contrib/less/os.c

   1 /*
   2  * Copyright (C) 1984-2007  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 about less, or for information on how to
   8  * contact the author, see the README file.
   9  */
  10
  11
  12 /*
  13  * Operating system dependent routines.
  14  *
  15  * Most of the stuff in here is based on Unix, but an attempt
  16  * has been made to make things work on other operating systems.
  17  * This will sometimes result in a loss of functionality, unless
  18  * someone rewrites code specifically for the new operating system.
  19  *
  20  * The makefile provides defines to decide whether various
  21  * Unix features are present.
  22  */
  23
  24 #include "less.h"
  25 #include <signal.h>
  26 #include <setjmp.h>
  27 #if HAVE_TIME_H
  28 #include <time.h>
  29 #endif
  30 #if HAVE_ERRNO_H
  31 #include <errno.h>
  32 #endif
  33 #if HAVE_VALUES_H
  34 #include <values.h>
  35 #endif
  36
  37 #if HAVE_TIME_T
  38 #define time_type       time_t
  39 #else
  40 #define time_type       long
  41 #endif
  42
  43 /*
  44  * BSD setjmp() saves (and longjmp() restores) the signal mask.
  45  * This costs a system call or two per setjmp(), so if possible we clear the
  46  * signal mask with sigsetmask(), and use _setjmp()/_longjmp() instead.
  47  * On other systems, setjmp() doesn't affect the signal mask and so
  48  * _setjmp() does not exist; we just use setjmp().
  49  */
  50 #if HAVE__SETJMP && HAVE_SIGSETMASK
  51 #define SET_JUMP        _setjmp
  52 #define LONG_JUMP       _longjmp
  53 #else
  54 #define SET_JUMP        setjmp
  55 #define LONG_JUMP       longjmp
  56 #endif
  57
  58 public int reading;
  59
  60 static jmp_buf read_label;
  61
  62 extern int sigs;
  63
  64 /*
  65  * Like read() system call, but is deliberately interruptible.
  66  * A call to intread() from a signal handler will interrupt
  67  * any pending iread().
  68  */
  69         public int
  70 iread(fd, buf, len)
  71         int fd;
  72         char *buf;
  73         unsigned int len;
  74 {
  75         register int n;
  76
  77 start:
  78 #if MSDOS_COMPILER==WIN32C
  79         if (ABORT_SIGS())
  80                 return (READ_INTR);
  81 #else
  82 #if MSDOS_COMPILER && MSDOS_COMPILER != DJGPPC
  83         if (kbhit())
  84         {
  85                 int c;
  86
  87                 c = getch();
  88                 if (c == '\003')
  89                         return (READ_INTR);
  90                 ungetch(c);
  91         }
  92 #endif
  93 #endif
  94         if (SET_JUMP(read_label))
  95         {
  96                 /*
  97                  * We jumped here from intread.
  98                  */
  99                 reading = 0;
 100 #if HAVE_SIGPROCMASK
 101                 {
 102                   sigset_t mask;
 103                   sigemptyset(&mask);
 104                   sigprocmask(SIG_SETMASK, &mask, NULL);
 105                 }
 106 #else
 107 #if HAVE_SIGSETMASK
 108                 sigsetmask(0);
 109 #else
 110 #ifdef _OSK
 111                 sigmask(~0);
 112 #endif
 113 #endif
 114 #endif
 115                 return (READ_INTR);
 116         }
 117
 118         flush();
 119         reading = 1;
 120 #if MSDOS_COMPILER==DJGPPC
 121         if (isatty(fd))
 122         {
 123                 /*
 124                  * Don't try reading from a TTY until a character is
 125                  * available, because that makes some background programs
 126                  * believe DOS is busy in a way that prevents those
 127                  * programs from working while "less" waits.
 128                  */
 129                 fd_set readfds;
 130
 131                 FD_ZERO(&readfds);
 132                 FD_SET(fd, &readfds);
 133                 if (select(fd+1, &readfds, 0, 0, 0) == -1)
 134                         return (-1);
 135         }
 136 #endif
 137         n = read(fd, buf, len);
 138 #if 1
 139         /*
 140          * This is a kludge to workaround a problem on some systems
 141          * where terminating a remote tty connection causes read() to
 142          * start returning 0 forever, instead of -1.
 143          */
 144         {
 145                 extern int ignore_eoi;
 146                 if (!ignore_eoi)
 147                 {
 148                         static int consecutive_nulls = 0;
 149                         if (n == 0)
 150                                 consecutive_nulls++;
 151                         else
 152                                 consecutive_nulls = 0;
 153                         if (consecutive_nulls > 20)
 154                                 quit(QUIT_ERROR);
 155                 }
 156         }
 157 #endif
 158         reading = 0;
 159         if (n < 0)
 160         {
 161 #if HAVE_ERRNO
 162                 /*
 163                  * Certain values of errno indicate we should just retry the read.
 164                  */
 165 #if MUST_DEFINE_ERRNO
 166                 extern int errno;
 167 #endif
 168 #ifdef EINTR
 169                 if (errno == EINTR)
 170                         goto start;
 171 #endif
 172 #ifdef EAGAIN
 173                 if (errno == EAGAIN)
 174                         goto start;
 175 #endif
 176 #endif
 177                 return (-1);
 178         }
 179         return (n);
 180 }
 181
 182 /*
 183  * Interrupt a pending iread().
 184  */
 185         public void
 186 intread()
 187 {
 188         LONG_JUMP(read_label, 1);
 189 }
 190
 191 /*
 192  * Return the current time.
 193  */
 194 #if HAVE_TIME
 195         public long
 196 get_time()
 197 {
 198         time_type t;
 199
 200         time(&t);
 201         return (t);
 202 }
 203 #endif
 204
 205
 206 #if !HAVE_STRERROR
 207 /*
 208  * Local version of strerror, if not available from the system.
 209  */
 210         static char *
 211 strerror(err)
 212         int err;
 213 {
 214 #if HAVE_SYS_ERRLIST
 215         static char buf[16];
 216         extern char *sys_errlist[];
 217         extern int sys_nerr;
 218
 219         if (err < sys_nerr)
 220                 return sys_errlist[err];
 221         sprintf(buf, "Error %d", err);
 222         return buf;
 223 #else
 224         return ("cannot open");
 225 #endif
 226 }
 227 #endif
 228
 229 /*
 230  * errno_message: Return an error message based on the value of "errno".
 231  */
 232         public char *
 233 errno_message(filename)
 234         char *filename;
 235 {
 236         register char *p;
 237         register char *m;
 238         int len;
 239 #if HAVE_ERRNO
 240 #if MUST_DEFINE_ERRNO
 241         extern int errno;
 242 #endif
 243         p = strerror(errno);
 244 #else
 245         p = "cannot open";
 246 #endif
 247         len = strlen(filename) + strlen(p) + 3;
 248         m = (char *) ecalloc(len, sizeof(char));
 249         SNPRINTF2(m, len, "%s: %s", filename, p);
 250         return (m);
 251 }
 252
 253 /*
 254  * Return the ratio of two POSITIONS, as a percentage.
 255  * {{ Assumes a POSITION is a long int. }}
 256  */
 257         public int
 258 percentage(num, den)
 259         POSITION num, den;
 260 {
 261         POSITION num100 = num * 100;
 262
 263         if (num100 / 100 == num)
 264                 return (num100 / den);
 265         else
 266                 return (num / (den / 100));
 267 }
 268
 269 /*
 270  * Return the specified percentage of a POSITION.
 271  */
 272         public POSITION
 273 percent_pos(pos, percent, fraction)
 274         POSITION pos;
 275         int percent;
 276         long fraction;
 277 {
 278         /* Change percent (parts per 100) to perden (parts per NUM_FRAC_DENOM). */
 279         long perden = (percent * (NUM_FRAC_DENOM / 100)) + (fraction / 100);
 280         POSITION temp;
 281
 282         if (perden == 0)
 283                 return (0);
 284         temp = pos * perden;  /* This might overflow. */
 285         if (temp / perden == pos)
 286                 /* No overflow */
 287                 return (temp / NUM_FRAC_DENOM);
 288         else
 289                 /* Above calculation overflows;
 290                  * use a method that is less precise but won't overflow. */
 291                 return (perden * (pos / NUM_FRAC_DENOM));
 292 }
 293
 294 #if !HAVE_STRCHR
 295 /*
 296  * strchr is used by regexp.c.
 297  */
 298         char *
 299 strchr(s, c)
 300         char *s;
 301         int c;
 302 {
 303         for ( ;  *s != '\0';  s++)
 304                 if (*s == c)
 305                         return (s);
 306         if (c == '\0')
 307                 return (s);
 308         return (NULL);
 309 }
 310 #endif
 311
 312 #if !HAVE_MEMCPY
 313         VOID_POINTER
 314 memcpy(dst, src, len)
 315         VOID_POINTER dst;
 316         VOID_POINTER src;
 317         int len;
 318 {
 319         char *dstp = (char *) dst;
 320         char *srcp = (char *) src;
 321         int i;
 322
 323         for (i = 0;  i < len;  i++)
 324                 dstp[i] = srcp[i];
 325         return (dst);
 326 }
 327 #endif
 328
 329 #ifdef _OSK_MWC32
 330
 331 /*
 332  * This implements an ANSI-style intercept setup for Microware C 3.2
 333  */
 334         public int
 335 os9_signal(type, handler)
 336         int type;
 337         RETSIGTYPE (*handler)();
 338 {
 339         intercept(handler);
 340 }
 341
 342 #include <sgstat.h>
 343
 344         int
 345 isatty(f)
 346         int f;
 347 {
 348         struct sgbuf sgbuf;
 349
 350         if (_gs_opt(f, &sgbuf) < 0)
 351                 return -1;
 352         return (sgbuf.sg_class == 0);
 353 }
 354
 355 #endif