contrib/less/os.c

   1 /*
   2  * Copyright (C) 1984-2015  Mark Nudelman
   3  *
   4  * You may distribute under the terms of either the GNU General Public
   5  * License or the Less License, as specified in the README file.
   6  *
   7  * For more information, see the README file.
   8  */
   9
  10
  11 /*
  12  * Operating system dependent routines.
  13  *
  14  * Most of the stuff in here is based on Unix, but an attempt
  15  * has been made to make things work on other operating systems.
  16  * This will sometimes result in a loss of functionality, unless
  17  * someone rewrites code specifically for the new operating system.
  18  *
  19  * The makefile provides defines to decide whether various
  20  * Unix features are present.
  21  */
  22
  23 #include "less.h"
  24 #include <signal.h>
  25 #include <setjmp.h>
  26 #if HAVE_TIME_H
  27 #include <time.h>
  28 #endif
  29 #if HAVE_ERRNO_H
  30 #include <errno.h>
  31 #endif
  32 #if HAVE_VALUES_H
  33 #include <values.h>
  34 #endif
  35
  36 /*
  37  * BSD setjmp() saves (and longjmp() restores) the signal mask.
  38  * This costs a system call or two per setjmp(), so if possible we clear the
  39  * signal mask with sigsetmask(), and use _setjmp()/_longjmp() instead.
  40  * On other systems, setjmp() doesn't affect the signal mask and so
  41  * _setjmp() does not exist; we just use setjmp().
  42  */
  43 #if HAVE__SETJMP && HAVE_SIGSETMASK
  44 #define SET_JUMP        _setjmp
  45 #define LONG_JUMP       _longjmp
  46 #else
  47 #define SET_JUMP        setjmp
  48 #define LONG_JUMP       longjmp
  49 #endif
  50
  51 public int reading;
  52
  53 static jmp_buf read_label;
  54
  55 extern int sigs;
  56
  57 /*
  58  * Like read() system call, but is deliberately interruptible.
  59  * A call to intread() from a signal handler will interrupt
  60  * any pending iread().
  61  */
  62         public int
  63 iread(fd, buf, len)
  64         int fd;
  65         char *buf;
  66         unsigned int len;
  67 {
  68         register int n;
  69
  70 start:
  71 #if MSDOS_COMPILER==WIN32C
  72         if (ABORT_SIGS())
  73                 return (READ_INTR);
  74 #else
  75 #if MSDOS_COMPILER && MSDOS_COMPILER != DJGPPC
  76         if (kbhit())
  77         {
  78                 int c;
  79
  80                 c = getch();
  81                 if (c == '\003')
  82                         return (READ_INTR);
  83                 ungetch(c);
  84         }
  85 #endif
  86 #endif
  87         if (SET_JUMP(read_label))
  88         {
  89                 /*
  90                  * We jumped here from intread.
  91                  */
  92                 reading = 0;
  93 #if HAVE_SIGPROCMASK
  94                 {
  95                   sigset_t mask;
  96                   sigemptyset(&mask);
  97                   sigprocmask(SIG_SETMASK, &mask, NULL);
  98                 }
  99 #else
 100 #if HAVE_SIGSETMASK
 101                 sigsetmask(0);
 102 #else
 103 #ifdef _OSK
 104                 sigmask(~0);
 105 #endif
 106 #endif
 107 #endif
 108                 return (READ_INTR);
 109         }
 110
 111         flush();
 112         reading = 1;
 113 #if MSDOS_COMPILER==DJGPPC
 114         if (isatty(fd))
 115         {
 116                 /*
 117                  * Don't try reading from a TTY until a character is
 118                  * available, because that makes some background programs
 119                  * believe DOS is busy in a way that prevents those
 120                  * programs from working while "less" waits.
 121                  */
 122                 fd_set readfds;
 123
 124                 FD_ZERO(&readfds);
 125                 FD_SET(fd, &readfds);
 126                 if (select(fd+1, &readfds, 0, 0, 0) == -1)
 127                         return (-1);
 128         }
 129 #endif
 130         n = read(fd, buf, len);
 131 #if 1
 132         /*
 133          * This is a kludge to workaround a problem on some systems
 134          * where terminating a remote tty connection causes read() to
 135          * start returning 0 forever, instead of -1.
 136          */
 137         {
 138                 extern int ignore_eoi;
 139                 if (!ignore_eoi)
 140                 {
 141                         static int consecutive_nulls = 0;
 142                         if (n == 0)
 143                                 consecutive_nulls++;
 144                         else
 145                                 consecutive_nulls = 0;
 146                         if (consecutive_nulls > 20)
 147                                 quit(QUIT_ERROR);
 148                 }
 149         }
 150 #endif
 151         reading = 0;
 152         if (n < 0)
 153         {
 154 #if HAVE_ERRNO
 155                 /*
 156                  * Certain values of errno indicate we should just retry the read.
 157                  */
 158 #if MUST_DEFINE_ERRNO
 159                 extern int errno;
 160 #endif
 161 #ifdef EINTR
 162                 if (errno == EINTR)
 163                         goto start;
 164 #endif
 165 #ifdef EAGAIN
 166                 if (errno == EAGAIN)
 167                         goto start;
 168 #endif
 169 #endif
 170                 return (-1);
 171         }
 172         return (n);
 173 }
 174
 175 /*
 176  * Interrupt a pending iread().
 177  */
 178         public void
 179 intread()
 180 {
 181         LONG_JUMP(read_label, 1);
 182 }
 183
 184 /*
 185  * Return the current time.
 186  */
 187 #if HAVE_TIME
 188         public time_type
 189 get_time()
 190 {
 191         time_type t;
 192
 193         time(&t);
 194         return (t);
 195 }
 196 #endif
 197
 198
 199 #if !HAVE_STRERROR
 200 /*
 201  * Local version of strerror, if not available from the system.
 202  */
 203         static char *
 204 strerror(err)
 205         int err;
 206 {
 207 #if HAVE_SYS_ERRLIST
 208         static char buf[16];
 209         extern char *sys_errlist[];
 210         extern int sys_nerr;
 211
 212         if (err < sys_nerr)
 213                 return sys_errlist[err];
 214         sprintf(buf, "Error %d", err);
 215         return buf;
 216 #else
 217         return ("cannot open");
 218 #endif
 219 }
 220 #endif
 221
 222 /*
 223  * errno_message: Return an error message based on the value of "errno".
 224  */
 225         public char *
 226 errno_message(filename)
 227         char *filename;
 228 {
 229         register char *p;
 230         register char *m;
 231         int len;
 232 #if HAVE_ERRNO
 233 #if MUST_DEFINE_ERRNO
 234         extern int errno;
 235 #endif
 236         p = strerror(errno);
 237 #else
 238         p = "cannot open";
 239 #endif
 240         len = (int) (strlen(filename) + strlen(p) + 3);
 241         m = (char *) ecalloc(len, sizeof(char));
 242         SNPRINTF2(m, len, "%s: %s", filename, p);
 243         return (m);
 244 }
 245
 246 /* #define HAVE_FLOAT 0 */
 247
 248         static POSITION
 249 muldiv(val, num, den)
 250         POSITION val, num, den;
 251 {
 252 #if HAVE_FLOAT
 253         double v = (((double) val) * num) / den;
 254         return ((POSITION) (v + 0.5));
 255 #else
 256         POSITION v = ((POSITION) val) * num;
 257
 258         if (v / num == val)
 259                 /* No overflow */
 260                 return (POSITION) (v / den);
 261         else
 262                 /* Above calculation overflows;
 263                  * use a method that is less precise but won't overflow. */
 264                 return (POSITION) (val / (den / num));
 265 #endif
 266 }
 267
 268 /*
 269  * Return the ratio of two POSITIONS, as a percentage.
 270  * {{ Assumes a POSITION is a long int. }}
 271  */
 272         public int
 273 percentage(num, den)
 274         POSITION num, den;
 275 {
 276         return (int) muldiv(num,  (POSITION) 100, den);
 277 }
 278
 279 /*
 280  * Return the specified percentage of a POSITION.
 281  */
 282         public POSITION
 283 percent_pos(pos, percent, fraction)
 284         POSITION pos;
 285         int percent;
 286         long fraction;
 287 {
 288         /* Change percent (parts per 100) to perden (parts per NUM_FRAC_DENOM). */
 289         POSITION perden = (percent * (NUM_FRAC_DENOM / 100)) + (fraction / 100);
 290
 291         if (perden == 0)
 292                 return (0);
 293         return (POSITION) muldiv(pos, perden, (POSITION) NUM_FRAC_DENOM);
 294 }
 295
 296 #if !HAVE_STRCHR
 297 /*
 298  * strchr is used by regexp.c.
 299  */
 300         char *
 301 strchr(s, c)
 302         char *s;
 303         int c;
 304 {
 305         for ( ;  *s != '\0';  s++)
 306                 if (*s == c)
 307                         return (s);
 308         if (c == '\0')
 309                 return (s);
 310         return (NULL);
 311 }
 312 #endif
 313
 314 #if !HAVE_MEMCPY
 315         VOID_POINTER
 316 memcpy(dst, src, len)
 317         VOID_POINTER dst;
 318         VOID_POINTER src;
 319         int len;
 320 {
 321         char *dstp = (char *) dst;
 322         char *srcp = (char *) src;
 323         int i;
 324
 325         for (i = 0;  i < len;  i++)
 326                 dstp[i] = srcp[i];
 327         return (dst);
 328 }
 329 #endif
 330
 331 #ifdef _OSK_MWC32
 332
 333 /*
 334  * This implements an ANSI-style intercept setup for Microware C 3.2
 335  */
 336         public int
 337 os9_signal(type, handler)
 338         int type;
 339         RETSIGTYPE (*handler)();
 340 {
 341         intercept(handler);
 342 }
 343
 344 #include <sgstat.h>
 345
 346         int
 347 isatty(f)
 348         int f;
 349 {
 350         struct sgbuf sgbuf;
 351
 352         if (_gs_opt(f, &sgbuf) < 0)
 353                 return -1;
 354         return (sgbuf.sg_class == 0);
 355 }
 356
 357 #endif