ex/ex_filter.c

   1 /*-
   2  * Copyright (c) 1991, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Copyright (c) 1991, 1993, 1994, 1995, 1996
   5  *      Keith Bostic.  All rights reserved.
   6  *
   7  * See the LICENSE file for redistribution information.
   8  */
   9
  10 #include "config.h"
  11
  12 #ifndef lint
  13 static const char sccsid[] = "$Id: ex_filter.c,v 10.35 2000/04/21 19:00:36 skimo Exp $ (Berkeley) $Date: 2000/04/21 19:00:36 $";
  14 #endif /* not lint */
  15
  16 #include <sys/types.h>
  17 #include <sys/queue.h>
  18
  19 #include <bitstring.h>
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <limits.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27
  28 #include "../common/common.h"
  29
  30 static int filter_ldisplay __P((SCR *, FILE *));
  31
  32 /*
  33  * ex_filter --
  34  *      Run a range of lines through a filter utility and optionally
  35  *      replace the original text with the stdout/stderr output of
  36  *      the utility.
  37  *
  38  * PUBLIC: int ex_filter __P((SCR *,
  39  * PUBLIC:    EXCMD *, MARK *, MARK *, MARK *, char *, enum filtertype));
  40  */
  41 int
  42 ex_filter(sp, cmdp, fm, tm, rp, cmd, ftype)
  43         SCR *sp;
  44         EXCMD *cmdp;
  45         MARK *fm, *tm, *rp;
  46         char *cmd;
  47         enum filtertype ftype;
  48 {
  49         FILE *ifp, *ofp;
  50         pid_t parent_writer_pid, utility_pid;
  51         db_recno_t nread;
  52         int input[2], output[2], rval;
  53         char *name;
  54
  55         rval = 0;
  56
  57         /* Set return cursor position, which is never less than line 1. */
  58         *rp = *fm;
  59         if (rp->lno == 0)
  60                 rp->lno = 1;
  61
  62         /* We're going to need a shell. */
  63         if (opts_empty(sp, O_SHELL, 0))
  64                 return (1);
  65
  66         /*
  67          * There are three different processes running through this code.
  68          * They are the utility, the parent-writer and the parent-reader.
  69          * The parent-writer is the process that writes from the file to
  70          * the utility, the parent reader is the process that reads from
  71          * the utility.
  72          *
  73          * Input and output are named from the utility's point of view.
  74          * The utility reads from input[0] and the parent(s) write to
  75          * input[1].  The parent(s) read from output[0] and the utility
  76          * writes to output[1].
  77          *
  78          * !!!
  79          * Historically, in the FILTER_READ case, the utility reads from
  80          * the terminal (e.g. :r! cat works).  Otherwise open up utility
  81          * input pipe.
  82          */
  83         ofp = NULL;
  84         input[0] = input[1] = output[0] = output[1] = -1;
  85         if (ftype != FILTER_READ && pipe(input) < 0) {
  86                 msgq(sp, M_SYSERR, "pipe");
  87                 goto err;
  88         }
  89
  90         /* Open up utility output pipe. */
  91         if (pipe(output) < 0) {
  92                 msgq(sp, M_SYSERR, "pipe");
  93                 goto err;
  94         }
  95         if ((ofp = fdopen(output[0], "r")) == NULL) {
  96                 msgq(sp, M_SYSERR, "fdopen");
  97                 goto err;
  98         }
  99
 100         /* Fork off the utility process. */
 101         switch (utility_pid = vfork()) {
 102         case -1:                        /* Error. */
 103                 msgq(sp, M_SYSERR, "vfork");
 104 err:            if (input[0] != -1)
 105                         (void)close(input[0]);
 106                 if (input[1] != -1)
 107                         (void)close(input[1]);
 108                 if (ofp != NULL)
 109                         (void)fclose(ofp);
 110                 else if (output[0] != -1)
 111                         (void)close(output[0]);
 112                 if (output[1] != -1)
 113                         (void)close(output[1]);
 114                 return (1);
 115         case 0:                         /* Utility. */
 116                 /*
 117                  * Redirect stdin from the read end of the input pipe, and
 118                  * redirect stdout/stderr to the write end of the output pipe.
 119                  *
 120                  * !!!
 121                  * Historically, ex only directed stdout into the input pipe,
 122                  * letting stderr come out on the terminal as usual.  Vi did
 123                  * not, directing both stdout and stderr into the input pipe.
 124                  * We match that practice in both ex and vi for consistency.
 125                  */
 126                 if (input[0] != -1)
 127                         (void)dup2(input[0], STDIN_FILENO);
 128                 (void)dup2(output[1], STDOUT_FILENO);
 129                 (void)dup2(output[1], STDERR_FILENO);
 130
 131                 /* Close the utility's file descriptors. */
 132                 if (input[0] != -1)
 133                         (void)close(input[0]);
 134                 if (input[1] != -1)
 135                         (void)close(input[1]);
 136                 (void)close(output[0]);
 137                 (void)close(output[1]);
 138
 139                 if ((name = strrchr(O_STR(sp, O_SHELL), '/')) == NULL)
 140                         name = O_STR(sp, O_SHELL);
 141                 else
 142                         ++name;
 143
 144                 execl(O_STR(sp, O_SHELL), name, "-c", cmd, NULL);
 145                 msgq_str(sp, M_SYSERR, O_STR(sp, O_SHELL), "execl: %s");
 146                 _exit (127);
 147                 /* NOTREACHED */
 148         default:                        /* Parent-reader, parent-writer. */
 149                 /* Close the pipe ends neither parent will use. */
 150                 if (input[0] != -1)
 151                         (void)close(input[0]);
 152                 (void)close(output[1]);
 153                 break;
 154         }
 155
 156         /*
 157          * FILTER_RBANG, FILTER_READ:
 158          *
 159          * Reading is the simple case -- we don't need a parent writer,
 160          * so the parent reads the output from the read end of the output
 161          * pipe until it finishes, then waits for the child.  Ex_readfp
 162          * appends to the MARK, and closes ofp.
 163          *
 164          * For FILTER_RBANG, there is nothing to write to the utility.
 165          * Make sure it doesn't wait forever by closing its standard
 166          * input.
 167          *
 168          * !!!
 169          * Set the return cursor to the last line read in for FILTER_READ.
 170          * Historically, this behaves differently from ":r file" command,
 171          * which leaves the cursor at the first line read in.  Check to
 172          * make sure that it's not past EOF because we were reading into an
 173          * empty file.
 174          */
 175         if (ftype == FILTER_RBANG || ftype == FILTER_READ) {
 176                 if (ftype == FILTER_RBANG)
 177                         (void)close(input[1]);
 178
 179                 if (ex_readfp(sp, "filter", ofp, fm, &nread, 1))
 180                         rval = 1;
 181                 sp->rptlines[L_ADDED] += nread;
 182                 if (ftype == FILTER_READ)
 183                         if (fm->lno == 0)
 184                                 rp->lno = nread;
 185                         else
 186                                 rp->lno += nread;
 187                 goto uwait;
 188         }
 189
 190         /*
 191          * FILTER_BANG, FILTER_WRITE
 192          *
 193          * Here we need both a reader and a writer.  Temporary files are
 194          * expensive and we'd like to avoid disk I/O.  Using pipes has the
 195          * obvious starvation conditions.  It's done as follows:
 196          *
 197          *      fork
 198          *      child
 199          *              write lines out
 200          *              exit
 201          *      parent
 202          *              FILTER_BANG:
 203          *                      read lines into the file
 204          *                      delete old lines
 205          *              FILTER_WRITE
 206          *                      read and display lines
 207          *              wait for child
 208          *
 209          * XXX
 210          * We get away without locking the underlying database because we know
 211          * that none of the records that we're reading will be modified until
 212          * after we've read them.  This depends on the fact that the current
 213          * B+tree implementation doesn't balance pages or similar things when
 214          * it inserts new records.  When the DB code has locking, we should
 215          * treat vi as if it were multiple applications sharing a database, and
 216          * do the required locking.  If necessary a work-around would be to do
 217          * explicit locking in the line.c:db_get() code, based on the flag set
 218          * here.
 219          */
 220         F_SET(sp->ep, F_MULTILOCK);
 221         switch (parent_writer_pid = fork()) {
 222         case -1:                        /* Error. */
 223                 msgq(sp, M_SYSERR, "fork");
 224                 (void)close(input[1]);
 225                 (void)close(output[0]);
 226                 rval = 1;
 227                 break;
 228         case 0:                         /* Parent-writer. */
 229                 /*
 230                  * Write the selected lines to the write end of the input
 231                  * pipe.  This instance of ifp is closed by ex_writefp.
 232                  */
 233                 (void)close(output[0]);
 234                 if ((ifp = fdopen(input[1], "w")) == NULL)
 235                         _exit (1);
 236                 _exit(ex_writefp(sp, "filter", ifp, fm, tm, NULL, NULL, 1));
 237
 238                 /* NOTREACHED */
 239         default:                        /* Parent-reader. */
 240                 (void)close(input[1]);
 241                 if (ftype == FILTER_WRITE) {
 242                         /*
 243                          * Read the output from the read end of the output
 244                          * pipe and display it.  Filter_ldisplay closes ofp.
 245                          */
 246                         if (filter_ldisplay(sp, ofp))
 247                                 rval = 1;
 248                 } else {
 249                         /*
 250                          * Read the output from the read end of the output
 251                          * pipe.  Ex_readfp appends to the MARK and closes
 252                          * ofp.
 253                          */
 254                         if (ex_readfp(sp, "filter", ofp, tm, &nread, 1))
 255                                 rval = 1;
 256                         sp->rptlines[L_ADDED] += nread;
 257                 }
 258
 259                 /* Wait for the parent-writer. */
 260                 if (proc_wait(sp,
 261                     (long)parent_writer_pid, "parent-writer", 0, 1))
 262                         rval = 1;
 263
 264                 /* Delete any lines written to the utility. */
 265                 if (rval == 0 && ftype == FILTER_BANG &&
 266                     (cut(sp, NULL, fm, tm, CUT_LINEMODE) ||
 267                     del(sp, fm, tm, 1))) {
 268                         rval = 1;
 269                         break;
 270                 }
 271
 272                 /*
 273                  * If the filter had no output, we may have just deleted
 274                  * the cursor.  Don't do any real error correction, we'll
 275                  * try and recover later.
 276                  */
 277                  if (rp->lno > 1 && !db_exist(sp, rp->lno))
 278                         --rp->lno;
 279                 break;
 280         }
 281         F_CLR(sp->ep, F_MULTILOCK);
 282
 283         /*
 284          * !!!
 285          * Ignore errors on vi file reads, to make reads prettier.  It's
 286          * completely inconsistent, and historic practice.
 287          */
 288 uwait:  return (proc_wait(sp, (long)utility_pid, cmd,
 289             ftype == FILTER_READ && F_ISSET(sp, SC_VI) ? 1 : 0, 0) || rval);
 290 }
 291
 292 /*
 293  * filter_ldisplay --
 294  *      Display output from a utility.
 295  *
 296  * !!!
 297  * Historically, the characters were passed unmodified to the terminal.
 298  * We use the ex print routines to make sure they're printable.
 299  */
 300 static int
 301 filter_ldisplay(sp, fp)
 302         SCR *sp;
 303         FILE *fp;
 304 {
 305         size_t len;
 306
 307         EX_PRIVATE *exp;
 308
 309         for (exp = EXP(sp); !ex_getline(sp, fp, &len) && !INTERRUPTED(sp);)
 310                 if (ex_ldisplay(sp, exp->ibp, len, 0, 0))
 311                         break;
 312         if (ferror(fp))
 313                 msgq(sp, M_SYSERR, "filter read");
 314         (void)fclose(fp);
 315         return (0);
 316 }