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Our mmap(2) has a limitation where the `offset' parameter must be

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page-aligned.  cmp(1) should know about this flaw, and work around it.

While i was at it, fixed an uninitialized variable as reported by
-Wall.
This commit is contained in:
Joerg Wunsch 1997-01-08 12:00:55 +00:00
parent b8b15e71f7
commit c28065c606
2 changed files with 13 additions and 3 deletions
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14
usr.bin/cmp/regular.c
View File

@ -44,9 +44,12 @@ static char sccsid[] = "@(#)regular.c 8.3 (Berkeley) 4/2/94";
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "extern.h"
#define ROUNDPAGE(i) ((i) & ~pagemask)
void
c_regular(fd1, file1, skip1, len1, fd2, file2, skip2, len2)
int fd1, fd2;
@ -56,6 +59,7 @@ c_regular(fd1, file1, skip1, len1, fd2, file2, skip2, len2)
u_char ch, *p1, *p2;
off_t byte, length, line;
int dfound;
off_t pagemask, off1, off2;
if (sflag && len1 != len2)
exit(1);
@ -67,21 +71,27 @@ c_regular(fd1, file1, skip1, len1, fd2, file2, skip2, len2)
eofmsg(file2);
len2 -= skip2;
pagemask = (off_t)getpagesize() - 1;
off1 = ROUNDPAGE(skip1);
off2 = ROUNDPAGE(skip2);
length = MIN(len1, len2);
if (length > SIZE_T_MAX)
return (c_special(fd1, file1, skip1, fd2, file2, skip2));
if ((p1 = (u_char *)mmap(NULL,
(size_t)length, PROT_READ, 0, fd1, skip1)) == (u_char *)-1)
(size_t)length, PROT_READ, 0, fd1, off1)) == (u_char *)-1)
err(ERR_EXIT, "%s", file1);
madvise(p1, length, MADV_SEQUENTIAL);
if ((p2 = (u_char *)mmap(NULL,
(size_t)length, PROT_READ, 0, fd2, skip2)) == (u_char *)-1)
(size_t)length, PROT_READ, 0, fd2, off2)) == (u_char *)-1)
err(ERR_EXIT, "%s", file2);
madvise(p2, length, MADV_SEQUENTIAL);
dfound = 0;
p1 += skip1 - off1;
p2 += skip2 - off2;
for (byte = line = 1; length--; ++p1, ++p2, ++byte) {
if ((ch = *p1) != *p2)
if (lflag) {

2
usr.bin/cmp/special.c
View File

@ -60,6 +60,7 @@ c_special(fd1, file1, skip1, fd2, file2, skip2)
if ((fp2 = fdopen(fd2, "r")) == NULL)
err(ERR_EXIT, "%s", file2);
dfound = 0;
while (skip1--)
if (getc(fp1) == EOF)
goto eof;
@ -67,7 +68,6 @@ c_special(fd1, file1, skip1, fd2, file2, skip2)
if (getc(fp2) == EOF)
goto eof;
dfound = 0;
for (byte = line = 1;; ++byte) {
ch1 = getc(fp1);
ch2 = getc(fp2);