1 /* file.c - describe file type
3 * Copyright 2016 The Android Open Source Project
5 * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/file.html
7 USE_FILE(NEWTOY(file, "<1hL[!hL]", TOYFLAG_USR|TOYFLAG_BIN))
13 usage: file [-hL] [file...]
15 Examine the given files and describe their content types.
17 -h don't follow symlinks (default)
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)
32 int endian = toybuf[5], bits = toybuf[4], i, j;
33 int64_t (*elf_int)(void *ptr, unsigned size) = peek_le;
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 {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 {0xbaab, "microblaze"}, {8, "mips"}, {10, "mips-old"}, {89, "mn10300"},
42 {0xbeef, "mn10300-old"}, {113, "nios2"}, {92, "openrisc"},
43 {0x8472, "openrisc-old"}, {15, "parisc"}, {20, "ppc"}, {21, "ppc64"},
44 {22, "s390"}, {0xa390, "s390-old"}, {135, "score"}, {42, "sh"},
45 {2, "sparc"}, {18, "sparc8+"}, {43, "sparc9"}, {188, "tile"},
46 {191, "tilegx"}, {3, "386"}, {6, "486"}, {62, "x86-64"}, {94, "xtensa"},
47 {0xabc7, "xtensa-old"}
53 int phentsize, phnum, shsize, shnum;
57 // executable (ELF says this is short but reality says byte, not MSB swapped)
59 if (i == 1) printf("relocatable");
60 else if (i == 2) printf("executable");
61 else if (i == 3) printf("shared object");
62 else if (i == 4) printf("core dump");
63 else printf("(bad type %d)", i);
67 if (bits == 1) printf("32-bit ");
68 else if (bits == 2) printf("64-bit ");
70 printf("(bad class %d) ", bits);
75 if (endian == 1) printf("LSB ");
76 else if (endian == 2) {
80 printf("(bad endian %d) \n", endian);
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);
91 // If what we've seen so far doesn't seem consistent, bail.
92 if (!((bits&1)==bits && endian)) {
93 printf(", corrupt?\n");
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);
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);
112 map = mmap(0, sb->st_size, PROT_READ, MAP_SHARED, fd, 0);
113 if (!map) perror_exit("mmap");
115 // We need to read the phdrs for dynamic vs static.
116 // (Note: fields got reordered for 64 bit)
117 for (i = 0; i<phnum; i++) {
118 char *phdr = map+phoff+i*phentsize;
119 int p_type = elf_int(phdr, 4);
120 long long p_offset, p_filesz;
122 if (p_type==2 /*PT_DYNAMIC*/) dynamic = 1;
123 if (p_type!=3 /*PT_INTERP*/ && p_type!=4 /*PT_NOTE*/) continue;
126 p_offset = elf_int(phdr+4*j, 4*j);
127 p_filesz = elf_int(phdr+16*j, 4*j);
129 if (p_type==3 /*PT_INTERP*/)
130 printf(", dynamic (%.*s)", (int)p_filesz, map+p_offset);
132 if (!dynamic) printf(", static");
134 // We need to read the shdrs for stripped/unstripped and any notes.
135 // Notes are in program headers *and* section headers, but some files don't
136 // contain program headers, so we prefer to check here.
137 // (Note: fields got reordered for 64 bit)
138 for (i = 0; i<shnum; i++) {
139 char *shdr = map+shoff+i*shsize;
140 int sh_type = elf_int(shdr+4, 4);
141 long sh_offset = elf_int(shdr+8+8*(bits+1), 4*(bits+1));
142 int sh_size = elf_int(shdr+8+12*(bits+1), 4);
144 if (sh_type == 2 /*SHT_SYMTAB*/) {
147 } else if (sh_type == 7 /*SHT_NOTE*/) {
148 char *note = map+sh_offset;
150 // An ELF note is a sequence of entries, each consisting of an
151 // ndhr followed by n_namesz+n_descsz bytes of data (each of those
152 // rounded up to the next 4 bytes, without this being reflected in
153 // the header byte counts themselves).
154 while (sh_size >= 3*4) { // Don't try to read a truncated entry.
155 int n_namesz = elf_int(note, 4);
156 int n_descsz = elf_int(note+4, 4);
157 int n_type = elf_int(note+8, 4);
158 int notesz = 3*4 + ((n_namesz+3)&~3) + ((n_descsz+3)&~3);
160 if (n_namesz==4 && !memcmp(note+12, "GNU", 4)) {
161 if (n_type==3 /*NT_GNU_BUILD_ID*/) {
162 printf(", BuildID=");
163 for (j = 0; j < n_descsz; ++j) printf("%02x", note[16 + j]);
165 } else if (n_namesz==8 && !memcmp(note+12, "Android", 8)) {
166 if (n_type==1 /*.android.note.ident*/) {
167 printf(", for Android %d", (int)elf_int(note+20, 4));
169 printf(", built by NDK %.64s (%.64s)", note+24, note+24+64);
178 printf(", %sstripped", stripped ? "" : "not ");
181 munmap(map, sb->st_size);
184 static void do_regular_file(int fd, char *name, struct stat *sb)
187 int len = read(fd, s = toybuf, sizeof(toybuf)-256);
190 if (len<0) perror_msg("%s", name);
192 if (len>40 && strstart(&s, "\177ELF")) do_elf_file(fd, sb);
193 else if (len>=8 && strstart(&s, "!<arch>\n")) xprintf("ar archive\n");
194 else if (len>28 && strstart(&s, "\x89PNG\x0d\x0a\x1a\x0a")) {
195 // PNG is big-endian: https://www.w3.org/TR/PNG/#7Integers-and-byte-order
196 int chunk_length = peek_be(s, 4);
198 xprintf("PNG image data");
200 // The IHDR chunk comes first: https://www.w3.org/TR/PNG/#11IHDR
202 if (chunk_length == 13 && strstart(&s, "IHDR")) {
203 // https://www.w3.org/TR/PNG/#6Colour-values
204 char *c = 0, *colors[] = {"grayscale", 0, "color RGB", "indexed color",
205 "grayscale with alpha", 0, "color RGBA"};
207 if (s[9]<ARRAY_LEN(colors)) c = colors[s[9]];
208 if (!c) c = "unknown";
210 xprintf(", %d x %d, %d-bit/%s, %sinterlaced", (int)peek_be(s, 4),
211 (int)peek_be(s+4, 4), s[8], c, s[12] ? "" : "non-");
216 // https://www.w3.org/Graphics/GIF/spec-gif89a.txt
217 } else if (len>16 && (strstart(&s, "GIF87a") || strstart(&s, "GIF89a")))
218 xprintf("GIF image data, %d x %d\n",
219 (int)peek_le(s, 2), (int)peek_le(s+8, 2));
221 // TODO: parsing JPEG for width/height is harder than GIF or PNG.
222 else if (len>32 && memcmp(toybuf, "\xff\xd8", 2) == 0)
223 xprintf("JPEG image data\n");
225 // https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html
226 else if (len>8 && strstart(&s, "\xca\xfe\xba\xbe"))
227 xprintf("Java class file, version %d.%d\n",
228 (int)peek_be(s+2, 2), (int)peek_be(s, 2));
230 // https://people.freebsd.org/~kientzle/libarchive/man/cpio.5.txt
231 // the lengths for cpio are size of header + 9 bytes, since any valid
232 // cpio archive ends with a record for "TARGET!!!"
233 else if (len>85 && strstart(&s, "07070")) {
234 char *cpioformat = "unknown type";
235 if (toybuf[5] == '7') cpioformat = "pre-SVR4 or odc";
236 else if (toybuf[5] == '1') cpioformat = "SVR4 with no CRC";
237 else if (toybuf[5] == '2') cpioformat = "SVR4 with CRC";
238 xprintf("ASCII cpio archive (%s)\n", cpioformat);
239 } else if (len>33 && (magic=peek(&s,2), magic==0143561 || magic==070707)) {
240 if (magic == 0143561) printf("byte-swapped ");
241 xprintf("cpio archive\n");
242 // tar archive (ustar/pax or gnu)
243 } else if (len>500 && !strncmp(s+257, "ustar", 5)) {
244 xprintf("POSIX tar archive%s\n", strncmp(s+262," ",2)?"":" (GNU)");
245 // zip/jar/apk archive, ODF/OOXML document, or such
246 } else if (len>5 && strstart(&s, "PK\03\04")) {
247 int ver = (int)(char)(toybuf[4]);
248 xprintf("Zip archive data");
250 xprintf(", requires at least v%d.%d to extract", ver/10, ver%10);
256 // If shell script, report which interpreter
257 if (len>3 && strstart(&s, "#!")) {
258 // Whitespace is allowed between the #! and the interpreter
259 while (isspace(*s)) s++;
260 if (strstart(&s, "/usr/bin/env")) while (isspace(*s)) s++;
261 for (what = s; (s-toybuf)<len && !isspace(*s); s++);
262 strcpy(s, " script");
264 // Distinguish ASCII text, UTF-8 text, or data
265 } else for (i = 0; i<len; ++i) {
266 if (!(isprint(toybuf[i]) || isspace(toybuf[i]))) {
268 if ((bytes = mbrtowc(&wc, s+i, len-i, 0))>0 && wcwidth(wc)>=0) {
270 if (!what) what = "UTF-8 text";
277 xputs(what ? what : "ASCII text");
285 for (arg = toys.optargs; *arg; ++arg) {
286 int name_len = strlen(*arg);
288 if (name_len > TT.max_name_len) TT.max_name_len = name_len;
291 // Can't use loopfiles here because it doesn't call function when can't open
292 for (arg = toys.optargs; *arg; arg++) {
293 char *name = *arg, *what = "cannot open";
295 int fd = !strcmp(name, "-");
297 xprintf("%s: %*s", name, (int)(TT.max_name_len - strlen(name)), "");
299 if (fd || !((toys.optflags & FLAG_L) ? stat : lstat)(name, &sb)) {
300 if (fd || S_ISREG(sb.st_mode)) {
301 if (!sb.st_size) what = "empty";
302 else if ((fd = openro(name, O_RDONLY)) != -1) {
303 do_regular_file(fd, name, &sb);
307 } else if (S_ISFIFO(sb.st_mode)) what = "fifo";
308 else if (S_ISBLK(sb.st_mode)) what = "block special";
309 else if (S_ISCHR(sb.st_mode)) what = "character special";
310 else if (S_ISDIR(sb.st_mode)) what = "directory";
311 else if (S_ISSOCK(sb.st_mode)) what = "socket";
312 else if (S_ISLNK(sb.st_mode)) what = "symbolic link";
313 else what = "unknown";