diff options
Diffstat (limited to 'toys/posix')
| -rw-r--r-- | toys/posix/file.c | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/toys/posix/file.c b/toys/posix/file.c new file mode 100644 index 00000000..d3e80f4e --- /dev/null +++ b/toys/posix/file.c @@ -0,0 +1,308 @@ +/* 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 y + 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, struct stat *sb) +{ + 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"} + }; + int dynamic = 0; + int stripped = 1; + char *map; + off_t phoff, shoff; + int phsize, phnum, shsize, shnum; + + 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 what we've seen so far doesn't seem consistent, bail. + if (!((bits&1)==bits && endian && + (i = elf_int(toybuf+42+12*bits, 2)) == 32+24*bits)) { + printf(", corrupt?\n"); + return; + } + + // Stash what we need from the header; it's okay to reuse toybuf after this. + phsize = i; + phnum = elf_int(toybuf+44+12*bits, 2); + phoff = elf_int(toybuf+28+4*bits, 4+4*bits); + shsize = elf_int(toybuf+46+12*bits, 2); + shnum = elf_int(toybuf+48+12*bits, 2); + shoff = elf_int(toybuf+32+8*bits, 4+4*bits); + + map = mmap(0, sb->st_size, PROT_READ, MAP_SHARED, fd, 0); + if (!map) perror_exit("mmap"); + + // We need to read the phdrs for dynamic vs static and any notes. + // (Note: fields got reordered for 64 bit) + for (i = 0; i<phnum; i++) { + char *phdr = map+phoff+i*phsize; + int p_type = elf_int(phdr, 4); + long long p_offset, p_filesz; + + if (p_type==2 /*PT_DYNAMIC*/) dynamic = 1; + if (p_type!=3 /*PT_INTERP*/ && p_type!=4 /*PT_NOTE*/) continue; + + j = bits+1; + p_offset = elf_int(phdr+4*j, 4*j); + p_filesz = elf_int(phdr+16*j, 4*j); + + if (p_type==3 /*PT_INTERP*/) + printf(", dynamic (%.*s)", (int)p_filesz, map+p_offset); + else { + char *note = map+p_offset; + + // A PT_NOTE phdr is a sequence of entries, each consisting of an + // ndhr followed by n_namesz+n_descsz bytes of data (each of those + // rounded up to the next 4 bytes, without this being reflected in + // the header byte counts themselves). + while (p_filesz >= 3*4) { // Don't try to read a truncated entry. + int n_namesz = elf_int(note, 4); + int n_descsz = elf_int(note+4, 4); + int n_type = elf_int(note+8, 4); + int notesz = 3*4 + ((n_namesz+3)&~3) + ((n_descsz+3)&~3); + + if (n_namesz==4 && !memcmp(note+12, "GNU", 4)) { + if (n_type == 3 /*NT_GNU_BUILD_ID*/) { + printf(", BuildID[%s]=", (n_descsz==20)?"sha1":"md5"); + for (j = 0; j < n_descsz; ++j) printf("%02x", note[16 + j]); + } + } else if (n_namesz==8 && !memcmp(note+12, "Android", 8)) { + if (n_type==1) printf(", for Android %d", (int)elf_int(note+20, 4)); + } + + note += notesz; + p_filesz -= notesz; + } + } + } + if (!dynamic) printf(", static"); + + // We need to read the shdrs for stripped/unstripped. + // (Note: fields got reordered for 64 bit) + for (i = 0; i<shnum; i++) { + char *shdr = map+shoff+i*shsize; + int sh_type = elf_int(shdr+4, 4); + + if (sh_type == 2 /*SHT_SYMTAB*/) { + stripped = 0; + break; + } + } + printf(", %sstripped", stripped ? "" : "not "); + xputc('\n'); + + munmap(map, sb->st_size); +} + +static void do_regular_file(int fd, char *name, struct stat *sb) +{ + 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, sb); + 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, &sb); + 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); + } +} |