efirestool -- tool to work with APPL efires archives

efirestool.c

#include <sys/types.h>
#include <unistd.h>       // write
#include <fcntl.h>        // open, close
#include <stdio.h>        // fprintf
#include <string.h>       // strerror, strdup, strchr
#include <stdlib.h>       // free, EXIT_*
#include <sys/mman.h>     // mmap, munmap
#include <sys/stat.h>     // fstat
#include <errno.h>        // errno
#include <dirent.h>       // DIR, dirent, opendir, readdir
#include <stdint.h>       // UINT32_MAX

typedef struct {
    char     name[64];
    uint32_t offset;
    uint32_t length;
}
__attribute__((packed, aligned(1)))
efires_file_t;

#define EFIRES_CURRENT_REVISION 2
typedef struct {
    uint16_t revision;   // EFIRES_CURRENT_REVISION
    uint16_t nentries;   // count of entries
    efires_file_t entries[/* nentries */];
}
__attribute__((packed, aligned(1)))
efires_hdr_t;

#ifdef __APPLE__
#include <libkern/OSByteOrder.h>

#define le16toh(x) OSSwapLittleToHostInt16(x)
#define le32toh(x) OSSwapLittleToHostInt32(x)
#define htole16(x) OSSwapHostToLittleInt16(x)
#define htole32(x) OSSwapHostToLittleInt32(x)
#else
#include <endian.h>
#endif

typedef enum {
    ONLY_LIST = 1,
} unpack_flag;

int unpack_efires(const char* fname, const char* destination, unpack_flag flags, char** filelist[]);
int pack_efires(const char* fname, const char* fromdir, const char* filelist[]);

int write_filelist(const char** filelist, const char* fname);
const char** parse_filelist(const char* fname);
void free_filelist(char** filelist);

#define ACTION_UNPACK  "unpack"
#define ACTION_PACK    "pack"
#define ACTION_LIST    "list"

void print_usage(const char* prog) {
    fprintf(stderr,
        "efirestool -- tool to work with APPL efires archives\n"
        "\n"
        "Usage:\n"
        "    %s " ACTION_UNPACK " efires destination [filelist]\n"
        "    %s " ACTION_PACK " efires from [filelist]\n"
        "    %s " ACTION_LIST " efires [-f filelist]\n"
        , prog, prog, prog);
}

int main(int argc, const char* argv[]) {
    if (argc < 3) {
        print_usage(argv[0]);
        return EXIT_FAILURE;
    }

    const char* action = argv[1];
    const char* efires = argv[2];
    const char* directory = NULL;
    const char* filelist_fname = NULL;
    const char** filelist = NULL;

    int retval = 0;

    if (argc > 3) {
        directory = argv[3];
    }

    if (argc > 4) {
        filelist_fname = argv[4];
    }

    if ((strcmp(action, ACTION_UNPACK) == 0) || (strcmp(action, ACTION_LIST) == 0)) {
        unpack_flag flags = 0;

        if (strcmp(action, ACTION_LIST) == 0) flags |= ONLY_LIST;

        retval = unpack_efires(efires, directory, flags, (char***) ((filelist_fname) ? &filelist : NULL));

        if (!retval && filelist_fname) {
            if (filelist == NULL) {
                fprintf(stderr, "Failed to build filelist\n");
                retval = 1;
            } else {
                retval = write_filelist(filelist, filelist_fname);
            }
        }
    } else if (strcmp(action, ACTION_PACK) == 0) {
        filelist = parse_filelist(filelist_fname);

        if (filelist == NULL) {
            fprintf(stderr, "Failed to parse filelist\n");
            retval = 1;
        } else {
            retval = pack_efires(efires, directory, filelist);
        }
    } else {
        print_usage(argv[0]);
        retval = EXIT_FAILURE;
    }

    if (filelist) {
        free_filelist((char**)filelist);
    }

    return retval;
}

void free_filelist(char** filelist) {
    for (char** p = filelist; *p != NULL; ++p) {
        free((char*)*p);
    }

    free(filelist);
}

const char** parse_filelist(const char* fname) {
    FILE *f = fopen(fname, "r");
    if (f == NULL) {
        fprintf(stderr, "Cant open filelist (%s): %s\n", fname, strerror(errno));
        return NULL;
    }

    // XXX realloc and grow
    size_t res_size = sizeof(char*) * UINT32_MAX / sizeof(efires_file_t);
    char** res = malloc(res_size);

    if (res == NULL) {
        fprintf(stderr, "Cant allocate memory for filelist\n");
        fclose(f);
        return NULL;
    }

    ssize_t linelen = 0;
    char** itm = res;
    size_t n = 0;
    
    for (*itm = NULL, n = 0;
        (itm < (res + res_size - 1)) && ((linelen = getline(itm, &n, f)) != -1);
        ++itm, *itm = NULL, n = 0, linelen = 0)
    {
        (*itm)[linelen - 1] = '\0';
    }

    if (linelen == 0) {
        *itm = NULL;
    } else if (*itm) {
        free(*itm);
        *itm = NULL;
    }

    fclose(f);

    return (const char**)res;
}

int write_filelist(const char** filelist, const char* fname) {
    if (filelist == NULL) {
        fprintf(stderr, "Cant write NULL filelist\n");
        return 1;
    }
    FILE *f = fopen(fname, "w");

    if (f == NULL) {
        fprintf(stderr, "Cant open filelist (%s): %s\n", fname, strerror(errno));
        return 1;
    }

    for (const char** itm = filelist; *itm != NULL; ++itm) {
        fprintf(f, "%s\n", *itm);
    }

    fclose(f);
    return 0;
}

int unpack_efires(const char* fname, const char* destination, unpack_flag flags, char** filelist[]) {
    int result = 1;
    size_t file_size = 0;
    const void *file_map = NULL;

    if (filelist) *filelist = NULL;

    if (((flags & ONLY_LIST) == 0) && (destination == NULL)) {
        fprintf(stderr, "Cant determine destination\n");
        goto out;
    }

    int fd = open(fname, O_RDONLY);
    if (fd == -1) {
        fprintf(stderr, "Cant open resource file (%s): %s\n", fname, strerror(errno));
        goto out;
    }

    struct stat s;
    if (fstat(fd, &s) != 0) {
        fprintf(stderr, "fstat failed for (%s): %s\n", fname, strerror(errno));
        goto out;
    }

    file_size = s.st_size;

    if (file_size < sizeof(efires_hdr_t)) {
        fprintf(stderr, "File is too short to be an efires file\n");
        goto out;
    }

    file_map = mmap(NULL, s.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    if (file_map == MAP_FAILED) {
        fprintf(stderr, "Cant mmap file (%s): %s\n", fname, strerror(errno));
        file_map = NULL;
        goto out;
    }

    const efires_hdr_t *hdr = (const efires_hdr_t *) file_map;
    if (le16toh(hdr->revision) != EFIRES_CURRENT_REVISION) {
        fprintf(stderr, "Wrong efires revision: 0x%02x (expected 0x%02x)\n", le16toh(hdr->revision), EFIRES_CURRENT_REVISION);
        goto out;
    }

    uint16_t nentries = le16toh(hdr->nentries);
    fprintf(stderr, "File with 0x%x entries: %s\n", nentries, fname);

    if (nentries * sizeof(efires_file_t) + sizeof(efires_hdr_t) > file_size) {
        fprintf(stderr, "File is too small to have so many entries\n");
        goto out;
    }

    char** filelist_iter = NULL;

    if (filelist) {
        *filelist = malloc((nentries + 1) * sizeof(char*));
        filelist_iter = *filelist;
        if (filelist_iter) {
            *filelist_iter = NULL;
        } else {
            fprintf(stderr, "Cant allocate memory for filelist\n");
            goto out;
        }
    }

    if ((flags & ONLY_LIST) == 0) {
        if (mkdir(destination, 0755) != 0) {
            fprintf(stderr, "Cant create destination directory '%s': %s\n", destination, strerror(errno));
            goto out;
        }

        if (chdir(destination) != 0) {
            fprintf(stderr, "Cant chdir to destination directory '%s': %s\n", destination, strerror(errno));
            goto out;
        }
    }

    for (uint16_t i = 0; i != nentries; ++i) {
        const efires_file_t *ent = &hdr->entries[i];
        uint32_t off = le32toh(ent->offset);
        uint32_t len = le32toh(ent->length);

        printf("0x%04x (0x%08x - 0x%08x): %s\n", i, off, off + len, ent->name);

        if (filelist_iter) *(filelist_iter++) = strdup(ent->name);

        if (flags & ONLY_LIST) continue;

        if (off + len > file_size) {
            fprintf(stderr, "File 0x%04x: overflows efires file -- skipping\n", i);
            continue;
        }

        int f = open(ent->name, O_WRONLY|O_CREAT|O_EXCL, 0755);

        if (f == -1) {
            fprintf(stderr, "File 0x%04x: Failed to create file: %s\n", i, strerror(errno));
            continue;
        }

        int wrote = write(f, (void*) ((uintptr_t)file_map + off), len);
        if (wrote != len) {
            fprintf(stderr, "File 0x%04x: Expected to write %d bytes, wrote %d: %s\n", i, len, wrote, strerror(errno));
        }

        close(f);
    }

    *filelist_iter = NULL;
    result = 0;

out:;
    
    if (result && filelist && *filelist) {
        free_filelist(*filelist);
        *filelist = NULL;
    }

    if (file_map) {
        munmap((void*)file_map, file_size);
    }
    return result;
}

int pack_efires(const char* fname, const char* fromdir, const char* filelist[]) {
    int result = 1;
    DIR *dir = NULL;
    int dfd = -1;
    int outfd = -1;
    size_t file_size = 0;
    void *file_map = NULL;
    uint32_t nentries = 0;

    dir = opendir(fromdir);
    dfd = dirfd(dir);
    if (dir == NULL || dfd == -1) {
        fprintf(stderr, "Cant open directory to pack (%s) : %s\n", fromdir, strerror(errno));
        goto out;
    }

    outfd = open(fname, O_RDWR | O_CREAT | O_EXCL, 0644);
    if (outfd == -1) {
        fprintf(stderr, "Cant open output file (%s) : %s\n", fname, strerror(errno));
        goto out;
    }

    {
        // write space for header
        efires_hdr_t tmp;
        write(outfd, &tmp, sizeof(tmp));
    }

    // header and one reserved zeroed entry
    uint32_t full_file_len = sizeof(efires_hdr_t) + sizeof(efires_file_t);

    efires_file_t cur_entr;
    struct dirent *ep = NULL;
    const char** itm = filelist;

    while ((itm && *itm) || ((itm == NULL) && (ep = readdir(dir)) != NULL)) {
        struct stat s;

        const char* d_name = NULL;

        if (itm) {
            d_name = *(itm++);
        } else {
            d_name = ep->d_name;
        }

        if (fstatat(dfd, d_name, &s, 0) != 0) {
            fprintf(stderr, "Cant stat file, skipping (%s/%s) : %s\n", fromdir, d_name, strerror(errno));
            continue;
        }

        if ((s.st_mode & S_IFMT) != S_IFREG) {
            fprintf(stderr, "Entry isn't regular file, skipping (%s/%s)\n", fromdir, d_name);
            continue;
        }

        if (s.st_size > UINT32_MAX) {
            fprintf(stderr, "File too big for efires, skipping (%s/%s)\n", fromdir, d_name);
            continue;
        }

        cur_entr.length = (uint32_t) s.st_size;

        if (full_file_len + cur_entr.length > UINT32_MAX) {
            fprintf(stderr, "File too big to fit in current state, skipping (%u bytes left, %u bytes needed) (%s/%s)\n", UINT32_MAX - full_file_len, cur_entr.length, fromdir, d_name);
            continue;
        }

        size_t e_name_len = strlen(d_name);
        if (e_name_len > sizeof(cur_entr.name)) {
            fprintf(stderr, "Filename too long, skipping (%s/%s)\n", fromdir, d_name);
            continue;
        }

        ++nentries;
        memcpy(cur_entr.name, d_name, e_name_len);

        if (e_name_len < sizeof(cur_entr.name)) {
            memset(cur_entr.name + e_name_len, 0, sizeof(cur_entr.name) - e_name_len);
        }

        if (write(outfd, &cur_entr, sizeof(cur_entr)) != sizeof(cur_entr)) {
            fprintf(stderr, "Write to result file failed: %s\n", strerror(errno));
            goto out;
        }

        full_file_len += sizeof(cur_entr) + cur_entr.length;

        if (nentries + 1 == UINT32_MAX) {
            fprintf(stderr, "Too many entries, only packing 0x%08x\n", nentries);
            break;
        }
    }

    // reserved zeroed entry
    memset(&cur_entr, 0, sizeof(cur_entr));
    if (write(outfd, &cur_entr, sizeof(cur_entr)) != sizeof(cur_entr)) {
        fprintf(stderr, "Write to result file failed: %s\n", strerror(errno));
        goto out;
    }

    if (ftruncate(outfd, full_file_len) != 0) {
        fprintf(stderr, "Failed to expand result file to needed size: %s\n", strerror(errno));
        goto out;
    }

    file_map = mmap(NULL, full_file_len, PROT_READ | PROT_WRITE, MAP_SHARED, outfd, 0);

    if (file_map == MAP_FAILED) {
        fprintf(stderr, "Cant mmap result file: %s\n", strerror(errno));
        file_map = NULL;
        goto out;
    }

    efires_hdr_t *hdr = (efires_hdr_t *) file_map;
    hdr->revision = htole16(EFIRES_CURRENT_REVISION);
    hdr->nentries = htole16(nentries);

    // header + nentries entries + reserved zeroed entry
    uint32_t current_offset = sizeof(efires_hdr_t) + (nentries + 1) * sizeof(efires_file_t);
    for (uint16_t i = 0; i != nentries; ++i) {
        efires_file_t *ent = &hdr->entries[i];

        uint32_t length = ent->length;
        uint32_t offset = current_offset;
        current_offset += length;

        ent->length = htole32(length);
        ent->offset = htole32(offset);

        printf("0x%04x (0x%08x - 0x%08x): %s\n", i, offset, offset + length, ent->name);

        int entfd = openat(dfd, ent->name, O_RDONLY);

        if (entfd == -1) {
            fprintf(stderr, "Cant open file, leaving zeroed (%s/%s): %s\n", fromdir, ent->name, strerror(errno));
            continue;
        }

        if (read(entfd, (void*) ((uintptr_t)file_map + offset), length) != length) {
            fprintf(stderr, "Cant read %u bytes from file, contents in efires undefined (%s/%s): %s\n", length, fromdir, ent->name, strerror(errno));
        }

        close(entfd);
    }

    result = 0;

out:;
    if (dir != NULL) {
        closedir(dir);
    }

    if (file_map != NULL) {
        munmap(file_map, file_size);
    }

    if (outfd != -1) {
        close(outfd);

        // delete file if error occured
        if (result) {
            unlink(fname);
        }
    }

    return result;
}

MIT license

@stek29 The latest build of file(1) doesn't appear to recognise these files (macOS Big Sur 11.2.3, EfiLoginUI/*.efires). Would you consider sending them a patch? Magic number appears to be the same.

Because it wasn't obvious to me, here is how you (using appleLogo.efires as an example):

• List files inside .efires: ./efirestool list appleLogo.efires
• Unpack .efires: ./efirestool unpack appleLogo.efires ./appleLogo
• Pack a new .efires: ./efirestool pack appleLogo.efires appleLogo appleLogo_flist.txt
  • appleLogo_flist.txt is simply a text file with list of filenames inside directory, i.e. ls appleLogo > appleLogo-flist.txt

It works perfectly fine on my end, although I am unable to change appleLogo.efires permanently.
I tried changing it as well from the Terminal while booted in Recovery but it keeps coming back to the unmodified one. Anyone knows?