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/*
 * sort.c
 *
 * Written by Adam Bryant as a replacement for 'sort'
 * for use with the conquer program.  Note that it
 * is initially written with this program in mind and
 * will not have many features useful elsewhere.
 *
 * INITIAL FORMAT USES [YIELDS SAME RESULTS]:
 *
 *   standard in to standard out:
 *          'cat foo | conqsort > foonew'
 *   file input to standard output:
 *          'conqsort foo > foonew'
 *   file input to file output:
 *          'conqsort foo foonew'
 *
 * OR MAY EVEN OVERWRITE INITIAL FILE VIA:
 *
 *          'conqsort infoo infoo'
 *
 * Design Notes:
 *   - all of the file will have to be placed into memory;
 *   - to allow for any line length, space will be malloced()
 *      as it comes in.
 *
 * Initial Revision:		(adb@bucsf.bu.edu)
 *     Tuesday March 21th, 1989 - Began the program at 23:26 EST
 *     Wednesday March 22nd, 1989 - Finished the initial version 11:29 EST
 *     Wednesday July 5th, 1989 - Stopped use of sysexits.h 7:22 EST
 */

#include <stdio.h>
#include <ctype.h>

/* system definitions just in case */
#ifndef FALSE
#define FALSE (0)
#define TRUE  (1)
#endif /* FALSE */

/* system exit definitions from sysexits.h on BSD machines */
#ifndef EX_OK
#define EX_OK             0   /* successful termination */
#define EX_USAGE          64  /* invalid command line format */
#define EX_NOINPUT        66  /* could not open input file */
#define EX_SOFTWARE       70  /* software error; couldn't malloc */
#define EX_CANTCREAT      73  /* could not create output file */
#endif /* EX_OK */

/* number of characters to compare by default */
#define DEFAULT_COMP 2
#define MAX_STR      200

/* structure for holding a line of information */
typedef struct holder {
	char *line;
	struct holder *next;
} L_DATA, *L_PTR;

/* pointer to head of list of lines */
L_PTR head;

/* usage string */
static char usage[]="Usage: %s [-num -h] [infile] [outfile]\n\
	-h		display this screen\n\
	-i		treat upper and lower case characters as equivalent\n\
	-num		Sort on first num characters\n";

/* number of characters for comparison */
int compnum=DEFAULT_COMP;

/* flag for folding upper and lowercase characters */
int iflag=FALSE;

/* file pointers to infile and outfile */
FILE *infile=stdin, *outfile=stdout;

/* macros */
#define UPPER(x) ((islower(x))?(toupper(x)):(x))

int
main(argc, argv)
	int argc;
	char *argv[];
{
	/* declare temporary variables and functions */
	int i,j,num_args=0,l,innum=0,outnum=0;
	FILE *fopen();
	int get_line();
	void place(), send_out();

	/* input string */
	char data[MAX_STR];

	/* parse command line arguments */
	for (i=1; i<argc; i++) {

		/* process non-switch statements */
		if (argv[i][0]!='-') {
			num_args++;
			switch(num_args) {
			   case 1:
				/* do not open unless arguments are valid */
				innum=i;
				break;
			   case 2:
				/* do not open unless arguments are valid */
				outnum=i;
				break;
			   default:
				fprintf(stderr,"%s: Too many parameters\n",argv[0]);
				fprintf(stderr,usage,argv[0]);
				exit(EX_USAGE);
				break;
			}
			continue;
		}

		/* process switch statements */
		l = strlen(argv[i]);
		for (j=1; j<l; j++) {
			switch(argv[i][j]) {
			   case 'h':
				fprintf(stderr,usage,argv[0]);
				exit(EX_OK);
				break;
			   case 'i':
				iflag=TRUE;
				break;
			   case '0':
			   case '1':
			   case '2':
			   case '3':
			   case '4':
			   case '5':
			   case '6':
			   case '7':
			   case '8':
			   case '9':
				/* assign new comparison number */
				compnum=0;
				for(;j<l && argv[i][j]>='0' && argv[i][j]<='9';j++)
				{
					compnum *= 10;
					compnum += argv[i][j]-'0';
				}
				/* compensate for increment on exit */
				j--;
				break;
			   default:
				fprintf(stderr,"%s: invalid option '%c' in <%s>\n",
					   argv[0],argv[i][j],argv[i]);
				fprintf(stderr,usage,argv[0]);
				exit(EX_USAGE);
				break;
			}
		}
	}

	/* open input file now */
	if(innum!=0) {
		if((infile=fopen(argv[innum],"r"))==(FILE *)NULL) {
			fprintf(stderr,"%s: can't open file <%s> for input\n",
				   argv[0],argv[innum]);
			exit(EX_NOINPUT);
		}
	}

	/* ======= main processing loop ======== */

	while(!feof(infile)) {

		/* remove any lines less than sort characters */
		if (get_line(data)>compnum) {
			place(data);
		}

	}

	/* ==== end of main processing loop ==== */

	/* close input file if not stdin */
	if (infile!=stdin) {
		(void) fclose(infile);
	}

	/* open output file now */
	if(outnum!=0) {
		if ((outfile=fopen(argv[outnum],"w"))==(FILE *)NULL) {
			fprintf(stderr,"%s: cannot open file <%s> for output\n",
				   argv[0],argv[outnum]);
			exit(EX_CANTCREAT);
		}
	}

	send_out();

	/* close output file if not stdout */
	if (outfile!=stdout) {
		(void) fclose(outfile);
	}

	exit(EX_OK);
}

/* routine to read all characters in until carriage returns */
int
get_line(data)
	char data[];
{
	int in,ch;

	/* discard exceptionally long lines */
	for(in=0;!feof(infile)&&(in<MAX_STR-1)&&((ch=getc(infile))!='\n');)
	{
		/* copy valid input into data */
		if((ch=='\t')||(ch==' ')||((ch>=' ')&&(ch<='~'))) {
			data[in]=ch;
			in++;
		}
	}
	/* end string */
	data[in]='\0';

	return(in);
}

/* routine to output entire sorted file to outfile */
void
send_out()
{
	L_PTR temp=head;

	while (temp!=(L_PTR)NULL) {
		fprintf(outfile,"%s\n",temp->line);
		temp = temp->next;
	}
}

/* routine to sort list as it comes in */
void
place(data)
	char data[];
{
	L_PTR temp, build_node();
	int comp_line();

	/* find location for placing input */
	if(head==(L_PTR)NULL) {
		/* begin list properly */
		head = build_node(data,(L_PTR)NULL);
	} else if (comp_line(head->line,data)==1) {
		/* add to beginning of list */
		head = build_node(data,head);
	} else {
		/* otherwise add in proper position */
		temp=head;
		while ((temp->next!=(L_PTR)NULL)
		&&(comp_line(temp->next->line,data)!=1)) {
			temp=temp->next;
		}
		temp->next = build_node(data,temp->next);
	}
}

/* routine to compare two lines through N characters */
/* where N is given by the variable compnum          */
/*    returns:  0 on equal                           */
/*             -1 on a preceding b                   */
/*              1 on a following b                   */
int
comp_line(a,b)
	char *a,*b;
{
	int i;

	for(i=0;i<compnum;i++) {
		/* do checks */
		if (iflag) {
			if (UPPER(a[i])<UPPER(b[i])) return(-1);
			if (UPPER(b[i])<UPPER(a[i])) return(1);
		} else {
			if (a[i]<b[i]) return(-1);
			if (b[i]<a[i]) return(1);
		}
		if (a[i]=='\0') return(0);
	}
	return(0);
}

/* create L_DATA structure containing a line of data */
/* and the next value set to the given location      */
L_PTR
build_node(data, nptr)
	char data[];
	L_PTR nptr;
{
	L_PTR temp;
	char *strcpy();

	/* build the memory space */
	if((temp=(L_PTR)malloc(sizeof(L_DATA)))==(L_PTR)NULL) {
		fprintf(stderr,"Error in creating structure memory!\n");
		exit(EX_SOFTWARE);
	}
	if((temp->line=(char *)malloc((strlen(data)+1)*sizeof(char)))==NULL) {
		fprintf(stderr,"Error in creating data memory!\n");
		exit(EX_SOFTWARE);
	}

	/* assign the values */
	(void) strcpy(temp->line,data);
	temp->next = nptr;
	return(temp);
}
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