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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
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;
)
// TODO: all the ELF magic numbers are available in <elf.h> --- use that?
static char *elf_arch(int e_machine)
{
// TODO: include obsolete stuff we'll never see, like "PDP-10" and "VAX"?
switch (e_machine) {
case 3: return "Intel 80386";
case 8: return "MIPS";
case 40: return "ARM";
case 62: return "x86-64";
case 183: return "ARM aarch64";
default: return NULL;
}
}
static int64_t elf_int(int endian, char *data, int bytes)
{
if (endian == 1) return peek_le(data, bytes);
return peek_be(data, bytes);
}
static void do_elf_file()
{
int elf_endian = toybuf[5];
int e_type, e_machine;
xprintf("ELF");
// "64-bit"
if (toybuf[4] == 1) xprintf(" 32-bit");
else if (toybuf[4] == 2) xprintf(" 64-bit");
else xprintf(" (invalid class %d)", toybuf[4]);
// "LSB"
if (elf_endian == 1) xprintf(" LSB");
else if (elf_endian == 2) xprintf(" MSB");
else xprintf("(invalid endian %d) ", elf_endian);
if (elf_endian == 1 || elf_endian == 2) {
char *arch;
// ", executable"
e_type = elf_int(elf_endian, &toybuf[0x10], 2);
if (e_type == 1) xprintf(" relocatable");
else if (e_type == 2) xprintf(" executable");
else if (e_type == 3) xprintf(" shared object");
else if (e_type == 4) xprintf(" core dump");
else xprintf(" (invalid type %d)", e_type);
// ", x86-64"
e_machine = elf_int(elf_endian, &toybuf[0x12], 2);
arch = elf_arch(e_machine);
if (arch) xprintf(", %s", arch);
else xprintf(", (unknown arch %d)", e_machine);
}
// "version 1"
xprintf(", version %d", toybuf[6]);
// " (SYSV)"
// TODO: will we ever meet any of the others in practice?
if (toybuf[7] == 0) xprintf(" (SYSV)");
else xprintf(" (OS %d)", toybuf[7]);
// TODO: we'd need to actually parse the ELF file to report the rest...
// ", dynamically linked"
// " (uses shared libs)"
// ", for GNU/Linux 2.6.24"
// ", BuildID[sha1]=SHA"
// ", stripped"
xputs("");
}
// https://www.w3.org/TR/PNG/#6Colour-values
static char *png_color_type(int color_type)
{
switch (color_type) {
case 0: return "grayscale";
case 2: return "color RGB";
case 3: return "indexed color";
case 4: return "grayscale with alpha";
case 6: return "color RGBA";
default: return "unknown";
}
}
static void do_png_file()
{
// PNG is big-endian: https://www.w3.org/TR/PNG/#7Integers-and-byte-order
int chunk_length = peek_be(&toybuf[8], 4);
xprintf("PNG image data");
// The IHDR chunk comes first.
// https://www.w3.org/TR/PNG/#11IHDR
if (chunk_length == 13 && memcmp(&toybuf[12], "IHDR", 4) == 0) {
int width = peek_be(&toybuf[16], 4);
int height = peek_be(&toybuf[20], 4);
int bits = toybuf[24] & 0xff;
int type = toybuf[25] & 0xff;
int interlaced = toybuf[28] & 0xff;
xprintf(", %d x %d, %d-bit/%s, %s", width, height, bits,
png_color_type(type),
interlaced ? "interlaced" : "non-interlaced");
}
xputs("");
}
static void do_gif_file()
{
// https://www.w3.org/Graphics/GIF/spec-gif89a.txt
int width = peek_le(&toybuf[6], 2);
int height = peek_le(&toybuf[8], 2);
xprintf("GIF image data, %d x %d\n", width, height);
}
static void do_jpeg_file()
{
// TODO: parsing JPEG for width/height is harder than GIF or PNG.
xprintf("JPEG image data\n");
}
static void do_java_class_file()
{
// https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html
int minor = peek_be(&toybuf[4], 2);
int major = peek_be(&toybuf[6], 2);
xprintf("Java class file, version %d.%d\n", major, minor);
}
static void do_regular_file(int fd, char *name)
{
int len = read(fd, toybuf, sizeof(toybuf));
if (len<0) perror_msg("cannot open");
if (len>20 && memcmp(toybuf, "\177ELF", 4) == 0) {
do_elf_file(len);
} else if (len>28 && memcmp(toybuf, "\x89PNG\x0d\x0a\x1a\x0a", 8) == 0) {
do_png_file();
} else if (len>16 && (memcmp(toybuf, "GIF87a", 6) == 0 ||
memcmp(toybuf, "GIF89a", 6) == 0)) {
do_gif_file();
} else if (len>32 && memcmp(toybuf, "\xff\xd8", 2) == 0) {
do_jpeg_file();
} else if (len>8 && memcmp(toybuf, "\xca\xfe\xba\xbe", 4) == 0) {
do_java_class_file();
// TODO: cpio archive.
// TODO: tar archive.
// TODO: zip/jar/apk archive.
} else {
char *what = "ASCII text";
int i;
// TODO: report which interpreter?
if (strncmp(toybuf, "#!", 2) == 0) what = "commands text";
// TODO: try UTF-8 too before falling back to "data".
for (i = 0; i < len; ++i) {
if (!(isprint(toybuf[i]) || isspace(toybuf[i]))) {
what = "data";
break;
}
}
xputs(what);
}
}
static void do_file(int fd, char *name)
{
struct stat sb;
char *what = "unknown";
xprintf("%s: %*s", name, (int)(TT.max_name_len - strlen(name)), "");
if (!fstat(fd, &sb)) what = "cannot open";
if (S_ISREG(sb.st_mode)) {
if (sb.st_size == 0) what = "empty";
else {
do_regular_file(fd, name);
return;
}
} 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_ISFIFO(sb.st_mode)) what = "fifo";
else if (S_ISSOCK(sb.st_mode)) what = "socket";
else if (S_ISLNK(sb.st_mode)) what = "symbolic link";
xputs(what);
}
static void init_max_name_len()
{
char **name;
int name_len;
for (name = toys.optargs; *name; ++name) {
name_len = strlen(*name);
if (name_len > TT.max_name_len) TT.max_name_len = name_len;
}
}
void file_main(void)
{
init_max_name_len();
loopfiles(toys.optargs, do_file);
}
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