/*
    * sdk-diag.c
    * Probes the exact libc/kernel layers the GCC driver depends on:
    * access/stat on the compiler backends, a direct posix_spawn of
    * cc1plus, and BFD-style ar archive reads on /sdk/lib/libc.a
    * (armap, member header at an armap offset, nested second fopen
    * of the same file, member ELF magic). Prints one line per probe.
*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <spawn.h>
#include <sys/wait.h>

#define CC1PLUS "/sdk/libexec/gcc/x86_64-montauk/14.2.0/cc1plus"
#define LIBC_A_DOTS "/sdk/bin/../lib/gcc/x86_64-montauk/14.2.0/../../../libc.a"

static void probe(const char *p) {
    struct stat st;
    int a = access(p, X_OK);
    int s = stat(p, &st);
    printf("%-52s access=%d stat=%d", p, a, s);
    if (s == 0) {
        printf(" mode=%o size=%ld", (unsigned)st.st_mode, (long)st.st_size);
    }
    printf("\n");
}

/* Replay the sequence BFD/ld performs on an ar archive. Each step
   prints ok/FAIL so the first broken layer is visible directly. */
static void ar_probe(const char *path) {
    unsigned char buf[64];
    char hdr[61];
    long armap_size, member_off, member_size, i;

    printf("ar_probe %s\n", path);

    FILE *f = fopen(path, "rb");
    if (f == NULL) { printf("  FAIL fopen\n"); return; }

    /* Global magic */
    if (fread(buf, 1, 8, f) != 8) { printf("  FAIL read magic\n"); fclose(f); return; }
    printf("  magic %s: %.7s\n", memcmp(buf, "!<arch>\n", 8) == 0 ? "ok" : "FAIL", (char *)buf);

    /* Armap ("/") member header at offset 8; size at header offset 48 */
    if (fseek(f, 8, SEEK_SET) != 0 || fread(hdr, 1, 60, f) != 60) {
        printf("  FAIL read armap header\n"); fclose(f); return;
    }
    hdr[60] = '\0';
    armap_size = strtol(hdr + 48, NULL, 10);
    printf("  armap hdr %s: name='%.4s' size=%ld fmag=%s\n",
           hdr[0] == '/' ? "ok" : "FAIL", hdr, armap_size,
           (hdr[58] == 0x60 && hdr[59] == '\n') ? "ok" : "FAIL");

    /* First armap entry: 4-byte BE count, then BE member offsets */
    if (fread(buf, 1, 8, f) != 8) { printf("  FAIL read armap data\n"); fclose(f); return; }
    member_off = ((long)buf[4] << 24) | ((long)buf[5] << 16) | ((long)buf[6] << 8) | (long)buf[7];
    printf("  armap syms=%ld first member offset=%ld\n",
           ((long)buf[0] << 24) | ((long)buf[1] << 16) | ((long)buf[2] << 8) | (long)buf[3],
           member_off);

    /* Member header at the armap offset, via the SAME stream */
    if (fseek(f, member_off, SEEK_SET) != 0 || fread(hdr, 1, 60, f) != 60) {
        printf("  FAIL read member header\n"); fclose(f); return;
    }
    hdr[60] = '\0';
    member_size = strtol(hdr + 48, NULL, 10);
    printf("  member hdr: name='%.16s' size=%ld fmag=%s\n",
           hdr, member_size, (hdr[58] == 0x60 && hdr[59] == '\n') ? "ok" : "FAIL");

    /* Nested second fopen of the same archive (ld does this per member),
       ELF magic read at the member data offset while `f` stays open. */
    FILE *g = fopen(path, "rb");
    if (g == NULL) { printf("  FAIL nested fopen\n"); fclose(f); return; }
    if (fseek(g, member_off + 60, SEEK_SET) != 0 || fread(buf, 1, 16, g) != 16) {
        printf("  FAIL nested read\n"); fclose(g); fclose(f); return;
    }
    printf("  member ELF magic %s:", memcmp(buf, "\177ELF", 4) == 0 ? "ok" : "FAIL");
    for (i = 0; i < 8; i++) printf(" %02x", buf[i]);
    printf("\n");

    /* Whole-member read through the nested stream + checksum */
    {
        unsigned long sum = 0;
        long total = 0;
        if (fseek(g, member_off + 60, SEEK_SET) != 0) { printf("  FAIL re-seek\n"); }
        while (total < member_size) {
            unsigned char chunk[4096];
            long want = member_size - total;
            size_t got;
            if (want > (long)sizeof(chunk)) want = sizeof(chunk);
            got = fread(chunk, 1, (size_t)want, g);
            if (got == 0) break;
            for (i = 0; i < (long)got; i++) sum = sum * 31 + chunk[i];
            total += (long)got;
        }
        printf("  member read %ld/%ld bytes %s (sum=%08lx)\n",
               total, member_size, total == member_size ? "ok" : "FAIL", sum);
    }

    /* Interleave: original stream must still read correctly after the
       nested stream was used (independent positions). */
    if (fseek(f, 0, SEEK_SET) == 0 && fread(buf, 1, 8, f) == 8) {
        printf("  interleaved re-read %s\n", memcmp(buf, "!<arch>\n", 8) == 0 ? "ok" : "FAIL");
    } else {
        printf("  FAIL interleaved re-read\n");
    }

    fclose(g);
    fclose(f);
}

int main(void) {
    probe(CC1PLUS);
    probe("/sdk/libexec/gcc/x86_64-montauk/14.2.0");
    probe("/sdk/libexec/gcc");
    probe("/sdk/bin/as.elf");
    probe("/tmp");
    probe("/sdk/lib/libc.a");
    probe(LIBC_A_DOTS);

    ar_probe("/sdk/lib/libc.a");
    ar_probe(LIBC_A_DOTS);

    pid_t pid = -1;
    char *argv[] = { (char *)"cc1plus", (char *)"--version", 0 };
    int r = posix_spawn(&pid, CC1PLUS, 0, 0, argv, 0);
    printf("posix_spawn(cc1plus --version) = %d pid=%d\n", r, (int)pid);
    if (r == 0) {
        int st = -1;
        waitpid(pid, &st, 0);
        printf("cc1plus wait status = %d (exit %d)\n", st, (st >> 8) & 0xFF);
    }
    return 0;
}