busybox/sort.c

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/*
* Mini sort implementation for busybox
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*
*
* Copyright (C) 1999 by Lineo, inc.
* Written by John Beppu <beppu@lineo.com>
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include "internal.h"
#include <sys/types.h>
#include <fcntl.h>
#include <dirent.h>
#include <stdio.h>
#include <errno.h>
static const char sort_usage[] =
"sort [OPTION]... [FILE]...\n\n"
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;
/* typedefs _______________________________________________________________ */
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/* line node */
typedef struct Line {
char *data; /* line data */
struct Line *next; /* pointer to next line node */
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} Line;
/* singly-linked list of lines */
typedef struct {
int len; /* number of Lines */
Line **sorted; /* array fed to qsort */
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Line *head; /* head of List */
Line *current; /* current Line */
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} List;
/* comparison function */
typedef int (Compare)(const void *, const void *);
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/* methods ________________________________________________________________ */
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static const int max = 1024;
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/* mallocate Line */
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static Line *
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line_alloc()
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{
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Line *self;
self = malloc(1 * sizeof(Line));
return self;
}
/* Initialize Line with string */
static Line *
line_init(Line *self, const char *string)
{
self->data = malloc((strlen(string) + 1) * sizeof(char));
if (self->data == NULL) { return NULL; }
strcpy(self->data, string);
self->next = NULL;
return self;
}
/* Construct Line from FILE* */
static Line *
line_newFromFile(FILE *src)
{
char buffer[max];
Line *self;
if (fgets(buffer, max, src)) {
self = line_alloc();
if (self == NULL) { return NULL; }
line_init(self, buffer);
return self;
}
return NULL;
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}
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/* Line destructor */
static Line *
line_release(Line *self)
{
if (self->data) {
free(self->data);
free(self);
}
return self;
}
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/* Comparison */
/* ascii order */
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static int
compare_ascii(const void *a, const void *b)
{
Line **doh;
Line *x, *y;
doh = (Line **) a;
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x = *doh;
doh = (Line **) b;
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y = *doh;
// fprintf(stdout, "> %p: %s< %p: %s", x, x->data, y, y->data);
return strcmp(x->data, y->data);
}
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/* numeric order */
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static int
compare_numeric(const void *a, const void *b)
{
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Line **doh;
Line *x, *y;
int xint, yint;
doh = (Line **) a;
x = *doh;
doh = (Line **) b;
y = *doh;
xint = strtoul(x->data, NULL, 10);
yint = strtoul(y->data, NULL, 10);
return (xint - yint);
}
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/* List */
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/* */
static List *
list_init(List *self)
{
self->len = 0;
self->sorted = NULL;
self->head = NULL;
self->current = NULL;
return self;
}
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/* for simplicity, the List gains ownership of the line */
static List *
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list_insert(List *self, Line *line)
{
if (line == NULL) { return NULL; }
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/* first insertion */
if (self->head == NULL) {
self->head = line;
self->current = line;
/* all subsequent insertions */
} else {
self->current->next = line;
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self->current = line;
}
self->len++;
return self;
}
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/* order the list according to compare() */
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static List *
list_sort(List *self, Compare *compare)
{
int i;
Line *line;
/* mallocate array of Line*s */
self->sorted = (Line **) malloc(self->len * sizeof(Line*));
if (self->sorted == NULL) { return NULL; }
/* fill array w/ List's contents */
i = 0;
line = self->head;
while (line) {
self->sorted[i++] = line;
line = line->next;
}
/* apply qsort */
qsort(self->sorted, self->len, sizeof(Line*), compare);
return self;
}
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/* precondition: list must be sorted */
static List *
list_writeToFile(List *self, FILE* dst)
{
int i;
Line **line = self->sorted;
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if (self->sorted == NULL) { return NULL; }
for (i = 0; i < self->len; i++) {
fprintf(dst, "%s", line[i]->data);
}
return self;
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}
/* deallocate */
static void
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list_release(List *self)
{
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Line *i;
Line *die;
i = self->head;
while (i) {
die = i;
i = die->next;
line_release(die);
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}
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}
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/*
* I need a list
* to insert lines into
* then I need to sort this list
* and finally print it
*/
int
sort_main(int argc, char **argv)
{
int i;
char opt;
List list;
Line *l;
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Compare *compare;
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/* init */
compare = compare_ascii;
list_init(&list);
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/* parse argv[] */
for (i = 1; i < argc; i++) {
if (argv[i][0] == '-') {
opt = argv[i][1];
switch (opt) {
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case 'g':
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/* what's the diff between -g && -n? */
compare = compare_numeric;
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break;
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case 'h':
usage(sort_usage);
break;
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case 'n':
/* what's the diff between -g && -n? */
compare = compare_numeric;
break;
case 'r':
/* reverse */
break;
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default:
fprintf(stderr, "sort: invalid option -- %c\n", opt);
usage(sort_usage);
}
} else {
break;
}
}
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/* this could be factored better */
/* work w/ stdin */
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if (i >= argc) {
while ( (l = line_newFromFile(stdin))) {
list_insert(&list, l);
}
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list_sort(&list, compare);
list_writeToFile(&list, stdout);
list_release(&list);
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/* work w/ what's left in argv[] */
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} else {
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FILE *src;
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for ( ; i < argc; i++) {
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src = fopen(argv[i], "r");
if (src == NULL) { break; }
while ( (l = line_newFromFile(src))) {
list_insert(&list, l);
}
fclose(src);
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}
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list_sort(&list, compare);
list_writeToFile(&list, stdout);
list_release(&list);
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}
exit(0);
}
/* $Id: sort.c,v 1.9 2000/01/23 18:19:02 erik Exp $ */