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Only attempt to mmap() files from a ufs or cd9660 fs for comparing or

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installing.  mmap'ing stuff over a nfs mount took out my machine during
a 'make world' last night while I was asleep.  I started out with a list
of fs's to avoid, when I realised that I really didn't know which ones
were safe with mmap, so I went for the ones I knew and implemented a
fallback compare.
This commit is contained in:
Peter Wemm 1996-09-05 07:27:43 +00:00
parent cb77de2327
commit 7b7fc30379
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=18038
1 changed files with 45 additions and 4 deletions
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49
usr.bin/xinstall/xinstall.c
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@ -40,7 +40,7 @@ static const char copyright[] =
#ifndef lint
/*static char sccsid[] = "From: @(#)xinstall.c 8.1 (Berkeley) 7/21/93";*/
static const char rcsid[] =
"$Id: xinstall.c,v 1.8 1996/06/23 12:59:18 bde Exp $";
"$Id: xinstall.c,v 1.9 1996/08/12 17:03:30 peter Exp $";
#endif /* not lint */
/*-
@ -62,6 +62,7 @@ static const char rcsid[] =
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <ctype.h>
#include <err.h>
@ -95,6 +96,7 @@ void install __P((char *, char *, u_long, u_int));
u_long string_to_flags __P((char **, u_long *, u_long *));
void strip __P((char *));
void usage __P((void));
int trymmap __P((int));
#define ALLOW_NUMERIC_IDS 1
#ifdef ALLOW_NUMERIC_IDS
@ -488,7 +490,7 @@ compare(int from_fd, const char *from_name, int to_fd, const char *to_name,
tsize = (size_t)from_sb->st_size;
if (tsize <= 8 * 1024 * 1024) {
if (tsize <= 8 * 1024 * 1024 && trymmap(from_fd) && trymmap(to_fd)) {
p = mmap(NULL, tsize, PROT_READ, 0, from_fd, (off_t)0);
if ((long)p == -1)
err(EX_OSERR, "mmap %s", from_name);
@ -500,7 +502,26 @@ compare(int from_fd, const char *from_name, int to_fd, const char *to_name,
munmap(p, tsize);
munmap(q, tsize);
} else {
rv = 1; /* don't bother in this case */
char buf1[16384];
char buf2[16384];
int n1, n2;
rv = 0;
lseek(from_fd, 0, SEEK_SET);
lseek(to_fd, 0, SEEK_SET);
while (rv == 0) {
n1 = read(from_fd, buf1, sizeof(buf1));
if (n1 == 0)
break;
else if (n1 > 0) {
n2 = read(to_fd, buf2, n1);
if (n2 == n1)
rv = memcmp(buf1, buf2, n1);
else
rv = 1;
} else
rv = 1;
}
}
return rv;
}
@ -524,7 +545,7 @@ copy(from_fd, from_name, to_fd, to_name, size)
* trash memory on big files. This is really a minor hack, but it
* wins some CPU back.
*/
if (size <= 8 * 1048576) {
if (size <= 8 * 1048576 && trymmap(from_fd)) {
if ((p = mmap(NULL, (size_t)size, PROT_READ,
0, from_fd, (off_t)0)) == (char *)-1)
err(EX_OSERR, "mmap %s", from_name);
@ -585,3 +606,23 @@ usage()
"usage: install [-Ccdps] [-f flags] [-g group] [-m mode] [-o owner] file1 file2;\n\tor file1 ... fileN directory\n");
exit(1);
}
/*
* trymmap --
* return true (1) if mmap should be tried, false (0) if not.
*/
int
trymmap(fd)
int fd;
{
struct statfs stfs;
if (fstatfs(fd, &stfs) < 0)
return 0;
switch(stfs.f_type) {
case MOUNT_UFS: /* should be safe.. */
case MOUNT_CD9660: /* should be safe.. */
return 1;
}
return 0;
}