123 lines
1.8 KiB
C
123 lines
1.8 KiB
C
#include <stdio.h>
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#include <errno.h>
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#include <string.h>
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#include <unistd.h>
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#include <stdlib.h>
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char s_flag;
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int compare(FILE *fp1, FILE *fp2) {
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if (fp1 == fp2)
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return 0;
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int ch1;
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int ch2;
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size_t byte = 0;
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do {
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ch1 = getc(fp1);
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ch2 = getc(fp2);
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if (ch1 != ch2) {
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if (!s_flag)
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printf("files differ at byte %zu\n", byte);
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return 1;
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}
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byte++;
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} while(ch1 != EOF);
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return 0;
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}
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long parse_int(const char *str) {
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char *ptr;
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long val = strtol(str, &ptr, 0);
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if (*ptr || val < 0) {
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fprintf(stderr, "cmp: invalid offset: %s\n", str);
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exit(1);
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}
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return val;
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}
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FILE *file_open(const char *path) {
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if (!strcmp(path, "-"))
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return stdin;
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FILE *fp = fopen(path, "r");
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if (fp == NULL) {
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fprintf(stderr, "cmp: %s\n", strerror(errno));
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exit(1);
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}
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return fp;
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}
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int main(int argc, char **argv) {
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int opt;
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while ((opt = getopt(argc, argv, "s")) != -1) {
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switch (opt) {
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case 's':
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s_flag = 1;
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break;
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default:
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printf("cmp [s] [file1] [file2] [skip1] [skip2]\n\t-s Silent\n");
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return 0;
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}
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}
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argv += optind;
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argc -= optind;
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long skip1 = 0;
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long skip2 = 0;
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FILE *fp1 = NULL;
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FILE *fp2 = stdin;
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switch (argc) {
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case 4:
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skip2 = parse_int(argv[3]);
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/* fallthrough */
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case 3:
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skip1 = parse_int(argv[2]);
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/* fallthrough */
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case 2:
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fp2 = file_open(argv[1]);
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/* fallthrough */
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case 1:
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fp1 = file_open(argv[0]);
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break;
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default:
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fprintf(stderr, "cmp: missing operand\n");
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return 1;
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}
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if (skip1 && fseek(fp1, skip1, SEEK_SET) < 0) {
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if (!s_flag)
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fprintf(stderr, "cmp: %s\n", strerror(errno));
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return 1;
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}
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if (skip2 && fseek(fp2, skip2, SEEK_SET) < 0) {
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if (!s_flag)
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fprintf(stderr, "cmp: %s\n", strerror(errno));
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return 1;
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}
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int ret = compare(fp1, fp2);
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fclose(fp1);
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fclose(fp2);
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return ret;
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}
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