/* 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;
)
// 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, struct stat *sb)
{
int endian = toybuf[5], bits = toybuf[4], i, j;
int64_t (*elf_int)(void *ptr, unsigned size) = peek_le;
// 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"},
{106, "blackfin"}, {140, "c6x"}, {23, "cell"}, {76, "cris"},
{0x5441, "frv"}, {46, "h8300"}, {164, "hexagon"}, {50, "ia64"},
{88, "m32r"}, {0x9041, "m32r"}, {4, "m68k"}, {174, "metag"},
{0xbaab, "microblaze"}, {8, "mips"}, {10, "mips-old"}, {89, "mn10300"},
{0xbeef, "mn10300-old"}, {113, "nios2"}, {92, "openrisc"},
{0x8472, "openrisc-old"}, {15, "parisc"}, {20, "ppc"}, {21, "ppc64"},
{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"}
};
int dynamic = 0;
int stripped = 1;
char *map;
off_t phoff, shoff;
int phentsize, phnum, shsize, shnum;
printf("ELF ");
// executable (ELF says this is short but reality says byte, not MSB swapped)
i = toybuf[16];
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);
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 ");
elf_int = peek_be;
} 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;
}
// 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?\n", phentsize);
return;
}
map = mmap(0, sb->st_size, PROT_READ, MAP_SHARED, fd, 0);
if (!map) perror_exit("mmap");
// We need to read the phdrs for dynamic vs static.
// (Note: fields got reordered for 64 bit)
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*/)
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)
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.
int n_namesz = elf_int(note, 4);
int n_descsz = elf_int(note+4, 4);
int n_type = elf_int(note+8, 4);
int 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*/) {
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*/) {
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 ");
xputc('\n');
munmap(map, sb->st_size);
}
static void do_regular_file(int fd, char *name, struct stat *sb)
{
char *s;
int len = read(fd, s = toybuf, sizeof(toybuf)-256);
int magic;
if (len<0) perror_msg("%s", name);
if (len>40 && strstart(&s, "\177ELF")) do_elf_file(fd, sb);
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) == 0)
xprintf("JPEG image data\n");
// https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html
else if (len>8 && strstart(&s, "\xca\xfe\xba\xbe"))
xprintf("Java class file, version %d.%d\n",
(int)peek_be(s+2, 2), (int)peek_be(s, 2));
// 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 = (int)(char)(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 {
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 = mbrtowc(&wc, s+i, len-i, 0))>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)), "");
if (fd || !((toys.optflags & FLAG_L) ? stat : lstat)(name, &sb)) {
if (fd || S_ISREG(sb.st_mode)) {
if (!sb.st_size) what = "empty";
else if ((fd = openro(name, O_RDONLY)) != -1) {
do_regular_file(fd, name, &sb);
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);
}
}