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 10.44 2003/11/05 17:11:54 skimo Exp $ (Berkeley) $Date: 2003/11/05 17:11:54 $";
  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_T *, enum filtertype));
  40  */
  41 int
  42 ex_filter(SCR *sp, EXCMD *cmdp, MARK *fm, MARK *tm, MARK *rp, CHAR_T *cmd, enum filtertype ftype)
  43 {
  44         FILE *ifp, *ofp;
  45         pid_t parent_writer_pid, utility_pid;
  46         db_recno_t nread;
  47         int input[2], output[2], rval;
  48         char *name;
  49         char *np;
  50         size_t nlen;
  51
  52         rval = 0;
  53
  54         /* Set return cursor position, which is never less than line 1. */
  55         *rp = *fm;
  56         if (rp->lno == 0)
  57                 rp->lno = 1;
  58
  59         /* We're going to need a shell. */
  60         if (opts_empty(sp, O_SHELL, 0))
  61                 return (1);
  62
  63         /*
  64          * There are three different processes running through this code.
  65          * They are the utility, the parent-writer and the parent-reader.
  66          * The parent-writer is the process that writes from the file to
  67          * the utility, the parent reader is the process that reads from
  68          * the utility.
  69          *
  70          * Input and output are named from the utility's point of view.
  71          * The utility reads from input[0] and the parent(s) write to
  72          * input[1].  The parent(s) read from output[0] and the utility
  73          * writes to output[1].
  74          *
  75          * !!!
  76          * Historically, in the FILTER_READ case, the utility reads from
  77          * the terminal (e.g. :r! cat works).  Otherwise open up utility
  78          * input pipe.
  79          */
  80         ofp = NULL;
  81         input[0] = input[1] = output[0] = output[1] = -1;
  82         if (ftype != FILTER_READ && pipe(input) < 0) {
  83                 msgq(sp, M_SYSERR, "pipe");
  84                 goto err;
  85         }
  86
  87         /* Open up utility output pipe. */
  88         if (pipe(output) < 0) {
  89                 msgq(sp, M_SYSERR, "pipe");
  90                 goto err;
  91         }
  92         if ((ofp = fdopen(output[0], "r")) == NULL) {
  93                 msgq(sp, M_SYSERR, "fdopen");
  94                 goto err;
  95         }
  96
  97         /* Fork off the utility process. */
  98         switch (utility_pid = vfork()) {
  99         case -1:                        /* Error. */
 100                 msgq(sp, M_SYSERR, "vfork");
 101 err:            if (input[0] != -1)
 102                         (void)close(input[0]);
 103                 if (input[1] != -1)
 104                         (void)close(input[1]);
 105                 if (ofp != NULL)
 106                         (void)fclose(ofp);
 107                 else if (output[0] != -1)
 108                         (void)close(output[0]);
 109                 if (output[1] != -1)
 110                         (void)close(output[1]);
 111                 return (1);
 112         case 0:                         /* Utility. */
 113                 /*
 114                  * Redirect stdin from the read end of the input pipe, and
 115                  * redirect stdout/stderr to the write end of the output pipe.
 116                  *
 117                  * !!!
 118                  * Historically, ex only directed stdout into the input pipe,
 119                  * letting stderr come out on the terminal as usual.  Vi did
 120                  * not, directing both stdout and stderr into the input pipe.
 121                  * We match that practice in both ex and vi for consistency.
 122                  */
 123                 if (input[0] != -1)
 124                         (void)dup2(input[0], STDIN_FILENO);
 125                 (void)dup2(output[1], STDOUT_FILENO);
 126                 (void)dup2(output[1], STDERR_FILENO);
 127
 128                 /* Close the utility's file descriptors. */
 129                 if (input[0] != -1)
 130                         (void)close(input[0]);
 131                 if (input[1] != -1)
 132                         (void)close(input[1]);
 133                 (void)close(output[0]);
 134                 (void)close(output[1]);
 135
 136                 if ((name = strrchr(O_STR(sp, O_SHELL), '/')) == NULL)
 137                         name = O_STR(sp, O_SHELL);
 138                 else
 139                         ++name;
 140
 141                 INT2SYS(sp, cmd, STRLEN(cmd)+1, np, nlen);
 142                 execl(O_STR(sp, O_SHELL), name, "-c", np, (char *)NULL);
 143                 msgq_str(sp, M_SYSERR, O_STR(sp, O_SHELL), "execl: %s");
 144                 _exit (127);
 145                 /* NOTREACHED */
 146         default:                        /* Parent-reader, parent-writer. */
 147                 /* Close the pipe ends neither parent will use. */
 148                 if (input[0] != -1)
 149                         (void)close(input[0]);
 150                 (void)close(output[1]);
 151                 break;
 152         }
 153
 154         /*
 155          * FILTER_RBANG, FILTER_READ:
 156          *
 157          * Reading is the simple case -- we don't need a parent writer,
 158          * so the parent reads the output from the read end of the output
 159          * pipe until it finishes, then waits for the child.  Ex_readfp
 160          * appends to the MARK, and closes ofp.
 161          *
 162          * For FILTER_RBANG, there is nothing to write to the utility.
 163          * Make sure it doesn't wait forever by closing its standard
 164          * input.
 165          *
 166          * !!!
 167          * Set the return cursor to the last line read in for FILTER_READ.
 168          * Historically, this behaves differently from ":r file" command,
 169          * which leaves the cursor at the first line read in.  Check to
 170          * make sure that it's not past EOF because we were reading into an
 171          * empty file.
 172          */
 173         if (ftype == FILTER_RBANG || ftype == FILTER_READ) {
 174                 if (ftype == FILTER_RBANG)
 175                         (void)close(input[1]);
 176
 177                 if (ex_readfp(sp, "filter", ofp, fm, &nread, 1))
 178                         rval = 1;
 179                 sp->rptlines[L_ADDED] += nread;
 180                 if (ftype == FILTER_READ)
 181                         if (fm->lno == 0)
 182                                 rp->lno = nread;
 183                         else
 184                                 rp->lno += nread;
 185                 goto uwait;
 186         }
 187
 188         /*
 189          * FILTER_BANG, FILTER_WRITE
 190          *
 191          * Here we need both a reader and a writer.  Temporary files are
 192          * expensive and we'd like to avoid disk I/O.  Using pipes has the
 193          * obvious starvation conditions.  It's done as follows:
 194          *
 195          *      fork
 196          *      child
 197          *              write lines out
 198          *              exit
 199          *      parent
 200          *              FILTER_BANG:
 201          *                      read lines into the file
 202          *                      delete old lines
 203          *              FILTER_WRITE
 204          *                      read and display lines
 205          *              wait for child
 206          *
 207          * XXX
 208          * We get away without locking the underlying database because we know
 209          * that none of the records that we're reading will be modified until
 210          * after we've read them.  This depends on the fact that the current
 211          * B+tree implementation doesn't balance pages or similar things when
 212          * it inserts new records.  When the DB code has locking, we should
 213          * treat vi as if it were multiple applications sharing a database, and
 214          * do the required locking.  If necessary a work-around would be to do
 215          * explicit locking in the line.c:db_get() code, based on the flag set
 216          * here.
 217          */
 218         F_SET(sp->ep, F_MULTILOCK);
 219         switch (parent_writer_pid = fork()) {
 220         case -1:                        /* Error. */
 221                 msgq(sp, M_SYSERR, "fork");
 222                 (void)close(input[1]);
 223                 (void)close(output[0]);
 224                 rval = 1;
 225                 break;
 226         case 0:                         /* Parent-writer. */
 227                 /*
 228                  * Write the selected lines to the write end of the input
 229                  * pipe.  This instance of ifp is closed by ex_writefp.
 230                  */
 231                 (void)close(output[0]);
 232                 if ((ifp = fdopen(input[1], "w")) == NULL)
 233                         _exit (1);
 234                 _exit(ex_writefp(sp, "filter", ifp, fm, tm, NULL, NULL, 1));
 235
 236                 /* NOTREACHED */
 237         default:                        /* Parent-reader. */
 238                 (void)close(input[1]);
 239                 if (ftype == FILTER_WRITE) {
 240                         /*
 241                          * Read the output from the read end of the output
 242                          * pipe and display it.  Filter_ldisplay closes ofp.
 243                          */
 244                         if (filter_ldisplay(sp, ofp))
 245                                 rval = 1;
 246                 } else {
 247                         /*
 248                          * Read the output from the read end of the output
 249                          * pipe.  Ex_readfp appends to the MARK and closes
 250                          * ofp.
 251                          */
 252                         if (ex_readfp(sp, "filter", ofp, tm, &nread, 1))
 253                                 rval = 1;
 254                         sp->rptlines[L_ADDED] += nread;
 255                 }
 256
 257                 /* Wait for the parent-writer. */
 258                 if (proc_wait(sp,
 259                     (long)parent_writer_pid, "parent-writer", 0, 1))
 260                         rval = 1;
 261
 262                 /* Delete any lines written to the utility. */
 263                 if (rval == 0 && ftype == FILTER_BANG &&
 264                     (cut(sp, NULL, fm, tm, CUT_LINEMODE) ||
 265                     del(sp, fm, tm, 1))) {
 266                         rval = 1;
 267                         break;
 268                 }
 269
 270                 /*
 271                  * If the filter had no output, we may have just deleted
 272                  * the cursor.  Don't do any real error correction, we'll
 273                  * try and recover later.
 274                  */
 275                  if (rp->lno > 1 && !db_exist(sp, rp->lno))
 276                         --rp->lno;
 277                 break;
 278         }
 279         F_CLR(sp->ep, F_MULTILOCK);
 280
 281         /*
 282          * !!!
 283          * Ignore errors on vi file reads, to make reads prettier.  It's
 284          * completely inconsistent, and historic practice.
 285          */
 286 uwait:  INT2CHAR(sp, cmd, STRLEN(cmd) + 1, np, nlen);
 287         return (proc_wait(sp, (long)utility_pid, np,
 288             ftype == FILTER_READ && F_ISSET(sp, SC_VI) ? 1 : 0, 0) || rval);
 289 }
 290
 291 /*
 292  * filter_ldisplay --
 293  *      Display output from a utility.
 294  *
 295  * !!!
 296  * Historically, the characters were passed unmodified to the terminal.
 297  * We use the ex print routines to make sure they're printable.
 298  */
 299 static int
 300 filter_ldisplay(SCR *sp, FILE *fp)
 301 {
 302         size_t len;
 303         size_t wlen;
 304         CHAR_T *wp;
 305
 306         EX_PRIVATE *exp;
 307
 308         for (exp = EXP(sp); !ex_getline(sp, fp, &len) && !INTERRUPTED(sp);) {
 309                 FILE2INT5(sp, exp->ibcw, exp->ibp, len, wp, wlen);
 310                 if (ex_ldisplay(sp, wp, wlen, 0, 0))
 311                         break;
 312         }
 313         if (ferror(fp))
 314                 msgq(sp, M_SYSERR, "filter read");
 315         (void)fclose(fp);
 316         return (0);
 317 }