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1 .\" Copyright (c) Michael Smith
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25 .\" $FreeBSD: src/lib/libstand/libstand.3,v 1.5.2.11 2002/06/26 19:14:43 schweikh Exp $
26 .\" $DragonFly: src/lib/libstand/libstand.3,v 1.8 2008/05/02 02:05:04 swildner Exp $
27 .\"
28 .Dd September 13, 2004
29 .Dt LIBSTAND 3
30 .Os
31 .Sh NAME
32 .Nm libstand
33 .Nd support library for standalone executables
34 .Sh LIBRARY
35 .Lb libstand
36 .Sh SYNOPSIS
37 .In stand.h
38 .Sh DESCRIPTION
39 .Nm
40 provides a set of supporting functions for standalone
41 applications, mimicking where possible the standard
42 .Bx
43 programming
44 environment. The following sections group these functions by kind.
45 Unless specifically described here, see the corresponding section 3
46 manpages for the given functions.
47 .Sh STRING FUNCTIONS
48 String functions are available as documented in
49 .Xr string 3
50 and
51 .Xr bstring 3 .
52 .Sh MEMORY ALLOCATION
53 .Bl -hang -width 10n
54 .It Xo
55 .Ft "void *"
56 .Fn malloc "size_t size"
57 .Xc
58 .Pp
59 Allocate
60 .Fa size
61 bytes of memory from the heap using a best-fit algorithm.
62 .It Xo
63 .Ft void
64 .Fn free "void *ptr"
65 .Xc
66 .Pp
67 Free the allocated object at
68 .Fa ptr .
69 .It Xo
70 .Ft void
71 .Fn setheap "void *start" "void *limit"
72 .Xc
73 .Pp
74 Initialise the heap. This function must be called before calling
75 .Fn alloc
76 for the first time. The region between
77 .Fa start
78 and
79 .Fa limit
80 will be used for the heap; attempting to allocate beyond this will result
81 in a panic.
82 .It Xo
83 .Ft "char *"
84 .Fn sbrk "int junk"
85 .Xc
86 .Pp
87 Provides the behaviour of
88 .Fn sbrk 0 ,
89 ie. returns the highest point that the heap has reached. This value can
90 be used during testing to determine the actual heap usage. The
91 .Fa junk
92 argument is ignored.
93 .El
94 .Sh ENVIRONMENT
95 A set of functions are provided for manipulating a flat variable space similar
96 to the traditional shell-supported environment. Major enhancements are support
97 for set/unset hook functions.
98 .Bl -hang -width 10n
99 .It Xo
100 .Ft "char *"
101 .Fn getenv "const char *name"
102 .Xc
103 .It Xo
104 .Ft int
105 .Fn setenv "const char *name" "char *value" "int overwrite"
106 .Xc
107 .It Xo
108 .Ft int
109 .Fn putenv "const char *string"
110 .Xc
111 .It Xo
112 .Ft int
113 .Fn unsetenv "const char *name"
114 .Xc
115 .Pp
116 These functions behave similarly to their standard library counterparts.
117 .It Xo
118 .Ft "struct env_var *"
119 .Fn env_getenv "const char *name"
120 .Xc
121 .Pp
122 Looks up a variable in the environment and returns its entire
123 data structure.
124 .It Xo
125 .Ft int
126 .Fn env_setenv "const char *name" "int flags" "char *value" "ev_sethook_t sethook" "ev_unsethook_t unsethook"
127 .Xc
128 .Pp
129 Creates a new or sets an existing environment variable called
130 .Fa name .
131 If creating a new variable, the
132 .Fa sethook
133 and
134 .Fa unsethook
135 arguments may be specified.
136 .Pp
137 The set hook is invoked whenever an attempt
138 is made to set the variable, unless the EV_NOHOOK flag is set. Typically
139 a set hook will validate the
140 .Fa value
141 argument, and then call
142 .Fn env_setenv
143 again with EV_NOHOOK set to actually save the value. The predefined function
144 .Fn env_noset
145 may be specified to refuse all attempts to set a variable.
146 .Pp
147 The unset hook is invoked when an attempt is made to unset a variable.
148 If it
149 returns zero, the variable will be unset. The predefined function
150 .Fa env_nounset
151 may be used to prevent a variable being unset.
152 .El
153 .Sh STANDARD LIBRARY SUPPORT
154 .Bl -hang -width 10n
155 .It Xo
156 .Ft int
157 .Fn getopt "int argc" "char * const *argv" "const char *optstring"
158 .Xc
159 .It Xo
160 .Ft long
161 .Fn strtol "const char *nptr" "char **endptr" "int base"
162 .Xc
163 .It Xo
164 .Ft void
165 .Fn srandom "unsigned long seed"
166 .Xc
167 .It Xo
168 .Ft "unsigned long"
169 .Fn random void
170 .Xc
171 .It Xo
172 .Ft "char *"
173 .Fn strerror "int error"
174 .Xc
175 .Pp
176 Returns error messages for the subset of
177 .Va errno
178 values supported by
179 .Nm .
180 .It Fn assert expression
181 .Pp
182 Requires
183 .In assert.h
184 .It Xo
185 .Ft int
186 .Fn setjmp "jmp_buf env"
187 .Xc
188 .It Xo
189 .Ft void
190 .Fn longjmp "jmp_buf env" "int val"
191 .Xc
192 .Pp
193 Defined as
194 .Fn _setjmp
195 and
196 .Fn _longjmp
197 respectively as there is no signal state to manipulate. Requires
198 .In setjmp.h
199 .El
200 .Sh CHARACTER I/O
201 .Bl -hang -width 10n
202 .It Xo
203 .Ft void
204 .Fn gets "char *buf"
205 .Xc
206 .Pp
207 Read characters from the console into
208 .Fa buf .
209 All of the standard cautions apply to this function.
210 .It Xo
211 .Ft void
212 .Fn ngets "char *buf" "size_t size"
213 .Xc
214 .Pp
215 Read at most
216 .Fa size
217 - 1 characters from the console into
218 .Fa buf .
219 If
220 .Fa size
221 is less than 1, the function's behaviour is as for
222 .Fn gets .
223 .It Xo
224 .Ft int
225 .Fn fgetstr "char *buf" "int size" "int fd"
226 .Xc
227 .Pp
228 Read a line of at most
229 .Fa size
230 characters into
231 .Fa buf .
232 Line terminating characters are stripped, and the buffer is always nul
233 terminated. Returns the number of characters in
234 .Fa buf
235 if successful, or -1 if a read error occurs.
236 .It Xo
237 .Ft int
238 .Fn printf "const char *fmt" "..."
239 .Xc
240 .It Xo
241 .Ft void
242 .Fn vprintf "const char *fmt" "va_list ap"
243 .Xc
244 .It Xo
245 .Ft int
246 .Fn sprintf "char *buf" "const char *fmt" "..."
247 .Xc
248 .It Xo
249 .Ft void
250 .Fn vsprintf "char *buf" "const char *fmt" "va_list ap"
251 .Xc
252 .Pp
253 The *printf functions implement a subset of the standard
254 .Fn printf
255 family functionality and some extensions. The following standard conversions
256 are supported: c,d,n,o,p,s,u,x. The following modifiers are supported:
257 +,-,#,*,0,field width,precision,l.
258 .Pp
259 The
260 .Li b
261 conversion is provided to decode error registers. Its usage is:
262 .Bd -ragged -offset indent
263 printf(
264 .Qq reg=%b\en ,
265 regval,
266 .Qq <base><arg>*
267 );
268 .Ed
269 .Pp
270 where <base> is the output expressed as a control character, eg. \e10 gives
271 octal, \e20 gives hex. Each <arg> is a sequence of characters, the first of
272 which gives the bit number to be inspected (origin 1) and the next characters
273 (up to a character less than 32) give the text to be displayed if the bit is set.
274 Thus
275 .Bd -ragged -offset indent
276 printf(
277 .Qq reg=%b\en ,
278 3,
279 .Qq \e10\e2BITTWO\e1BITONE\en
280 );
281 .Ed
282 .Pp
283 would give the output
284 .Bd -ragged -offset indent
285 reg=3<BITTWO,BITONE>
286 .Ed
287 .Pp
288 The
289 .Li D
290 conversion provides a hexdump facility, eg.
291 .Bd -ragged -offset indent
292 printf(
293 .Qq %6D ,
294 ptr,
295 .Qq \&:
296 ); gives
297 .Qq XX:XX:XX:XX:XX:XX
298 .Ed
299 .Bd -ragged -offset indent
300 printf(
301 .Qq %*D ,
302 len,
303 ptr,
304 .Qq "\ "
305 ); gives
306 .Qq XX XX XX ...
307 .Ed
308 .El
309 .Sh CHARACTER TESTS AND CONVERSIONS
310 .Bl -hang -width 10n
311 .It Xo
312 .Ft int
313 .Fn isupper "int c"
314 .Xc
315 .It Xo
316 .Ft int
317 .Fn islower "int c"
318 .Xc
319 .It Xo
320 .Ft int
321 .Fn isspace "int c"
322 .Xc
323 .It Xo
324 .Ft int
325 .Fn isdigit "int c"
326 .Xc
327 .It Xo
328 .Ft int
329 .Fn isxdigit "int c"
330 .Xc
331 .It Xo
332 .Ft int
333 .Fn isascii "int c"
334 .Xc
335 .It Xo
336 .Ft int
337 .Fn isalpha "int c"
338 .Xc
339 .It Xo
340 .Ft int
341 .Fn toupper "int c"
342 .Xc
343 .It Xo
344 .Ft int
345 .Fn tolower "int c"
346 .Xc
347 .El
348 .Sh FILE I/O
349 .Bl -hang -width 10n
350 .It Xo
351 .Ft int
352 .Fn open "const char *path" "int flags"
353 .Xc
354 .Pp
355 Similar to the behaviour as specified in
356 .Xr open 2 ,
357 except that file creation is not supported, so the mode parameter is not
358 required. The
359 .Fa flags
360 argument may be one of O_RDONLY, O_WRONLY and O_RDWR (although no filesystems
361 currently support writing).
362 .It Xo
363 .Ft int
364 .Fn close "int fd"
365 .Xc
366 .It Xo
367 .Ft void
368 .Fn closeall void
369 .Xc
370 .Pp
371 Close all open files.
372 .It Xo
373 .Ft ssize_t
374 .Fn read "int fd" "void *buf" "size_t len"
375 .Xc
376 .It Xo
377 .Ft ssize_t
378 .Fn write "int fd" "void *buf" "size_t len"
379 .Xc
380 .Pp
381 (No filesystems currently support writing.)
382 .It Xo
383 .Ft off_t
384 .Fn lseek "int fd" "off_t offset" "int whence"
385 .Xc
386 .Pp
387 Files being automatically uncompressed during reading cannot seek backwards
388 from the current point.
389 .It Xo
390 .Ft int
391 .Fn stat "const char *path" "struct stat *sb"
392 .Xc
393 .It Xo
394 .Ft int
395 .Fn fstat "int fd" "struct stat *sb"
396 .Xc
397 .Pp
398 The
399 .Fn stat
400 and
401 .Fn fstat
402 functions only fill out the following fields in the
403 .Fa sb
404 structure: st_mode,st_nlink,st_uid,st_gid,st_size. The
405 .Nm tftp
406 filesystem cannot provide meaningful values for this call, and the
407 .Nm cd9660
408 filesystem always reports files having uid/gid of zero.
409 .El
410 .Sh PAGER
411 .Nm
412 supplies a simple internal pager to ease reading the output of large commands.
413 .Bl -hang -width 10n
414 .It Xo
415 .Ft void
416 .Fn pager_open
417 .Xc
418 .Pp
419 Initialises the pager and tells it that the next line output will be the top of the
420 display. The environment variable LINES is consulted to determine the number of
421 lines to be displayed before pausing.
422 .It Xo
423 .Ft void
424 .Fn pager_close void
425 .Xc
426 .Pp
427 Closes the pager.
428 .It Xo
429 .Ft int
430 .Fn pager_output "char *lines"
431 .Xc
432 .Pp
433 Sends the lines in the nul-terminated buffer at
434 .Fa lines
435 to the pager. Newline characters are counted in order to determine the number
436 of lines being output (wrapped lines are not accounted for).
437 .Fn pager_output
438 will return zero when all of the lines have been output, or nonzero if the
439 display was paused and the user elected to quit.
440 .It Xo
441 .Ft int
442 .Fn pager_file "char *fname"
443 .Xc
444 .Pp
445 Attempts to open and display the file
446 .Fa fname .
447 Returns -1 on error, 0 at EOF, or 1 if the user elects to quit while reading.
448 .El
449 .Sh MISC
450 .Bl -hang -width 10n
451 .It Xo
452 .Ft void
453 .Fn twiddle void
454 .Xc
455 .Pp
456 Successive calls emit the characters in the sequence |,/,-,\\ followed by a
457 backspace in order to provide reassurance to the user.
458 .El
459 .Sh REQUIRED LOW-LEVEL SUPPORT
460 The following resources are consumed by
461 .Nm
462 - stack, heap, console and devices.
463 .Pp
464 The stack must be established before
465 .Nm
466 functions can be invoked. Stack requirements vary depending on the functions
467 and filesystems used by the consumer and the support layer functions detailed
468 below.
469 .Pp
470 The heap must be established before calling
471 .Fn alloc
472 or
473 .Fn open
474 by calling
475 .Fn setheap .
476 Heap usage will vary depending on the number of simultaneously open files,
477 as well as client behaviour. Automatic decompression will allocate more
478 than 64K of data per open file.
479 .Pp
480 Console access is performed via the
481 .Fn getchar ,
482 .Fn putchar
483 and
484 .Fn ischar
485 functions detailed below.
486 .Pp
487 Device access is initiated via
488 .Fn devopen
489 and is performed through the
490 .Fn dv_strategy ,
491 .Fn dv_ioctl
492 and
493 .Fn dv_close
494 functions in the device switch structure that
495 .Fn devopen
496 returns.
497 .Pp
498 The consumer must provide the following support functions:
499 .Bl -hang -width 10n
500 .It Xo
501 .Ft int
502 .Fn getchar void
503 .Xc
504 .Pp
505 Return a character from the console, used by
506 .Fn gets ,
507 .Fn ngets
508 and pager functions.
509 .It Xo
510 .Ft int
511 .Fn ischar void
512 .Xc
513 .Pp
514 Returns nonzero if a character is waiting from the console.
515 .It Xo
516 .Ft void
517 .Fn putchar int
518 .Xc
519 .Pp
520 Write a character to the console, used by
521 .Fn gets ,
522 .Fn ngets ,
523 .Fn *printf ,
524 .Fn panic
525 and
526 .Fn twiddle
527 and thus by many other functions for debugging and informational output.
528 .It Xo
529 .Ft int
530 .Fn devopen "struct open_file *of" "const char *name" "char **file"
531 .Xc
532 .Pp
533 Open the appropriate device for the file named in
534 .Fa name ,
535 returning in
536 .Fa file
537 a pointer to the remaining body of
538 .Fa name
539 which does not refer to the device. The
540 .Va f_dev
541 field in
542 .Fa of
543 will be set to point to the
544 .Vt devsw
545 structure for the opened device if successful. Device identifiers must
546 always precede the path component, but may otherwise be arbitrarily formatted.
547 Used by
548 .Fn open
549 and thus for all device-related I/O.
550 .It Xo
551 .Ft int
552 .Fn devclose "struct open_file *of"
553 .Xc
554 Close the device allocated for
555 .Fa of .
556 The device driver itself will already have been called for the close; this call
557 should clean up any allocation made by devopen only.
558 .It Xo
559 .Ft void
560 .Fn panic "const char *msg" "..."
561 .Xc
562 .Pp
563 Signal a fatal and unrecoverable error condition. The
564 .Fa msg ...
565 arguments are as for
566 .Fn printf .
567 .El
568 .Sh INTERNAL FILESYSTEMS
569 Internal filesystems are enabled by the consumer exporting the array
570 .Vt struct fs_ops *file_system[] ,
571 which should be initialised with pointers
572 to
573 .Vt struct fs_ops
574 structures. The following filesystem handlers are supplied by
575 .Nm ,
576 the consumer may supply other filesystems of their own:
577 .Bl -hang -width ".Va cd9660_fsops"
578 .It Va ufs_fsops
579 The
580 .Bx
581 UFS.
582 .It Va ext2fs_fsops
583 Linux ext2fs filesystem.
584 .It Va tftp_fsops
585 File access via TFTP.
586 .It Va nfs_fsops
587 File access via NFS.
588 .It Va cd9660_fsops
589 ISO 9660 (CD-ROM) filesystem.
590 .It Va zipfs_fsops
591 Stacked filesystem supporting gzipped files.
592 When trying the zipfs filesystem,
593 .Nm
594 appends
595 .Li .gz
596 to the end of the filename, and then tries to locate the file using the other
597 filesystems. Placement of this filesystem in the
598 .Va file_system[]
599 array determines whether gzipped files will be opened in preference to non-gzipped
600 files. It is only possible to seek a gzipped file forwards, and
601 .Fn stat
602 and
603 .Fn fstat
604 on gzipped files will report an invalid length.
605 .It Va bzipfs_fsops
606 The same as
607 .Va zipfs_fsops ,
608 but for
609 .Xr bzip2 1 Ns -compressed
610 files.
611 .El
612 .Pp
613 The array of
614 .Vt struct fs_ops
615 pointers should be terminated with a NULL.
616 .Sh DEVICES
617 Devices are exported by the supporting code via the array
618 .Vt struct devsw *devsw[]
619 which is a NULL terminated array of pointers to device switch structures.
620 .Sh HISTORY
621 .Nm
622 contains contributions from many sources, including:
623 .Bl -bullet -compact
624 .It
625 .Nm libsa
626 from
627 .Nx
628 .It
629 .Nm libc
630 and
631 .Nm libkern
632 from
633 .Fx 3.0 .
634 .It
635 .Nm zalloc
636 from
637 .An Matthew Dillon Aq dillon@backplane.com
638 .El
639 .Pp
640 The reorganisation and port to
641 .Fx 3.0 ,
642 the environment functions and this manpage were written by
643 .An Mike Smith Aq msmith@FreeBSD.org .
644 .Sh BUGS
645 The lack of detailed memory usage data is unhelpful.