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,
12 sd_bus_error_has_names_sentinel, sd_bus_error_has_names - sd-bus error
13 handling
14
16 #include <systemd/sd-bus.h>
17 typedef struct {
19 const char *name;
20 const char *message;
21 ...
22 } sd_bus_error;
23 SD_BUS_ERROR_MAKE_CONST(name, message)
25 SD_BUS_ERROR_NULL
27 void sd_bus_error_free(sd_bus_error *e);
29 int sd_bus_error_set(sd_bus_error *e, const char *name,
31 const char *message);
32 int sd_bus_error_setf(sd_bus_error *e, const char *name,
34 const char *format, ...);
35 int sd_bus_error_set_const(sd_bus_error *e, const char *name,
37 const char *message);
38 int sd_bus_error_set_errno(sd_bus_error *e, int error);
40 int sd_bus_error_set_errnof(sd_bus_error *e, int error,
42 const char *format, ...);
43 int sd_bus_error_set_errnofv(sd_bus_error *e, int error,
45 const char *format, va_list ap);
46 int sd_bus_error_get_errno(const sd_bus_error *e);
48 int sd_bus_error_copy(sd_bus_error *dst, const sd_bus_error *e);
50 int sd_bus_error_move(sd_bus_error *dst, sd_bus_error *e);
52 int sd_bus_error_is_set(const sd_bus_error *e);
54 int sd_bus_error_has_name(const sd_bus_error *e, const char *name);
56 int sd_bus_error_has_names_sentinel(const sd_bus_error *e, ...);
58 #define sd_bus_error_has_names(e, ...)
60 sd_bus_error_has_names_sentinel(e, ..., NULL)
61
63 The sd_bus_error structure carries information about a D-Bus error
64 condition. The functions described below may be used to set and query
65 fields in this structure. The name field contains a short identifier of
66 an error. It should follow the rules for error names described in the
67 D-Bus specification, subsection Valid Names[1]. A number of common,
68 standardized error names are described in sd-bus-errors(3), but
69 additional domain-specific errors may be defined by applications. The
70 message field usually contains a human-readable string describing the
71 details, but might be NULL. An unset sd_bus_error structure should have
72 both fields initialized to NULL. Set an error structure to
73 SD_BUS_ERROR_NULL in order to reset both fields to NULL. When no longer
74 necessary, resources held by the sd_bus_error structure should be
75 destroyed with sd_bus_error_free().
76 sd_bus_error_set() sets an error structure to the specified name and
78 message strings. The strings will be copied into internal, newly
79 allocated memory. It is essential to free the error structure again
80 when it is not required anymore (see above). The function will return
81 an errno-like negative value (see errno(3)) determined from the
82 specified error name. Various well-known D-Bus errors are converted to
83 well-known errno counterparts, and the other ones to -EIO. See sd-bus-
84 errors(3) for a list of well-known error names. Additional error
85 mappings may be defined with sd_bus_error_add_map(3). If e is NULL, no
86 error structure is initialized, but the error is still converted into
87 an errno-style error. If name is NULL, it is assumed that no error
88 occurred, and 0 is returned. This means that this function may be
89 conveniently used in a return statement. If message is NULL, no message
90 is set. This call can fail if no memory may be allocated for the name
91 and message strings, in which case an SD_BUS_ERROR_NO_MEMORY error
92 might be set instead and -ENOMEM be returned. Do not use this call on
93 error structures that are already initialized. If you intend to reuse
94 an error structure, free the old data stored in it with
95 sd_bus_error_free() first.
96 sd_bus_error_setf() is similar to sd_bus_error_set(), but takes a
98 printf(3) format string and corresponding arguments to generate the
99 message field.
100 sd_bus_error_set_const() is similar to sd_bus_error_set(), but the
102 string parameters are not copied internally, and must hence remain
103 constant and valid for the lifetime of e. Use this call to avoid memory
104 allocations when setting error structures. Since this call does not
105 allocate memory, it will not fail with an out-of-memory condition as
106 sd_bus_error_set() can, as described above. Alternatively, the
107 SD_BUS_ERROR_MAKE_CONST() macro may be used to generate a literal,
108 constant bus error structure on-the-fly.
109 sd_bus_error_set_errno() will set name from an errno-like value that is
111 converted to a D-Bus error. strerror_r(3) will be used to set message.
112 Well-known D-Bus error names will be used for name if applicable,
113 otherwise a name in the "System.Error." namespace will be generated.
114 The sign of the specified error number is ignored. The absolute value
115 is used implicitly. The call always returns a negative value, for
116 convenient usage in return statements. This call might fail due to lack
117 of memory, in which case an SD_BUS_ERROR_NO_MEMORY error is set
118 instead, and -ENOMEM is returned.
119 sd_bus_error_set_errnof() is similar to sd_bus_error_set_errno(), but
121 in addition to error, takes a printf(3) format string and corresponding
122 arguments. The message field will be generated from format and the
123 arguments.
124 sd_bus_error_set_errnofv() is similar to sd_bus_error_set_errnof(), but
126 takes the format string parameters as va_arg(3) parameter list.
127 sd_bus_error_get_errno() converts the name field of an error structure
129 to an errno-like (positive) value using the same rules as
130 sd_bus_error_set(). If e is NULL, 0 will be returned.
131 sd_bus_error_copy() will initialize dst using the values in e. If the
133 strings in e were set using sd_bus_error_set_const(), they will be
134 shared. Otherwise, they will be copied. Returns a converted errno-like,
135 negative error code.
136 sd_bus_error_move() is similar to sd_bus_error_copy(), but will move
138 any error information from e into dst, resetting the former. This
139 function cannot fail, as no new memory is allocated. Note that if e is
140 not set (or NULL) dst is initializated to SD_BUS_ERROR_NULL. Moreover,
141 if dst is NULL no operation is executed on it and resources held by e
142 are freed and reset. Returns a converted errno-like, negative error
143 code.
144 sd_bus_error_is_set() will return a non-zero value if e is non-NULL and
146 an error has been set, false otherwise.
147 sd_bus_error_has_name() will return a non-zero value if e is non-NULL
149 and an error with the same name has been set, false otherwise.
150 sd_bus_error_has_names_sentinel() is similar to
152 sd_bus_error_has_name(), but takes multiple names to check against. The
153 list must be terminated with NULL. sd_bus_error_has_names() is a macro
154 wrapper around sd_bus_error_has_names_sentinel() that adds the NULL
155 sentinel automatically.
156 sd_bus_error_free() will destroy resources held by e. The parameter
158 itself will not be deallocated, and must be free(3)d by the caller if
159 necessary. The function may also be called safely on unset errors
160 (error structures with both fields set to NULL), in which case it
161 performs no operation. This call will reset the error structure after
162 freeing the data, so that all fields are set to NULL. The structure may
163 be reused afterwards.
164
166 The functions sd_bus_error_set(), sd_bus_error_setf(), and
167 sd_bus_error_set_const(), when successful, return the negative errno
168 value corresponding to the name parameter. The functions
169 sd_bus_error_set_errno(), sd_bus_error_set_errnof() and
170 sd_bus_error_set_errnofv(), when successful, return the negative value
171 of the error parameter. If an error occurs, one of the negative error
172 values listed below will be returned.
173 sd_bus_error_get_errno() returns false when e is NULL, and a positive
175 errno value mapped from e->name otherwise.
176 sd_bus_error_copy() and sd_bus_error_move() return 0 or a positive
178 integer on success, and a negative error value converted from the error
179 name otherwise.
180 sd_bus_error_is_set() returns a non-zero value when e and the name
182 field are non-NULL, zero otherwise.
183 sd_bus_error_has_name(), sd_bus_error_has_names(), and
185 sd_bus_error_has_names_sentinel() return a non-zero value when e is
186 non-NULL and the name field is equal to one of the given names, zero
187 otherwise.
188
190 sd_bus_error is not reference counted. Users should destroy resources
191 held by it by calling sd_bus_error_free(). Usually, error structures
192 are allocated on the stack or passed in as function parameters, but
193 they may also be allocated dynamically, in which case it is the duty of
194 the caller to free(3) the memory held by the structure itself after
195 freeing its contents with sd_bus_error_free().
196 Errors
198 Returned errors may indicate the following problems:
199 -EINVAL
201 Error was already set in sd_bus_error structure when one the
202 error-setting functions was called.
203 -ENOMEM
205 Memory allocation failed.
206
208 These APIs are implemented as a shared library, which can be compiled
209 and linked to with the libsystemd pkg-config(1) file.
210
212 systemd(1), sd-bus(3), sd-bus-errors(3), sd_bus_error_add_map(3),
213 errno(3), strerror_r(3)
214
216 1. Valid Names
217 http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names
218systemd 248 SD_BUS_ERROR(3)