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file.c
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C/C++ Source or Header
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1990-07-23
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4KB
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186 lines
/* file - report on file type. Author: Andy Tanenbaum */
#include <blocksize.h>
#include <ar.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <minix/config.h>
#if (CHIP == M68000)
#define A_OUT 0x410 /* magic number for executables */
#define A_OUT_SPLIT 0x420 /* magic number for executables split I/D */
#define A_OUT_SEC 0x301 /* second check for executables */
#define OBJECT 0x102 /* minix/st object */
#else
#define A_OUT 001401 /* magic number for executables */
#define SPLIT 002040 /* second word on split I/D binaries */
#endif
#define XBITS 00111 /* rwXrwXrwX (x bits in the mode) */
#define ENGLISH 25 /* cutoff for determining if text is Eng. */
char buf[BLOCK_SIZE];
main(argc, argv)
int argc;
char *argv[];
{
/* This program uses some heuristics to try to guess about a file type by
* looking at its contents.
*/
int i;
if (argc < 2) usage();
for (i = 1; i < argc; i++) file(argv[i]);
}
file(name)
char *name;
{
int i, fd, n, magic, second, mode, nonascii, special, funnypct, etaoins;
int symbols;
long engpct;
char c;
struct stat st_buf;
printf("%s: ", name);
/* Open the file, stat it, and read in 1 block. */
fd = open(name, O_RDONLY);
if (fd < 0) {
printf("cannot open\n");
return;
}
n = fstat(fd, &st_buf);
if (n < 0) {
printf("cannot stat\n");
close(fd);
return;
}
mode = st_buf.st_mode;
/* Check for directories and special files. */
if ((mode & S_IFMT) == S_IFDIR) {
printf("directory\n");
close(fd);
return;
}
if ((mode & S_IFMT) == S_IFCHR) {
printf("character special file\n");
close(fd);
return;
}
if ((mode & S_IFMT) == S_IFBLK) {
printf("block special file\n");
close(fd);
return;
}
n = read(fd, buf, BLOCK_SIZE);
if (n < 0) {
printf("cannot read\n");
close(fd);
return;
}
/* Check to see if file is an archive. */
#if (CHIP == M68000)
magic = (buf[0] << 8) | (buf[1] & 0377);
if (magic == 026377) {
#else
magic = (buf[1] << 8) | (buf[0] & 0377);
if (magic == ARMAG) {
#endif
printf("archive\n");
close(fd);
return;
}
#if (CHIP == M68000)
/* Check to see if file is an object file. */
if (magic == OBJECT) {
printf("MINIX/ST object file\n");
close(fd);
return;
}
#endif
/* Check to see if file is an executable binary. */
#if (CHIP != M68000)
if (magic == A_OUT) {
/* File is executable. Check for split I/D. */
printf("MINIX/PC executable");
second = (buf[3] << 8) | (buf[2] & 0377);
if (second == SPLIT)
printf(" separate I & D space");
else
printf(" combined I & D space");
#else
if (magic == A_OUT || magic == A_OUT_SPLIT) {
/* File is executable. Check for split I/D. */
printf("MINIX/ST executable");
second = (buf[2] << 8) | (buf[3] & 0377);
if (second == A_OUT_SEC) {
if (magic == A_OUT_SPLIT)
printf(" separate I & D space");
else
printf(" combined I & D space");
}
#endif
symbols = buf[28] | buf[29] | buf[30] | buf[31];
if (symbols != 0)
printf(" not stripped\n");
else
printf(" stripped\n");
close(fd);
return;
}
/* Check to see if file is a shell script. */
if (mode & XBITS) {
/* Not a binary, but executable. Probably a shell script. */
printf("shell script\n");
close(fd);
return;
}
/* Check for ASCII data and certain punctuation. */
nonascii = 0;
special = 0;
etaoins = 0;
for (i = 0; i < n; i++) {
c = buf[i];
if (c & 0200) nonascii++;
if (c == ';' || c == '{' || c == '}' || c == '#') special++;
if (c == '*' || c == '<' || c == '>' || c == '/') special++;
if (c >= 'A' && c <= 'Z') c = c - 'A' + 'a';
if (c == 'e' || c == 't' || c == 'a' || c == 'o') etaoins++;
if (c == 'i' || c == 'n' || c == 's') etaoins++;
}
if (nonascii == 0) {
/* File only contains ASCII characters. Continue processing. */
funnypct = 100 * special / n;
engpct = 100L * (long) etaoins / n;
if (funnypct > 1) {
printf("C program\n");
} else {
if (engpct > (long) ENGLISH)
printf("English text\n");
else
printf("ASCII text\n", engpct);
}
close(fd);
return;
}
/* Give up. Call it data. */
printf("data\n");
close(fd);
return;
}
usage()
{
printf("Usage: file name ...\n");
exit(1);
}