usr.bin/file/fsmagic.c

/*
 * fsmagic - magic based on filesystem info - directory, special files, etc.
 *
 * Copyright (c) Ian F. Darwin, 1987.
 * Written by Ian F. Darwin.
 *
 * This software is not subject to any license of the American Telephone
 * and Telegraph Company or of the Regents of the University of California.
 *
 * Permission is granted to anyone to use this software for any purpose on
 * any computer system, and to alter it and redistribute it freely, subject
 * to the following restrictions:
 *
 * 1. The author is not responsible for the consequences of use of this
 *    software, no matter how awful, even if they arise from flaws in it.
 *
 * 2. The origin of this software must not be misrepresented, either by
 *    explicit claim or by omission.  Since few users ever read sources,
 *    credits must appear in the documentation.
 *
 * 3. Altered versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.  Since few users
 *    ever read sources, credits must appear in the documentation.
 *
 * 4. This notice may not be removed or altered.
 */

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#ifndef major                   /* if `major' not defined in types.h, */
#include <sys/sysmacros.h>      /* try this one. */
#endif
#ifndef major   /* still not defined? give up, manual intervention needed */
                /* If cc tries to compile this, read and act on it. */
                /* On most systems cpp will discard it automatically */
                Congratulations, you have found a portability bug.
                Please grep /usr/include/sys and edit the above #include
                to point at the file that defines the "major" macro.
#endif  /*major*/

#include "file.h"

#ifndef lint
static char *moduleid =
        "@(#)fsmagic.c,v 1.3 1993/06/10 00:38:10 jtc Exp";
#endif  /* lint */

int
fsmagic(fn, sb)
const char *fn;
struct stat *sb;
{
        int ret = 0;

        /*
         * Fstat is cheaper but fails for files you don't have read perms on.
         * On 4.2BSD and similar systems, use lstat() to identify symlinks.
         */
#ifdef  S_IFLNK
        if (!lflag)
                ret = lstat(fn, sb);
        else
#endif
        ret = stat(fn, sb);     /* don't merge into if; see "ret =" above */

        if (ret) {
                ckfprintf(stdout,
                        /* Yes, I do mean stdout. */
                        /* No \n, caller will provide. */
                        "can't stat `%s' (%s).", fn, strerror(errno));
                return 1;
        }

        if (sb->st_mode & S_ISUID) ckfputs("setuid ", stdout);
        if (sb->st_mode & S_ISGID) ckfputs("setgid ", stdout);
        if (sb->st_mode & S_ISVTX) ckfputs("sticky ", stdout);

        switch (sb->st_mode & S_IFMT) {
        case S_IFDIR:
                ckfputs("directory", stdout);
                return 1;
        case S_IFCHR:
                (void) printf("character special (%d/%d)",
                        major(sb->st_rdev), minor(sb->st_rdev));
                return 1;
        case S_IFBLK:
                (void) printf("block special (%d/%d)",
                        major(sb->st_rdev), minor(sb->st_rdev));
                return 1;
        /* TODO add code to handle V7 MUX and Blit MUX files */
#ifdef  S_IFIFO
        case S_IFIFO:
                ckfputs("fifo (named pipe)", stdout);
                return 1;
#endif
#ifdef  S_IFLNK
        case S_IFLNK:
                {
                        char buf[BUFSIZ+4];
                        register int nch;
                        struct stat tstatbuf;

                        if ((nch = readlink(fn, buf, BUFSIZ-1)) <= 0) {
                                ckfprintf(stdout, "unreadable symlink (%s).",
                                      strerror(errno));
                                return 1;
                        }
                        buf[nch] = '\0';        /* readlink(2) forgets this */

                        /* If broken symlink, say so and quit early. */
                        if (*buf == '/') {
                            if (stat(buf, &tstatbuf) < 0) {
                                ckfprintf(stdout,
                                        "broken symbolic link to %s", buf);
                                return 1;
                            }
                        }
                        else {
                            char *tmp;
                            char buf2[BUFSIZ+BUFSIZ+4];

                            if ((tmp = strrchr(fn,  '/')) == NULL) {
                                tmp = buf; /* in current directory anyway */
                            }
                            else {
                                strcpy (buf2, fn);  /* take directory part */
                                buf2[tmp-fn+1] = '\0';
                                strcat (buf2, buf); /* plus (relative) symlink */
                                tmp = buf2;
                            }
                            if (stat(tmp, &tstatbuf) < 0) {
                                ckfprintf(stdout,
                                        "broken symbolic link to %s", buf);
                                return 1;
                            }
                        }

                        /* Otherwise, handle it. */
                        if (lflag) {
                                process(buf, strlen(buf));
                                return 1;
                        } else { /* just print what it points to */
                                ckfputs("symbolic link to ", stdout);
                                ckfputs(buf, stdout);
                        }
                }
                return 1;
#endif
#ifdef  S_IFSOCK
        case S_IFSOCK:
                ckfputs("socket", stdout);
                return 1;
#endif
        case S_IFREG:
                break;
        default:
                error("invalid mode 0%o.\n", sb->st_mode);
                /*NOTREACHED*/
        }

        /*
         * regular file, check next possibility
         */
        if (sb->st_size == 0) {
                ckfputs("empty", stdout);
                return 1;
        }
        return 0;
}