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1 /* file.c - describe file type
2  *
3  * Copyright 2016 The Android Open Source Project
4  *
5  * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/file.html
6 
7 USE_FILE(NEWTOY(file, "<1hL[!hL]", TOYFLAG_USR|TOYFLAG_BIN))
8 
9 config FILE
10   bool "file"
11   default y
12   help
13     usage: file [-hL] [file...]
14 
15     Examine the given files and describe their content types.
16 
17     -h	don't follow symlinks (default)
18     -L	follow symlinks
19 */
20 
21 #define FOR_file
22 #include "toys.h"
23 
GLOBALS(int max_name_len;)24 GLOBALS(
25   int max_name_len;
26 )
27 
28 // We don't trust elf.h to be there, and two codepaths for 32/64 is awkward
29 // anyway, so calculate struct offsets manually. (It's a fixed ABI.)
30 static void do_elf_file(int fd, struct stat *sb)
31 {
32   int endian = toybuf[5], bits = toybuf[4], i, j;
33   int64_t (*elf_int)(void *ptr, unsigned size);
34   // Values from include/linux/elf-em.h (plus arch/*/include/asm/elf.h)
35   // Names are linux/arch/ directory (sometimes before 32/64 bit merges)
36   struct {int val; char *name;} type[] = {{0x9026, "alpha"}, {93, "arc"},
37     {195, "arcv2"}, {40, "arm"}, {183, "arm64"}, {0x18ad, "avr32"},
38     {247, "bpf"}, {106, "blackfin"}, {140, "c6x"}, {23, "cell"}, {76, "cris"},
39     {0x5441, "frv"}, {46, "h8300"}, {164, "hexagon"}, {50, "ia64"},
40     {88, "m32r"}, {0x9041, "m32r"}, {4, "m68k"}, {174, "metag"},
41     {189, "microblaze"}, {0xbaab, "microblaze-old"}, {8, "mips"},
42     {10, "mips-old"}, {89, "mn10300"}, {0xbeef, "mn10300-old"}, {113, "nios2"},
43     {92, "openrisc"}, {0x8472, "openrisc-old"}, {15, "parisc"}, {20, "ppc"},
44     {21, "ppc64"}, {22, "s390"}, {0xa390, "s390-old"}, {135, "score"},
45     {42, "sh"}, {2, "sparc"}, {18, "sparc8+"}, {43, "sparc9"}, {188, "tile"},
46     {191, "tilegx"}, {3, "386"}, {6, "486"}, {62, "x86-64"}, {94, "xtensa"},
47     {0xabc7, "xtensa-old"}
48   };
49   int dynamic = 0;
50   int stripped = 1;
51   char *map;
52   off_t phoff, shoff;
53   int phentsize, phnum, shsize, shnum;
54 
55   printf("ELF ");
56   elf_int = (endian==2) ? peek_be : peek_le;
57 
58   // executable type
59   i = elf_int(toybuf+16, 2);
60   if (i == 1) printf("relocatable");
61   else if (i == 2) printf("executable");
62   else if (i == 3) printf("shared object");
63   else if (i == 4) printf("core dump");
64   else printf("(bad type %d)", i);
65   if (elf_int(toybuf+36+12*(bits==2), 4) & 0x8000) printf(" (fdpic)");
66   printf(", ");
67 
68   // "64-bit"
69   if (bits == 1) printf("32-bit ");
70   else if (bits == 2) printf("64-bit ");
71   else {
72     printf("(bad class %d) ", bits);
73     bits = 0;
74   }
75 
76   // "LSB"
77   if (endian == 1) printf("LSB ");
78   else if (endian == 2) printf("MSB ");
79   else {
80     printf("(bad endian %d) \n", endian);
81     endian = 0;
82   }
83 
84   // e_machine, ala "x86", from big table above
85   j = elf_int(toybuf+18, 2);
86   for (i = 0; i<ARRAY_LEN(type); i++) if (j==type[i].val) break;
87   if (i<ARRAY_LEN(type)) printf("%s", type[i].name);
88   else printf("(unknown arch %d)", j);
89 
90   bits--;
91   // If what we've seen so far doesn't seem consistent, bail.
92   if (!((bits&1)==bits && endian)) {
93     printf(", corrupt?\n");
94     return;
95   }
96 
97   // Stash what we need from the header; it's okay to reuse toybuf after this.
98   phentsize = elf_int(toybuf+42+12*bits, 2);
99   phnum = elf_int(toybuf+44+12*bits, 2);
100   phoff = elf_int(toybuf+28+4*bits, 4+4*bits);
101   shsize = elf_int(toybuf+46+12*bits, 2);
102   shnum = elf_int(toybuf+48+12*bits, 2);
103   shoff = elf_int(toybuf+32+8*bits, 4+4*bits);
104 
105   // With binutils, phentsize seems to only be non-zero if phnum is non-zero.
106   // Such ELF files are rare, but do exist. (Android's crtbegin files, say.)
107   if (phnum && (phentsize != 32+24*bits)) {
108     printf(", corrupt phentsize %d?\n", phentsize);
109     return;
110   }
111 
112   map = xmmap(0, sb->st_size, PROT_READ, MAP_SHARED, fd, 0);
113 
114   // We need to read the phdrs for dynamic vs static.
115   // (Note: fields got reordered for 64 bit)
116   for (i = 0; i<phnum; i++) {
117     char *phdr = map+phoff+i*phentsize;
118     int p_type = elf_int(phdr, 4);
119     long long p_offset, p_filesz;
120 
121     if (p_type==2 /*PT_DYNAMIC*/) dynamic = 1;
122     if (p_type!=3 /*PT_INTERP*/ && p_type!=4 /*PT_NOTE*/) continue;
123 
124     j = bits+1;
125     p_offset = elf_int(phdr+4*j, 4*j);
126     p_filesz = elf_int(phdr+16*j, 4*j);
127 
128     if (p_type==3 /*PT_INTERP*/)
129       printf(", dynamic (%.*s)", (int)p_filesz, map+p_offset);
130   }
131   if (!dynamic) printf(", static");
132 
133   // We need to read the shdrs for stripped/unstripped and any notes.
134   // Notes are in program headers *and* section headers, but some files don't
135   // contain program headers, so we prefer to check here.
136   // (Note: fields got reordered for 64 bit)
137   for (i = 0; i<shnum; i++) {
138     char *shdr = map+shoff+i*shsize;
139     int sh_type = elf_int(shdr+4, 4);
140     long sh_offset = elf_int(shdr+8+8*(bits+1), 4*(bits+1));
141     int sh_size = elf_int(shdr+8+12*(bits+1), 4);
142 
143     if (sh_type == 2 /*SHT_SYMTAB*/) {
144       stripped = 0;
145       break;
146     } else if (sh_type == 7 /*SHT_NOTE*/) {
147       char *note = map+sh_offset;
148 
149       // An ELF note is a sequence of entries, each consisting of an
150       // ndhr followed by n_namesz+n_descsz bytes of data (each of those
151       // rounded up to the next 4 bytes, without this being reflected in
152       // the header byte counts themselves).
153       while (sh_size >= 3*4) { // Don't try to read a truncated entry.
154         int n_namesz = elf_int(note, 4);
155         int n_descsz = elf_int(note+4, 4);
156         int n_type = elf_int(note+8, 4);
157         int notesz = 3*4 + ((n_namesz+3)&~3) + ((n_descsz+3)&~3);
158 
159         if (n_namesz==4 && !memcmp(note+12, "GNU", 4)) {
160           if (n_type==3 /*NT_GNU_BUILD_ID*/) {
161             printf(", BuildID=");
162             for (j = 0; j < n_descsz; ++j) printf("%02x", note[16 + j]);
163           }
164         } else if (n_namesz==8 && !memcmp(note+12, "Android", 8)) {
165           if (n_type==1 /*.android.note.ident*/) {
166             printf(", for Android %d", (int)elf_int(note+20, 4));
167             if (n_descsz > 24)
168               printf(", built by NDK %.64s (%.64s)", note+24, note+24+64);
169           }
170         }
171 
172         note += notesz;
173         sh_size -= notesz;
174       }
175     }
176   }
177   printf(", %sstripped", stripped ? "" : "not ");
178   xputc('\n');
179 
180   munmap(map, sb->st_size);
181 }
182 
do_regular_file(int fd,char * name,struct stat * sb)183 static void do_regular_file(int fd, char *name, struct stat *sb)
184 {
185   char *s;
186   int len = read(fd, s = toybuf, sizeof(toybuf)-256);
187   int magic;
188 
189   if (len<0) perror_msg("%s", name);
190 
191   if (len>40 && strstart(&s, "\177ELF")) do_elf_file(fd, sb);
192   else if (len>=8 && strstart(&s, "!<arch>\n")) xprintf("ar archive\n");
193   else if (len>28 && strstart(&s, "\x89PNG\x0d\x0a\x1a\x0a")) {
194     // PNG is big-endian: https://www.w3.org/TR/PNG/#7Integers-and-byte-order
195     int chunk_length = peek_be(s, 4);
196 
197     xprintf("PNG image data");
198 
199     // The IHDR chunk comes first: https://www.w3.org/TR/PNG/#11IHDR
200     s += 4;
201     if (chunk_length == 13 && strstart(&s, "IHDR")) {
202       // https://www.w3.org/TR/PNG/#6Colour-values
203       char *c = 0, *colors[] = {"grayscale", 0, "color RGB", "indexed color",
204                                 "grayscale with alpha", 0, "color RGBA"};
205 
206       if (s[9]<ARRAY_LEN(colors)) c = colors[s[9]];
207       if (!c) c = "unknown";
208 
209       xprintf(", %d x %d, %d-bit/%s, %sinterlaced", (int)peek_be(s, 4),
210         (int)peek_be(s+4, 4), s[8], c, s[12] ? "" : "non-");
211     }
212 
213     xputc('\n');
214 
215   // https://www.w3.org/Graphics/GIF/spec-gif89a.txt
216   } else if (len>16 && (strstart(&s, "GIF87a") || strstart(&s, "GIF89a")))
217     xprintf("GIF image data, %d x %d\n",
218       (int)peek_le(s, 2), (int)peek_le(s+8, 2));
219 
220   // TODO: parsing JPEG for width/height is harder than GIF or PNG.
221   else if (len>32 && !memcmp(toybuf, "\xff\xd8", 2)) xputs("JPEG image data");
222 
223   // https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html
224   else if (len>8 && strstart(&s, "\xca\xfe\xba\xbe"))
225     xprintf("Java class file, version %d.%d\n",
226       (int)peek_be(s+2, 2), (int)peek_be(s, 2));
227 
228   // https://people.freebsd.org/~kientzle/libarchive/man/cpio.5.txt
229   // the lengths for cpio are size of header + 9 bytes, since any valid
230   // cpio archive ends with a record for "TARGET!!!"
231   else if (len>85 && strstart(&s, "07070")) {
232     char *cpioformat = "unknown type";
233 
234     if (toybuf[5] == '7') cpioformat = "pre-SVR4 or odc";
235     else if (toybuf[5] == '1') cpioformat = "SVR4 with no CRC";
236     else if (toybuf[5] == '2') cpioformat = "SVR4 with CRC";
237     xprintf("ASCII cpio archive (%s)\n", cpioformat);
238   } else if (len>33 && (magic=peek(&s,2), magic==0143561 || magic==070707)) {
239     if (magic == 0143561) printf("byte-swapped ");
240     xprintf("cpio archive\n");
241   // tar archive (ustar/pax or gnu)
242   } else if (len>500 && !strncmp(s+257, "ustar", 5))
243     xprintf("POSIX tar archive%s\n", strncmp(s+262,"  ",2)?"":" (GNU)");
244   // zip/jar/apk archive, ODF/OOXML document, or such
245   else if (len>5 && strstart(&s, "PK\03\04")) {
246     int ver = toybuf[4];
247 
248     xprintf("Zip archive data");
249     if (ver) xprintf(", requires at least v%d.%d to extract", ver/10, ver%10);
250     xputc('\n');
251   } else if (len>4 && strstart(&s, "BZh") && isdigit(*s))
252     xprintf("bzip2 compressed data, block size = %c00k\n", *s);
253   else if (len>10 && strstart(&s, "\x1f\x8b")) xputs("gzip compressed data");
254   else if (len>32 && !memcmp(s+1, "\xfa\xed\xfe", 3)) {
255     int bit = s[0]=='\xce'?32:64;
256     char *what;
257 
258     xprintf("Mach-O %d-bit ", bit);
259 
260     if (s[4] == 7) what = (bit==32)?"x86":"x86-";
261     else if (s[4] == 12) what = "arm";
262     else if (s[4] == 18) what = "ppc";
263     else what = NULL;
264     if (what) xprintf("%s%s ", what, (bit==32)?"":"64");
265     else xprintf("(bad arch %d) ", s[4]);
266 
267     if (s[12] == 1) what = "object";
268     else if (s[12] == 2) what = "executable";
269     else if (s[12] == 6) what = "shared library";
270     else what = NULL;
271     if (what) xprintf("%s\n", what);
272     else xprintf("(bad type %d)\n", s[9]);
273   } else if (len>36 && !memcmp(s, "OggS\x00\x02", 6)) {
274     xprintf("Ogg data");
275     // https://wiki.xiph.org/MIMETypesCodecs
276     if (!memcmp(s+28, "CELT    ", 8)) xprintf(", celt audio");
277     if (!memcmp(s+28, "CMML    ", 8)) xprintf(", cmml text");
278     if (!memcmp(s+28, "BBCD\0", 5)) xprintf(", dirac video");
279     if (!memcmp(s+28, "\177FLAC", 5)) xprintf(", flac audio");
280     if (!memcmp(s+28, "\x8bJNG\r\n\x1a\n", 8)) xprintf(", jng video");
281     if (!memcmp(s+28, "\x80kate\0\0\0", 8)) xprintf(", kate text");
282     if (!memcmp(s+28, "OggMIDI\0", 8)) xprintf(", midi text");
283     if (!memcmp(s+28, "\x8aMNG\r\n\x1a\n", 8)) xprintf(", mng video");
284     if (!memcmp(s+28, "OpusHead", 8)) xprintf(", opus audio");
285     if (!memcmp(s+28, "PCM     ", 8)) xprintf(", pcm audio");
286     if (!memcmp(s+28, "\x89PNG\r\n\x1a\n", 8)) xprintf(", png video");
287     if (!memcmp(s+28, "Speex   ", 8)) xprintf(", speex audio");
288     if (!memcmp(s+28, "\x80theora", 7)) xprintf(", theora video");
289     if (!memcmp(s+28, "\x01vorbis", 7)) xprintf(", vorbis audio");
290     if (!memcmp(s+28, "YUV4MPEG", 8)) xprintf(", yuv4mpeg video");
291     xputc('\n');
292   } else if (len>12 && !memcmp(s, "\x00\x01\x00\x00", 4)) {
293     xputs("TrueType font");
294   } else if (len>12 && !memcmp(s, "ttcf\x00", 5)) {
295     xprintf("TrueType font collection, version %d, %d fonts\n",
296             (int)peek_be(s+4, 2), (int)peek_be(s+8, 4));
297   } else if (len>4 && !memcmp(s, "BC\xc0\xde", 4)) {
298     xputs("LLVM IR bitcode");
299   } else if (strstart(&s, "-----BEGIN CERTIFICATE-----")) {
300     xputs("PEM certificate");
301 
302   // https://msdn.microsoft.com/en-us/library/windows/desktop/ms680547(v=vs.85).aspx
303   } else if (len>0x70 && !memcmp(s, "MZ", 2) &&
304       (magic=peek_le(s+0x3c,4))<len-4 && !memcmp(s+magic, "\x50\x45\0\0", 4)) {
305     xprintf("MS PE32%s executable %s", (peek_le(s+magic+24, 2)==0x20b)?"+":"",
306         (peek_le(s+magic+22, 2)&0x2000)?"(DLL) ":"");
307     if (peek_le(s+magic+20, 2)>70) {
308       char *types[] = {0, "native", "GUI", "console", "OS/2", "driver", "CE",
309           "EFI", "EFI boot", "EFI runtime", "EFI ROM", "XBOX", 0, "boot"};
310       int type = peek_le(s+magic+92, 2);
311       char *name = (type>0 && type<ARRAY_LEN(types))?types[type]:0;
312 
313       xprintf("(%s) ", name?name:"unknown");
314     }
315     xprintf("%s\n", (peek_le(s+magic+4, 2)==0x14c)?"x86":"x86-64");
316   } else {
317     char *what = 0;
318     int i, bytes;
319 
320     // If shell script, report which interpreter
321     if (len>3 && strstart(&s, "#!")) {
322       // Whitespace is allowed between the #! and the interpreter
323       while (isspace(*s)) s++;
324       if (strstart(&s, "/usr/bin/env")) while (isspace(*s)) s++;
325       for (what = s; (s-toybuf)<len && !isspace(*s); s++);
326       strcpy(s, " script");
327 
328     // Distinguish ASCII text, UTF-8 text, or data
329     } else for (i = 0; i<len; ++i) {
330       if (!(isprint(toybuf[i]) || isspace(toybuf[i]))) {
331         wchar_t wc;
332         if ((bytes = utf8towc(&wc, s+i, len-i))>0 && wcwidth(wc)>=0) {
333           i += bytes-1;
334           if (!what) what = "UTF-8 text";
335         } else {
336           what = "data";
337           break;
338         }
339       }
340     }
341     xputs(what ? what : "ASCII text");
342   }
343 }
344 
file_main(void)345 void file_main(void)
346 {
347   char **arg;
348 
349   for (arg = toys.optargs; *arg; ++arg) {
350     int name_len = strlen(*arg);
351 
352     if (name_len > TT.max_name_len) TT.max_name_len = name_len;
353   }
354 
355   // Can't use loopfiles here because it doesn't call function when can't open
356   for (arg = toys.optargs; *arg; arg++) {
357     char *name = *arg, *what = "cannot open";
358     struct stat sb;
359     int fd = !strcmp(name, "-");
360 
361     xprintf("%s: %*s", name, (int)(TT.max_name_len - strlen(name)), "");
362 
363     if (fd || !((toys.optflags & FLAG_L) ? stat : lstat)(name, &sb)) {
364       if (fd || S_ISREG(sb.st_mode)) {
365         if (!sb.st_size) what = "empty";
366         else if ((fd = openro(name, O_RDONLY)) != -1) {
367           do_regular_file(fd, name, &sb);
368           if (fd) close(fd);
369           continue;
370         }
371       } else if (S_ISFIFO(sb.st_mode)) what = "fifo";
372       else if (S_ISBLK(sb.st_mode)) what = "block special";
373       else if (S_ISCHR(sb.st_mode)) what = "character special";
374       else if (S_ISDIR(sb.st_mode)) what = "directory";
375       else if (S_ISSOCK(sb.st_mode)) what = "socket";
376       else if (S_ISLNK(sb.st_mode)) what = "symbolic link";
377       else what = "unknown";
378     }
379 
380     xputs(what);
381   }
382 }
383