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Diffstat (limited to 'examples/loadables/head.c')
| -rw-r--r-- | examples/loadables/head.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/examples/loadables/head.c b/examples/loadables/head.c new file mode 100644 index 0000000..f9f022a --- /dev/null +++ b/examples/loadables/head.c @@ -0,0 +1,170 @@ +/* head - copy first part of files. */ + +/* See Makefile for compilation details. */ + +/* + Copyright (C) 1999-2009 Free Software Foundation, Inc. + + This file is part of GNU Bash. + Bash is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + Bash is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with Bash. If not, see <http://www.gnu.org/licenses/>. +*/ + +#include "config.h" + +#include "bashtypes.h" +#include "posixstat.h" +#include "filecntl.h" + +#if defined (HAVE_UNISTD_H) +# include <unistd.h> +#endif + +#include "bashansi.h" + +#include <stdio.h> +#include <errno.h> +#include "chartypes.h" + +#include "builtins.h" +#include "shell.h" +#include "bashgetopt.h" +#include "common.h" + +#if !defined (errno) +extern int errno; +#endif + +static void +munge_list (list) + WORD_LIST *list; +{ + WORD_LIST *l, *nl; + WORD_DESC *wd; + char *arg; + + for (l = list; l; l = l->next) + { + arg = l->word->word; + if (arg[0] != '-' || arg[1] == '-' || (DIGIT(arg[1]) == 0)) + return; + /* We have -[0-9]* */ + wd = make_bare_word (arg+1); + nl = make_word_list (wd, l->next); + l->word->word[1] = 'n'; + l->word->word[2] = '\0'; + l->next = nl; + l = nl; /* skip over new argument */ + } +} + +static int +file_head (fp, cnt) + FILE *fp; + int cnt; +{ + int ch; + + while (cnt--) + { + while ((ch = getc (fp)) != EOF) + { + QUIT; + if (putchar (ch) == EOF) + { + builtin_error ("write error: %s", strerror (errno)); + return EXECUTION_FAILURE; + } + QUIT; + if (ch == '\n') + break; + } + } + return (EXECUTION_SUCCESS); +} + +int +head_builtin (list) + WORD_LIST *list; +{ + int nline, opt, rval; + WORD_LIST *l; + FILE *fp; + + char *t; + + munge_list (list); /* change -num into -n num */ + + reset_internal_getopt (); + nline = 10; + while ((opt = internal_getopt (list, "n:")) != -1) + { + switch (opt) + { + case 'n': + nline = atoi (list_optarg); + if (nline <= 0) + { + builtin_error ("bad line count: %s", list_optarg); + return (EX_USAGE); + } + break; + CASE_HELPOPT; + default: + builtin_usage (); + return (EX_USAGE); + } + } + list = loptend; + + if (list == 0) + return (file_head (stdin, nline)); + + for (rval = EXECUTION_SUCCESS, opt = 1, l = list; l; l = l->next) + { + fp = fopen (l->word->word, "r"); + if (fp == NULL) + { + builtin_error ("%s: %s", l->word->word, strerror (errno)); + continue; + } + if (list->next) /* more than one file */ + { + printf ("%s==> %s <==\n", opt ? "" : "\n", l->word->word); + opt = 0; + } + QUIT; + rval = file_head (fp, nline); + fclose (fp); + } + + return (rval); +} + +char *head_doc[] = { + "Display lines from beginning of file.", + "", + "Copy the first N lines from the input files to the standard output.", + "N is supplied as an argument to the `-n' option. If N is not given,", + "the first ten lines are copied.", + (char *)NULL +}; + +struct builtin head_struct = { + "head", /* builtin name */ + head_builtin, /* function implementing the builtin */ + BUILTIN_ENABLED, /* initial flags for builtin */ + head_doc, /* array of long documentation strings. */ + "head [-n num] [file ...]", /* usage synopsis; becomes short_doc */ + 0 /* reserved for internal use */ +}; |