aboutsummaryrefslogtreecommitdiff
path: root/toys/pending/file.c
blob: 18941227737e67f165ce1015a81bed9f1acf49cd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
/* file.c - describe file type
 *
 * Copyright 2016 The Android Open Source Project
 *
 * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/file.html
 *
 * TODO: ar

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;
)

// We don't trust elf.h to be there, and two codepaths for 32/64 is awkward
// anyway, so calculate struct offsets manually. (It's a fixed ABI.)
static void do_elf_file(int fd)
{
  int endian = toybuf[5], bits = toybuf[4], i, j;
  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 (sometimes before 32/64 bit merges)
  struct {int val; char *name;} type[] = {{0x9026, "alpha"}, {93, "arc"},
    {195, "arcv2"}, {40, "arm"}, {183, "arm64"}, {0x18ad, "avr32"},
    {106, "blackfin"}, {140, "c6x"}, {23, "cell"}, {76, "cris"},
    {0x5441, "frv"}, {46, "h8300"}, {164, "hexagon"}, {50, "ia64"},
    {88, "m32r"}, {0x9041, "m32r"}, {4, "m68k"}, {174, "metag"},
    {0xbaab, "microblaze"}, {8, "mips"}, {10, "mips-old"}, {89, "mn10300"},
    {0xbeef, "mn10300-old"}, {113, "nios2"}, {92, "openrisc"},
    {0x8472, "openrisc-old"}, {15, "parisc"}, {20, "ppc"}, {21, "ppc64"},
    {22, "s390"}, {0xa390, "s390-old"}, {135, "score"}, {42, "sh"},
    {2, "sparc"}, {18, "sparc8+"}, {43, "sparc9"}, {188, "tile"},
    {191, "tilegx"}, {3, "386"}, {6, "486"}, {62, "x86-64"}, {94, "xtensa"},
    {0xabc7, "xtensa-old"}
  };

  printf("ELF ");

  // executable (ELF says this is short but reality says byte, not MSB swapped)
  i = toybuf[16];
  if (i == 1) printf("relocatable");
  else if (i == 2) printf("executable");
  else if (i == 3) printf("shared object");
  else if (i == 4) printf("core dump");
  else printf("(bad type %d)", i);
  printf(", ");

  // "64-bit"
  if (bits == 1) printf("32-bit ");
  else if (bits == 2) printf("64-bit ");
  else {
    printf("(bad class %d) ", bits);
    bits = 0;
  }

  // "LSB"
  if (endian == 1) printf("LSB ");
  else if (endian == 2) {
    printf("MSB ");
    elf_int = peek_be;
  } else {
    printf("(bad endian %d) \n", endian);
    endian = 0;
  }

  // e_machine, ala "x86", from big table above
  j = elf_int(toybuf+18, 2);
  for (i = 0; i<ARRAY_LEN(type); i++) if (j==type[i].val) break;
  if (i<ARRAY_LEN(type)) printf("%s", type[i].name);
  else printf("(unknown arch %d)", j);

  bits--;
  // If we know our bits and endianness and phentsize agrees show dynamic linker
  if ((bits&1)==bits && endian &&
      (i = elf_int(toybuf+42+12*bits, 2)) == 32+24*bits)
  {
    char *map, *phdr;
    int phsize = i, phnum = elf_int(toybuf+44+12*bits, 2),
        psz = sysconf(_SC_PAGE_SIZE), lib = 0;
    off_t phoff = elf_int(toybuf+28+4*bits, 4+4*bits),
          mapoff = phoff^(phoff&(psz-1));

    // map e_phentsize*e_phnum bytes at e_phoff
    map = mmap(0, phsize*phnum, PROT_READ, MAP_SHARED, fd, mapoff);
    if (map) {
      // Find PT_INTERP entry. (Note: fields got reordered for 64 bit)
      for (i = 0; i<phnum; i++) {
        long long dlpos, dllen;

        // skip non-PT_INTERP entries
        j = elf_int(phdr = map+(phoff-mapoff)+i*phsize, 4);
        if (j==2) lib++;
        if (j!=3) continue;

        // Read p_offset and p_filesz
        j = bits+1;
        dlpos = elf_int(phdr+4*j, 4*j);
        dllen = elf_int(phdr+16*j, 4*j);
        if (dllen<0 || dllen>sizeof(toybuf)-128
            || dlpos!=lseek(fd, dlpos, SEEK_SET)
            || dllen!=readall(fd, toybuf+128, dllen)) break;
        printf(", dynamic (%.*s", (int)dllen, toybuf+128);
      }
      if (!lib) printf(", static");
      else printf(" loads %d lib%s)", lib, lib>1 ? "s" : "");
      munmap(map, phsize*phnum);
    }
  }

  // TODO: we'd need to actually parse the ELF file to report the rest...
  // ", dynamically linked"
  // " (uses shared libs)"
  // ", for Linux 2.6.24"
  // ", BuildID[sha1]=SHA"
  // ", stripped"
  xputc('\n');
}

static void do_regular_file(int fd, char *name)
{
  char *s;
  int len = read(fd, s = toybuf, sizeof(toybuf)-256);
  int magic;

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

  if (len>40 && strstart(&s, "\177ELF")) do_elf_file(fd);
  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);

    xprintf("PNG image data");

    // 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"};

      if (s[9]<ARRAY_LEN(colors)) c = colors[s[9]];
      if (!c) c = "unknown";

      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-");
    }

    xputc('\n');

  // 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));

  // 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");

  // 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+2, 2), (int)peek_be(s, 2));

  // https://people.freebsd.org/~kientzle/libarchive/man/cpio.5.txt
  // the lengths for cpio are size of header + 9 bytes, since any valid
  // cpio archive ends with a record for "TARGET!!!"
  else if (len>85 && strstart(&s, "07070")) {
    char *cpioformat = "unknown type";
    if (toybuf[5] == '7') cpioformat = "pre-SVR4 or odc";
    else if (toybuf[5] == '1') cpioformat = "SVR4 with no CRC";
    else if (toybuf[5] == '2') cpioformat = "SVR4 with CRC";
    xprintf("ASCII cpio archive (%s)\n", cpioformat);
  }
  else if (len>33 && (magic=peek(&s,2), magic==0143561 || magic==070707)) {
    if (magic == 0143561) printf("byte-swapped ");
    xprintf("cpio archive\n");
  }
  // tar archive (ustar/pax or gnu)
  else if (len>500 && !strncmp(s+257, "ustar", 5)) {
    xprintf("POSIX tar archive%s\n", strncmp(s+262,"  ",2)?"":" (GNU)");
  }
  // zip/jar/apk archive, ODF/OOXML document, or such
  else if (len>5 && strstart(&s, "PK\03\04")) {
    int ver = (int)(char)(toybuf[4]);
    xprintf("Zip archive data");
    if (ver)
      xprintf(", requires at least v%d.%d to extract", ver/10, ver%10);
    xputc('\n');
  }
  else {
    char *what = 0;
    int i, bytes;

    // If shell script, report which interpreter
    if (len>3 && strstart(&s, "#!")) {
      // Whitespace is allowed between the #! and the interpreter
      while (isspace(*s)) s++;
      if (strstart(&s, "/usr/bin/env")) while (isspace(*s)) s++;
      for (what = s; (s-toybuf)<len && !isspace(*s); s++);
      strcpy(s, " script");

    // Distinguish ASCII text, UTF-8 text, or data
    } else for (i = 0; i<len; ++i) {
      if (!(isprint(toybuf[i]) || isspace(toybuf[i]))) {
        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 ? what : "ASCII text");
  }
}

void file_main(void)
{
  char **arg;

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

    if (name_len > TT.max_name_len) TT.max_name_len = name_len;
  }

  // Can't use loopfiles here because it doesn't call function when can't open
  for (arg = toys.optargs; *arg; arg++) {
    struct stat sb;
    char *name = *arg, *what = "cannot open";

    xprintf("%s: %*s", name, (int)(TT.max_name_len - strlen(name)), "");

    if (!lstat(name, &sb)) {
      if (S_ISFIFO(sb.st_mode)) what = "fifo";
      else if (S_ISREG(sb.st_mode)) {
        int fd = !strcmp(name, "-") ? 0 : open(name, O_RDONLY);

        if (fd!=-1) {
          if (!sb.st_size) what = "empty";
          else do_regular_file(fd, name);
          if (fd) close(fd);
          if (sb.st_size) continue;
        }
      } 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_ISSOCK(sb.st_mode)) what = "socket";
      else if (S_ISLNK(sb.st_mode)) what = "symbolic link";
      else what = "unknown";
    }

    xputs(what);
  }
}