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.\" $Id: ukcprog.3,v 1.18 1993/02/23 11:31:42 gjap Exp $ UKC |
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.\" .fX - print the argument in a fixed font |
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.de fX |
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\&\\$3\f(CR\\$1\fP\\$2 |
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.. |
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.\" .Vs - start example |
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.de Vs |
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.LP |
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.ne 1i |
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.RS |
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.nf |
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.ft CR |
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.. |
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.\" .Ve - end example |
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.de Ve |
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.ft P |
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.fi |
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.hy 0 |
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.RE |
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.LP |
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.. |
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.TH UKCPROG 3 "February 1991" "UKC Local" |
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.SH NAME |
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ukcprog \- Library of utilities for C programmers |
| 25 |
.SH SYNOPSIS |
| 26 |
.nf |
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.LP |
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In source code, |
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.Vs |
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#include <ukcprog.h> |
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.Ve |
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and link with |
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.Vs |
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cc ... -lukcprog |
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.Ve |
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.SH AVAILABILITY |
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.LP |
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.\" |
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.\" The following sentence motivated the port to MS-DOG. |
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.\" |
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This is a UKC library, available for the \s-1UNIX\s0 and \s-1VMS\s0 |
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operating systems, and for MS-DOS. |
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.\" |
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.\" It was worth it ... |
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.\" |
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The source code is freely available so if you want to make |
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a source release of your application you can include a copy of the |
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source of this library as well. |
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.SH DESCRIPTION |
| 50 |
.LP |
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The ukcprog library contains generally useful low level routines. |
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The |
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.fX ukcprog.h |
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header file contains prototypes for the |
| 55 |
routines as well as defining some useful macros and types. |
| 56 |
.Vs |
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#ifdef __STDC__ |
| 58 |
#define PROTO(a) a |
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typedef void *voidptr; |
| 60 |
#else |
| 61 |
#define PROTO(a) () |
| 62 |
#define const |
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#define volatile |
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#define signed |
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typedef char *voidptr; |
| 66 |
#endif |
| 67 |
.Ve |
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.LP |
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The definitions of |
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.fX const , |
| 71 |
.fX volatile |
| 72 |
and |
| 73 |
.fX signed |
| 74 |
allow these ANSI C keywords to be used in code which must be portable |
| 75 |
to pre-ANSI C compilers. |
| 76 |
.LP |
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The |
| 78 |
.fX voidptr |
| 79 |
typedef is similarly there to help with code for pre-ANSI compilers |
| 80 |
which do not support the |
| 81 |
.fX "void *" ' ` |
| 82 |
type. |
| 83 |
Functions which are documented here as returning |
| 84 |
.fX "void *" ' ` |
| 85 |
return |
| 86 |
.fX "char *" ' ` |
| 87 |
when compiling with a non-ANSI C compiler. |
| 88 |
.LP |
| 89 |
The |
| 90 |
.fX PROTO |
| 91 |
macro is useful for declaring function prototypes |
| 92 |
for use with ANSI C while still allowing the code to be compiled with |
| 93 |
K&R compilers. |
| 94 |
It is used thus: |
| 95 |
.Vs |
| 96 |
int myfunc PROTO((int arg1, char *arg2)); |
| 97 |
.Ve |
| 98 |
With an ANSI C compiler this expands to |
| 99 |
.Vs |
| 100 |
int myfunc (int arg1, char *arg2); |
| 101 |
.Ve |
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whereas a pre-ANSI compiler sees: |
| 103 |
.Vs |
| 104 |
int myfunc (); |
| 105 |
.Ve |
| 106 |
.LP |
| 107 |
Note the double brackets; these are necessary to make all the parameters |
| 108 |
a single argument to the |
| 109 |
.fX PROTO |
| 110 |
macro. |
| 111 |
.Vs |
| 112 |
#ifndef FALSE |
| 113 |
#define FALSE 0 |
| 114 |
#endif |
| 115 |
#ifndef TRUE |
| 116 |
#define TRUE 1 |
| 117 |
#endif |
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#ifndef bool |
| 119 |
#define bool int |
| 120 |
#endif |
| 121 |
.Ve |
| 122 |
These define the commonly used |
| 123 |
.fX TRUE |
| 124 |
and |
| 125 |
.fX FALSE |
| 126 |
macros to their usual values. |
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The definitions are protected in case these are already defined. |
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The |
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.fX bool |
| 130 |
macro is intended to be used to declared variables |
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that are conceptually boolean. |
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A |
| 133 |
.fX #define |
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is used rather than a typedef because there might already be a typedef |
| 135 |
for |
| 136 |
.fX bool . |
| 137 |
.Vs |
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#ifdef __STDC__ |
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#define CAT(a,b) a ## b |
| 140 |
#else |
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#define _IDENT(a) a |
| 142 |
#define CAT(a,b) _IDENT(a)b |
| 143 |
#endif /* !__STDC__ */ |
| 144 |
.Ve |
| 145 |
The |
| 146 |
.fX CAT |
| 147 |
macro can be used to glue two tokens together in the same way as |
| 148 |
the ANSI C |
| 149 |
.fX ## |
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operator. |
| 151 |
.fX CAT |
| 152 |
also works with many (but not all) pre-ANSI C preprocessors. |
| 153 |
.Vs |
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void panic(const char *message) |
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.sp |
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typedef void (*panic_handler_t)(const char *message); |
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panic_handler_t install_panic_handler(panic_hander_t handler) |
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.Ve |
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By default |
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.fX panic() |
| 161 |
produces a message on stderr of the form |
| 162 |
.Vs |
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fatal internal error: \fIsomething\fP (aborting)... |
| 164 |
.Ve |
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It then calls |
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.fX abort(3) |
| 167 |
to produce a core dump. |
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Alternative `panic handlers' can be installed using |
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.fX install_panic_handler() |
| 170 |
which returns the previous handler. |
| 171 |
Panic handlers can perform tidy-up tasks, such as |
| 172 |
removing temporary files or calling |
| 173 |
.fX chdir(2) |
| 174 |
to arrange for |
| 175 |
the core to land in a safe place. |
| 176 |
If a panic handler is called and returns then the default |
| 177 |
action is carried out. |
| 178 |
.Vs |
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void *e_malloc(size_t size) |
| 180 |
void *e_realloc(void *old, size_t size) |
| 181 |
char *strsave(const char *str) |
| 182 |
.Ve |
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.fX e_malloc() |
| 184 |
and |
| 185 |
.fX e_realloc() |
| 186 |
are error-checking versions |
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of the corresponding routines in the standard C library. |
| 188 |
They call |
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.fX panic() |
| 190 |
if the request fails. |
| 191 |
.fX e_realloc() |
| 192 |
behaves according to the ANSI specification for |
| 193 |
.fX realloc() ; |
| 194 |
that is, if |
| 195 |
.fX old |
| 196 |
is NULL it behaves like |
| 197 |
.fX malloc() |
| 198 |
and if size is 0, it behaves like |
| 199 |
.fX free() . |
| 200 |
.fX strsave() |
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allocates some memory using |
| 202 |
.fX e_malloc() , |
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copies |
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.fX str |
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into it, and returns a pointer to the copy. |
| 206 |
.Vs |
| 207 |
char *fpgetline(FILE *fp) |
| 208 |
.Ve |
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.fX fpgetline() |
| 210 |
reads characters from the standard IO stream |
| 211 |
.fX fp |
| 212 |
until a newline character or EOF is encountered. |
| 213 |
.fX fpgetline() |
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returns |
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.fX NULL |
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if EOF or an error occurred before any characters were read; |
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otherwise it returns a pointer to the NUL terminated line. |
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.fX fpgetline() |
| 219 |
never adds a newline to the buffer. |
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The user can check for a missing final newline in a file by checking |
| 221 |
the EOF flag of the stream pointer when |
| 222 |
.fX fpgetline() |
| 223 |
returns a non-NULL pointer. |
| 224 |
.LP |
| 225 |
When |
| 226 |
.fX fpgetline() |
| 227 |
returns |
| 228 |
.fX NULL |
| 229 |
the caller should check with |
| 230 |
.fX ferror(3) |
| 231 |
whether the cause was EOF or an error reading the stream |
| 232 |
.fX fp . |
| 233 |
.LP |
| 234 |
.fX fpgetline() |
| 235 |
returns a pointer to a static buffer that is resized as necessary |
| 236 |
to handle long lines. |
| 237 |
The caller can modify the contents of the buffer but must not free |
| 238 |
it or realloc it. |
| 239 |
The buffer is valid only until the next call of |
| 240 |
.fX fpgetline() . |
| 241 |
.Vs |
| 242 |
char *config_trim_line(char *line) |
| 243 |
.Ve |
| 244 |
.fX config_trim_line() |
| 245 |
trims comments and white space in place from a line. |
| 246 |
First it scans for the first |
| 247 |
.fX # ' ` |
| 248 |
character in the line. |
| 249 |
If there is one it is removed along with any following characters. |
| 250 |
Then leading and trailing whitespace characters (as defined by |
| 251 |
.IR isspace (3)) |
| 252 |
are removed. |
| 253 |
.fX config_trim_line() |
| 254 |
returns a pointer to the trimmed line (which will point into the line |
| 255 |
that it was given). |
| 256 |
.LP |
| 257 |
A typical use of this routine is to skip blank lines and comments from |
| 258 |
a configuration file. |
| 259 |
.Vs |
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typedef void (*errf_ofunc_t)(const char *string); |
| 261 |
.sp |
| 262 |
void errf(const char *fmt, ...) |
| 263 |
char *strf(const char *fmt, ...) |
| 264 |
.sp |
| 265 |
errf_ofunc_t errf_set_ofunc(errf_ofunc_t func) |
| 266 |
const char *errf_set_prefix(const char *prefix) |
| 267 |
const char *errf_get_prefix(void) |
| 268 |
void_errf_set_progname(const char *progname) |
| 269 |
const char *errf_get_progname(void) |
| 270 |
char *formf(char *buffer, int buffer_size, |
| 271 |
const char *format, va_list args) |
| 272 |
void errf_usage(const char *usage) |
| 273 |
.Ve |
| 274 |
These routines form the basis of a generalised error handling system. |
| 275 |
.fX errf() |
| 276 |
formats an error message, much like |
| 277 |
.fX printf(3) , |
| 278 |
but then passes the formatted text to the `current output function'. |
| 279 |
The default output function appends a newline to the message and |
| 280 |
sends it to stderr. |
| 281 |
An alternative output function can be installed with |
| 282 |
.fX errf_set_ofunc() ; |
| 283 |
it returns the old one which can be re-installed as required. |
| 284 |
The default output function can optionally prefix the message with |
| 285 |
a fixed string; this can be inserted with |
| 286 |
.fX errf_set_prefix() . |
| 287 |
A pointer to the current prefix is returned by |
| 288 |
.fX errf_get_prefix() . |
| 289 |
By convention, this prefix is derived from the name of the program. |
| 290 |
.fX errf_set_progname() |
| 291 |
is a convenience routine which, when passed |
| 292 |
.fX argv[0] , |
| 293 |
munges it in an operating system specific way to produce the program name |
| 294 |
and sets the prefix to something that looks `nice'. |
| 295 |
A pointer to the program name (after munging) can be obtained by |
| 296 |
.fX errf_get_progname(). |
| 297 |
A usage line can be sent to the current output function by |
| 298 |
.fX errf_usage() ; |
| 299 |
it prefixes |
| 300 |
.Vs |
| 301 |
Usage: \fIprogname\fP |
| 302 |
.Ve |
| 303 |
to its argument, and exits with status 1. |
| 304 |
.LP |
| 305 |
.fX strf() |
| 306 |
formats a string in the same way as |
| 307 |
.fX errf() , |
| 308 |
but returns a pointer to a buffer obtained from |
| 309 |
.fX malloc(3) |
| 310 |
that |
| 311 |
contains the result. |
| 312 |
.LP |
| 313 |
.fX formf() |
| 314 |
is used in the internal implementation of |
| 315 |
.fX errf() |
| 316 |
and |
| 317 |
.fX strf() |
| 318 |
and |
| 319 |
.fX logf() |
| 320 |
(see below) and is not for the faint-hearted. |
| 321 |
It is made visible because it is useful if you need to implement |
| 322 |
other |
| 323 |
.fX errf() "-style" |
| 324 |
functions. |
| 325 |
In addition to the normal format conversions, |
| 326 |
.fX formf() |
| 327 |
provides |
| 328 |
.fX %m ' ` |
| 329 |
which inserts an error message |
| 330 |
corresponding to the current value of |
| 331 |
.fX errno |
| 332 |
into the output string. |
| 333 |
.Vs |
| 334 |
int logf_set_ofile PROTO((const char *filename, const char *prefix)); |
| 335 |
void logf(int level, const char *fmt, ...) |
| 336 |
int logf_set_level PROTO((int level)); |
| 337 |
void logf_errf_ofunc PROTO((const char *str)); |
| 338 |
.Ve |
| 339 |
These routines are an alternative to |
| 340 |
.I syslog (3) |
| 341 |
for applications that need to log messages to a specified file. |
| 342 |
.fX logf() |
| 343 |
handles the |
| 344 |
.fX fmt |
| 345 |
format string and arguments in the same same way as |
| 346 |
.fX errf() . |
| 347 |
If there has been no prior call to |
| 348 |
.fX logf_set_ofile () |
| 349 |
(see below) the message is |
| 350 |
displayed on stderr, prefixed with the current date and time. |
| 351 |
If the output |
| 352 |
.I is |
| 353 |
going to a file, |
| 354 |
.fX logf() |
| 355 |
tries to ensure that messages from multiple processes to a single log |
| 356 |
file are interleaved correctly. |
| 357 |
.LP |
| 358 |
The |
| 359 |
.fX level |
| 360 |
argument specifies the class of the message; it is one of |
| 361 |
.fX LG_DEBUG , |
| 362 |
.fX LG_INFO , |
| 363 |
or |
| 364 |
.fX LG_ERR |
| 365 |
(which are in increasing numerical order). |
| 366 |
Messages at a level less than the current log level are discarded. |
| 367 |
The default log level is |
| 368 |
.fX LG_INFO ; |
| 369 |
it can be set using |
| 370 |
.fX logf_set_level() , |
| 371 |
which also returns the previous log level. |
| 372 |
The log levels |
| 373 |
.fX LG_ALL |
| 374 |
and |
| 375 |
.fX LG_LOG |
| 376 |
are valid only in calls to |
| 377 |
.fX logf_set_level() ; |
| 378 |
.fX LG_ALL |
| 379 |
means log all messages and |
| 380 |
.fX LG_LOG |
| 381 |
means log only messages relating to |
| 382 |
.fX logf() |
| 383 |
itself. |
| 384 |
.LP |
| 385 |
.fX logf_set_ofile() |
| 386 |
sets the output file for |
| 387 |
.fX logf() |
| 388 |
messages. |
| 389 |
If the log file does not exist |
| 390 |
.fX logf_set_ofile() |
| 391 |
attempts to create it; otherwise it is opened for writing (without |
| 392 |
discarding any existing contents). |
| 393 |
If the attempt to create or open the file fails, |
| 394 |
.fX logf_set_ofile() |
| 395 |
gives an error message and returns -1, otherwise it returns zero. |
| 396 |
If the |
| 397 |
.fX prefix |
| 398 |
argument is not |
| 399 |
.fX NULL , |
| 400 |
the string specified is prepended to all future log messages. |
| 401 |
.fX logf_set_ofile() |
| 402 |
makes a copy of the string so it need not be preserved after the call. |
| 403 |
.LP |
| 404 |
.fX logf_errf_ofunc() |
| 405 |
logs the message |
| 406 |
.fX str |
| 407 |
at level |
| 408 |
.fX LG_ERR . |
| 409 |
It can be passed as an output function to |
| 410 |
.fX errf_set_ofunc() |
| 411 |
to arrange that all error messages are sent to a log file. |
| 412 |
.Ve |
| 413 |
.fX ssplit() |
| 414 |
splits a string into a vector of words, treating |
| 415 |
occurrences in the string of any of the characters in the |
| 416 |
.fX delimiters |
| 417 |
string as word separators. |
| 418 |
.LP |
| 419 |
If the delimiters string starts with a NUL character then multiple |
| 420 |
adjacent delimiters and leading delimiters generate zero length fields. |
| 421 |
Otherwise, leading delimiter characters are skipped and multiple adjacent |
| 422 |
delimiters are treated as a single delimiter. |
| 423 |
Thus |
| 424 |
.Vs |
| 425 |
char **words = ssplit(line, " \\t"); |
| 426 |
.Ve |
| 427 |
will to a shell-like split of a command line into words, and |
| 428 |
.Vs |
| 429 |
char **fields = ssplit(pwline, "\\0:"); |
| 430 |
.Ve |
| 431 |
would be good for splitting lines from the password file. |
| 432 |
.LP |
| 433 |
.fX ssplit() |
| 434 |
returns a |
| 435 |
.fX NULL |
| 436 |
terminated vector of words. |
| 437 |
The space for this vector and the pointed to words is allocated with |
| 438 |
a (single) call to |
| 439 |
.fX e_malloc() . |
| 440 |
.fX ssplit() |
| 441 |
thus never returns |
| 442 |
.fX NULL ; |
| 443 |
it aborts the program |
| 444 |
by calling |
| 445 |
.fX panic() |
| 446 |
if memory runs out. |
| 447 |
.LP |
| 448 |
The vector returned by |
| 449 |
.fX ssplit() |
| 450 |
should be freed when it is finished |
| 451 |
with by passing it to |
| 452 |
.fX free() . |
| 453 |
.Vs |
| 454 |
int get_host_addr(const char *hostname, struct in_addr *p_addr) |
| 455 |
.Ve |
| 456 |
.fX get_host_addr() |
| 457 |
looks up the IP address of |
| 458 |
.fX hostname |
| 459 |
using |
| 460 |
.IR gethostbyaddr (3). |
| 461 |
If the lookup succeeds it sets |
| 462 |
.fX *p_addr |
| 463 |
to the IP address of the host in network byte order. |
| 464 |
If the lookup fails it gives an error message with |
| 465 |
.fX errf() |
| 466 |
and returns -1. |
| 467 |
If |
| 468 |
.fX hostname |
| 469 |
consists of four decimal numbers separated by dots then |
| 470 |
.fX get_host_addr |
| 471 |
parses this as an IP quad and does not call |
| 472 |
.IR gethostbyname . |
| 473 |
.Vs |
| 474 |
int get_service_port(const char *servname, int *p_port) |
| 475 |
.Ve |
| 476 |
.fX get_service_port |
| 477 |
looks up the port number of the TCP service |
| 478 |
.fX servname |
| 479 |
using |
| 480 |
.IR getservbyname (3). |
| 481 |
If it succeeds it sets |
| 482 |
.fX *p_port |
| 483 |
to the port number in network byte order. |
| 484 |
Otherwise it gives an error message with |
| 485 |
.fX errf() |
| 486 |
and returns -1. |
| 487 |
If |
| 488 |
.fX servname |
| 489 |
is an \s-2ASCII\s0 decimal number then |
| 490 |
.fX get_service_port() |
| 491 |
returns that number (again in network byte order). |
| 492 |
.Vs |
| 493 |
ebuf_t *ebuf_create(bool errors_are_fatal); |
| 494 |
void ebuf_reset(ebuf_t *eb); |
| 495 |
ebuf_t *ebuf_start(ebuf_t *eb, bool errors_are_fatal); |
| 496 |
int ebuf_add(ebuf_t *eb, const char *buf, int count); |
| 497 |
char *ebuf_get(ebuf_t *eb, int *p_len); |
| 498 |
void ebuf_free(ebuf_t *eb); |
| 499 |
.Ve |
| 500 |
These routines implement variable sized contiguous buffers to which data |
| 501 |
can be appended at any time. |
| 502 |
.fX ebuf_create() |
| 503 |
creates a new zero length buffer. |
| 504 |
The |
| 505 |
.fX errors_are_fatal |
| 506 |
parameter controls the handling of errors; if it is |
| 507 |
.fX TRUE |
| 508 |
then all of the routines will call |
| 509 |
.fX panic() |
| 510 |
on failure. |
| 511 |
.LP |
| 512 |
|
| 513 |
.fX ebuf_add() |
| 514 |
appends |
| 515 |
.fX count |
| 516 |
bytes of memory pointed at by |
| 517 |
.fX data |
| 518 |
to the buffer |
| 519 |
.fX eb |
| 520 |
(which must have been created using |
| 521 |
.fX ebuf_create() ). |
| 522 |
.fX ebuf_add() |
| 523 |
returns zero on success. |
| 524 |
On failure it panics or returns |
| 525 |
.fX -1 |
| 526 |
(depending on the setting of |
| 527 |
.fX errors_are_fatal |
| 528 |
in the call of |
| 529 |
.fX ebuf_create()). |
| 530 |
.LP |
| 531 |
.fX ebuf_get() |
| 532 |
returns a pointer to the current contents of |
| 533 |
.fX eb ; |
| 534 |
if the |
| 535 |
.fX p_len |
| 536 |
parameter is not |
| 537 |
.fX NULL |
| 538 |
the current length of the buffer in bytes is stored there. |
| 539 |
The returned buffer and length are only valid up to the next call of |
| 540 |
.fX ebuf_add() , |
| 541 |
.fX ebuf_reset() |
| 542 |
or |
| 543 |
.fX ebuf_free(). |
| 544 |
.LP |
| 545 |
.fX ebuf_reset() |
| 546 |
frees the data associated with |
| 547 |
.fX eb |
| 548 |
and resets the length to zero. |
| 549 |
Furthur calls of |
| 550 |
.fX ebuf_add() |
| 551 |
can be used to add fresh data to |
| 552 |
.fX eb . |
| 553 |
.fX ebuf_free() |
| 554 |
frees and destroys |
| 555 |
.fX eb . |
| 556 |
.LP |
| 557 |
.fX ebuf_start() |
| 558 |
is a convenience routine which either creates or resets a buffer. |
| 559 |
If |
| 560 |
.fX eb |
| 561 |
is |
| 562 |
.fX NULL |
| 563 |
it calls |
| 564 |
.fX ebuf_create() |
| 565 |
with the supplied value of |
| 566 |
.fX errors_are_fatal . |
| 567 |
If |
| 568 |
.fX eb |
| 569 |
is not |
| 570 |
.fX NULL |
| 571 |
then it is passed to |
| 572 |
.fX ebuf_reset(). |
| 573 |
The routine is intended to be used like for static buffers in the following |
| 574 |
way: |
| 575 |
.Vs |
| 576 |
void foo(void) |
| 577 |
{ |
| 578 |
static ebuf_t *eb = NULL; |
| 579 |
|
| 580 |
eb = ebuf_start(eb, TRUE); |
| 581 |
... |
| 582 |
} |
| 583 |
.Ve |
| 584 |
The first time the function is called the buffer is created; on subsequent |
| 585 |
calls it is reset. |
| 586 |
.Vs |
| 587 |
alloc_pool_t *alloc_create_pool(void) |
| 588 |
.sp |
| 589 |
void *alloc(alloc_pool_t *ap, int nbytes) |
| 590 |
void *alloc_ck(alloc_pool_t *ap, int nbytes) |
| 591 |
.Ve |
| 592 |
.fX alloc_create_pool() |
| 593 |
creates a memory allocation `pool' and |
| 594 |
returns a handle referring to it. |
| 595 |
.fX alloc() |
| 596 |
allocates memory like |
| 597 |
.fX malloc(3) |
| 598 |
but from the |
| 599 |
specified pool rather from the general malloc arena. |
| 600 |
.fX alloc() |
| 601 |
calls |
| 602 |
.fX e_malloc() |
| 603 |
to obtain memory in reasonably |
| 604 |
large chunks when necessary. |
| 605 |
This means that it never returns |
| 606 |
.fX NULL ; |
| 607 |
the program is aborted |
| 608 |
via |
| 609 |
.fX panic() |
| 610 |
if there is insufficient memory to satisfy the |
| 611 |
request. |
| 612 |
The alternative interface |
| 613 |
.fX alloc_ck() |
| 614 |
returns |
| 615 |
.fX NULL |
| 616 |
if |
| 617 |
it runs out of memory; it is otherwise identical to |
| 618 |
.fX alloc() . |
| 619 |
Memory obtained with |
| 620 |
.fX alloc() |
| 621 |
cannot be freed individually; only |
| 622 |
entire pools can be freed. |
| 623 |
.Vs |
| 624 |
void alloc_free_pool(alloc_pool_t *ap) |
| 625 |
void alloc_reset_pool(alloc_pool_t *ap) |
| 626 |
.Ve |
| 627 |
.fX alloc_free_pool() |
| 628 |
frees an alloc pool, releasing all memory |
| 629 |
allocated from it with |
| 630 |
.fX alloc() . |
| 631 |
The pool is no longer valid after this call. |
| 632 |
.fX alloc_reset_pool() |
| 633 |
conceptually frees all the memory associated with |
| 634 |
a pool but does not return it via |
| 635 |
.fX free() . |
| 636 |
The pool remains valid and subsequent calls to |
| 637 |
.fX alloc() |
| 638 |
allocate |
| 639 |
memory from the existing memory associated with the pool if possible. |
| 640 |
.LP |
| 641 |
These routines are suitable for applications which make lots of small |
| 642 |
allocations for a data structure which is to be freed in one go. |
| 643 |
.fX alloc() |
| 644 |
is much faster than |
| 645 |
.fX malloc() |
| 646 |
as it does not do |
| 647 |
the bookkeeping to support individual freeing of allocated memory. |
| 648 |
It also has no space overhead other than that necessary to correctly |
| 649 |
align objects in memory. |
| 650 |
.LP |
| 651 |
.fX alloc_create_pool() |
| 652 |
is a lightweight routine \- it involves a |
| 653 |
single call to |
| 654 |
.fX malloc() |
| 655 |
plus some assignments to initialise the |
| 656 |
pool header structure. |
| 657 |
It is thus reasonable to use the |
| 658 |
.fX alloc() |
| 659 |
routines in situations where |
| 660 |
there are only going to be a few tens of calls to |
| 661 |
.fX alloc() . |
| 662 |
.Vs |
| 663 |
bool alloc_set_default_debug_flag(bool val) |
| 664 |
bool alloc_set_debug_flag(alloc_pool_t *ap, bool val) |
| 665 |
.Ve |
| 666 |
By default all memory obtained with |
| 667 |
.fX alloc() |
| 668 |
and related routines |
| 669 |
is initialised to the repeated byte |
| 670 |
.fX 0x53 . |
| 671 |
When memory is freed (with |
| 672 |
.fX alloc_free_pool() , |
| 673 |
.fX alloc_reset_pool() |
| 674 |
or |
| 675 |
.fX alloc_release() ) |
| 676 |
it is set |
| 677 |
to the repeated byte |
| 678 |
.fX 0x42 . |
| 679 |
This is intended to trap erroneous use of uninitialised data and data |
| 680 |
that has been freed \- newly allocated memory contains obvious garbage |
| 681 |
and freed memory is immediately stamped on. |
| 682 |
.LP |
| 683 |
Of course these safety features cost speed, so they can be turned off |
| 684 |
globally or per-pool. |
| 685 |
.fX alloc_set_debug_flag() |
| 686 |
sets the debugging flag for a pool; memory |
| 687 |
will be initialised to garbage and stamped on when freed only of the flag |
| 688 |
is non-zero. |
| 689 |
.fX alloc_set_default_debug_flag() |
| 690 |
sets the value of the flag used |
| 691 |
for pools created from then on with |
| 692 |
.fX alloc_create_pool() . |
| 693 |
Both routines return the previous value of the flag they set. |
| 694 |
.Vs |
| 695 |
char *allocstr(alloc_pool_t *ap, int nbytes) |
| 696 |
char *allocstr_ck(alloc_pool_t *ap, int nbytes) |
| 697 |
.Ve |
| 698 |
.fX allocstr() |
| 699 |
is like |
| 700 |
.fX alloc() |
| 701 |
except that it assumes that |
| 702 |
no alignment is required. |
| 703 |
It is thus suitable only for allocating space for strings. |
| 704 |
.fX allocstr() |
| 705 |
is implemented such that interspersed calls to |
| 706 |
.fX alloc() |
| 707 |
and |
| 708 |
.fX allocstr() |
| 709 |
will pack both |
| 710 |
the strings and the other objects tightly in memory with no space |
| 711 |
wasted on alignment. |
| 712 |
.fX allocstr() |
| 713 |
never returns |
| 714 |
.fX NULL |
| 715 |
\- it panics like |
| 716 |
.fX alloc() |
| 717 |
if there is no memory. |
| 718 |
.fX allocstr_ck() |
| 719 |
is the same as |
| 720 |
.fX allocstr() |
| 721 |
except that |
| 722 |
it returns |
| 723 |
.fX NULL |
| 724 |
if there is no memory. |
| 725 |
.Vs |
| 726 |
char *alloc_strdup(alloc_pool_t *ap, const char *s) |
| 727 |
.Ve |
| 728 |
.fX alloc_strdup() |
| 729 |
is a convenience routine that returns a pointer |
| 730 |
to a copy of a string allocated using |
| 731 |
.fX allocstr() . |
| 732 |
Note that it will never return |
| 733 |
.fX NULL |
| 734 |
as it uses |
| 735 |
.fX allocstr() |
| 736 |
rather than |
| 737 |
.fX allocstr_ck() . |
| 738 |
.Vs |
| 739 |
alloc_mark_t *alloc_mark(alloc_pool_t *ap) |
| 740 |
void alloc_release(alloc_pool_t *ap, alloc_mark_t *am) |
| 741 |
.Ve |
| 742 |
.fX alloc_mark() |
| 743 |
returns an opaque handle that `remembers' the |
| 744 |
current position in an alloc pool. |
| 745 |
A subsequent call to |
| 746 |
.fX alloc_release() |
| 747 |
conceptually frees all |
| 748 |
memory allocated from the pool since the corresponding call of |
| 749 |
.fX alloc_mark() . |
| 750 |
Subsequent calls to |
| 751 |
.fX alloc() |
| 752 |
et al will reuse the freed memory. |
| 753 |
A call to |
| 754 |
.fX alloc_release() |
| 755 |
renders invalid any marks that were |
| 756 |
returned after the |
| 757 |
.fX alloc_mark() |
| 758 |
call that returned the mark |
| 759 |
being passed to |
| 760 |
.fX alloc_release() . |
| 761 |
.Vs |
| 762 |
const char *ukcprog_version(void) |
| 763 |
.Ve |
| 764 |
.fX ukcprog_version() |
| 765 |
returns a string giving the current version number of the library. |
| 766 |
.SH BUGS |
| 767 |
This library treads rather freely on the name space. |
| 768 |
.SH AUTHORS |
| 769 |
.LP |
| 770 |
Godfrey Paul |
| 771 |
.br |
| 772 |
Mark Russell |
| 773 |
.sp |
| 774 |
Computing Laboratory, University of Kent at Canterbury. |
| 775 |
.br |
| 776 |
Contact: cs-sysadmin@ukc.ac.uk |
