153 lines
3.3 KiB
C
153 lines
3.3 KiB
C
#include <ctype.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "args.h"
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#include "libcharin.h"
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#include "libstris.h"
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#define DEFAULT_LENGTH 10
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#define OFLOW(STR) (STR[strlen(STR)-1] != '\n')
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#ifndef PAGE_SIZE
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# ifndef PAGESIZE
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# define PAGE_SIZE 1024
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# else
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# define PAGE_SIZE PAGESIZE
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# endif
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#endif
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/*
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TODO
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* fix limits.h stuff; if limits.h isn't on the system define
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reasonable limits in its place
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* don't use unsafe string functions
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* fix bugs
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*/
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void
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tail(FILE *input, FILE *output, int length){
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bool loop = 1;
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char *lines[length];
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size_t ls[length];
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int i;
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int filelines = 0;
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size_t offset = 0;
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for(i = 0; i < length; i++){
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ls[i] = PAGE_SIZE;
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lines[i] = (char *)calloc(ls[i], sizeof(char));
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}
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i = 0;
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while(fgets(lines[i] + offset, ls[i], input)){
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if(OFLOW(lines[i])){
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offset += ls[i] - 1;
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ls[i] += PAGE_SIZE;
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/* should be more resilient */
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if(realloc(lines[i], ls[i]) == NULL){
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fprintf(stderr, "tail: Couldn't re-allocate memory (%d bytes)\n", ls[i] * sizeof(char));
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exit(1);
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}
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continue;
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}
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offset = 0;
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++filelines;
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i = (i + 1) % length;
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}
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for(i = filelines % length; loop || i != filelines % length; i = (i + 1) % length){
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if(loop && i == filelines % length)
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loop = 0;
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printf("%s", lines[i]);
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}
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/* glitch here when `tail`ing normal files */
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for(i = 0; i < length; i++){
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free(lines[i]);
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}
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return;
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}
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void
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usage(char *name){
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fprintf(stderr, "Usage: %s [-ht] [-n integer] [file...]\n", name);
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exit(1);
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}
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int
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main(int argc, char *argv[]){
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char **argsv = getargsv(argc, argv);
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char *flags = getflags(argc, argv);
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char mode[3] = "rb";
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char filepath[NAME_MAX+PATH_MAX];
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char *lengthstr;
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size_t fplen = NAME_MAX+PATH_MAX;
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FILE *input;
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FILE *output = stdout;
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int argsc = getargsc(argc, argv);
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int i;
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int length = DEFAULT_LENGTH;
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size_t s;
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if(charin(flags, 'h'))
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usage(argv[0]);
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if(charin(flags, 'n')){
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lengthstr = getflag(argc, argv, 'n');
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if(!strisint(lengthstr) || *lengthstr == '\0')
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usage(argv[0]);
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else
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length = atoi(lengthstr);
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}
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if(charin(flags, 't'))
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/* Explicitly open files as text rather than as binary.
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* this changes "rb" to "r". Should have no effect on
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* POSIX systems but may change CRLF to just LF with
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* MS Windows. I don't know why anyone would need this
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* but it's here for those that do. */
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mode[1] = '\0';
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if(argsc == 0)
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tail(stdin, output, length);
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else
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for(i = 1; i < argsc; ++i){
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if(i > 1)
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fprintf(output, "\n");
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if(!strcmp(argv[i], "-")){
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realpath(argv[i], filepath);
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input = fopen(argv[i], "r");
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if(input == NULL){
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fprintf(stderr, "%s: %s: Could not open file for reading\n", argv[0], filepath);
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exit(1);
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}
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}else{
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input = stdin;
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/* probably safe but could be vulnerable */
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/* just making filepath[] = "<stdin>" */
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s = strlen("<stdin>") + 1; /* minimum size for filepath */
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if(fplen >= s)
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strcpy(filepath, "<stdin>");
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else if(realloc(filepath, s) == NULL)
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fprintf(stderr, "%s: Failed to reallocate path string, using <stdin>\n", argv[0]);
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}
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fprintf(output, "==> %s <==\n", filepath);
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tail(input, output, length);
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if(input != stdin && fclose(input) != 0){
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fprintf(stderr, "%s: %s: Could not close file. Exiting...\n", argv[0], filepath);
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exit(1);
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}
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}
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return 0;
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}
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