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