_NULL,
7 sd_bus_error_free, sd_bus_error_set, sd_bus_error_setf,
8 sd_bus_error_set_const, sd_bus_error_set_errno,
9 sd_bus_error_set_errnof, sd_bus_error_set_errnofv,
10 sd_bus_error_get_errno, sd_bus_error_copy, sd_bus_error_move,
11 sd_bus_error_is_set, sd_bus_error_has_name - sd-bus error handling
12
14 #include <systemd/sd-bus.h>
15 typedef struct {
17 const char *name;
18 const char *message;
19 ...
20 } sd_bus_error;
21 SD_BUS_ERROR_MAKE_CONST(name, message)
23 SD_BUS_ERROR_NULL
25 void sd_bus_error_free(sd_bus_error *e);
27 int sd_bus_error_set(sd_bus_error *e, const char *name,
29 const char *message);
30 int sd_bus_error_setf(sd_bus_error *e, const char *name,
32 const char *format, ...);
33 int sd_bus_error_set_const(sd_bus_error *e, const char *name,
35 const char *message);
36 int sd_bus_error_set_errno(sd_bus_error *e, int error);
38 int sd_bus_error_set_errnof(sd_bus_error *e, int error,
40 const char *format, ...);
41 int sd_bus_error_set_errnofv(sd_bus_error *e, int error,
43 const char *format, va_list ap);
44 int sd_bus_error_get_errno(const sd_bus_error *e);
46 int sd_bus_error_copy(sd_bus_error *dst, const sd_bus_error *e);
48 int sd_bus_error_move(sd_bus_error *dst, sd_bus_error *e);
50 int sd_bus_error_is_set(const sd_bus_error *e);
52 int sd_bus_error_has_name(const sd_bus_error *e, const char *name);
54
56 The sd_bus_error structure carries information about a D-Bus error
57 condition. The functions described below may be used to set and query
58 fields in this structure. The name field contains a short identifier of
59 an error. It should follow the rules for error names described in the
60 D-Bus specification, subsection Valid Names[1]. A number of common,
61 standardized error names are described in sd-bus-errors(3), but
62 additional domain-specific errors may be defined by applications. The
63 message field usually contains a human-readable string describing the
64 details, but might be NULL. An unset sd_bus_error structure should have
65 both fields initialized to NULL. Set an error structure to
66 SD_BUS_ERROR_NULL in order to reset both fields to NULL. When no longer
67 necessary, resources held by the sd_bus_error structure should be
68 destroyed with sd_bus_error_free().
69 sd_bus_error_set() sets an error structure to the specified name and
71 message strings. The strings will be copied into internal, newly
72 allocated memory. It is essential to free the error structure again
73 when it is not required anymore (see above). The function will return
74 an errno-like negative value (see errno(3)) determined from the
75 specified error name. Various well-known D-Bus errors are converted to
76 well-known errno counterparts, and the other ones to -EIO. See sd-bus-
77 errors(3) for a list of well-known error names. Additional error
78 mappings may be defined with sd_bus_error_add_map(3). If e is NULL, no
79 error structure is initialized, but the error is still converted into
80 an errno-style error. If name is NULL, it is assumed that no error
81 occurred, and 0 is returned. This means that this function may be
82 conveniently used in a return statement. If message is NULL, no message
83 is set. This call can fail if no memory may be allocated for the name
84 and message strings, in which case an SD_BUS_ERROR_NO_MEMORY error
85 might be set instead and -ENOMEM be returned. Do not use this call on
86 error structures that are already initialized. If you intend to reuse
87 an error structure, free the old data stored in it with
88 sd_bus_error_free() first.
89 sd_bus_error_setf() is similar to sd_bus_error_set(), but takes a
91 printf(3) format string and corresponding arguments to generate the
92 message field.
93 sd_bus_error_set_const() is similar to sd_bus_error_set(), but the
95 string parameters are not copied internally, and must hence remain
96 constant and valid for the lifetime of e. Use this call to avoid memory
97 allocations when setting error structures. Since this call does not
98 allocate memory, it will not fail with an out-of-memory condition as
99 sd_bus_error_set() can, as described above. Alternatively, the
100 SD_BUS_ERROR_MAKE_CONST() macro may be used to generate a literal,
101 constant bus error structure on-the-fly.
102 sd_bus_error_set_errno() will set name from an errno-like value that is
104 converted to a D-Bus error. strerror_r(3) will be used to set message.
105 Well-known D-Bus error names will be used for name if applicable,
106 otherwise a name in the "System.Error." namespace will be generated.
107 The sign of the specified error number is ignored. The absolute value
108 is used implicitly. The call always returns a negative value, for
109 convenient usage in return statements. This call might fail due to lack
110 of memory, in which case an SD_BUS_ERROR_NO_MEMORY error is set
111 instead, and -ENOMEM is returned.
112 sd_bus_error_set_errnof() is similar to sd_bus_error_set_errno(), but
114 in addition to error, takes a printf(3) format string and corresponding
115 arguments. The message field will be generated from format and the
116 arguments.
117 sd_bus_error_set_errnofv() is similar to sd_bus_error_set_errnof(), but
119 takes the format string parameters as va_arg(3) parameter list.
120 sd_bus_error_get_errno() converts the name field of an error structure
122 to an errno-like (positive) value using the same rules as
123 sd_bus_error_set(). If e is NULL, 0 will be returned.
124 sd_bus_error_copy() will initialize dst using the values in e. If the
126 strings in e were set using sd_bus_error_set_const(), they will be
127 shared. Otherwise, they will be copied. Returns a converted errno-like,
128 negative error code.
129 sd_bus_error_move() is similar to sd_bus_error_copy(), but will move
131 any error information from e into dst, resetting the former. This
132 function cannot fail, as no new memory is allocated. Note that if e is
133 not set (or NULL) dst is initializated to SD_BUS_ERROR_NULL. Moreover,
134 if dst is NULL no operation is executed on it and and resources held by
135 e are freed and reset. Returns a converted errno-like, negative error
136 code.
137 sd_bus_error_is_set() will return a non-zero value if e is non-NULL and
139 an error has been set, false otherwise.
140 sd_bus_error_has_name() will return a non-zero value if e is non-NULL
142 and an error with the same name has been set, false otherwise.
143 sd_bus_error_free() will destroy resources held by e. The parameter
145 itself will not be deallocated, and must be free(3)d by the caller if
146 necessary. The function may also be called safely on unset errors
147 (error structures with both fields set to NULL), in which case it
148 performs no operation. This call will reset the error structure after
149 freeing the data, so that all fields are set to NULL. The structure may
150 be reused afterwards.
151
153 The functions sd_bus_error_set(), sd_bus_error_setf(), and
154 sd_bus_error_set_const(), when successful, return the negative errno
155 value corresponding to the name parameter. The functions
156 sd_bus_error_set_errno(), sd_bus_error_set_errnof() and
157 sd_bus_error_set_errnofv(), when successful, return the negative value
158 of the error parameter. If an error occurs, one of the negative error
159 values listed below will be returned.
160 sd_bus_error_get_errno() returns false when e is NULL, and a positive
162 errno value mapped from e->name otherwise.
163 sd_bus_error_copy() and sd_bus_error_move() return 0 or a positive
165 integer on success, and a negative error value converted from the error
166 name otherwise.
167 sd_bus_error_is_set() returns a non-zero value when e and the name
169 field are non-NULL, zero otherwise.
170 sd_bus_error_has_name() returns a non-zero value when e is non-NULL and
172 the name field is equal to name, zero otherwise.
173
175 sd_bus_error is not reference counted. Users should destroy resources
176 held by it by calling sd_bus_error_free(). Usually, error structures
177 are allocated on the stack or passed in as function parameters, but
178 they may also be allocated dynamically, in which case it is the duty of
179 the caller to free(3) the memory held by the structure itself after
180 freeing its contents with sd_bus_error_free().
181 Errors
183 Returned errors may indicate the following problems:
184 -EINVAL
186 Error was already set in sd_bus_error structure when one the
187 error-setting functions was called.
188 -ENOMEM
190 Memory allocation failed.
191
193 These APIs are implemented as a shared library, which can be compiled
194 and linked to with the libsystemd pkg-config(1) file.
195
197 systemd(1), sd-bus(3), sd-bus-errors(3), sd_bus_error_add_map(3),
198 errno(3), strerror_r(3)
199
201 1. Valid Names
202 http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names
203systemd 246 SD_BUS_ERROR(3)