// SPDX-License-Identifier: GPL-2.0-only
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <link.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include "kselftest.h"

struct Statistics {
        unsigned long long load_address;
        unsigned long long alignment;
        bool interp;
};

int ExtractStatistics(struct dl_phdr_info *info, size_t size, void *data)
{
        struct Statistics *stats = (struct Statistics *) data;
        int i;

        if (info->dlpi_name != NULL && info->dlpi_name[0] != '\0') {
                // Ignore headers from other than the executable.
                return 2;
        }

        stats->load_address = (unsigned long long) info->dlpi_addr;
        stats->alignment = 0;

        for (i = 0; i < info->dlpi_phnum; i++) {
                unsigned long long align;

                if (info->dlpi_phdr[i].p_type == PT_INTERP) {
                        stats->interp = true;
                        continue;
                }

                if (info->dlpi_phdr[i].p_type != PT_LOAD)
                        continue;

                align = info->dlpi_phdr[i].p_align;

                if (align > stats->alignment)
                        stats->alignment = align;
        }

        return 1;  // Terminate dl_iterate_phdr.
}

int main(int argc, char **argv)
{
        struct Statistics extracted = { };
        unsigned long long misalign, pow2;
        bool interp_needed;
        char buf[1024];
        FILE *maps;
        int ret;

        ksft_print_header();
        ksft_set_plan(4);

        /* Dump maps file for debugging reference. */
        maps = fopen("/proc/self/maps", "r");
        if (!maps)
                ksft_exit_fail_msg("FAILED: /proc/self/maps: %s\n", strerror(errno));
        while (fgets(buf, sizeof(buf), maps)) {
                ksft_print_msg("%s", buf);
        }
        fclose(maps);

        /* Walk the program headers. */
        ret = dl_iterate_phdr(ExtractStatistics, &extracted);
        if (ret != 1)
                ksft_exit_fail_msg("FAILED: dl_iterate_phdr\n");

        /* Report our findings. */
        ksft_print_msg("load_address=%#llx alignment=%#llx\n",
                       extracted.load_address, extracted.alignment);

        /* If we're named with ".static." we expect no INTERP. */
        interp_needed = strstr(argv[0], ".static.") == NULL;

        /* Were we built as expected? */
        ksft_test_result(interp_needed == extracted.interp,
                         "%s INTERP program header %s\n",
                         interp_needed ? "Wanted" : "Unwanted",
                         extracted.interp ? "seen" : "missing");

        /* Did we find an alignment? */
        ksft_test_result(extracted.alignment != 0,
                         "Alignment%s found\n", extracted.alignment ? "" : " NOT");

        /* Is the alignment sane? */
        pow2 = extracted.alignment & (extracted.alignment - 1);
        ksft_test_result(pow2 == 0,
                         "Alignment is%s a power of 2: %#llx\n",
                         pow2 == 0 ? "" : " NOT", extracted.alignment);

        /* Is the load address aligned? */
        misalign = extracted.load_address & (extracted.alignment - 1);
        ksft_test_result(misalign == 0, "Load Address is %saligned (%#llx)\n",
                         misalign ? "MIS" : "", misalign);

        ksft_finished();
}