104 lines
2.6 KiB
C
104 lines
2.6 KiB
C
#include <assert.h>
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#include <stdio.h>
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#include <ctype.h>
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char rot_char(char c, int amt) {
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if (c >= 'A' && c <= 'Z')
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return 'A' + ((c - 'A') + amt) % 26;
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else if (c >= 'a' && c <= 'z')
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return 'a' + ((c - 'a') + amt) % 26;
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else
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return c;
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}
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void transform(char *in_buf, char *out_buf, int out_size) {
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char *p = in_buf;
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char *bp = out_buf;
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char *buflim = &out_buf[out_size - 8];
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char c;
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int in_ul, last_ul, rot_amt, skipping;
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int brack_lvl, brace_lvl;
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in_ul = brack_lvl = brace_lvl = last_ul = rot_amt = skipping = 0;
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while ((c = *p++) != '\0') {
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if (brack_lvl > 0)
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c = toupper(c);
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c = rot_char(c, rot_amt);
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if (c == '/')
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in_ul = !in_ul;
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skipping = (bp >= buflim);
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if ((unsigned)c - (unsigned)'[' < 3u && c != '\\') {
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int i = (c & 2) ? 1 : -1;
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if (brack_lvl + i >= 0 && !skipping) {
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brack_lvl += i;
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buflim -= i;
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}
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}
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if (c == '{') {
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if (!skipping) {
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brace_lvl++;
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}
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rot_amt += 13;
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if (rot_amt == 26) {
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rot_amt = 0;
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buflim -= 2;
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}
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}
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if (c == '}' && brace_lvl > 0) {
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if (!skipping) {
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brace_lvl--;
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buflim++;
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}
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rot_amt -= 13;
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if (rot_amt < 0)
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rot_amt = 0;
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}
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if (in_ul && isalpha(c) && !last_ul && !skipping)
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*bp++ = '_';
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if (c != '/' && !skipping)
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*bp++ = c;
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if (in_ul && isalpha(c)) {
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if (!skipping)
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*bp++ = '_';
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last_ul = 1;
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} else {
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last_ul = 0;
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}
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}
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while (brack_lvl-- > 0)
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*bp++ = ']';
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while (brace_lvl-- > 0)
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*bp++ = '}';
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*bp++ = ' ';
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*bp++ = 'e';
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*bp++ = 'n';
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*bp++ = 'd';
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*bp++ = '\0';
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}
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int main(int argc, char **argv) {
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char buf[64];
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if (argc != 2) {
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fprintf(stderr, "Usage: transform <string>\n");
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fprintf(stderr, "You should probably use quotes around the string.\n");
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return 1;
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}
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printf("%s\n", argv[1]);
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buf[20] = '\242';
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transform(argv[1], buf, 20);
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printf("%s\n", buf);
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/* This canary-like check isn't foolproof, and it isn't the point
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of the exercise, but for testing purposes it makes it easy to
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see that an overflow has happened. */
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if (buf[20] != '\242')
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fprintf(stderr, "Overflow detected\n");
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return 0;
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}
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