zircon/system/ulib/launchpad/elf.c

// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "elf.h"

#include <elfload/elfload.h>

#include <zircon/process.h>
#include <zircon/syscalls.h>
#include <stdlib.h>

struct elf_load_info {
    elf_load_header_t header;
    elf_phdr_t phdrs[];
};

void elf_load_destroy(elf_load_info_t* info) {
    free(info);
}

zx_status_t elf_load_start(zx_handle_t vmo, const void* hdr_buf, size_t buf_sz,
                           elf_load_info_t** infop) {
    elf_load_header_t header;
    uintptr_t phoff;
    zx_status_t status = elf_load_prepare(vmo, hdr_buf, buf_sz, &header, &phoff);
    if (status == ZX_OK) {
        // Now allocate the data structure and read in the phdrs.
        size_t phdrs_size = (size_t)header.e_phnum * sizeof(elf_phdr_t);
        elf_load_info_t* info = malloc(sizeof(*info) + phdrs_size);
        if (info == NULL)
            return ZX_ERR_NO_MEMORY;
        status = elf_load_read_phdrs(vmo, info->phdrs, phoff, header.e_phnum);
        if (status == ZX_OK) {
            info->header = header;
            *infop = info;
        } else {
            free(info);
        }
    }
    return status;
}

zx_status_t elf_load_get_interp(elf_load_info_t* info, zx_handle_t vmo,
                                char** interp, size_t* interp_len) {
    char *buffer = NULL;
    uintptr_t offset;
    if (elf_load_find_interp(info->phdrs, info->header.e_phnum,
                             &offset, interp_len)) {
        buffer = malloc(*interp_len + 1);
        if (buffer == NULL)
            return ZX_ERR_NO_MEMORY;
        zx_status_t status = zx_vmo_read(vmo, buffer, offset, *interp_len);
        if (status < 0) {
            free(buffer);
            return status;
        }
        buffer[*interp_len] = '\0';
    }
    *interp = buffer;
    return ZX_OK;
}

zx_status_t elf_load_finish(zx_handle_t vmar, elf_load_info_t* info,
                            zx_handle_t vmo,
                            zx_handle_t* segments_vmar,
                            zx_vaddr_t* base, zx_vaddr_t* entry) {
    return elf_load_map_segments(vmar, &info->header, info->phdrs, vmo,
                                 segments_vmar, base, entry);
}

size_t elf_load_get_stack_size(elf_load_info_t* info) {
    for (uint_fast16_t i = 0; i < info->header.e_phnum; ++i) {
        if (info->phdrs[i].p_type == PT_GNU_STACK)
            return info->phdrs[i].p_memsz;
    }
    return 0;
}