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mmap normal files in 1MB chunks.

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Due to a bug in mmap() the address space isn't counted against ulimit
until the page is faulted in - so mmapping a large file suceeds, but
cmp SIGSEGVs when it runs out of address space.
Also I don't believe that the madvise( MAP_SEQUENTIAL) has the desired
effect, and mmaping a large file is probably very bad for the UBC.
This commit is contained in:
dsl 2005-02-06 21:19:46 +00:00
parent 6ffe77ddd2
commit afc59ef61f
1 changed files with 34 additions and 28 deletions
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62
usr.bin/cmp/regular.c
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@ -1,4 +1,4 @@
/* $NetBSD: regular.c,v 1.13 2005/02/06 20:50:34 dsl Exp $ */
/* $NetBSD: regular.c,v 1.14 2005/02/06 21:19:46 dsl Exp $ */
/*-
* Copyright (c) 1991, 1993, 1994
@ -34,7 +34,7 @@
#if 0
static char sccsid[] = "@(#)regular.c 8.3 (Berkeley) 4/2/94";
#else
__RCSID("$NetBSD: regular.c,v 1.13 2005/02/06 20:50:34 dsl Exp $");
__RCSID("$NetBSD: regular.c,v 1.14 2005/02/06 21:19:46 dsl Exp $");
#endif
#endif /* not lint */
@ -57,6 +57,7 @@ c_regular(int fd1, char *file1, off_t skip1, off_t len1,
u_char ch, *p1, *p2;
off_t byte, length, line;
int dfound;
size_t blk_sz, blk_cnt;
if (sflag && len1 != len2)
exit(1);
@ -69,41 +70,46 @@ c_regular(int fd1, char *file1, off_t skip1, off_t len1,
len2 -= skip2;
length = MIN(len1, len2);
if (length > SIZE_T_MAX) {
mmap_failed:
c_special(fd1, file1, skip1, fd2, file2, skip2);
return;
}
for (blk_sz = 1024 * 1024; length != 0; length -= blk_sz) {
if (blk_sz > length)
blk_sz = length;
p1 = mmap(NULL, blk_sz, PROT_READ, MAP_FILE|MAP_SHARED, fd1, skip1);
if (p1 == MAP_FAILED)
goto mmap_failed;
if ((p1 = (u_char *)mmap(NULL, (size_t)length,
PROT_READ, MAP_FILE|MAP_SHARED, fd1, skip1)) == MAP_FAILED)
goto mmap_failed;
(void)madvise(p1, (size_t)length, MADV_SEQUENTIAL);
p2 = mmap(NULL, blk_sz, PROT_READ, MAP_FILE|MAP_SHARED, fd2, skip2);
if (p2 == MAP_FAILED) {
munmap(p1, blk_sz);
goto mmap_failed;
}
if ((p2 = (u_char *)mmap(NULL, (size_t)length,
PROT_READ, MAP_FILE|MAP_SHARED, fd2, skip2)) == MAP_FAILED) {
munmap(p1, (size_t) length);
goto mmap_failed;
}
(void)madvise(p2, (size_t)length, MADV_SEQUENTIAL);
dfound = 0;
for (byte = line = 1; length--; ++p1, ++p2, ++byte) {
if ((ch = *p1) != *p2) {
if (lflag) {
dfound = 0;
blk_cnt = blk_sz;
for (byte = line = 1; blk_cnt--; ++p1, ++p2, ++byte) {
if ((ch = *p1) != *p2) {
if (!lflag) {
diffmsg(file1, file2, byte, line);
/* NOTREACHED */
}
dfound = 1;
(void)printf("%6lld %3o %3o\n", (long long)byte,
ch, *p2);
} else
diffmsg(file1, file2, byte, line);
/* NOTREACHED */
ch, *p2);
}
if (ch == '\n')
++line;
}
if (ch == '\n')
++line;
munmap(p1 - blk_sz, blk_sz);
munmap(p2 - blk_sz, blk_sz);
skip1 += blk_sz;
skip2 += blk_sz;
}
if (len1 != len2)
eofmsg (len1 > len2 ? file2 : file1);
if (dfound)
exit(DIFF_EXIT);
return;
mmap_failed:
c_special(fd1, file1, skip1, fd2, file2, skip2);
}