minix/commands/printroot/printroot.c

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/* printroot - print root device on stdout Author: Bruce Evans */
/* This program figures out what the root device is by doing a stat on it, and
* then searching /dev until it finds an entry with the same device number.
* A typical use (probably the only use) is in /etc/rc for initializing
* /etc/mtab, as follows:
*
* /usr/bin/printroot >/etc/mtab
*
* 9 Dec 1989 - clean up for 1.5 - full prototypes (BDE)
* 15 Oct 1989 - avoid ACK cc bugs (BDE):
* - sizeof "foo" is 2 (from wrong type char *) instead of 4
* - char foo[10] = "bar"; allocates 4 bytes instead of 10
* 1 Oct 1989 - Minor changes by Andy Tanenbaum
* 5 Oct 1992 - Use readdir (kjb)
* 26 Nov 1994 - Flag -r: print just the root device (kjb)
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <minix/minlib.h>
#include <dirent.h>
static char DEV_PATH[] = "/dev/"; /* #define would step on sizeof bug */
static char MESSAGE[] = " / "; /* ditto */
#define UNKNOWN_DEV "/dev/unknown"
#define ROOT "/"
int rflag;
int main(int argc, char **argv);
void done(char *name, int status);
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int main(argc, argv)
int argc;
char **argv;
{
DIR *dp;
struct dirent *entry;
struct stat filestat, rootstat;
static char namebuf[sizeof DEV_PATH + NAME_MAX];
rflag = (argc > 1 && strcmp(argv[1], "-r") == 0);
if (stat(ROOT, &rootstat) == 0 && (dp = opendir(DEV_PATH)) != (DIR *) NULL) {
while ((entry = readdir(dp)) != (struct dirent *) NULL) {
strcpy(namebuf, DEV_PATH);
strcat(namebuf, entry->d_name);
if (stat(namebuf, &filestat) != 0) continue;
if ((filestat.st_mode & S_IFMT) != S_IFBLK) continue;
if (filestat.st_rdev != rootstat.st_dev) continue;
done(namebuf, 0);
}
}
done(UNKNOWN_DEV, 1);
return(0); /* not reached */
}
void done(name, status)
char *name;
int status;
{
int v;
write(1, name, strlen(name));
if (rflag) {
write(1, "\n", 1);
exit(status);
}
write(1, MESSAGE, sizeof MESSAGE - 1);
v = fsversion(name, "printroot"); /* determine file system version */
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switch (v) {
case FSVERSION_MFS1: write(1, "1 rw\n", 5); break;
case FSVERSION_MFS2: write(1, "2 rw\n", 5); break;
case FSVERSION_MFS3: write(1, "3 rw\n", 5); break;
case FSVERSION_EXT2: write(1, "ext2 rw\n", 8); break;
default: write(1, "0 rw\n", 5); break;
}
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exit(status);
}