123 lines
3.0 KiB
C
123 lines
3.0 KiB
C
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/* This package consists of 4 routines for handling the /etc/mtab file.
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* The /etc/mtab file contains information about the root and mounted file
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* systems as a series of lines, each one with exactly four fields separated
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* by one space as follows:
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*
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* special mounted_on version rw_flag
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*
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* where
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* special is the name of the block special file
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* mounted_on is the directory on which it is mounted
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* version is either 1 or 2 for MINIX V1 and V2 file systems
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* rw_flag is rw or ro for read/write or read only
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*
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* An example /etc/mtab:
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*
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* /dev/ram / 2 rw
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* /dev/hd1 /usr 2 rw
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* /dev/fd0 /user 1 ro
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*
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*
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* The four routines for handling /etc/mtab are as follows. They use two
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* (hidden) internal buffers, mtab_in for input and mtab_out for output.
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*
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* load_mtab(&prog_name) - read /etc/mtab into mtab_in
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* get_mtab_entry(&s1, &s2, &s3, &s4) - arrays that are filled in
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*
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* If load_mtab works, it returns 0. If it fails, it prints its own error
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* message on stderr and returns -1. When get_mtab_entry
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* runs out of entries to return, it sets the first pointer to NULL and returns
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* -1 instead of 0.
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*/
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#include <sys/types.h>
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#include <lib.h>
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#include <minix/minlib.h>
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#include <ctype.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <stdio.h>
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#define BUF_SIZE 512 /* size of the /etc/mtab buffer */
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char *etc_mtab = "/etc/mtab"; /* name of the /etc/mtab file */
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static char mtab_in[BUF_SIZE+1]; /* holds /etc/mtab when it is read in */
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static char *iptr = mtab_in; /* pointer to next line to feed out. */
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int load_mtab(char *prog_name);
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int get_mtab_entry(char dev[PATH_MAX], char mount_point[PATH_MAX],
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char type[MNTNAMELEN], char flags[MNTFLAGLEN]);
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static void err(char *prog_name, const char *str);
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int load_mtab(char *prog_name)
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{
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/* Read in /etc/mtab and store it in /etc/mtab. */
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int fd, n;
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char *ptr;
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/* Open the file. */
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fd = open(etc_mtab, O_RDONLY);
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if (fd < 0) {
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err(prog_name, ": cannot open ");
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return(-1);
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}
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/* File opened. Read it in. */
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n = read(fd, mtab_in, BUF_SIZE);
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if (n <= 0) {
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/* Read failed. */
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err(prog_name, ": cannot read ");
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return(-1);
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}
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if (n == BUF_SIZE) {
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/* Some nut has mounted 50 file systems or something like that. */
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std_err(prog_name);
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std_err(": file too large: ");
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std_err(etc_mtab);
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return(-1);
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}
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close(fd);
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ptr = mtab_in;
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return(0);
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}
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int get_mtab_entry(char dev[PATH_MAX], char mount_point[PATH_MAX],
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char type[MNTNAMELEN], char flags[MNTFLAGLEN])
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{
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/* Return the next entry from mtab_in. */
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int r;
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if (iptr >= &mtab_in[BUF_SIZE]) {
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dev[0] = '\0';
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return(-1);
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}
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r = sscanf(iptr, "%s on %s type %s (%[^)]s\n",
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dev, mount_point, type, flags);
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if (r != 4) {
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dev[0] = '\0';
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return(-1);
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}
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iptr = strchr(iptr, '\n'); /* Find end of line */
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if (iptr != NULL) iptr++; /* Move to next line */
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return(0);
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}
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static void err(char *prog_name, const char *str)
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{
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std_err(prog_name);
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std_err(str);
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std_err(etc_mtab);
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perror(" ");
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}
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