305 lines
10 KiB
C
305 lines
10 KiB
C
/* file.c - describe file type
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*
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* Copyright 2016 The Android Open Source Project
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*
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* See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/file.html
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USE_FILE(NEWTOY(file, "<1hL[!hL]", TOYFLAG_USR|TOYFLAG_BIN))
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config FILE
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bool "file"
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default y
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help
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usage: file [-hL] [file...]
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Examine the given files and describe their content types.
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-h don't follow symlinks (default)
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-L follow symlinks
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*/
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#define FOR_file
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#include "toys.h"
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GLOBALS(
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int max_name_len;
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)
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// We don't trust elf.h to be there, and two codepaths for 32/64 is awkward
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// anyway, so calculate struct offsets manually. (It's a fixed ABI.)
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static void do_elf_file(int fd, struct stat *sb)
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{
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int endian = toybuf[5], bits = toybuf[4], i, j;
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int64_t (*elf_int)(void *ptr, unsigned size) = peek_le;
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// Values from include/linux/elf-em.h (plus arch/*/include/asm/elf.h)
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// Names are linux/arch/ directory (sometimes before 32/64 bit merges)
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struct {int val; char *name;} type[] = {{0x9026, "alpha"}, {93, "arc"},
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{195, "arcv2"}, {40, "arm"}, {183, "arm64"}, {0x18ad, "avr32"},
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{106, "blackfin"}, {140, "c6x"}, {23, "cell"}, {76, "cris"},
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{0x5441, "frv"}, {46, "h8300"}, {164, "hexagon"}, {50, "ia64"},
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{88, "m32r"}, {0x9041, "m32r"}, {4, "m68k"}, {174, "metag"},
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{0xbaab, "microblaze"}, {8, "mips"}, {10, "mips-old"}, {89, "mn10300"},
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{0xbeef, "mn10300-old"}, {113, "nios2"}, {92, "openrisc"},
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{0x8472, "openrisc-old"}, {15, "parisc"}, {20, "ppc"}, {21, "ppc64"},
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{22, "s390"}, {0xa390, "s390-old"}, {135, "score"}, {42, "sh"},
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{2, "sparc"}, {18, "sparc8+"}, {43, "sparc9"}, {188, "tile"},
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{191, "tilegx"}, {3, "386"}, {6, "486"}, {62, "x86-64"}, {94, "xtensa"},
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{0xabc7, "xtensa-old"}
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};
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int dynamic = 0;
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int stripped = 1;
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char *map;
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off_t phoff, shoff;
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int phsize, phnum, shsize, shnum;
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printf("ELF ");
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// executable (ELF says this is short but reality says byte, not MSB swapped)
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i = toybuf[16];
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if (i == 1) printf("relocatable");
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else if (i == 2) printf("executable");
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else if (i == 3) printf("shared object");
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else if (i == 4) printf("core dump");
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else printf("(bad type %d)", i);
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printf(", ");
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// "64-bit"
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if (bits == 1) printf("32-bit ");
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else if (bits == 2) printf("64-bit ");
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else {
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printf("(bad class %d) ", bits);
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bits = 0;
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}
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// "LSB"
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if (endian == 1) printf("LSB ");
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else if (endian == 2) {
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printf("MSB ");
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elf_int = peek_be;
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} else {
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printf("(bad endian %d) \n", endian);
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endian = 0;
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}
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// e_machine, ala "x86", from big table above
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j = elf_int(toybuf+18, 2);
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for (i = 0; i<ARRAY_LEN(type); i++) if (j==type[i].val) break;
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if (i<ARRAY_LEN(type)) printf("%s", type[i].name);
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else printf("(unknown arch %d)", j);
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bits--;
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// If what we've seen so far doesn't seem consistent, bail.
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if (!((bits&1)==bits && endian &&
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(i = elf_int(toybuf+42+12*bits, 2)) == 32+24*bits)) {
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printf(", corrupt?\n");
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return;
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}
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// Stash what we need from the header; it's okay to reuse toybuf after this.
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phsize = i;
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phnum = elf_int(toybuf+44+12*bits, 2);
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phoff = elf_int(toybuf+28+4*bits, 4+4*bits);
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shsize = elf_int(toybuf+46+12*bits, 2);
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shnum = elf_int(toybuf+48+12*bits, 2);
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shoff = elf_int(toybuf+32+8*bits, 4+4*bits);
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map = mmap(0, sb->st_size, PROT_READ, MAP_SHARED, fd, 0);
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if (!map) perror_exit("mmap");
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// We need to read the phdrs for dynamic vs static and any notes.
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// (Note: fields got reordered for 64 bit)
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for (i = 0; i<phnum; i++) {
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char *phdr = map+phoff+i*phsize;
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int p_type = elf_int(phdr, 4);
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long long p_offset, p_filesz;
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if (p_type==2 /*PT_DYNAMIC*/) dynamic = 1;
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if (p_type!=3 /*PT_INTERP*/ && p_type!=4 /*PT_NOTE*/) continue;
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j = bits+1;
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p_offset = elf_int(phdr+4*j, 4*j);
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p_filesz = elf_int(phdr+16*j, 4*j);
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if (p_type==3 /*PT_INTERP*/)
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printf(", dynamic (%.*s)", (int)p_filesz, map+p_offset);
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else {
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char *note = map+p_offset;
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// A PT_NOTE phdr is a sequence of entries, each consisting of an
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// ndhr followed by n_namesz+n_descsz bytes of data (each of those
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// rounded up to the next 4 bytes, without this being reflected in
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// the header byte counts themselves).
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while (p_filesz >= 3*4) { // Don't try to read a truncated entry.
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int n_namesz = elf_int(note, 4);
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int n_descsz = elf_int(note+4, 4);
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int n_type = elf_int(note+8, 4);
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int notesz = 3*4 + ((n_namesz+3)&~3) + ((n_descsz+3)&~3);
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if (n_namesz==4 && !memcmp(note+12, "GNU", 4)) {
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if (n_type == 3 /*NT_GNU_BUILD_ID*/) {
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printf(", BuildID=");
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for (j = 0; j < n_descsz; ++j) printf("%02x", note[16 + j]);
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}
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} else if (n_namesz==8 && !memcmp(note+12, "Android", 8)) {
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if (n_type==1) printf(", for Android %d", (int)elf_int(note+20, 4));
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}
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note += notesz;
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p_filesz -= notesz;
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}
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}
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}
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if (!dynamic) printf(", static");
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// We need to read the shdrs for stripped/unstripped.
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// (Note: fields got reordered for 64 bit)
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for (i = 0; i<shnum; i++) {
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char *shdr = map+shoff+i*shsize;
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int sh_type = elf_int(shdr+4, 4);
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if (sh_type == 2 /*SHT_SYMTAB*/) {
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stripped = 0;
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break;
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}
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}
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printf(", %sstripped", stripped ? "" : "not ");
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xputc('\n');
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munmap(map, sb->st_size);
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}
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static void do_regular_file(int fd, char *name, struct stat *sb)
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{
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char *s;
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int len = read(fd, s = toybuf, sizeof(toybuf)-256);
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int magic;
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if (len<0) perror_msg("%s", name);
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if (len>40 && strstart(&s, "\177ELF")) do_elf_file(fd, sb);
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else if (len>=8 && strstart(&s, "!<arch>\n")) xprintf("ar archive\n");
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else if (len>28 && strstart(&s, "\x89PNG\x0d\x0a\x1a\x0a")) {
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// PNG is big-endian: https://www.w3.org/TR/PNG/#7Integers-and-byte-order
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int chunk_length = peek_be(s, 4);
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xprintf("PNG image data");
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// The IHDR chunk comes first: https://www.w3.org/TR/PNG/#11IHDR
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s += 4;
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if (chunk_length == 13 && strstart(&s, "IHDR")) {
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// https://www.w3.org/TR/PNG/#6Colour-values
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char *c = 0, *colors[] = {"grayscale", 0, "color RGB", "indexed color",
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"grayscale with alpha", 0, "color RGBA"};
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if (s[9]<ARRAY_LEN(colors)) c = colors[s[9]];
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if (!c) c = "unknown";
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xprintf(", %d x %d, %d-bit/%s, %sinterlaced", (int)peek_be(s, 4),
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(int)peek_be(s+4, 4), s[8], c, s[12] ? "" : "non-");
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}
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xputc('\n');
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// https://www.w3.org/Graphics/GIF/spec-gif89a.txt
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} else if (len>16 && (strstart(&s, "GIF87a") || strstart(&s, "GIF89a")))
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xprintf("GIF image data, %d x %d\n",
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(int)peek_le(s, 2), (int)peek_le(s+8, 2));
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// TODO: parsing JPEG for width/height is harder than GIF or PNG.
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else if (len>32 && memcmp(toybuf, "\xff\xd8", 2) == 0)
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xprintf("JPEG image data\n");
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// https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html
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else if (len>8 && strstart(&s, "\xca\xfe\xba\xbe"))
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xprintf("Java class file, version %d.%d\n",
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(int)peek_be(s+2, 2), (int)peek_be(s, 2));
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// https://people.freebsd.org/~kientzle/libarchive/man/cpio.5.txt
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// the lengths for cpio are size of header + 9 bytes, since any valid
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// cpio archive ends with a record for "TARGET!!!"
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else if (len>85 && strstart(&s, "07070")) {
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char *cpioformat = "unknown type";
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if (toybuf[5] == '7') cpioformat = "pre-SVR4 or odc";
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else if (toybuf[5] == '1') cpioformat = "SVR4 with no CRC";
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else if (toybuf[5] == '2') cpioformat = "SVR4 with CRC";
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xprintf("ASCII cpio archive (%s)\n", cpioformat);
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} else if (len>33 && (magic=peek(&s,2), magic==0143561 || magic==070707)) {
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if (magic == 0143561) printf("byte-swapped ");
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xprintf("cpio archive\n");
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// tar archive (ustar/pax or gnu)
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} else if (len>500 && !strncmp(s+257, "ustar", 5)) {
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xprintf("POSIX tar archive%s\n", strncmp(s+262," ",2)?"":" (GNU)");
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// zip/jar/apk archive, ODF/OOXML document, or such
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} else if (len>5 && strstart(&s, "PK\03\04")) {
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int ver = (int)(char)(toybuf[4]);
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xprintf("Zip archive data");
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if (ver)
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xprintf(", requires at least v%d.%d to extract", ver/10, ver%10);
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xputc('\n');
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} else {
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char *what = 0;
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int i, bytes;
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// If shell script, report which interpreter
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if (len>3 && strstart(&s, "#!")) {
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// Whitespace is allowed between the #! and the interpreter
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while (isspace(*s)) s++;
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if (strstart(&s, "/usr/bin/env")) while (isspace(*s)) s++;
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for (what = s; (s-toybuf)<len && !isspace(*s); s++);
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strcpy(s, " script");
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// Distinguish ASCII text, UTF-8 text, or data
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} else for (i = 0; i<len; ++i) {
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if (!(isprint(toybuf[i]) || isspace(toybuf[i]))) {
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wchar_t wc;
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if ((bytes = mbrtowc(&wc, s+i, len-i, 0))>0 && wcwidth(wc)>=0) {
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i += bytes-1;
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if (!what) what = "UTF-8 text";
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} else {
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what = "data";
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break;
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}
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}
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}
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xputs(what ? what : "ASCII text");
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}
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}
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void file_main(void)
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{
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char **arg;
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for (arg = toys.optargs; *arg; ++arg) {
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int name_len = strlen(*arg);
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if (name_len > TT.max_name_len) TT.max_name_len = name_len;
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}
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// Can't use loopfiles here because it doesn't call function when can't open
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for (arg = toys.optargs; *arg; arg++) {
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char *name = *arg, *what = "cannot open";
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struct stat sb;
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int fd = !strcmp(name, "-");
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xprintf("%s: %*s", name, (int)(TT.max_name_len - strlen(name)), "");
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if (fd || !((toys.optflags & FLAG_L) ? stat : lstat)(name, &sb)) {
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if (fd || S_ISREG(sb.st_mode)) {
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if (!sb.st_size) what = "empty";
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else if ((fd = openro(name, O_RDONLY)) != -1) {
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do_regular_file(fd, name, &sb);
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if (fd) close(fd);
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continue;
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}
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} else if (S_ISFIFO(sb.st_mode)) what = "fifo";
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else if (S_ISBLK(sb.st_mode)) what = "block special";
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else if (S_ISCHR(sb.st_mode)) what = "character special";
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else if (S_ISDIR(sb.st_mode)) what = "directory";
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else if (S_ISSOCK(sb.st_mode)) what = "socket";
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else if (S_ISLNK(sb.st_mode)) what = "symbolic link";
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else what = "unknown";
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}
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xputs(what);
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}
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}
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