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97 lines
2.3 KiB
C
97 lines
2.3 KiB
C
/* Open a pipe to read from a program without intermediary sh.
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Copyright (C) 1992, 1997 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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/* Written by David MacKenzie. */
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <stdio.h>
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#if __STDC__
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#include <stdarg.h>
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#else
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#include <varargs.h>
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#endif
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#if HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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/* Open a pipe to read from a program without intermediary sh. Checks
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PATH. Sample use:
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stream = readpipe ("progname", "arg1", "arg2", (char *) 0);
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Return 0 on error. */
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#if __STDC__
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FILE *
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readpipe (char *progname, ...)
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#else
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FILE *
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readpipe (va_alist)
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#endif
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{
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#if ! __STDC__
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char *progname;
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#endif
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int fds[2];
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va_list ap;
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char *args[100];
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int argno = 0;
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/* Copy arguments into `args'. */
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#if __STDC__
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va_start (ap, progname);
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#else
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va_start (ap);
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progname = va_arg (ap, char *);
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#endif
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args[argno++] = progname;
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while ((args[argno++] = va_arg (ap, char *)) != NULL)
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;
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va_end (ap);
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if (pipe (fds) == -1)
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return 0;
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switch (fork ())
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{
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case 0: /* Child. Write to pipe. */
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close (fds[0]); /* Not needed. */
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if (fds[1] != 1) /* Redirect 1 (stdout) only if needed. */
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{
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close (1); /* We don't want the old stdout. */
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if (dup (fds[1]) == 0)/* Maybe stdin was closed. */
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{
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dup (fds[1]); /* Guaranteed to dup to 1 (stdout). */
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close (0);
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}
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close (fds[1]); /* No longer needed. */
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}
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execvp (args[0], args);
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_exit (2); /* 2 for `cmp'. */
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case -1: /* Error. */
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return 0;
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default: /* Parent. Read from pipe. */
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close (fds[1]); /* Not needed. */
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return fdopen (fds[0], "r");
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}
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}
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