141 lines
3.1 KiB
C
141 lines
3.1 KiB
C
#include <stdio.h> // fprintf, stdout, stderr.
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#include <stdlib.h> // exit, EXIT_FAILURE, EXIT_SUCCESS.
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#include <string.h> // strerror.
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#include <errno.h> // errno.
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#include <stdbool.h>
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enum FileType{ASCII, ISO, UTF, data};
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bool is_utf8(FILE* f) {
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rewind(f);
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unsigned char byte;
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int char_length = -1;
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for (;;) {
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if (fread(&byte, 1, 1, f) == 0) {
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break;
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}
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if (byte == 0){
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return false;
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}
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for (int j = 0 ; j <= 8 ; j++) {
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if (byte >> 7 == 0) {
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char_length = j;
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break;
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}
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byte = byte << 1;
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}
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if (char_length == -1) {
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return false;
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}
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for (int i = 1 ; i < char_length ; i++) {
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if (fread(&byte, 1, 1, f) == 0 || byte >> 6 != 2) {
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return false;
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}
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}
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}
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return true;
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}
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bool is_iso8859(FILE* f) {
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rewind(f);
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int iso8859_CHARACTERS[197];
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for (int i = 0 ; i < 7 ; i++) {
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iso8859_CHARACTERS[i] = i+7;
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}
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iso8859_CHARACTERS[7] = 27;
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for (int i = 0 ; i < 94 ; i++) {
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iso8859_CHARACTERS[i+8] = i+32;
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}
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for (int i = 0 ; i < 95 ; i++) {
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iso8859_CHARACTERS[i+102] = i+160;
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}
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unsigned char byte;
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bool iso_byte;
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for (;;) {
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if (fread(&byte, 1, 1, f) == 0) {
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break;
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}
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iso_byte = false;
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for (int i = 0 ; i < 197 ; i++) {
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if (byte == iso8859_CHARACTERS[i]) {
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iso_byte = true;
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break;
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}
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}
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if (! iso_byte) {
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return false;
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}
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}
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return true;
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}
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bool is_ascii(FILE* f) {
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rewind(f);
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int ASCII_CHARACTERS[102];
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for (int i = 0 ; i < 7 ; i++) {
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ASCII_CHARACTERS[i] = i+7;
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}
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ASCII_CHARACTERS[7] = 27;
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for (int i = 0 ; i < 94 ; i++) {
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ASCII_CHARACTERS[i+8] = i+32;
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}
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unsigned char byte;
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bool ascii_byte;
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for (;;) {
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if (fread(&byte, 1, 1, f) == 0) {
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break;
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}
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ascii_byte = false;
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for (int i = 0 ; i < 102 ; i++) {
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if (byte == ASCII_CHARACTERS[i]) {
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ascii_byte = true;
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break;
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}
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}
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if (! ascii_byte) {
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return false;
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}
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}
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return true;
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}
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int print_error(char* path, int errnum) {
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return fprintf(stderr, "%s: cannot determine (%s)\n", path, strerror(errnum));
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}
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int main(int argc, char* argv[]) {
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if (argc != 2) {
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printf("Wrong number of arguments!\n");
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return EXIT_FAILURE;
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}
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FILE* f = fopen(argv[1], "r");
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if (f == NULL) {
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print_error(argv[2], errno);
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}
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char byte;
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if (fread(&byte, sizeof(char), 1, f) == 0) {
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fprintf(stdout, "%s: empty\n", argv[1]);
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} else if (is_ascii(f)) {
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fprintf(stdout, "%s: ASCII text\n", argv[1]);
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} else if (is_iso8859(f)) {
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fprintf(stdout, "%s: ISO-8859 text\n", argv[1]);
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} else if (is_utf8(f)) {
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fprintf(stdout, "%s: UTF-8 Unicode text\n", argv[1]);
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} else {
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fprintf(stdout, "%s: data\n", argv[1]);
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}
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fclose(f);
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return EXIT_SUCCESS;
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}
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