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/* file.c - describe file type
*
* Copyright 2016 The Android Open Source Project
*
* See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/file.html
*
* TODO: ar
USE_FILE(NEWTOY(file, "<1", TOYFLAG_USR|TOYFLAG_BIN))
config FILE
bool "file"
default n
help
usage: file [file...]
Examine the given files and describe their content types.
*/
#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)
{
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"}
};
xprintf("ELF ");
// "64-bit"
if (bits == 1) xprintf("32-bit ");
else if (bits == 2) xprintf("64-bit ");
else {
xprintf("(bad class %d) ", bits);
bits = 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)) xprintf("%s ", type[i].name);
else xprintf("(unknown arch %d) ", j);
// "LSB"
if (endian == 1) xprintf("LSB ");
else if (endian == 2) {
xprintf("MSB ");
elf_int = peek_be;
} else {
xprintf("(bad endian %d)\n", endian);
endian = 0;
}
// ", executable"
i = elf_int(toybuf+16, 2);
if (i == 1) xprintf("relocatable");
else if (i == 2) xprintf("executable");
else if (i == 3) xprintf("shared object");
else if (i == 4) xprintf("core dump");
else xprintf("(bad type %d)", i);
bits--;
// If we know our bits and endianness and phentsize agrees show dynamic linker
if ((bits&1)==bits && endian &&
(i = elf_int(toybuf+42+12*bits, 2)) == 32+24*bits)
{
char *map, *phdr;
int phsize = i, phnum = elf_int(toybuf+44+12*bits, 2),
psz = sysconf(_SC_PAGE_SIZE), lib = 0;
off_t phoff = elf_int(toybuf+28+4*bits, 4+4*bits),
mapoff = phoff^(phoff&(psz-1));
// map e_phentsize*e_phnum bytes at e_phoff
map = mmap(0, phsize*phnum, PROT_READ, MAP_SHARED, fd, mapoff);
if (map) {
// Find PT_INTERP entry. (Not: fields got reordered for 64 bit)
for (i = 0; i<phnum; i++) {
long long dlpos, dllen;
// skip non-PT_INTERP entries
j = elf_int(phdr = map+(phoff-mapoff)+i*phsize, 4);
if (j==2) lib++;
if (j!=3) continue;
// Read p_offset and p_filesz
j = bits+1;
dlpos = elf_int(phdr+4*j, 4*j);
dllen = elf_int(phdr+16*j, 4*j);
if (dllen<0 || dllen>sizeof(toybuf)-128
|| dlpos!=lseek(fd, dlpos, SEEK_SET)
|| dllen!=readall(fd, toybuf+128, dllen)) break;
printf(", dynamic (%.*s)", (int)dllen, toybuf+128);
}
if (!lib) printf(", static");
else printf(", needs %d lib%s", lib, lib>1 ? "s" : "");
munmap(map, phsize*phnum);
}
}
// TODO: we'd need to actually parse the ELF file to report the rest...
// ", dynamically linked"
// " (uses shared libs)"
// ", for Linux 2.6.24"
// ", BuildID[sha1]=SHA"
// ", stripped"
xputc('\n');
}
static void do_regular_file(int fd, char *name)
{
char *s;
int len = read(fd, s = toybuf, sizeof(toybuf)-256);
if (len<0) perror_msg("%s", name);
if (len>40 && strstart(&s, "\177ELF")) do_elf_file(fd);
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+6, 2), (int)peek_be(s, 2));
// TODO: cpio archive.
// TODO: tar archive.
// TODO: zip/jar/apk archive.
else {
char *what = 0;
int i, bytes;
// If shell script, report which interpreter
if (len>3 && strstart(&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++) {
struct stat sb;
char *name = *arg, *what = "cannot open";
xprintf("%s: %*s", name, (int)(TT.max_name_len - strlen(name)), "");
if (!lstat(name, &sb)) {
if (S_ISFIFO(sb.st_mode)) what = "fifo";
else if (S_ISREG(sb.st_mode)) {
int fd = strcmp(name, "-") ? 0 : open(name, O_RDONLY);
if (fd!=-1) {
if (sb.st_size == 0) what = "empty";
else do_regular_file(fd, name);
}
if (fd>0) close(fd);
} 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);
}
}
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