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up1510b.tgz
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umount.c
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C/C++ Source or Header
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1990-07-15
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1KB
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75 lines
/* umount - unmount a file system Author: Andy Tanenbaum */
#include <sys/types.h>
#include <fcntl.h>
#include <errno.h>
#define BUFSIZE 1024
extern int errno;
char *mounttable = "/etc/mtab";
char buffer[BUFSIZE], *p = &buffer[0], *q;
main(argc, argv)
int argc;
char *argv[];
{
if (argc != 2) usage();
if (umount(argv[1]) < 0) {
if (errno == EINVAL)
std_err("Device not mounted\n");
else
perror("umount");
exit(1);
}
std_err(argv[1]);
std_err(" unmounted\n");
do_mtab(argv[1]);
exit(0);
}
do_mtab(devname)
char *devname;
{
/* Remove an entry from mtab. */
int n, fd;
char line[256];
/* Read in the mount table and then overwrite the file. */
fd = open(mounttable, O_RDWR);
n = read(fd, buffer, BUFSIZE);
close(fd);
q = &buffer[n];
fd = creat(mounttable, 0554);
n = strlen(devname);
while (getline(line) != 0) {
if (strncmp(line, devname, n) == 0) continue;
write(fd, line, strlen(line));
}
}
int getline(ptr)
char *ptr;
{
char c;
while (p < q) {
c = *p++;
*ptr++ = c;
if (c == '\n') {
*ptr++ = 0;
return(1);
}
}
return(0);
}
usage()
{
std_err("Usage: umount special\n");
exit(1);
}