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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 "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
168 .Fn getopt "int argc" "char * const *argv" "const char *optstring"
172 .Fn strtol "const char *nptr" "char **endptr" "int base"
176 .Fn strtoll "const char *nptr" "char **endptr" "int base"
180 .Fn strtoul "const char *nptr" "char **endptr" "int base"
184 .Fn strtoull "const char *nptr" "char **endptr" "int base"
188 .Fn srandom "unsigned int seed"
196 .Fn strerror "int error"
199 Returns error messages for the subset of errno values supported by
201 .It Fn assert expression
207 .Fn setjmp "jmp_buf env"
211 .Fn longjmp "jmp_buf env" "int val"
218 respectively as there is no signal state to manipulate.
229 Read characters from the console into
231 All of the standard cautions apply to this function.
234 .Fn ngets "char *buf" "int size"
239 - 1 characters from the console into
243 is less than 1, the function's behaviour is as for
247 .Fn fgetstr "char *buf" "int size" "int fd"
250 Read a line of at most
254 Line terminating characters are stripped, and the buffer is always
257 Returns the number of characters in
259 if successful, or -1 if a read error occurs.
262 .Fn printf "const char *fmt" "..."
266 .Fn vprintf "const char *fmt" "va_list ap"
270 .Fn sprintf "char *buf" "const char *fmt" "..."
274 .Fn vsprintf "char *buf" "const char *fmt" "va_list ap"
277 The *printf functions implement a subset of the standard
279 family functionality and some extensions.
280 The following standard conversions
281 are supported: c,d,n,o,p,s,u,x.
282 The following modifiers are supported:
283 +,-,#,*,0,field width,precision,l.
287 conversion is provided to decode error registers.
289 .Bd -ragged -offset indent
297 where <base> is the output expressed as a control character, e.g.\& \e10 gives
298 octal, \e20 gives hex.
299 Each <arg> is a sequence of characters, the first of
300 which gives the bit number to be inspected (origin 1) and the next characters
301 (up to a character less than 32) give the text to be displayed if the bit is set.
303 .Bd -ragged -offset indent
307 .Qq \e10\e2BITTWO\e1BITONE
311 would give the output
312 .Bd -ragged -offset indent
318 conversion provides a hexdump facility, e.g.
319 .Bd -ragged -offset indent
325 .Qq XX:XX:XX:XX:XX:XX
327 .Bd -ragged -offset indent
337 .Sh CHARACTER TESTS AND CONVERSIONS
396 .Fn open "const char *path" "int flags"
399 Similar to the behaviour as specified in
401 except that file creation is not supported, so the mode parameter is not
405 argument may be one of O_RDONLY, O_WRONLY and O_RDWR.
406 Only UFS currently supports writing.
416 Close all open files.
419 .Fn read "int fd" "void *buf" "size_t len"
423 .Fn write "int fd" "void *buf" "size_t len"
426 (No file systems currently support writing.)
429 .Fn lseek "int fd" "off_t offset" "int whence"
432 Files being automatically uncompressed during reading cannot seek backwards
433 from the current point.
436 .Fn stat "const char *path" "struct stat *sb"
440 .Fn fstat "int fd" "struct stat *sb"
447 functions only fill out the following fields in the
449 structure: st_mode,st_nlink,st_uid,st_gid,st_size.
452 file system cannot provide meaningful values for this call, and the
454 file system always reports files having uid/gid of zero.
459 library supplies a simple internal pager to ease reading the output of large
467 Initialises the pager and tells it that the next line output will be the top of the
469 The environment variable LINES is consulted to determine the number of
470 lines to be displayed before pausing.
479 .Fn pager_output "const char *lines"
482 Sends the lines in the
484 -terminated buffer at
487 Newline characters are counted in order to determine the number
488 of lines being output (wrapped lines are not accounted for).
491 function will return zero when all of the lines have been output, or nonzero
492 if the display was paused and the user elected to quit.
495 .Fn pager_file "const char *fname"
498 Attempts to open and display the file
500 Returns -1 on error, 0 at EOF, or 1 if the user elects to quit while reading.
509 Successive calls emit the characters in the sequence |,/,-,\\ followed by a
510 backspace in order to provide reassurance to the user.
512 .Sh REQUIRED LOW-LEVEL SUPPORT
513 The following resources are consumed by
515 - stack, heap, console and devices.
517 The stack must be established before
519 functions can be invoked.
520 Stack requirements vary depending on the functions
521 and file systems used by the consumer and the support layer functions detailed
524 The heap must be established before calling
530 Heap usage will vary depending on the number of simultaneously open files,
531 as well as client behaviour.
532 Automatic decompression will allocate more
533 than 64K of data per open file.
535 Console access is performed via the
540 functions detailed below.
542 Device access is initiated via
544 and is performed through the
549 functions in the device switch structure that
553 The consumer must provide the following support functions:
560 Return a character from the console, used by
569 Returns nonzero if a character is waiting from the console.
575 Write a character to the console, used by
582 and thus by many other functions for debugging and informational output.
585 .Fn devopen "struct open_file *of" "const char *name" "const char **file"
588 Open the appropriate device for the file named in
592 a pointer to the remaining body of
594 which does not refer to the device.
599 will be set to point to the
601 structure for the opened device if successful.
602 Device identifiers must
603 always precede the path component, but may otherwise be arbitrarily formatted.
606 and thus for all device-related I/O.
609 .Fn devclose "struct open_file *of"
612 Close the device allocated for
614 The device driver itself will already have been called for the close; this call
615 should clean up any allocation made by devopen only.
626 .Fn panic "const char *msg" "..."
629 Signal a fatal and unrecoverable error condition.
635 .Sh INTERNAL FILE SYSTEMS
636 Internal file systems are enabled by the consumer exporting the array
637 .Vt struct fs_ops *file_system[] ,
638 which should be initialised with pointers
642 The following file system handlers are supplied by
644 the consumer may supply other file systems of their own:
645 .Bl -hang -width ".Va cd9660_fsops"
651 Linux ext2fs file system.
653 File access via TFTP.
657 ISO 9660 (CD-ROM) file system.
659 Stacked file system supporting gzipped files.
660 When trying the gzipfs file system,
664 to the end of the filename, and then tries to locate the file using the other
666 Placement of this file system in the
668 array determines whether gzipped files will be opened in preference to non-gzipped
670 It is only possible to seek a gzipped file forwards, and
674 on gzipped files will report an invalid length.
679 .Xr bzip2 1 Ns -compressed
685 pointers should be terminated with a NULL.
687 Devices are exported by the supporting code via the array
688 .Vt struct devsw *devsw[]
689 which is a NULL terminated array of pointers to device switch structures.
693 library contains contributions from many sources, including:
708 .An Matthew Dillon Aq Mt dillon@backplane.com
711 The reorganisation and port to
713 the environment functions and this manpage were written by
714 .An Mike Smith Aq Mt msmith@FreeBSD.org .
716 The lack of detailed memory usage data is unhelpful.