/* file.c - describe file type * * Copyright 2016 The Android Open Source Project * * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/file.html USE_FILE(NEWTOY(file, "<1hL[!hL]", TOYFLAG_USR|TOYFLAG_BIN)) config FILE bool "file" default y help usage: file [-hL] [file...] Examine the given files and describe their content types. -h Don't follow symlinks (default) -L Follow symlinks */ #define FOR_file #include "toys.h" GLOBALS( int max_name_len; off_t len; ) // We don't trust elf.h to be there, and two codepaths for 32/64 is awkward // anyway, so calculate struct offsets manually. (It's a fixed ABI.) static void do_elf_file(int fd) { int endian = toybuf[5], bits = toybuf[4], i, j, dynamic = 0, stripped = 1, phentsize, phnum, shsize, shnum; int64_t (*elf_int)(void *ptr, unsigned size); // Values from include/linux/elf-em.h (plus arch/*/include/asm/elf.h) // Names are linux/arch/ directory (sometimes before 32/64 bit merges) struct {int val; char *name;} type[] = {{0x9026, "alpha"}, {93, "arc"}, {195, "arcv2"}, {40, "arm"}, {183, "arm64"}, {0x18ad, "avr32"}, {247, "bpf"}, {106, "blackfin"}, {140, "c6x"}, {23, "cell"}, {76, "cris"}, {252, "csky"}, {0x5441, "frv"}, {46, "h8300"}, {164, "hexagon"}, {50, "ia64"}, {88, "m32r"}, {0x9041, "m32r"}, {4, "m68k"}, {174, "metag"}, {189, "microblaze"}, {0xbaab, "microblaze-old"}, {8, "mips"}, {10, "mips-old"}, {89, "mn10300"}, {0xbeef, "mn10300-old"}, {113, "nios2"}, {92, "openrisc"}, {0x8472, "openrisc-old"}, {15, "parisc"}, {20, "ppc"}, {21, "ppc64"}, {243, "riscv"}, {22, "s390"}, {0xa390, "s390-old"}, {135, "score"}, {42, "sh"}, {2, "sparc"}, {18, "sparc8+"}, {43, "sparc9"}, {188, "tile"}, {191, "tilegx"}, {3, "386"}, {6, "486"}, {62, "x86-64"}, {94, "xtensa"}, {0xabc7, "xtensa-old"} }; char *map = 0; off_t phoff, shoff; printf("ELF "); elf_int = (endian==2) ? peek_be : peek_le; // executable type i = elf_int(toybuf+16, 2); if (i == 1) printf("relocatable"); else if (i == 2) printf("executable"); else if (i == 3) printf("shared object"); else if (i == 4) printf("core dump"); else printf("(bad type %d)", i); if (elf_int(toybuf+36+12*(bits==2), 4) & 0x8000) printf(" (fdpic)"); printf(", "); // "64-bit" if (bits == 1) printf("32-bit "); else if (bits == 2) printf("64-bit "); else { printf("(bad class %d) ", bits); bits = 0; } // "LSB" if (endian == 1) printf("LSB "); else if (endian == 2) printf("MSB "); else { printf("(bad endian %d) \n", endian); endian = 0; } // e_machine, ala "x86", from big table above j = elf_int(toybuf+18, 2); for (i = 0; i<ARRAY_LEN(type); i++) if (j==type[i].val) break; if (i<ARRAY_LEN(type)) printf("%s", type[i].name); else printf("(unknown arch %d)", j); bits--; // If what we've seen so far doesn't seem consistent, bail. if (!((bits&1)==bits && endian)) { printf(", corrupt?\n"); return; } // Parsing ELF means following tables that may point to data earlier in // the file, so sequential reading involves buffering unknown amounts of // data. Just skip it if we can't mmap. if (MAP_FAILED == (map = mmap(0, TT.len, PROT_READ, MAP_SHARED, fd, 0))) goto bad; // Stash what we need from the header; it's okay to reuse toybuf after this. phentsize = elf_int(toybuf+42+12*bits, 2); phnum = elf_int(toybuf+44+12*bits, 2); phoff = elf_int(toybuf+28+4*bits, 4+4*bits); shsize = elf_int(toybuf+46+12*bits, 2); shnum = elf_int(toybuf+48+12*bits, 2); shoff = elf_int(toybuf+32+8*bits, 4+4*bits); // With binutils, phentsize seems to only be non-zero if phnum is non-zero. // Such ELF files are rare, but do exist. (Android's crtbegin files, say.) if (phnum && (phentsize != 32+24*bits)) { printf(", corrupt phentsize %d?", phentsize); goto bad; } // Parsing ELF means following tables that may point to data earlier in // the file, so sequential reading involves buffering unknown amounts of // data. Just skip it if we can't mmap. if (MAP_FAILED == (map = mmap(0, TT.len, PROT_READ, MAP_SHARED, fd, 0))) goto bad; // We need to read the phdrs for dynamic vs static. // (Note: fields got reordered for 64 bit) if (phoff+phnum*phentsize>TT.len) goto bad; for (i = 0; i<phnum; i++) { char *phdr = map+phoff+i*phentsize; int p_type = elf_int(phdr, 4); long long p_offset, p_filesz; if (p_type==2 /*PT_DYNAMIC*/) dynamic = 1; if (p_type!=3 /*PT_INTERP*/ && p_type!=4 /*PT_NOTE*/) continue; j = bits+1; p_offset = elf_int(phdr+4*j, 4*j); p_filesz = elf_int(phdr+16*j, 4*j); if (p_type==3 /*PT_INTERP*/) { if (p_offset+p_filesz>TT.len) goto bad; printf(", dynamic (%.*s)", (int)p_filesz, map+p_offset); } } if (!dynamic) printf(", static"); // We need to read the shdrs for stripped/unstripped and any notes. // Notes are in program headers *and* section headers, but some files don't // contain program headers, so we prefer to check here. // (Note: fields got reordered for 64 bit) if (shoff+i*shnum>TT.len) goto bad; for (i = 0; i<shnum; i++) { char *shdr = map+shoff+i*shsize; int sh_type = elf_int(shdr+4, 4); long sh_offset = elf_int(shdr+8+8*(bits+1), 4*(bits+1)); int sh_size = elf_int(shdr+8+12*(bits+1), 4); if (sh_type == 2 /*SHT_SYMTAB*/) { stripped = 0; break; } else if (sh_type == 7 /*SHT_NOTE*/) { char *note = map+sh_offset; // An ELF note is a sequence of entries, each consisting of an // ndhr followed by n_namesz+n_descsz bytes of data (each of those // rounded up to the next 4 bytes, without this being reflected in // the header byte counts themselves). while (sh_size >= 3*4) { // Don't try to read a truncated entry. unsigned n_namesz, n_descsz, n_type, notesz; if (sh_offset+sh_size>TT.len) goto bad; n_namesz = elf_int(note, 4); n_descsz = elf_int(note+4, 4); n_type = elf_int(note+8, 4); notesz = 3*4 + ((n_namesz+3)&~3) + ((n_descsz+3)&~3); if (n_namesz==4 && !memcmp(note+12, "GNU", 4)) { if (n_type==3 /*NT_GNU_BUILD_ID*/) { if (n_descsz+16>sh_size) goto bad; printf(", BuildID="); for (j = 0; j < n_descsz; ++j) printf("%02x", note[16 + j]); } } else if (n_namesz==8 && !memcmp(note+12, "Android", 8)) { if (n_type==1 /*.android.note.ident*/) { if (n_descsz+24+64>sh_size) goto bad; printf(", for Android %d", (int)elf_int(note+20, 4)); if (n_descsz > 24) printf(", built by NDK %.64s (%.64s)", note+24, note+24+64); } } note += notesz; sh_size -= notesz; } } } printf(", %sstripped", stripped ? "" : "not "); bad: xputc('\n'); if (map && map != MAP_FAILED) munmap(map, TT.len); } static void do_regular_file(int fd, char *name) { char *s; int len, magic; // zero through elf shnum, just in case memset(toybuf, 0, 80); if ((len = readall(fd, s = toybuf, sizeof(toybuf)))<0) perror_msg("%s", name); if (!len) xputs("empty"); // 45 bytes: https://www.muppetlabs.com/~breadbox/software/tiny/teensy.html else if (len>=45 && strstart(&s, "\177ELF")) do_elf_file(fd); else if (len>=8 && strstart(&s, "!<arch>\n")) xprintf("ar archive\n"); else if (len>28 && strstart(&s, "\x89PNG\x0d\x0a\x1a\x0a")) { // PNG is big-endian: https://www.w3.org/TR/PNG/#7Integers-and-byte-order int chunk_length = peek_be(s, 4); xprintf("PNG image data"); // The IHDR chunk comes first: https://www.w3.org/TR/PNG/#11IHDR s += 4; if (chunk_length == 13 && strstart(&s, "IHDR")) { // https://www.w3.org/TR/PNG/#6Colour-values char *c = 0, *colors[] = {"grayscale", 0, "color RGB", "indexed color", "grayscale with alpha", 0, "color RGBA"}; if (s[9]<ARRAY_LEN(colors)) c = colors[s[9]]; if (!c) c = "unknown"; xprintf(", %d x %d, %d-bit/%s, %sinterlaced", (int)peek_be(s, 4), (int)peek_be(s+4, 4), s[8], c, s[12] ? "" : "non-"); } xputc('\n'); // https://www.w3.org/Graphics/GIF/spec-gif89a.txt } else if (len>16 && (strstart(&s, "GIF87a") || strstart(&s, "GIF89a"))) xprintf("GIF image data, %d x %d\n", (int)peek_le(s, 2), (int)peek_le(s+8, 2)); // TODO: parsing JPEG for width/height is harder than GIF or PNG. else if (len>32 && !memcmp(toybuf, "\xff\xd8", 2)) xputs("JPEG image data"); // https://en.wikipedia.org/wiki/Java_class_file#General_layout else if (len>8 && strstart(&s, "\xca\xfe\xba\xbe")) xprintf("Java class file, version %d.%d (Java 1.%d)\n", (int)peek_be(s+2, 2), (int)peek_be(s, 2), (int)peek_be(s+2, 2)-44); // https://source.android.com/devices/tech/dalvik/dex-format#dex-file-magic else if (len>8 && strstart(&s, "dex\n") && s[3] == 0) xprintf("Android dex file, version %s\n", s); // https://people.freebsd.org/~kientzle/libarchive/man/cpio.5.txt // the lengths for cpio are size of header + 9 bytes, since any valid // cpio archive ends with a record for "TARGET!!!" else if (len>85 && strstart(&s, "07070")) { char *cpioformat = "unknown type"; if (toybuf[5] == '7') cpioformat = "pre-SVR4 or odc"; else if (toybuf[5] == '1') cpioformat = "SVR4 with no CRC"; else if (toybuf[5] == '2') cpioformat = "SVR4 with CRC"; xprintf("ASCII cpio archive (%s)\n", cpioformat); } else if (len>33 && (magic=peek(&s,2), magic==0143561 || magic==070707)) { if (magic == 0143561) printf("byte-swapped "); xprintf("cpio archive\n"); // tar archive (ustar/pax or gnu) } else if (len>500 && !strncmp(s+257, "ustar", 5)) xprintf("POSIX tar archive%s\n", strncmp(s+262," ",2)?"":" (GNU)"); // zip/jar/apk archive, ODF/OOXML document, or such else if (len>5 && strstart(&s, "PK\03\04")) { int ver = toybuf[4]; xprintf("Zip archive data"); if (ver) xprintf(", requires at least v%d.%d to extract", ver/10, ver%10); xputc('\n'); } else if (len>4 && strstart(&s, "BZh") && isdigit(*s)) xprintf("bzip2 compressed data, block size = %c00k\n", *s); else if (len>10 && strstart(&s, "\x1f\x8b")) xputs("gzip compressed data"); else if (len>32 && !memcmp(s+1, "\xfa\xed\xfe", 3)) { int bit = s[0]=='\xce'?32:64; char *what; xprintf("Mach-O %d-bit ", bit); if (s[4] == 7) what = (bit==32)?"x86":"x86-"; else if (s[4] == 12) what = "arm"; else if (s[4] == 18) what = "ppc"; else what = NULL; if (what) xprintf("%s%s ", what, (bit==32)?"":"64"); else xprintf("(bad arch %d) ", s[4]); if (s[12] == 1) what = "object"; else if (s[12] == 2) what = "executable"; else if (s[12] == 6) what = "shared library"; else what = NULL; if (what) xprintf("%s\n", what); else xprintf("(bad type %d)\n", s[9]); } else if (len>36 && !memcmp(s, "OggS\x00\x02", 6)) { xprintf("Ogg data"); // https://wiki.xiph.org/MIMETypesCodecs if (!memcmp(s+28, "CELT ", 8)) xprintf(", celt audio"); else if (!memcmp(s+28, "CMML ", 8)) xprintf(", cmml text"); else if (!memcmp(s+28, "BBCD\0", 5)) xprintf(", dirac video"); else if (!memcmp(s+28, "\177FLAC", 5)) xprintf(", flac audio"); else if (!memcmp(s+28, "\x8bJNG\r\n\x1a\n", 8)) xprintf(", jng video"); else if (!memcmp(s+28, "\x80kate\0\0\0", 8)) xprintf(", kate text"); else if (!memcmp(s+28, "OggMIDI\0", 8)) xprintf(", midi text"); else if (!memcmp(s+28, "\x8aMNG\r\n\x1a\n", 8)) xprintf(", mng video"); else if (!memcmp(s+28, "OpusHead", 8)) xprintf(", opus audio"); else if (!memcmp(s+28, "PCM ", 8)) xprintf(", pcm audio"); else if (!memcmp(s+28, "\x89PNG\r\n\x1a\n", 8)) xprintf(", png video"); else if (!memcmp(s+28, "Speex ", 8)) xprintf(", speex audio"); else if (!memcmp(s+28, "\x80theora", 7)) xprintf(", theora video"); else if (!memcmp(s+28, "\x01vorbis", 7)) xprintf(", vorbis audio"); else if (!memcmp(s+28, "YUV4MPEG", 8)) xprintf(", yuv4mpeg video"); xputc('\n'); } else if (len>32 && !memcmp(s, "RIF", 3) && !memcmp(s+8, "WAVEfmt ", 8)) { // https://en.wikipedia.org/wiki/WAV int le = (s[3] == 'F'); int format = le ? peek_le(s+20,2) : peek_be(s+20,2); int channels = le ? peek_le(s+22,2) : peek_be(s+22,2); int hz = le ? peek_le(s+24,4) : peek_be(s+24,4); int bits = le ? peek_le(s+34,2) : peek_be(s+34,2); xprintf("WAV audio, %s, ", le ? "LE" : "BE"); if (bits != 0) xprintf("%d-bit, ", bits); if (channels==1||channels==2) xprintf("%s, ", channels==1?"mono":"stereo"); else xprintf("%d-channel, ", channels); xprintf("%d Hz, ", hz); // See https://tools.ietf.org/html/rfc2361, though there appear to be bugs // in the RFC. This assumes wikipedia's example files are more correct. if (format == 0x01) xprintf("PCM"); else if (format == 0x03) xprintf("IEEE float"); else if (format == 0x06) xprintf("A-law"); else if (format == 0x07) xprintf("µ-law"); else if (format == 0x11) xprintf("ADPCM"); else if (format == 0x22) xprintf("Truespeech"); else if (format == 0x31) xprintf("GSM"); else if (format == 0x55) xprintf("MP3"); else if (format == 0x70) xprintf("CELP"); else if (format == 0xfffe) xprintf("extensible"); else xprintf("unknown format %d", format); xputc('\n'); } else if (len>12 && !memcmp(s, "\x00\x01\x00\x00", 4)) { xputs("TrueType font"); } else if (len>12 && !memcmp(s, "ttcf\x00", 5)) { xprintf("TrueType font collection, version %d, %d fonts\n", (int)peek_be(s+4, 2), (int)peek_be(s+8, 4)); } else if (len>4 && !memcmp(s, "BC\xc0\xde", 4)) { xputs("LLVM IR bitcode"); } else if (strstart(&s, "-----BEGIN CERTIFICATE-----")) { xputs("PEM certificate"); // https://msdn.microsoft.com/en-us/library/windows/desktop/ms680547(v=vs.85).aspx } else if (len>0x70 && !memcmp(s, "MZ", 2) && (magic=peek_le(s+0x3c,4))<len-4 && !memcmp(s+magic, "\x50\x45\0\0", 4)) { xprintf("MS PE32%s executable %s", (peek_le(s+magic+24, 2)==0x20b)?"+":"", (peek_le(s+magic+22, 2)&0x2000)?"(DLL) ":""); if (peek_le(s+magic+20, 2)>70) { char *types[] = {0, "native", "GUI", "console", "OS/2", "driver", "CE", "EFI", "EFI boot", "EFI runtime", "EFI ROM", "XBOX", 0, "boot"}; int type = peek_le(s+magic+92, 2); char *name = (type>0 && type<ARRAY_LEN(types))?types[type]:0; xprintf("(%s) ", name?name:"unknown"); } xprintf("%s\n", (peek_le(s+magic+4, 2)==0x14c)?"x86":"x86-64"); // https://en.wikipedia.org/wiki/BMP_file_format } else if (len > 0x32 && !memcmp(s, "BM", 2) && !memcmp(s+6, "\0\0\0\0", 4)) { int w = peek_le(s+0x12,4), h = peek_le(s+0x16,4), bpp = peek_le(s+0x1c,2); xprintf("BMP image, %d x %d, %d bpp\n", w, h, bpp); } else { char *what = 0; int i, bytes; // If shell script, report which interpreter if (len>3 && strstart(&s, "#!")) { // Whitespace is allowed between the #! and the interpreter while (isspace(*s)) s++; if (strstart(&s, "/usr/bin/env")) while (isspace(*s)) s++; for (what = s; (s-toybuf)<len && !isspace(*s); s++); strcpy(s, " script"); // Distinguish ASCII text, UTF-8 text, or data } else for (i = 0; i<len; ++i) { if (!(isprint(toybuf[i]) || isspace(toybuf[i]))) { wchar_t wc; if ((bytes = utf8towc(&wc, s+i, len-i))>0 && wcwidth(wc)>=0) { i += bytes-1; if (!what) what = "UTF-8 text"; } else { what = "data"; break; } } } xputs(what ? what : "ASCII text"); } } void file_main(void) { char **arg; for (arg = toys.optargs; *arg; ++arg) { int name_len = strlen(*arg); if (name_len > TT.max_name_len) TT.max_name_len = name_len; } // Can't use loopfiles here because it doesn't call function when can't open for (arg = toys.optargs; *arg; arg++) { char *name = *arg, *what = "cannot open"; struct stat sb; int fd = !strcmp(name, "-"); xprintf("%s: %*s", name, (int)(TT.max_name_len - strlen(name)), ""); sb.st_size = 0; if (fd || !((toys.optflags & FLAG_L) ? stat : lstat)(name, &sb)) { if (fd || S_ISREG(sb.st_mode)) { TT.len = sb.st_size; // This test identifies an empty file we don't have permission to read if (!fd && !sb.st_size) what = "empty"; else if ((fd = openro(name, O_RDONLY)) != -1) { do_regular_file(fd, name); if (fd) close(fd); continue; } } else if (S_ISFIFO(sb.st_mode)) what = "fifo"; else if (S_ISBLK(sb.st_mode)) what = "block special"; else if (S_ISCHR(sb.st_mode)) what = "character special"; else if (S_ISDIR(sb.st_mode)) what = "directory"; else if (S_ISSOCK(sb.st_mode)) what = "socket"; else if (S_ISLNK(sb.st_mode)) what = "symbolic link"; else what = "unknown"; } xputs(what); } }