cut.c

操作系统源代码

/* cut - extract columns from a file or stdin. 	Author: Michael J. Holme
 *
 *	Copyright 1989, Michael John Holme, All rights reserved.
 *	This code may be freely distributed, provided that this notice
 *	remains intact.
 *
 *	V1.1: 6th September 1989
 *
 *	Bugs, criticisms, etc,
 *      c/o Mark Powell
 *          JANET [e-mail]
 *          ARPA  [e-mail]
 *          UUCP  ...!mcvax!ukc!liv.ac.uk!sq79
 *-------------------------------------------------------------------------
 *	Changed for POSIX1003.2/Draft10 conformance
 *	Thomas Brupbacher ([e-mail]), September 1990.
 *	Changes:
 *	    - separation of error messages ( stderr) and output (stdout).
 *	    - support for -b and -n (no effect, -b acts as -c)
 *	    - support for -s
 *-------------------------------------------------------------------------
 */

#include <sys/types.h>
#include <ctype.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>

#define MAX_FIELD	80	/* Pointers to the beginning of each field
			 * are stored in columns[], if a line holds
			 * more than MAX_FIELD columns the array
			 * boundary is exceed. But unlikely at 80 */

#define MAX_ARGS	32	/* Maximum number of fields following -f or
			 * -c switches												  	  */
int args[MAX_ARGS * 2];
int num_args;

/* Lots of new defines, should easen maintainance...			*/
#define DUMP_STDIN	0	/* define for mode: no options	 */
#define OPTIONF		1	/* define for mode: option -f 	 */
#define OPTIONC		2	/* define for mode: option -c	 */
#define OPTIONB		3	/* define for mode: option -b	 */
#define NOTSET		0	/* option not selected		 */
#define SET		1	/* option selected		 */

/* Defines for the warnings						*/
#define DELIMITER_NOT_APPLICABLE	0
#define OVERRIDING_PREVIOUS_MODE	1
#define OPTION_NOT_APPLICABLE		2
#define UNKNOWN_OPTION			3
#define FILE_NOT_READABLE		4

/* Defines for the fatal errors						*/
#define SYNTAX_ERROR			101
#define POSITION_ERROR			102
#define USAGE				103
#define LINE_TO_LONG_ERROR		104
#define RANGE_ERROR			105
#define MAX_FIELDS_EXEEDED_ERROR	106
#define MAX_ARGS_EXEEDED_ERROR		107


int mode;			/* 0 = dump stdin to stdout, 1=-f, 2=-c   */
int flag_i;			/* SET = -i set on command line	 */
int flag_s;			/* SET = -s set on command line	 */
char delim = '\t';		/* default delimiting character	  */
FILE *fd;
char *name;
char line[BUFSIZ];
int exit_status;

_PROTOTYPE(int main, (int argc, char **argv));
_PROTOTYPE(void warn, (int warn_number, char *option));
_PROTOTYPE(void cuterror, (int err));
_PROTOTYPE(void get_args, (void));
_PROTOTYPE(void cut, (void));

void warn(warn_number, option)
int warn_number;
char *option;
{
  static char *warn_msg[] = {
			   "%s: Option -d allowed only with -f\n",
			   "%s: -%s overrides earlier option\n",
			   "%s: -%s not allowed in current mode\n",
			   "%s: Cannot open %s\n"
  };

  fprintf(stderr, warn_msg[warn_number], name, option);
  exit_status = warn_number + 1;

}

void cuterror(err)
int err;
{
  static char *err_mes[] = {
			  "%s: syntax error\n",
			  "%s: position must be >0\n",
  "%s: usage: cut [-f args [-i] [-d x]]|[-c args] [filename [...]]\n",
			  "%s: line longer than BUFSIZ\n",
		 "%s: range must not decrease from left to right\n",
			  "%s: MAX_FIELD exceeded\n",
			  "%s: MAX_ARGS exceeded\n"
  };

  fprintf(stderr, err_mes[err - 101], name);
  exit(err);
}


void get_args()
{
  int i = 0;
  int arg_ptr = 0;
  int flag;

  num_args = 0;
  do {
	if (num_args == MAX_ARGS) cuterror(MAX_ARGS_EXEEDED_ERROR);
	if (!isdigit(line[i]) && line[i] != '-') cuterror(SYNTAX_ERROR);

	args[arg_ptr] = 1;
	args[arg_ptr + 1] = BUFSIZ;
	flag = 1;

	while (line[i] != ',' && line[i] != 0) {
		if (isdigit(line[i])) {
			args[arg_ptr] = 0;
			while (isdigit(line[i]))
				args[arg_ptr] = 10 * args[arg_ptr] + line[i++] - '0';
			if (!args[arg_ptr]) cuterror(POSITION_ERROR);
			arg_ptr++;
		}
		if (line[i] == '-') {
			arg_ptr |= 1;
			i++;
			flag = 0;
		}
	}
	if (flag && arg_ptr & 1) args[arg_ptr] = args[arg_ptr - 1];
	if (args[num_args * 2] > args[num_args * 2 + 1])
		cuterror(RANGE_ERROR);
	num_args++;
	arg_ptr = num_args * 2;
  }
  while (line[i++]);
}


void cut()
{
  int i, j, length, maxcol;
  char *columns[MAX_FIELD];

  while (fgets(line, BUFSIZ, fd)) {
	length = strlen(line) - 1;
	*(line + length) = 0;
	switch (mode) {
	    case DUMP_STDIN:	printf("%s", line);	break;
	    case OPTIONF:
		maxcol = 0;
		columns[maxcol++] = line;
		for (i = 0; i < length; i++) {
			if (*(line + i) == delim) {
				*(line + i) = 0;
				if (maxcol == MAX_FIELD)
					cuterror(MAX_FIELDS_EXEEDED_ERROR);
				columns[maxcol] = line + i + 1;
				while (*(line + i + 1) == delim && flag_i) {
					columns[maxcol]++;
					i++;
				}
				maxcol++;
			}
		}
		if (maxcol == 1) {
			if (flag_s != SET) printf("%s", line);
		} else {
			for (i = 0; i < num_args; i++) {
				for (j = args[i * 2]; j <= args[i * 2 + 1]; j++)
					if (j <= maxcol) {
						printf("%s", columns[j - 1]);
						if (i != num_args - 1 || j != args[i * 2 + 1])
							putchar(delim);
					}
			}
		}
		break;
	    case OPTIONC:
		for (i = 0; i < num_args; i++) {
			for (j = args[i * 2]; j <= (args[i * 2 + 1] > length ? length :
					      args[i * 2 + 1]); j++)
				putchar(*(line + j - 1));
		}
	}
	if (maxcol == 1 && flag_s == SET);
	else
		putchar('\n');
  }
}


int main(argc, argv)
int argc;
char *argv[];
{
  int i = 1;
  int numberFilenames = 0;
  name = argv[0];

  if (argc == 1) cuterror(USAGE);

  while (i < argc) {
	if (argv[i][0] == '-') {
		switch (argv[i++][1]) {
		    case 'd':
			if (mode == OPTIONC || mode == OPTIONB)
				warn(DELIMITER_NOT_APPLICABLE, "d");
			delim = argv[i++][0];
			break;
		    case 'f':
			sprintf(line, "%s", argv[i++]);
			if (mode == OPTIONC || mode == OPTIONB)
				warn(OVERRIDING_PREVIOUS_MODE, "f");
			mode = OPTIONF;
			break;
		    case 'b':
			sprintf(line, "%s", argv[i++]);
			if (mode == OPTIONF || mode == OPTIONC)
				warn(OVERRIDING_PREVIOUS_MODE, "b");
			mode = OPTIONB;
			break;
		    case 'c':
			sprintf(line, "%s", argv[i++]);
			if (mode == OPTIONF || mode == OPTIONB)
				warn(OVERRIDING_PREVIOUS_MODE, "c");
			mode = OPTIONC;
			break;
		    case 'i':	flag_i = SET;	break;
		    case 's':	flag_s = SET;	break;
		    case '\0':	/* - means: read from stdin		 */
			numberFilenames++;
			break;
		    case 'n':	/* needed for Posix, but no effect here	 */
			if (mode != OPTIONB)
				warn(OPTION_NOT_APPLICABLE, "n");
			break;
		    default:
			warn(UNKNOWN_OPTION, &(argv[i - 1][1]));
		}
	} else {
		i++;
		numberFilenames++;
	}
  }

/* Here follow the checks, if the selected options are reasonable.	*/
  if (mode == OPTIONB)		/* since in Minix char := byte		 */
	mode = OPTIONC;
/* Flag -s is only allowed with -f, otherwise warn and reset flag_s	*/
  if (flag_s == SET && (mode == OPTIONB || mode == OPTIONC)) {
	warn(OPTION_NOT_APPLICABLE, "s");
	flag_s = NOTSET;
  }

/* Flag -i is only allowed with -f, otherwise warn and reset flag_i	*/
  if (flag_i == SET && mode == OPTIONF) {
	warn(OPTION_NOT_APPLICABLE, "s");
	flag_i = NOTSET;
  }
  get_args();
  if (numberFilenames != 0) {
	i = 1;
	while (i < argc) {
		if (argv[i][0] == '-') {
			switch (argv[i][1]) {
			    case 'f':
			    case 'c':
			    case 'b':
			    case 'd':	i += 2;	break;
			    case 'n':
			    case 'i':
			    case 's':	i++;	break;
			    case '\0':
				fd = stdin;
				i++;
				cut();
				break;
			    default:	i++;
			}
		} else {
			if ((fd = fopen(argv[i++], "r")) == NULL) {
				warn(FILE_NOT_READABLE, argv[i - 1]);
			} else {
				cut();
				fclose(fd);
			}
		}
	}
  } else {
	fd = stdin;
	cut();
  }

  return(exit_status);
}