NetBSD/sbin/dump/main.c
2006-03-18 09:51:08 +00:00

810 lines
20 KiB
C

/* $NetBSD: main.c,v 1.60 2006/03/18 09:51:08 christos Exp $ */
/*-
* Copyright (c) 1980, 1991, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1980, 1991, 1993, 1994\n\
The Regents of the University of California. All rights reserved.\n");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)main.c 8.6 (Berkeley) 5/1/95";
#else
__RCSID("$NetBSD: main.c,v 1.60 2006/03/18 09:51:08 christos Exp $");
#endif
#endif /* not lint */
#include <sys/param.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <ufs/ufs/dinode.h>
#include <ufs/ffs/fs.h>
#include <ufs/ffs/ffs_extern.h>
#include <protocols/dumprestore.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <fstab.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "dump.h"
#include "pathnames.h"
#include "snapshot.h"
int timestamp; /* print message timestamps */
int notify; /* notify operator flag */
int blockswritten; /* number of blocks written on current tape */
int tapeno; /* current tape number */
int density; /* density in bytes/0.1" */
int ntrec = NTREC; /* # tape blocks in each tape record */
int cartridge; /* Assume non-cartridge tape */
long dev_bsize = 1; /* recalculated below */
long blocksperfile; /* output blocks per file */
const char *host; /* remote host (if any) */
int readcache = -1; /* read cache size (in readblksize blks) */
int readblksize = 32 * 1024; /* read block size */
char default_time_string[] = "%T %Z"; /* default timestamp string */
char *time_string = default_time_string; /* timestamp string */
int main(int, char *[]);
static long numarg(const char *, long, long);
static void obsolete(int *, char **[]);
static void usage(void);
int
main(int argc, char *argv[])
{
ino_t ino;
int dirty;
union dinode *dp;
struct fstab *dt;
struct statvfs *mntinfo, fsbuf;
char *map, *cp;
int ch;
int i, anydirskipped, bflag = 0, Tflag = 0, Fflag = 0, honorlevel = 1;
int snap_internal = 0;
ino_t maxino;
time_t tnow, date;
int dirc;
char *mountpoint;
int just_estimate = 0;
char labelstr[LBLSIZE];
char *new_time_format;
char *snap_backup = NULL;
spcl.c_date = 0;
(void)time(&tnow);
spcl.c_date = tnow;
tzset(); /* set up timezone for strftime */
if ((new_time_format = getenv("TIMEFORMAT")) != NULL)
time_string = new_time_format;
tsize = 0; /* Default later, based on 'c' option for cart tapes */
if ((tape = getenv("TAPE")) == NULL)
tape = _PATH_DEFTAPE;
dumpdates = _PATH_DUMPDATES;
temp = _PATH_DTMP;
strcpy(labelstr, "none"); /* XXX safe strcpy. */
if (TP_BSIZE / DEV_BSIZE == 0 || TP_BSIZE % DEV_BSIZE != 0)
quit("TP_BSIZE must be a multiple of DEV_BSIZE\n");
level = '0';
timestamp = 0;
if (argc < 2)
usage();
obsolete(&argc, &argv);
while ((ch = getopt(argc, argv,
"0123456789aB:b:cd:eFf:h:k:l:L:nr:s:StT:uWwx:X")) != -1)
switch (ch) {
/* dump level */
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
level = ch;
break;
case 'a': /* `auto-size', Write to EOM. */
unlimited = 1;
break;
case 'B': /* blocks per output file */
blocksperfile = numarg("blocks per file", 1L, 0L);
break;
case 'b': /* blocks per tape write */
ntrec = numarg("blocks per write", 1L, 1000L);
bflag = 1;
break;
case 'c': /* Tape is cart. not 9-track */
cartridge = 1;
break;
case 'd': /* density, in bits per inch */
density = numarg("density", 10L, 327670L) / 10;
if (density >= 625 && !bflag)
ntrec = HIGHDENSITYTREC;
break;
case 'e': /* eject full tapes */
eflag = 1;
break;
case 'F': /* files-to-dump is an fs image */
Fflag = 1;
break;
case 'f': /* output file */
tape = optarg;
break;
case 'h':
honorlevel = numarg("honor level", 0L, 10L);
break;
case 'k':
readblksize = numarg("read block size", 0, 64) * 1024;
break;
case 'l': /* autoload after eject full tapes */
eflag = 1;
lflag = numarg("timeout (in seconds)", 1, 0);
break;
case 'L':
/*
* Note that although there are LBLSIZE characters,
* the last must be '\0', so the limit on strlen()
* is really LBLSIZE-1.
*/
if (strlcpy(labelstr, optarg, sizeof(labelstr))
>= sizeof(labelstr)) {
msg(
"WARNING Label `%s' is larger than limit of %lu characters.\n",
optarg,
(unsigned long)sizeof(labelstr) - 1);
msg("WARNING: Using truncated label `%s'.\n",
labelstr);
}
break;
case 'n': /* notify operators */
notify = 1;
break;
case 'r': /* read cache size */
readcache = numarg("read cache size", 0, 512);
break;
case 's': /* tape size, feet */
tsize = numarg("tape size", 1L, 0L) * 12 * 10;
break;
case 'S': /* exit after estimating # of tapes */
just_estimate = 1;
break;
case 't':
timestamp = 1;
break;
case 'T': /* time of last dump */
spcl.c_ddate = unctime(optarg);
if (spcl.c_ddate < 0) {
(void)fprintf(stderr, "bad time \"%s\"\n",
optarg);
exit(X_STARTUP);
}
Tflag = 1;
lastlevel = '?';
break;
case 'u': /* update /etc/dumpdates */
uflag = 1;
break;
case 'W': /* what to do */
case 'w':
lastdump(ch);
exit(X_FINOK); /* do nothing else */
case 'x':
snap_backup = optarg;
break;
case 'X':
snap_internal = 1;
break;
default:
usage();
}
argc -= optind;
argv += optind;
if (argc < 1) {
(void)fprintf(stderr,
"Must specify disk or image, or file list\n");
exit(X_STARTUP);
}
/*
* determine if disk is a subdirectory, and setup appropriately
*/
getfstab(); /* /etc/fstab snarfed */
disk = NULL;
mountpoint = NULL;
dirc = 0;
for (i = 0; i < argc; i++) {
struct stat sb;
if (lstat(argv[i], &sb) == -1)
quit("Cannot stat %s: %s\n", argv[i], strerror(errno));
if (Fflag || S_ISCHR(sb.st_mode) || S_ISBLK(sb.st_mode)) {
disk = argv[i];
multicheck:
if (dirc != 0)
quit(
"Can't dump a disk or image at the same time as a file list\n");
break;
}
if ((dt = fstabsearch(argv[i])) != NULL) {
disk = dt->fs_spec;
mountpoint = xstrdup(dt->fs_file);
goto multicheck;
}
if (statvfs(argv[i], &fsbuf) == -1)
quit("Cannot statvfs %s: %s\n", argv[i],
strerror(errno));
disk = fsbuf.f_mntfromname;
if (strcmp(argv[i], fsbuf.f_mntonname) == 0)
goto multicheck;
if (mountpoint == NULL) {
mountpoint = xstrdup(fsbuf.f_mntonname);
if (uflag) {
msg("Ignoring u flag for subdir dump\n");
uflag = 0;
}
if (level > '0') {
msg("Subdir dump is done at level 0\n");
level = '0';
}
msg("Dumping sub files/directories from %s\n",
mountpoint);
} else {
if (strcmp(mountpoint, fsbuf.f_mntonname) != 0)
quit("%s is not on %s\n", argv[i], mountpoint);
}
msg("Dumping file/directory %s\n", argv[i]);
dirc++;
}
if (mountpoint)
free(mountpoint);
if (dirc == 0) {
argv++;
if (argc != 1) {
(void)fprintf(stderr, "Excess arguments to dump:");
while (--argc)
(void)fprintf(stderr, " %s", *argv++);
(void)fprintf(stderr, "\n");
exit(X_STARTUP);
}
}
if (Tflag && uflag) {
(void)fprintf(stderr,
"You cannot use the T and u flags together.\n");
exit(X_STARTUP);
}
if (strcmp(tape, "-") == 0) {
pipeout++;
tape = "standard output";
}
if (blocksperfile)
blocksperfile = blocksperfile / ntrec * ntrec; /* round down */
else if (!unlimited) {
/*
* Determine how to default tape size and density
*
* density tape size
* 9-track 1600 bpi (160 bytes/.1") 2300 ft.
* 9-track 6250 bpi (625 bytes/.1") 2300 ft.
* cartridge 8000 bpi (100 bytes/.1") 1700 ft.
* (450*4 - slop)
*/
if (density == 0)
density = cartridge ? 100 : 160;
if (tsize == 0)
tsize = cartridge ? 1700L*120L : 2300L*120L;
}
if ((cp = strchr(tape, ':')) != NULL) {
host = tape;
/* This is fine, because all the const strings don't have : */
*cp++ = '\0';
tape = cp;
#ifdef RDUMP
if (rmthost(host) == 0)
exit(X_STARTUP);
#else
(void)fprintf(stderr, "remote dump not enabled\n");
exit(X_STARTUP);
#endif
}
if (signal(SIGHUP, SIG_IGN) != SIG_IGN)
signal(SIGHUP, sig);
if (signal(SIGTRAP, SIG_IGN) != SIG_IGN)
signal(SIGTRAP, sig);
if (signal(SIGFPE, SIG_IGN) != SIG_IGN)
signal(SIGFPE, sig);
if (signal(SIGBUS, SIG_IGN) != SIG_IGN)
signal(SIGBUS, sig);
#if 0
if (signal(SIGSEGV, SIG_IGN) != SIG_IGN)
signal(SIGSEGV, sig);
#endif
if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
signal(SIGTERM, sig);
if (signal(SIGINT, interrupt) == SIG_IGN)
signal(SIGINT, SIG_IGN);
/*
* disk can be either the full special file name, or
* the file system name.
*/
mountpoint = NULL;
mntinfo = mntinfosearch(disk);
if ((dt = fstabsearch(disk)) != NULL) {
disk = rawname(dt->fs_spec);
mountpoint = dt->fs_file;
msg("Found %s on %s in %s\n", disk, mountpoint, _PATH_FSTAB);
} else if (mntinfo != NULL) {
disk = rawname(mntinfo->f_mntfromname);
mountpoint = mntinfo->f_mntonname;
msg("Found %s on %s in mount table\n", disk, mountpoint);
}
if (mountpoint != NULL) {
if (dirc != 0)
(void)snprintf(spcl.c_filesys, sizeof(spcl.c_filesys),
"a subset of %s", mountpoint);
else
(void)strlcpy(spcl.c_filesys, mountpoint,
sizeof(spcl.c_filesys));
} else if (Fflag) {
(void)strlcpy(spcl.c_filesys, "a file system image",
sizeof(spcl.c_filesys));
} else {
(void)strlcpy(spcl.c_filesys, "an unlisted file system",
sizeof(spcl.c_filesys));
}
(void)strlcpy(spcl.c_dev, disk, sizeof(spcl.c_dev));
(void)strlcpy(spcl.c_label, labelstr, sizeof(spcl.c_label));
(void)gethostname(spcl.c_host, sizeof(spcl.c_host));
spcl.c_host[sizeof(spcl.c_host) - 1] = '\0';
if ((snap_backup != NULL || snap_internal) && mntinfo == NULL) {
msg("WARNING: Cannot use -x or -X on unmounted file system.\n");
snap_backup = NULL;
snap_internal = 0;
}
if (snap_backup != NULL || snap_internal) {
diskfd = snap_open(mntinfo->f_mntonname, snap_backup, &tnow);
if (diskfd < 0) {
msg("Cannot open snapshot of %s\n",
mntinfo->f_mntonname);
exit(X_STARTUP);
}
spcl.c_date = tnow;
} else {
if ((diskfd = open(disk, O_RDONLY)) < 0) {
msg("Cannot open %s\n", disk);
exit(X_STARTUP);
}
}
sync();
needswap = fs_read_sblock(sblock_buf);
spcl.c_level = iswap32(level - '0');
spcl.c_type = iswap32(TS_TAPE);
spcl.c_date = iswap32(spcl.c_date);
spcl.c_ddate = iswap32(spcl.c_ddate);
if (!Tflag)
getdumptime(); /* /etc/dumpdates snarfed */
date = iswap32(spcl.c_date);
msg("Date of this level %c dump: %s", level,
spcl.c_date == 0 ? "the epoch\n" : ctime(&date));
date = iswap32(spcl.c_ddate);
msg("Date of last level %c dump: %s", lastlevel,
spcl.c_ddate == 0 ? "the epoch\n" : ctime(&date));
msg("Dumping ");
if (snap_backup != NULL)
msgtail("a snapshot of ");
if (dirc != 0)
msgtail("a subset of ");
msgtail("%s (%s) ", disk, spcl.c_filesys);
if (host)
msgtail("to %s on host %s\n", tape, host);
else
msgtail("to %s\n", tape);
msg("Label: %s\n", labelstr);
ufsib = fs_parametrize();
dev_bshift = ffs(dev_bsize) - 1;
if (dev_bsize != (1 << dev_bshift))
quit("dev_bsize (%ld) is not a power of 2", dev_bsize);
tp_bshift = ffs(TP_BSIZE) - 1;
if (TP_BSIZE != (1 << tp_bshift))
quit("TP_BSIZE (%d) is not a power of 2", TP_BSIZE);
maxino = fs_maxino();
mapsize = roundup(howmany(maxino, NBBY), TP_BSIZE);
usedinomap = (char *)xcalloc((unsigned) mapsize, sizeof(char));
dumpdirmap = (char *)xcalloc((unsigned) mapsize, sizeof(char));
dumpinomap = (char *)xcalloc((unsigned) mapsize, sizeof(char));
tapesize = 3 * (howmany(mapsize * sizeof(char), TP_BSIZE) + 1);
nonodump = iswap32(spcl.c_level) < honorlevel;
initcache(readcache, readblksize);
(void)signal(SIGINFO, statussig);
msg("mapping (Pass I) [regular files]\n");
anydirskipped = mapfiles(maxino, &tapesize, mountpoint,
(dirc ? argv : NULL));
msg("mapping (Pass II) [directories]\n");
while (anydirskipped) {
anydirskipped = mapdirs(maxino, &tapesize);
}
if (pipeout || unlimited) {
tapesize += 10; /* 10 trailer blocks */
msg("estimated %llu tape blocks.\n",
(unsigned long long)tapesize);
} else {
double fetapes;
if (blocksperfile)
fetapes = (double) tapesize / blocksperfile;
else if (cartridge) {
/* Estimate number of tapes, assuming streaming stops at
the end of each block written, and not in mid-block.
Assume no erroneous blocks; this can be compensated
for with an artificially low tape size. */
fetapes =
( (double) tapesize /* blocks */
* TP_BSIZE /* bytes/block */
* (1.0/density) /* 0.1" / byte */
+
(double) tapesize /* blocks */
* (1.0/ntrec) /* streaming-stops per block */
* 15.48 /* 0.1" / streaming-stop */
) * (1.0 / tsize ); /* tape / 0.1" */
} else {
/* Estimate number of tapes, for old fashioned 9-track
tape */
int tenthsperirg = (density == 625) ? 3 : 7;
fetapes =
( tapesize /* blocks */
* TP_BSIZE /* bytes / block */
* (1.0/density) /* 0.1" / byte */
+
tapesize /* blocks */
* (1.0/ntrec) /* IRG's / block */
* tenthsperirg /* 0.1" / IRG */
) * (1.0 / tsize ); /* tape / 0.1" */
}
etapes = fetapes; /* truncating assignment */
etapes++;
/* count the dumped inodes map on each additional tape */
tapesize += (etapes - 1) *
(howmany(mapsize * sizeof(char), TP_BSIZE) + 1);
tapesize += etapes + 10; /* headers + 10 trailer blks */
msg("estimated %llu tape blocks on %3.2f tape(s).\n",
(unsigned long long)tapesize, fetapes);
}
/*
* If the user only wants an estimate of the number of
* tapes, exit now.
*/
if (just_estimate)
exit(X_FINOK);
/*
* Allocate tape buffer.
*/
if (!alloctape())
quit("can't allocate tape buffers - try a smaller blocking factor.\n");
startnewtape(1);
(void)time((time_t *)&(tstart_writing));
xferrate = 0;
dumpmap(usedinomap, TS_CLRI, maxino - 1);
msg("dumping (Pass III) [directories]\n");
dirty = 0; /* XXX just to get gcc to shut up */
for (map = dumpdirmap, ino = 1; ino < maxino; ino++) {
if (((ino - 1) % NBBY) == 0) /* map is offset by 1 */
dirty = *map++;
else
dirty >>= 1;
if ((dirty & 1) == 0)
continue;
/*
* Skip directory inodes deleted and maybe reallocated
*/
dp = getino(ino);
if ((DIP(dp, mode) & IFMT) != IFDIR)
continue;
(void)dumpino(dp, ino);
}
msg("dumping (Pass IV) [regular files]\n");
for (map = dumpinomap, ino = 1; ino < maxino; ino++) {
int mode;
if (((ino - 1) % NBBY) == 0) /* map is offset by 1 */
dirty = *map++;
else
dirty >>= 1;
if ((dirty & 1) == 0)
continue;
/*
* Skip inodes deleted and reallocated as directories.
*/
dp = getino(ino);
mode = DIP(dp, mode) & IFMT;
if (mode == IFDIR)
continue;
(void)dumpino(dp, ino);
}
spcl.c_type = iswap32(TS_END);
for (i = 0; i < ntrec; i++)
writeheader(maxino - 1);
if (pipeout)
msg("%d tape blocks\n",iswap32(spcl.c_tapea));
else
msg("%d tape blocks on %d volume%s\n",
iswap32(spcl.c_tapea), iswap32(spcl.c_volume),
(iswap32(spcl.c_volume) == 1) ? "" : "s");
tnow = do_stats();
date = iswap32(spcl.c_date);
msg("Date of this level %c dump: %s", level,
spcl.c_date == 0 ? "the epoch\n" : ctime(&date));
msg("Date this dump completed: %s", ctime(&tnow));
msg("Average transfer rate: %d KB/s\n", xferrate / tapeno);
putdumptime();
trewind(0);
broadcast("DUMP IS DONE!\a\a\n");
msg("DUMP IS DONE\n");
Exit(X_FINOK);
/* NOTREACHED */
exit(X_FINOK); /* XXX: to satisfy gcc */
}
static void
usage(void)
{
const char *prog = getprogname();
(void)fprintf(stderr,
"usage: %s [-0123456789aceFnStuX] [-B records] [-b blocksize]\n"
" [-d density] [-f file] [-h level] [-k read-blocksize]\n"
" [-L label] [-l timeout] [-r read-cache] [-s feet]\n"
" [-T date] [-x snap-backup] files-to-dump\n"
" %s [-W | -w]\n", prog, prog);
exit(X_STARTUP);
}
/*
* Pick up a numeric argument. It must be nonnegative and in the given
* range (except that a vmax of 0 means unlimited).
*/
static long
numarg(const char *meaning, long vmin, long vmax)
{
char *p;
long val;
val = strtol(optarg, &p, 10);
if (*p)
errx(X_STARTUP, "illegal %s -- %s", meaning, optarg);
if (val < vmin || (vmax && val > vmax))
errx(X_STARTUP, "%s must be between %ld and %ld",
meaning, vmin, vmax);
return (val);
}
void
sig(int signo)
{
switch(signo) {
case SIGALRM:
case SIGBUS:
case SIGFPE:
case SIGHUP:
case SIGTERM:
case SIGTRAP:
if (pipeout)
quit("Signal on pipe: cannot recover\n");
msg("Rewriting attempted as response to signal %s.\n", sys_siglist[signo]);
(void)fflush(stderr);
(void)fflush(stdout);
close_rewind();
exit(X_REWRITE);
/* NOTREACHED */
case SIGSEGV:
msg("SIGSEGV: ABORTING!\n");
(void)signal(SIGSEGV, SIG_DFL);
(void)kill(0, SIGSEGV);
/* NOTREACHED */
}
}
char *
rawname(char *cp)
{
static char rawbuf[MAXPATHLEN];
char *dp = strrchr(cp, '/');
if (dp == NULL)
return (NULL);
*dp = '\0';
(void)snprintf(rawbuf, sizeof rawbuf, "%s/r%s", cp, dp + 1);
*dp = '/';
return (rawbuf);
}
/*
* obsolete --
* Change set of key letters and ordered arguments into something
* getopt(3) will like.
*/
static void
obsolete(int *argcp, char **argvp[])
{
int argc, flags;
char *ap, **argv, *flagsp, **nargv, *p;
/* Setup. */
argv = *argvp;
argc = *argcp;
/* Return if no arguments or first argument has leading dash. */
ap = argv[1];
if (argc == 1 || *ap == '-')
return;
/* Allocate space for new arguments. */
*argvp = nargv = xmalloc((argc + 1) * sizeof(char *));
p = flagsp = xmalloc(strlen(ap) + 2);
*nargv++ = *argv;
argv += 2;
for (flags = 0; *ap; ++ap) {
switch (*ap) {
case 'B':
case 'b':
case 'd':
case 'f':
case 'h':
case 's':
case 'T':
case 'x':
if (*argv == NULL) {
warnx("option requires an argument -- %c", *ap);
usage();
}
nargv[0] = xmalloc(strlen(*argv) + 2 + 1);
nargv[0][0] = '-';
nargv[0][1] = *ap;
(void)strcpy(&nargv[0][2], *argv); /* XXX safe strcpy */
++argv;
++nargv;
break;
default:
if (!flags) {
*p++ = '-';
flags = 1;
}
*p++ = *ap;
break;
}
}
/* Terminate flags. */
if (flags) {
*p = '\0';
*nargv++ = flagsp;
} else
free(flagsp);
/* Copy remaining arguments. */
while ((*nargv++ = *argv++) != NULL)
;
/* Update argument count. */
*argcp = nargv - *argvp - 1;
}
void *
xcalloc(size_t number, size_t size)
{
void *p;
p = calloc(number, size);
if (p == NULL)
quit("%s\n", strerror(errno));
return (p);
}
void *
xmalloc(size_t size)
{
void *p;
p = malloc(size);
if (p == NULL)
quit("%s\n", strerror(errno));
return (p);
}
char *
xstrdup(const char *str)
{
char *p;
p = strdup(str);
if (p == NULL)
quit("%s\n", strerror(errno));
return (p);
}