164 lines
3.5 KiB
C
164 lines
3.5 KiB
C
/* head - copy first part of files. */
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/* See Makefile for compilation details. */
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/*
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Copyright (C) 1999-2009 Free Software Foundation, Inc.
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This file is part of GNU Bash.
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Bash 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 3 of the License, or
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(at your option) any later version.
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Bash 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 Bash. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "config.h"
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#include "bashtypes.h"
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#include "posixstat.h"
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#include "filecntl.h"
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#if defined (HAVE_UNISTD_H)
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# include <unistd.h>
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#endif
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#include "bashansi.h"
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#include <stdio.h>
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#include <errno.h>
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#include "chartypes.h"
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#include "builtins.h"
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#include "shell.h"
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#include "bashgetopt.h"
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#include "common.h"
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#if !defined (errno)
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extern int errno;
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#endif
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static void
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munge_list (list)
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WORD_LIST *list;
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{
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WORD_LIST *l, *nl;
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WORD_DESC *wd;
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char *arg;
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for (l = list; l; l = l->next)
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{
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arg = l->word->word;
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if (arg[0] != '-' || arg[1] == '-' || (DIGIT(arg[1]) == 0))
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return;
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/* We have -[0-9]* */
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wd = make_bare_word (arg+1);
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nl = make_word_list (wd, l->next);
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l->word->word[1] = 'n';
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l->word->word[2] = '\0';
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l->next = nl;
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l = nl; /* skip over new argument */
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}
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}
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static int
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file_head (fp, cnt)
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FILE *fp;
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int cnt;
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{
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int ch;
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while (cnt--)
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{
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while ((ch = getc (fp)) != EOF)
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{
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if (putchar (ch) == EOF)
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{
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builtin_error ("write error: %s", strerror (errno));
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return EXECUTION_FAILURE;
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}
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if (ch == '\n')
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break;
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}
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}
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}
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head_builtin (list)
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WORD_LIST *list;
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{
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int nline, opt, rval;
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WORD_LIST *l;
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FILE *fp;
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char *t;
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munge_list (list); /* change -num into -n num */
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reset_internal_getopt ();
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nline = 10;
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while ((opt = internal_getopt (list, "n:")) != -1)
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{
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switch (opt)
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{
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case 'n':
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nline = atoi (list_optarg);
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if (nline <= 0)
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{
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builtin_error ("bad line count: %s", list_optarg);
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return (EX_USAGE);
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}
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break;
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default:
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builtin_usage ();
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return (EX_USAGE);
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}
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}
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list = loptend;
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if (list == 0)
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return (file_head (stdin, nline));
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for (rval = EXECUTION_SUCCESS, opt = 1, l = list; l; l = l->next)
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{
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fp = fopen (l->word->word, "r");
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if (fp == NULL)
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{
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builtin_error ("%s: %s", l->word->word, strerror (errno));
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continue;
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}
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if (list->next) /* more than one file */
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{
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printf ("%s==> %s <==\n", opt ? "" : "\n", l->word->word);
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opt = 0;
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}
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rval = file_head (fp, nline);
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fclose (fp);
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}
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return (rval);
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}
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char *head_doc[] = {
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"Display lines from beginning of file.",
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"",
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"Copy the first N lines from the input files to the standard output.",
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"N is supplied as an argument to the `-n' option. If N is not given,",
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"the first ten lines are copied.",
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(char *)NULL
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};
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struct builtin head_struct = {
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"head", /* builtin name */
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head_builtin, /* function implementing the builtin */
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BUILTIN_ENABLED, /* initial flags for builtin */
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head_doc, /* array of long documentation strings. */
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"head [-n num] [file ...]", /* usage synopsis; becomes short_doc */
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0 /* reserved for internal use */
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};
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