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32 .Nd support library for standalone executables
38 library provides a set of supporting functions for standalone
39 applications, mimicking where possible the standard
43 The following sections group these functions by kind.
44 Unless specifically described here, see the corresponding section 3
45 manpages for the given functions.
47 String functions are available as documented in
55 .Fn malloc "size_t size"
60 bytes of memory from the heap using a best-fit algorithm.
66 Free the allocated object at
70 .Fn setheap "void *start" "void *limit"
74 This function must be called before calling
81 will be used for the heap; attempting to allocate beyond this will result
88 Provides the behaviour of
90 i.e., returns the highest point that the heap has reached.
92 be used during testing to determine the actual heap usage.
98 A set of functions are provided for manipulating a flat variable space similar
99 to the traditional shell-supported environment.
100 Major enhancements are support
101 for set/unset hook functions.
105 .Fn getenv "const char *name"
109 .Fn setenv "const char *name" "const char *value" "int overwrite"
113 .Fn putenv "const char *string"
117 .Fn unsetenv "const char *name"
120 These functions behave similarly to their standard library counterparts.
122 .Ft "struct env_var *"
123 .Fn env_getenv "const char *name"
126 Looks up a variable in the environment and returns its entire
130 .Fn env_setenv "const char *name" "int flags" "const void *value" "ev_sethook_t sethook" "ev_unsethook_t unsethook"
133 Creates a new or sets an existing environment variable called
135 If creating a new variable, the
139 arguments may be specified.
141 The set hook is invoked whenever an attempt
142 is made to set the variable, unless the EV_NOHOOK flag is set.
144 a set hook will validate the
146 argument, and then call
148 again with EV_NOHOOK set to actually save the value.
149 The predefined function
151 may be specified to refuse all attempts to set a variable.
153 The unset hook is invoked when an attempt is made to unset a variable.
155 returns zero, the variable will be unset.
156 The predefined function
158 may be used to prevent a variable being unset.
160 .Sh STANDARD LIBRARY SUPPORT
164 .Fn getopt "int argc" "char * const *argv" "const char *optstring"
168 .Fn strtol "const char *nptr" "char **endptr" "int base"
172 .Fn srandom "unsigned long seed"
180 .Fn strerror "int error"
183 Returns error messages for the subset of errno values supported by
185 .It Fn assert expression
191 .Fn setjmp "jmp_buf env"
195 .Fn longjmp "jmp_buf env" "int val"
202 respectively as there is no signal state to manipulate.
213 Read characters from the console into
215 All of the standard cautions apply to this function.
218 .Fn ngets "char *buf" "int size"
223 - 1 characters from the console into
227 is less than 1, the function's behaviour is as for
231 .Fn fgetstr "char *buf" "int size" "int fd"
234 Read a line of at most
238 Line terminating characters are stripped, and the buffer is always
241 Returns the number of characters in
243 if successful, or -1 if a read error occurs.
246 .Fn printf "const char *fmt" "..."
250 .Fn vprintf "const char *fmt" "va_list ap"
254 .Fn sprintf "char *buf" "const char *fmt" "..."
258 .Fn vsprintf "char *buf" "const char *fmt" "va_list ap"
261 The *printf functions implement a subset of the standard
263 family functionality and some extensions.
264 The following standard conversions
265 are supported: c,d,n,o,p,s,u,x.
266 The following modifiers are supported:
267 +,-,#,*,0,field width,precision,l.
271 conversion is provided to decode error registers.
274 .Bd -ragged -offset indent
282 where <base> is the output expressed as a control character, e.g.\& \e10 gives
283 octal, \e20 gives hex.
284 Each <arg> is a sequence of characters, the first of
285 which gives the bit number to be inspected (origin 1) and the next characters
286 (up to a character less than 32) give the text to be displayed if the bit is set.
289 .Bd -ragged -offset indent
293 .Qq \e10\e2BITTWO\e1BITONE\en
297 would give the output
299 .Bd -ragged -offset indent
305 conversion provides a hexdump facility, e.g.
307 .Bd -ragged -offset indent
313 .Qq XX:XX:XX:XX:XX:XX
315 .Bd -ragged -offset indent
325 .Sh CHARACTER TESTS AND CONVERSIONS
368 .Fn open "const char *path" "int flags"
371 Similar to the behaviour as specified in
373 except that file creation is not supported, so the mode parameter is not
377 argument may be one of O_RDONLY, O_WRONLY and O_RDWR (although no file systems
378 currently support writing).
388 Close all open files.
391 .Fn read "int fd" "void *buf" "size_t len"
395 .Fn write "int fd" "void *buf" "size_t len"
398 (No file systems currently support writing.)
401 .Fn lseek "int fd" "off_t offset" "int whence"
404 Files being automatically uncompressed during reading cannot seek backwards
405 from the current point.
408 .Fn stat "const char *path" "struct stat *sb"
412 .Fn fstat "int fd" "struct stat *sb"
419 functions only fill out the following fields in the
421 structure: st_mode,st_nlink,st_uid,st_gid,st_size.
424 file system cannot provide meaningful values for this call, and the
426 file system always reports files having uid/gid of zero.
431 library supplies a simple internal pager to ease reading the output of large
439 Initialises the pager and tells it that the next line output will be the top of the
441 The environment variable LINES is consulted to determine the number of
442 lines to be displayed before pausing.
451 .Fn pager_output "const char *lines"
454 Sends the lines in the
456 -terminated buffer at
459 Newline characters are counted in order to determine the number
460 of lines being output (wrapped lines are not accounted for).
463 function will return zero when all of the lines have been output, or nonzero
464 if the display was paused and the user elected to quit.
467 .Fn pager_file "const char *fname"
470 Attempts to open and display the file
472 Returns -1 on error, 0 at EOF, or 1 if the user elects to quit while reading.
481 Successive calls emit the characters in the sequence |,/,-,\\ followed by a
482 backspace in order to provide reassurance to the user.
484 .Sh REQUIRED LOW-LEVEL SUPPORT
485 The following resources are consumed by
487 - stack, heap, console and devices.
489 The stack must be established before
491 functions can be invoked.
492 Stack requirements vary depending on the functions
493 and file systems used by the consumer and the support layer functions detailed
496 The heap must be established before calling
502 Heap usage will vary depending on the number of simultaneously open files,
503 as well as client behaviour.
504 Automatic decompression will allocate more
505 than 64K of data per open file.
507 Console access is performed via the
512 functions detailed below.
514 Device access is initiated via
516 and is performed through the
521 functions in the device switch structure that
525 The consumer must provide the following support functions:
532 Return a character from the console, used by
541 Returns nonzero if a character is waiting from the console.
547 Write a character to the console, used by
554 and thus by many other functions for debugging and informational output.
557 .Fn devopen "struct open_file *of" "const char *name" "const char **file"
560 Open the appropriate device for the file named in
564 a pointer to the remaining body of
566 which does not refer to the device.
571 will be set to point to the
573 structure for the opened device if successful.
574 Device identifiers must
575 always precede the path component, but may otherwise be arbitrarily formatted.
578 and thus for all device-related I/O.
581 .Fn devclose "struct open_file *of"
584 Close the device allocated for
586 The device driver itself will already have been called for the close; this call
587 should clean up any allocation made by devopen only.
590 .Fn panic "const char *msg" "..."
593 Signal a fatal and unrecoverable error condition.
599 .Sh INTERNAL FILE SYSTEMS
600 Internal file systems are enabled by the consumer exporting the array
601 .Vt struct fs_ops *file_system[] ,
602 which should be initialised with pointers
606 The following file system handlers are supplied by
608 the consumer may supply other file systems of their own:
609 .Bl -hang -width ".Va cd9660_fsops"
615 Linux ext2fs file system.
617 File access via TFTP.
621 ISO 9660 (CD-ROM) file system.
623 Stacked file system supporting gzipped files.
624 When trying the gzipfs file system,
628 to the end of the filename, and then tries to locate the file using the other
630 Placement of this file system in the
632 array determines whether gzipped files will be opened in preference to non-gzipped
634 It is only possible to seek a gzipped file forwards, and
638 on gzipped files will report an invalid length.
643 .Xr bzip2 1 Ns -compressed
649 pointers should be terminated with a NULL.
651 Devices are exported by the supporting code via the array
652 .Vt struct devsw *devsw[]
653 which is a NULL terminated array of pointers to device switch structures.
657 library contains contributions from many sources, including:
672 .An Matthew Dillon Aq dillon@backplane.com
675 The reorganisation and port to
677 the environment functions and this manpage were written by
678 .An Mike Smith Aq msmith@FreeBSD.org .
680 The lack of detailed memory usage data is unhelpful.