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30 .Nd support library for standalone executables
36 library provides a set of supporting functions for standalone
37 applications, mimicking where possible the standard
41 The following sections group these functions by kind.
42 Unless specifically described here, see the corresponding section 3
43 manpages for the given functions.
45 String functions are available as documented in
53 .Fn malloc "size_t size"
58 bytes of memory from the heap using a best-fit algorithm.
64 Free the allocated object at
68 .Fn setheap "void *start" "void *limit"
72 This function must be called before calling
79 will be used for the heap; attempting to allocate beyond this will result
86 Provides the behaviour of
88 i.e., returns the highest point that the heap has reached.
90 be used during testing to determine the actual heap usage.
96 A set of functions are provided for manipulating a flat variable space similar
97 to the traditional shell-supported environment.
98 Major enhancements are support
99 for set/unset hook functions.
103 .Fn getenv "const char *name"
107 .Fn setenv "const char *name" "const char *value" "int overwrite"
111 .Fn putenv "char *string"
115 .Fn unsetenv "const char *name"
118 These functions behave similarly to their standard library counterparts.
120 .Ft "struct env_var *"
121 .Fn env_getenv "const char *name"
124 Looks up a variable in the environment and returns its entire
128 .Fn env_setenv "const char *name" "int flags" "const void *value" "ev_sethook_t sethook" "ev_unsethook_t unsethook"
131 Creates a new or sets an existing environment variable called
133 If creating a new variable, the
137 arguments may be specified.
139 The set hook is invoked whenever an attempt
140 is made to set the variable, unless the EV_NOHOOK flag is set.
142 a set hook will validate the
144 argument, and then call
146 again with EV_NOHOOK set to actually save the value.
147 The predefined function
149 may be specified to refuse all attempts to set a variable.
151 The unset hook is invoked when an attempt is made to unset a variable.
153 returns zero, the variable will be unset.
154 The predefined function
156 may be used to prevent a variable being unset.
158 .Sh STANDARD LIBRARY SUPPORT
166 .Fn getopt "int argc" "char * const *argv" "const char *optstring"
170 .Fn strtol "const char *nptr" "char **endptr" "int base"
174 .Fn strtoll "const char *nptr" "char **endptr" "int base"
178 .Fn strtoul "const char *nptr" "char **endptr" "int base"
182 .Fn strtoull "const char *nptr" "char **endptr" "int base"
186 .Fn srandom "unsigned int seed"
194 .Fn strerror "int error"
197 Returns error messages for the subset of errno values supported by
199 .It Fn assert expression
205 .Fn setjmp "jmp_buf env"
209 .Fn longjmp "jmp_buf env" "int val"
216 respectively as there is no signal state to manipulate.
227 Read characters from the console into
229 All of the standard cautions apply to this function.
232 .Fn ngets "char *buf" "int size"
237 - 1 characters from the console into
241 is less than 1, the function's behaviour is as for
245 .Fn fgetstr "char *buf" "int size" "int fd"
248 Read a line of at most
252 Line terminating characters are stripped, and the buffer is always
255 Returns the number of characters in
257 if successful, or -1 if a read error occurs.
260 .Fn printf "const char *fmt" "..."
264 .Fn vprintf "const char *fmt" "va_list ap"
268 .Fn sprintf "char *buf" "const char *fmt" "..."
272 .Fn vsprintf "char *buf" "const char *fmt" "va_list ap"
275 The *printf functions implement a subset of the standard
277 family functionality and some extensions.
278 The following standard conversions
279 are supported: c,d,n,o,p,s,u,x.
280 The following modifiers are supported:
281 +,-,#,*,0,field width,precision,l.
285 conversion is provided to decode error registers.
287 .Bd -ragged -offset indent
295 where <base> is the output expressed as a control character, e.g.\& \e10 gives
296 octal, \e20 gives hex.
297 Each <arg> is a sequence of characters, the first of
298 which gives the bit number to be inspected (origin 1) and the next characters
299 (up to a character less than 32) give the text to be displayed if the bit is set.
301 .Bd -ragged -offset indent
305 .Qq \e10\e2BITTWO\e1BITONE
309 would give the output
310 .Bd -ragged -offset indent
316 conversion provides a hexdump facility, e.g.
317 .Bd -ragged -offset indent
323 .Qq XX:XX:XX:XX:XX:XX
325 .Bd -ragged -offset indent
335 .Sh CHARACTER TESTS AND CONVERSIONS
394 .Fn open "const char *path" "int flags"
397 Similar to the behaviour as specified in
399 except that file creation is not supported, so the mode parameter is not
403 argument may be one of O_RDONLY, O_WRONLY and O_RDWR.
404 Only UFS currently supports writing.
414 Close all open files.
417 .Fn read "int fd" "void *buf" "size_t len"
421 .Fn write "int fd" "void *buf" "size_t len"
424 (No file systems currently support writing.)
427 .Fn lseek "int fd" "off_t offset" "int whence"
430 Files being automatically uncompressed during reading cannot seek backwards
431 from the current point.
434 .Fn stat "const char *path" "struct stat *sb"
438 .Fn fstat "int fd" "struct stat *sb"
445 functions only fill out the following fields in the
447 structure: st_mode,st_nlink,st_uid,st_gid,st_size.
450 file system cannot provide meaningful values for this call, and the
452 file system always reports files having uid/gid of zero.
457 library supplies a simple internal pager to ease reading the output of large
465 Initialises the pager and tells it that the next line output will be the top of the
467 The environment variable LINES is consulted to determine the number of
468 lines to be displayed before pausing.
477 .Fn pager_output "const char *lines"
480 Sends the lines in the
482 -terminated buffer at
485 Newline characters are counted in order to determine the number
486 of lines being output (wrapped lines are not accounted for).
489 function will return zero when all of the lines have been output, or nonzero
490 if the display was paused and the user elected to quit.
493 .Fn pager_file "const char *fname"
496 Attempts to open and display the file
498 Returns -1 on error, 0 at EOF, or 1 if the user elects to quit while reading.
504 .Fn devformat "struct devdesc *"
507 Format the specified device as a string.
510 .Fn devparse "struct devdesc **dev" "const char *devdesc" "const char **path"
516 .Sq device:[/path/to/file] .
519 table is used to match the start of the
525 is non-NULL, then it will be called to parse the rest of the string and allocate
529 If NULL, then a default routine will be called that will allocate a simple
531 parse a unit number and ensure there's no trailing characters.
534 is non-NULL, then a pointer to the remainder of the
536 string after the device specification is written.
544 array, returning the number of routines that returned an error.
550 Successive calls emit the characters in the sequence |,/,-,\\ followed by a
551 backspace in order to provide reassurance to the user.
553 .Sh REQUIRED LOW-LEVEL SUPPORT
554 The following resources are consumed by
556 - stack, heap, console and devices.
558 The stack must be established before
560 functions can be invoked.
561 Stack requirements vary depending on the functions
562 and file systems used by the consumer and the support layer functions detailed
565 The heap must be established before calling
571 Heap usage will vary depending on the number of simultaneously open files,
572 as well as client behaviour.
573 Automatic decompression will allocate more
574 than 64K of data per open file.
576 Console access is performed via the
581 functions detailed below.
583 Device access is initiated via
585 and is performed through the
590 functions in the device switch structure that
594 The consumer must provide the following support functions:
601 Return a character from the console, used by
610 Returns nonzero if a character is waiting from the console.
616 Write a character to the console, used by
623 and thus by many other functions for debugging and informational output.
626 .Fn devopen "struct open_file *of" "const char *name" "const char **file"
629 Open the appropriate device for the file named in
633 a pointer to the remaining body of
635 which does not refer to the device.
640 will be set to point to the
642 structure for the opened device if successful.
643 Device identifiers must
644 always precede the path component, but may otherwise be arbitrarily formatted.
647 and thus for all device-related I/O.
650 .Fn devclose "struct open_file *of"
653 Close the device allocated for
655 The device driver itself will already have been called for the close; this call
656 should clean up any allocation made by devopen only.
667 .Fn panic "const char *msg" "..."
670 Signal a fatal and unrecoverable error condition.
676 .Sh INTERNAL FILE SYSTEMS
677 Internal file systems are enabled by the consumer exporting the array
678 .Vt struct fs_ops *file_system[] ,
679 which should be initialised with pointers
683 The following file system handlers are supplied by
685 the consumer may supply other file systems of their own:
686 .Bl -hang -width ".Va cd9660_fsops"
692 Linux ext2fs file system.
694 File access via TFTP.
698 ISO 9660 (CD-ROM) file system.
700 Stacked file system supporting gzipped files.
701 When trying the gzipfs file system,
705 to the end of the filename, and then tries to locate the file using the other
707 Placement of this file system in the
709 array determines whether gzipped files will be opened in preference to non-gzipped
711 It is only possible to seek a gzipped file forwards, and
715 on gzipped files will report an invalid length.
720 .Xr bzip2 1 Ns -compressed
726 pointers should be terminated with a NULL.
728 Devices are exported by the supporting code via the array
729 .Vt struct devsw *devsw[]
730 which is a NULL terminated array of pointers to device switch structures.
732 The driver needs to provide a common set of entry points that are
735 to interface with the device.
738 const char dv_name[DEV_NAMLEN];
740 int (*dv_init)(void);
741 int (*dv_strategy)(void *devdata, int rw, daddr_t blk,
742 size_t size, char *buf, size_t *rsize);
743 int (*dv_open)(struct open_file *f, ...);
744 int (*dv_close)(struct open_file *f);
745 int (*dv_ioctl)(struct open_file *f, u_long cmd, void *data);
746 int (*dv_print)(int verbose);
747 void (*dv_cleanup)(void);
748 char * (*dv_fmtdev)(struct devdesc *);
749 int (*dv_parsedev)(struct devdesc **dev, const char *devpart,
751 bool (*dv_match)(struct devsw *dv, const char *devspec);
754 .Bl -tag -width ".Fn dv_strategy"
759 The supported types are:
760 .Bl -tag -width "DEVT_NONE"
768 Each type may have its own associated (struct type_devdesc),
769 which has the generic (struct devdesc) as its first member.
771 Driver initialization routine.
772 This routine should probe for available units.
773 Drivers are responsible for maintaining lists of units for later enumeration.
774 No other driver routines may be called before
778 The driver open routine.
780 The driver close routine.
782 The driver ioctl routine.
784 Prints information about the available devices.
785 Information should be presented with
788 Cleans up any memory used by the device before the next stage is run.
790 Converts the specified devdesc to the canonical string representation
793 Parses the device portion of a file path.
798 of device name, possibly followed by a colon and a path within the device.
801 is, by convention, the part of the device specification that follows the
806 is parsing the string
812 The parsing routine is expected to allocate a new
814 or subclass and return it in
817 This routine should set
819 to point to the portion of the string after device specification, or
821 in the earlier example.
822 Generally, code needing to parse a path will use
824 instead of calling this routine directly.
827 to specify that all device paths starting with
830 Otherwise, this function returns 0 for a match and a non-zero
832 to indicate why it didn't match.
833 This is helpful when you claim the device path after using it to query
834 properties on systems that have uniform naming for different types of
840 library contains contributions from many sources, including:
855 .An Matthew Dillon Aq Mt dillon@backplane.com
858 The reorganisation and port to
860 the environment functions and this manpage were written by
861 .An Mike Smith Aq Mt msmith@FreeBSD.org .
863 The lack of detailed memory usage data is unhelpful.