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Cleanup pass on file.c, and add detection of different ELF architectu…
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…res.
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@landley
landley committed Feb 15, 2016
1 parent 05b7529 commit 0332b60
Showing 1 changed file with 97 additions and 135 deletions.
232 changes: 97 additions & 135 deletions toys/pending/file.c
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Original file line number Diff line number Diff line change
Expand Up @@ -22,177 +22,143 @@ 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");
int elf_endian = toybuf[5], e_type, e_machine, i;
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 name
struct {int val; char *name;} type[] = {{0x9026, "alpha"},
{40, "arm"}, {183, "arm"}, {0x18ad, "avr32"}, {106, "blackfin"},
{76, "cris"}, {0x5441, "frv"}, {46, "h8300"}, {50, "ia64"},//ia intel ftaghn
{88, "m32r"}, {4, "m68k"}, {0xbaab, "microblaze"}, {8, "mips"},
{10, "mips"}, {89, "mn10300"}, {15, "parisc"}, {22, "s390"},
{135, "score"}, {42, "sh"}, {2, "sparc"}, {18, "sparc"}, {43, "sparc"},
{187, "tile"}, {188, "tile"}, {191, "tile"}, {3, "x86"}, {6, "x86"},
{62, "x86"}, {94, "xtensa"}, {0xabc7, "xtensa"}};

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]);
if (toybuf[4] == 1) xprintf("32-bit ");
else if (toybuf[4] == 2) xprintf("64-bit ");
else xprintf("(bad 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);
if (elf_endian == 1) xprintf("LSB ");
else if (elf_endian == 2) {
xprintf("MSB ");
elf_int = peek_be;
} else {
xprintf("(bad endian %d)\n", elf_endian);

// At this point we can't parse remaining fields.
return;
}

// ", executable"
e_type = elf_int(&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(&toybuf[0x12], 2);
for (i = 0; i<ARRAY_LEN(type); i++) if (e_machine == type[i].val) break;
if (i<ARRAY_LEN(type)) xprintf(", %s", type[i].name);
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)");
if (!toybuf[7]) 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"
// ", for Linux 2.6.24"
// ", BuildID[sha1]=SHA"
// ", stripped"

xputs("");
xputc('\n');
}

// https://www.w3.org/TR/PNG/#6Colour-values
static char *png_color_type(int color_type)
static void do_regular_file(int fd, char *name)
{
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";
}
}
char *s;
int len = read(fd, s = toybuf, sizeof(toybuf)-256);

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");
}
if (len<0) perror_msg("%s", name);

xputs("");
}
if (len>20 && strstart(&s, "\177ELF")) {
do_elf_file(len);
} 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);

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("PNG image data");

xprintf("GIF image data, %d x %d\n", width, height);
}
// 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"};

static void do_jpeg_file()
{
// TODO: parsing JPEG for width/height is harder than GIF or PNG.
xprintf("JPEG image data\n");
}
if (s[9]<ARRAY_LEN(colors)) c = colors[s[9]];
if (!c) c = "unknown";

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(", %d x %d, %d-bit/%s, %sinterlaced", (int)peek_be(s, 4),
(int)peek_be(s+4, 4), s[8], c, s[12] ? "" : "non-");
}

xprintf("Java class file, version %d.%d\n", major, minor);
}
xputc('\n');

static void do_regular_file(int fd, char *name)
{
int len = read(fd, toybuf, sizeof(toybuf));
// 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));

if (len<0) perror_msg("cannot open");
// 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");

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();
// 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 = "ASCII text";
int i;
else {
char *what = 0;
int i, bytes;

// TODO: report which interpreter?
if (strncmp(toybuf, "#!", 2) == 0) what = "commands text";
// If shell script, report which interpreter
if (len>3 && strstart(&s, "#!")) {
for (what = s; (s-toybuf)<len && !isspace(*s); s++);
strcpy(s, " script");

// TODO: try UTF-8 too before falling back to "data".
for (i = 0; i < len; ++i) {
// Distinguish ASCII text, UTF-8 text, or data
} else for (i = 0; i<len; ++i) {
if (!(isprint(toybuf[i]) || isspace(toybuf[i]))) {
what = "data";
break;
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);
xputs(what ? what : "ASCII text");
}
}

Expand All @@ -219,19 +185,15 @@ static void do_file(int fd, char *name)
xputs(what);
}

static void init_max_name_len()
void file_main(void)
{
char **name;
int name_len;

for (name = toys.optargs; *name; ++name) {
name_len = strlen(*name);
int 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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