1 OFMT(3OFMT) Formatted Output Functions OFMT(3OFMT)
2
3 NAME
4 ofmt_open, ofmt_print, ofmt_print_header, ofmt_update_winsize,
5 ofmt_set_fs, ofmt_strerror, ofmt_close - data structures and routines for
6 printing output
7
8 LIBRARY
9 Formatted output library (libofmt, -lofmt)
10
11 SYNOPSIS
12 #include <ofmt.h>
13
14 ofmt_status_t
15 ofmt_open(const char *fields, const ofmt_field_t *template, uint_t flags,
16 uint_t maxcols, ofmt_handle_t *ofmt);
17
18 void
19 ofmt_print(ofmt_handle_t ofmt, void *cbarg);
20
21 void
22 ofmt_print_header(ofmt_handle_t ofmt);
23
24 void
25 ofmt_update_winsize(ofmt_handle_t ofmt);
26
27 void
28 ofmt_set_fs(ofmt_handle_t ofmt, char fs);
29
30 char *
31 ofmt_strerror(ofmt_handle_t ofmt, ofmt_status_t error, char *buf,
32 uint_t bufsize);
33
34 void
35 ofmt_close(ofmt_handle_t ofmt);
36
37 DESCRIPTION
38 The libofmt library provides data structures and routines for printing
39 output.
40
41 Currently this is an internal interface. The interface can and will
42 change without notice as the project needs, at any time.
43
44 All output is assumed to be in a columnar format, where each column
45 represents a field to be printed out. Multiple fields in parsable output
46 are separated by `:', with the `:' character itself escaped by a `\'
47 (e.g., IPv6 addresses may be printed as "fe80\:\:1"); single field output
48 is printed as-is. In multiline mode, every [field,value] pair is printed
49 in a line of its own, thus: "field: value".
50
51 Data Structures
52 The ofmt_field_t data structure used in ofmt_open is defined as follows:
53
54 typedef struct ofmt_field_s {
55 char *of_name; /* column name */
56 uint_t of_width; /* output column width */
57 uint_t of_id; /* implementation specific cookie */
58 ofmt_cb_t *of_cb; /* callback function defined by caller */
59 } ofmt_field_t;
60
61 The ofmt_arg_t data structure which is passed to callback function is
62 defined as follows:
63
64 typedef struct ofmt_arg_s {
65 uint_t ofmt_id; /* implementation specific cookie */
66 uint_t ofmt_width; /* output column width */
67 uint_t ofmt_index; /* unused */
68 void *ofmt_cbarg; /* argument passed to ofmt_print() */
69 } ofmt_arg_t;
70
71 ofmt_open()
72 The ofmt_open() function opens a handle returned in ofmt for each set of
73 fields to be printed.
74
75 fields is a comma-separated list of the fields that have been selected
76 for output (typically the string passed to -o in the command-line).
77 Columns selected for output are identified by a match between the of_name
78 value in the template and the fields requested. In human-friendly (non
79 machine-parsable) mode, NULL fields, or a value of "all" is treated as a
80 request to print all allowable fields that fit other applicable
81 constraints.
82
83 template specifies the list of supported fields, along with formatting
84 information (e.g., field width), and a pointer to a callback function
85 that can provide a string representation of the value to be printed out.
86 The set of supported fields must be a NULL terminated array of type
87 ofmt_field_t, described in Data Structures, as follows:
88
89 {<of_name>, <of_width>, <of_id>, <of_cb> },
90 ...
91 {<of_name>, <of_width>, <of_id>, <of_cb> },
92 {NULL, 0, 0, NULL}
93
94 of_cb is the application-specified callback function with the following
95 prototype that provides a string representation of the value to be
96 printed for the field:
97
98 boolean_t (*of_cb)(ofmt_arg_t *ofmt_arg, char *buf, uint_t bufsize)
99
100 The callback must not write beyond bufsize bytes of the string form into
101 buf. If the function successfully translates the field into its string
102 representation and places it into buf, then the callback function should
103 return B_TRUE. Otherwise, the callback function should return B_FALSE.
104
105 The interpretation of the of_id field is completely private to the
106 caller, and can be optionally used by the callback function as a cookie
107 to identify the field being printed when a single callback function is
108 shared between multiple template entries.
109
110 The flags can be any valid combination of the following:
111
112 OFMT_PARSABLE Machine-parsable mode. Specifying a null or empty fields
113 in the machine-parsable mode will result in a returned
114 error value of OFMT_EPARSENONE. An attempt to create a
115 handle in machine-parsable mode with the fields set to
116 "all" will result in a returned error value of
117 OFMT_EPARSEALL.
118 OFMT_WRAP Wrap output if field width is exceeded. Currently output
119 is wrapped at whitespace or comma characters.
120 OFMT_MULTILINE Multiline mode. Specifying both OFMT_MULTILINE and
121 OFMT_PARSABLE will result in OFMT_EPARSEMULTI.
122 OFMT_RIGHTJUST Right justified output.
123 OFMT_NOHEADER Skip printing the header when calling ofmt_print().
124
125 The non-zero maxcols limits the number of output columns.
126
127 ofmt_print()
128 The ofmt_print() function prints a row of output.
129
130 cbarg points at the arguments to be passed to the callback function for
131 each column in the row. The call to ofmt_print() will result in the
132 callback function of each selected field invoked with of_id, of_width and
133 cbarg embedded in ofmt_arg, described in Data Structures.
134
135 The callback function should fill buf with the string to be printed for
136 the field using the data in cbarg.
137
138 ofmt_print_header()
139 The ofmt_print_header() function prints the output header. This is
140 usually done as part of calling ofmt_print(), but is skipped when using
141 OFMT_NOHEADER. This function allows you to insert it when and where
142 desired.
143
144 ofmt_update_winsize()
145 The ofmt_update_winsize() function updates the window size information
146 (which is initially computed when the handle is created) in the ofmt. If
147 the TIOCGWINSZ ioctl fails, the window size is set to 80x24.
148
149 ofmt_set_fs()
150 The ofmt_set_fs() function sets the output field separator for parsable
151 output.
152
153 ofmt_strerror()
154 The ofmt_strerror() function returns error diagnostics in buf using the
155 information in the ofmt and error.
156
157 Using a buf size of OFMT_BUFSIZE is recommended.
158
159 ofmt_close()
160 The ofmt_close() function frees any resources allocated for the handle
161 after printing is completed.
162
163 RETURN VALUES
164 If successful, the ofmt_open() function will return OFMT_SUCCESS, with a
165 non-null ofmt_handle. The function returns one of the failure codes
166 (enumerated in ofmt_status_t) listed below otherwise:
167
168 OFMT_ENOMEM out of memory
169 OFMT_EBADFIELDS one or more bad fields with good fields
170 OFMT_ENOFIELDS no valid output fields
171 OFMT_EPARSEALL "all" is invalid in parsable mode
172 OFMT_EPARSENONE output fields missing in parsable mode
173 OFMT_EPARSEWRAP parsable mode incompatible with wrap mode
174 OFMT_ENOTEMPLATE no template provided for fields
175 OFMT_EPARSEMULTI parsable and multiline don't mix
176
177 More information about the type of failure can be obtained by calling
178 ofmt_strerror().
179
180 The ofmt_strerror() function returns the buf.
181
182 INTERFACE STABILITY
183 Private.
184
185 SEE ALSO
186 ioctl(2), strerror(3C), attributes(5)
187
188 illumos February 13, 2019 illumos