878ba523ac
This library includes various random and minix-specific functions included in the Minix libc. Most of them should be part of libsys, and in general it would be nice to extinguish this library over time.
63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
/* This procedure examines a file system and figures out whether it is
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* version 1 or version 2. It returns the result as an int. If the
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* file system is neither, it returns -1. A typical call is:
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*
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* n = fsversion("/dev/hd1", "df");
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*
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* The first argument is the special file for the file system.
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* The second is the program name, which is used in error messages.
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*/
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#include <sys/types.h>
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#include <minix/config.h>
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#include <minix/const.h>
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#include <minix/minlib.h>
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#include <minix/type.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <string.h>
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#include "mfs/const.h"
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static char super[SUPER_BLOCK_BYTES];
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#define MAGIC_OFFSET_MFS 0x18
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#define MAGIC_OFFSET_EXT 0x38
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#define MAGIC_VALUE_EXT2 0xef53
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static int check_super(off_t offset, unsigned short magic)
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{
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return (memcmp(super + offset, &magic, sizeof(magic)) == 0) ? 1 : 0;
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}
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int fsversion(dev, prog)
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char *dev, *prog;
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{
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int fd;
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if ((fd = open(dev, O_RDONLY)) < 0) {
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std_err(prog);
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std_err(" cannot open ");
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perror(dev);
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return(-1);
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}
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lseek(fd, (off_t) SUPER_BLOCK_BYTES, SEEK_SET); /* skip boot block */
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if (read(fd, (char *) &super, sizeof(super)) != sizeof(super)) {
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std_err(prog);
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std_err(" cannot read super block on ");
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perror(dev);
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close(fd);
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return(-1);
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}
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close(fd);
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/* first check MFS, a valid MFS may look like EXT but not vice versa */
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if (check_super(MAGIC_OFFSET_MFS, SUPER_MAGIC)) return FSVERSION_MFS1;
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if (check_super(MAGIC_OFFSET_MFS, SUPER_V2)) return FSVERSION_MFS2;
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if (check_super(MAGIC_OFFSET_MFS, SUPER_V3)) return FSVERSION_MFS3;
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if (check_super(MAGIC_OFFSET_EXT, MAGIC_VALUE_EXT2)) return FSVERSION_EXT2;
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return(-1);
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}
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