[net.unix-wizards] 4.2BSD newfs's special file name restriction lifted; mkfs

geoff@utcs.uucp (11/30/85)

Index:	etc/newfs.c 4.2BSD
Index:	man/man8/mkfs.8 4.2BSD

Description:
	Newfs used to require that the special file name argument be of
	the form /dev/ra6t, which is unnecessarily and offensively
	restrictive.  We have links, bearing the names of the file
	systems which live upon them, to the special files of the form
	/dev/ra7q and normally use the mnemonic names, such as
	/dev/usr.  Our machines have varying disk layouts and models of
	disk and it is highly inconvenient to have to determine the
	other name of /dev/tmp if we want to newfs it, the moreso since
	newfs is the only program so afflicted.

	mkfs(8) didn't document its final parameter, bytes per i-node,
	nor that it silently limits certain values.

	installboot used to be undocumented.
Repeat-By:
	Try to "newfs /dev/tmp ra81" and watch it fail.

	Read mkfs(8); note the absence of a description of the parameter
	following rps and the stunning silence regarding its sullen
	misbehaviour when given extreme values.

	Type "man installboot"; note the lack of a manual page.
Fix:
	Apply the patches below to newfs.c and mkfs.8 respectively.
	The patch to newfs means that it will not install a boot
	program on a root partition, since this is now very difficult
	for newfs.  This never belonged in newfs to start with and on
	the rare occasions that it is needed, can be done trivially by
	the undocumented /usr/mdec/installboot (source and de facto
	documentation in /sys/mdec/installboot.c).  Connoisseurs of
	poor coding practices may note that the installboot function of
	newfs almost, but not quite, exactly duplicates the source of
	/sys/mdec/installboot.c, courtesy of code sharing via the
	editor.

	A brand-new, shiny installboot(8) is included.

*** /tmp/,RCSt1009574	Sat Nov 30 08:33:49 1985
--- /tmp/,RCSt2009574	Sat Nov 30 08:33:51 1985
***************
*** 38,44
  char	a8[20];
  char	a9[20];
  char	a10[20];
- char	device[MAXPATHLEN];
  char	cmd[BUFSIZ];
  
  char *index();

--- 38,43 -----
  char	a8[20];
  char	a9[20];
  char	a10[20];
  char	cmd[BUFSIZ];
  
  char *index();
***************
*** 53,58
  	register struct disktab *dp;
  	register struct partition *pp;
  	register int i;
  	char *cp, *special;
  	int status;
  	struct stat st;

--- 52,58 -----
  	register struct disktab *dp;
  	register struct partition *pp;
  	register int i;
+ 	int status, part = -1;
  	char *cp, *special;
  	struct stat st;
  
***************
*** 54,60
  	register struct partition *pp;
  	register int i;
  	char *cp, *special;
- 	int status;
  	struct stat st;
  
  	argc--, argv++;

--- 54,59 -----
  	register int i;
  	int status, part = -1;
  	char *cp, *special;
  	struct stat st;
  
  	argc--, argv++;
***************
*** 175,180
  		(void) fprintf(stderr, "\t-i number of bytes per inode\n");
  		exit(1);
  	}
  	special = argv[0];
  	cp = rindex(special, '/');
  	if (cp != 0)

--- 174,186 -----
  		(void) fprintf(stderr, "\t-i number of bytes per inode\n");
  		exit(1);
  	}
+ 
+ 	/*
+ 	 * If special file is a block device, try to use the raw device.
+ 	 * Glue "/dev/r" onto the front of the last component of the
+ 	 * special file name and hope for the best.  The result must
+ 	 * be a character special file or newfs quits.
+ 	 */
  	special = argv[0];
  	if (stat(special, &st) >= 0 && (st.st_mode&S_IFMT) == S_IFBLK) {
  		static char device[MAXPATHLEN];
***************
*** 176,187
  		exit(1);
  	}
  	special = argv[0];
! 	cp = rindex(special, '/');
! 	if (cp != 0)
! 		special = cp + 1;
! 	if (*special == 'r' && special[1] != 'a' && special[1] != 'b')
! 		special++;
! 	special = sprintf(device, "/dev/r%s", special);
  	if (stat(special, &st) < 0) {
  		(void) fprintf(stderr, "newfs: "); perror(special);
  		exit(2);

--- 182,196 -----
  	 * be a character special file or newfs quits.
  	 */
  	special = argv[0];
! 	if (stat(special, &st) >= 0 && (st.st_mode&S_IFMT) == S_IFBLK) {
! 		static char device[MAXPATHLEN];
! 
! 		cp = rindex(special, '/');
! 		if (cp != NULL)			/* name contains a slash */
! 			special = cp + 1;	/* point at last component */
! 		(void) sprintf(device, "/dev/r%s", special);
! 		special = device;
! 	}
  	if (stat(special, &st) < 0) {
  		(void) fprintf(stderr, "newfs: ");
  		perror(special);
***************
*** 183,189
  		special++;
  	special = sprintf(device, "/dev/r%s", special);
  	if (stat(special, &st) < 0) {
! 		(void) fprintf(stderr, "newfs: "); perror(special);
  		exit(2);
  	}
  	if ((st.st_mode & S_IFMT) != S_IFCHR)

--- 192,199 -----
  		special = device;
  	}
  	if (stat(special, &st) < 0) {
! 		(void) fprintf(stderr, "newfs: ");
! 		perror(special);
  		exit(2);
  	}
  	if ((st.st_mode & S_IFMT) != S_IFCHR)
***************
*** 188,193
  	}
  	if ((st.st_mode & S_IFMT) != S_IFCHR)
  		fatal("%s: not a character device", special);
  	dp = getdiskbyname(argv[1]);
  	if (dp == 0)
  		fatal("%s: unknown disk type", argv[1]);

--- 198,211 -----
  	}
  	if ((st.st_mode & S_IFMT) != S_IFCHR)
  		fatal("%s: not a character device", special);
+ 	/*
+ 	 * Compute disk partition from minor device number.
+ 	 * This is arguably something that user code should not know
+ 	 * but it's far cleaner than the previous algorithm.
+ 	 */
+ 	part = minor(st.st_rdev) % 8;
+ 
+ 	/* Grub up the disktab entry */
  	dp = getdiskbyname(argv[1]);
  	if (dp == 0)
  		fatal("%s: unknown disk type", argv[1]);
***************
*** 191,200
  	dp = getdiskbyname(argv[1]);
  	if (dp == 0)
  		fatal("%s: unknown disk type", argv[1]);
! 	cp = index(argv[0], '\0') - 1;
! 	if (cp == 0 || *cp < 'a' || *cp > 'h')
! 		fatal("%s: can't figure out file system partition", argv[0]);
! 	pp = &dp->d_partitions[*cp - 'a'];
  	if (fssize == 0) {
  		fssize = pp->p_size;
  		if (fssize < 0)

--- 209,217 -----
  	dp = getdiskbyname(argv[1]);
  	if (dp == 0)
  		fatal("%s: unknown disk type", argv[1]);
! 
! 	pp = &dp->d_partitions[part];
! 
  	if (fssize == 0) {
  		fssize = pp->p_size;
  		if (fssize < 0)
***************
*** 234,239
  			fatal("%s: no default revolutions/minute value",
  				argv[1]);
  	}
  	if (density <= 0)
  		density = 2048;
  	if (minfree < 0)

--- 251,261 -----
  			fatal("%s: no default revolutions/minute value",
  				argv[1]);
  	}
+ 
+ 	/*
+ 	 * Almost all the useful work of newfs is done here.
+ 	 * The getdiskbyname above is the rest of it.
+ 	 */
  	if (density <= 0)
  		density = 2048;
  	if (minfree < 0)
***************
*** 240,245
  		minfree = 10;
  	if (cpg == 0)
  		cpg = 16;
  	i = 0;
  	av[i++] = sprintf(a2, "%d", fssize);
  	av[i++] = sprintf(a3, "%d", nsectors);

--- 262,271 -----
  		minfree = 10;
  	if (cpg == 0)
  		cpg = 16;
+ 
+ 	/*
+ 	 * This code is broken; ANSI & Uglix sprintf's return ints.
+ 	 */
  	i = 0;
  	av[i++] = sprintf(a2, "%d", fssize);
  	av[i++] = sprintf(a3, "%d", nsectors);
***************
*** 260,266
  		(void) printf("%s\n", cmd);
  	if (status = system(cmd))
  		exit(status);
! 	if (*cp == 'a' && !noboot) {
  		char type[3];
  		struct stat sb;
  

--- 286,294 -----
  		(void) printf("%s\n", cmd);
  	if (status = system(cmd))
  		exit(status);
! 
! 	if (part == 0 && !noboot) {		/* root partition & okay */
! #ifdef notdef					/* would be nice, but needs AI */
  		char type[3];
  		struct stat sb;
  
***************
*** 268,275
  		if (cp == NULL)
  			fatal("%s: can't figure out disk type from name",
  				special);
! 		if (stat(special, &sb) >= 0 && (sb.st_mode & S_IFMT) == S_IFCHR)
! 			cp++;
  		type[0] = *++cp;
  		type[1] = *++cp;
  		type[2] = '\0';

--- 296,312 -----
  		if (cp == NULL)
  			fatal("%s: can't figure out disk type from name",
  				special);
! 		/* If special is a character (raw) device, */
! 		if (stat(special, &sb) >= 0 && (sb.st_mode&S_IFMT) == S_IFCHR)
! 			cp++;			/* use the block device */
! 		/*
! 		 * Copy 0002 characters for installboot.
! 		 * This simple-minded copy assumes that the special file
! 		 * name is of the form .../rra7q; this is unacceptable,
! 		 * since it requires one to know the mapping from /dev/usr
! 		 * to /dev/rra6t, which is error-prone and varies from
! 		 * machine to machine.
! 		 */
  		type[0] = *++cp;
  		type[1] = *++cp;
  		type[2] = '\0';
***************
*** 274,279
  		type[1] = *++cp;
  		type[2] = '\0';
  		installboot(special, type);
  	}
  	exit(0);
  }

--- 311,319 -----
  		type[1] = *++cp;
  		type[2] = '\0';
  		installboot(special, type);
+ #else
+ 		fatal("no boot program installed; use /usr/mdec/installboot");
+ #endif
  	}
  	exit(0);
  }


*** /usr/man/man8/mkfs.8	Mon Apr  4 07:08:32 1983
--- mkfs.8	Sat Nov 30 08:20:08 1985
***************
*** 12,17
  [ ncpg ]
  [ minfree ]
  [ rps ]
  .SH DESCRIPTION
  .B N.B.:
  file system are normally created with the

--- 12,18 -----
  [ ncpg ]
  [ minfree ]
  [ rps ]
+ [ bpino ]
  .SH DESCRIPTION
  .B N.B.:
  file system are normally created with the
***************
*** 61,66
  If a disk does not revolve at 60 revolutions per second, the
  .B rps
  parameter may be specified.
  Users with special demands for their file systems are referred to
  the paper cited below for a discussion of the tradeoffs in using
  different configurations.

--- 62,74 -----
  If a disk does not revolve at 60 revolutions per second, the
  .I rps
  parameter may be specified.
+ .I Bpino
+ is the number of data bytes per i-node:
+ an i-node will be allocated for every
+ .I bpino
+ bytes allocated to data,
+ subject to the BUGS below.
+ .PP
  Users with special demands for their file systems are referred to
  the paper cited below for a discussion of the tradeoffs in using
  different configurations.
***************
*** 76,78
  TR #7, September 1982.
  .SH BUGS
  There should be some way to specify bad blocks.

--- 84,99 -----
  TR #7, September 1982.
  .SH BUGS
  There should be some way to specify bad blocks.
+ .br
+ .I Mkfs
+ silently imposes upper and lower limits on various values.
+ It should tell its invoker what limits have been imposed.
+ In particular,
+ decreasing
+ .I bpino
+ to give a filesystem more i-nodes may exceed the limit on the
+ number of i-nodes per cylinder group (MAXIPG in <sys/fs.h>);
+ in such a case,
+ try decreasing
+ .I ncpg
+ too.


.TH INSTALLBOOT 8 local
.DA 30 Nov 1985
.SH NAME
installboot \- installs a boot program in a file system
.SH SYNOPSIS
.B /usr/mdec/installboot
bootblock bootprog special
.SH DESCRIPTION
.I Installboot
concatentates
.I bootblock
and
.I bootprog
and writes at most BBSIZE bytes (from <sys/fs.h>)
of them on the first bytes of
.IR special .
.SH FILES
/usr/mdec/??boot	boot blocks
.br
/usr/mdec/boot??	boot programs
.SH SEE ALSO
newfs(8), dd(1)
.SH EXAMPLES
cd /usr/mdec
.br
installboot raboot bootra /dev/ra0a
.SH HISTORY
.I Installboot
comes undocumented with 4.2BSD.
This manual page was written by Geoff Collyer.
.SH BUGS
There is no convenient way to determine the names of the boot blocks
and boot programs without
.I "a priori"
knowledge of one's make of disk.