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cmp: add -n, --bytes to limit number of bytes to compare

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This is compatible with GNU cmp.

Reviewed by:	markj
Sponsored by:	Klara, Inc.
Differential Revision:	https://reviews.freebsd.org/D32072
This commit is contained in:
Kyle Evans 2021-09-23 00:26:52 -05:00
parent f6787614fd
commit 4e380e8474
7 changed files with 57 additions and 15 deletions
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6
usr.bin/cmp/cmp.1
View File

@ -41,6 +41,7 @@
.Nm
.Op Fl l | s | x
.Op Fl hz
.Op Fl -bytes Ns Cm = Ns Ar num
.Ar file1 file2
.Op Ar skip1 Op Ar skip2
.Sh DESCRIPTION
@ -62,6 +63,10 @@ Do not follow symbolic links.
.It Fl l , Fl -verbose
Print the byte number (decimal) and the differing
byte values (octal) for each difference.
.It Fl n Ar num , Fl -bytes= Ns num
Only compare up to
.Ar num
bytes.
.It Fl s , Fl -silent , Fl -quiet
Print nothing for differing files; return exit
status only.
@ -165,6 +170,7 @@ utility is expected to be
compatible.
The
.Fl h ,
.Fl n ,
.Fl x ,
and
.Fl z

18
usr.bin/cmp/cmp.c
View File

@ -67,6 +67,7 @@ bool lflag, sflag, xflag, zflag;
static const struct option long_opts[] =
{
{"verbose", no_argument, NULL, 'l'},
{"bytes", required_argument, NULL, 'n'},
{"silent", no_argument, NULL, 's'},
{"quiet", no_argument, NULL, 's'},
{NULL, no_argument, NULL, 0}
@ -78,14 +79,14 @@ int
main(int argc, char *argv[])
{
struct stat sb1, sb2;
off_t skip1, skip2;
off_t skip1, skip2, limit;
int ch, fd1, fd2, oflag;
bool special;
const char *file1, *file2;
skip1 = skip2 = 0;
oflag = O_RDONLY;
while ((ch = getopt_long(argc, argv, "+hlsxz", long_opts, NULL)) != -1)
while ((ch = getopt_long(argc, argv, "+hln:sxz", long_opts, NULL)) != -1)
switch (ch) {
case 'h': /* Don't follow symlinks */
oflag |= O_NOFOLLOW;
@ -93,6 +94,13 @@ main(int argc, char *argv[])
case 'l': /* print all differences */
lflag = true;
break;
case 'n': /* Limit */
if (expand_number(optarg, &limit) < 0 || limit < 0) {
fprintf(stderr, "Invalid --bytes: %s\n",
optarg);
usage();
}
break;
case 's': /* silent run */
sflag = true;
break;
@ -163,7 +171,7 @@ main(int argc, char *argv[])
if (fd1 == -1) {
if (fd2 == -1) {
c_link(file1, skip1, file2, skip2);
c_link(file1, skip1, file2, skip2, limit);
exit(0);
} else if (!sflag)
errx(ERR_EXIT, "%s: Not a symbolic link", file2);
@ -201,7 +209,7 @@ main(int argc, char *argv[])
}
if (special)
c_special(fd1, file1, skip1, fd2, file2, skip2);
c_special(fd1, file1, skip1, fd2, file2, skip2, limit);
else {
if (zflag && sb1.st_size != sb2.st_size) {
if (!sflag)
@ -210,7 +218,7 @@ main(int argc, char *argv[])
exit(DIFF_EXIT);
}
c_regular(fd1, file1, skip1, sb1.st_size,
fd2, file2, skip2, sb2.st_size);
fd2, file2, skip2, sb2.st_size, limit);
}
exit(0);
}

7
usr.bin/cmp/extern.h
View File

@ -38,9 +38,10 @@
#define DIFF_EXIT 1
#define ERR_EXIT 2 /* error exit code */
void c_link(const char *, off_t, const char *, off_t);
void c_regular(int, const char *, off_t, off_t, int, const char *, off_t, off_t);
void c_special(int, const char *, off_t, int, const char *, off_t);
void c_link(const char *, off_t, const char *, off_t, off_t);
void c_regular(int, const char *, off_t, off_t, int, const char *, off_t,
off_t, off_t);
void c_special(int, const char *, off_t, int, const char *, off_t, off_t);
void diffmsg(const char *, const char *, off_t, off_t);
void eofmsg(const char *);

6
usr.bin/cmp/link.c
View File

@ -40,7 +40,8 @@ __FBSDID("$FreeBSD$");
#include "extern.h"
void
c_link(const char *file1, off_t skip1, const char *file2, off_t skip2)
c_link(const char *file1, off_t skip1, const char *file2, off_t skip2,
off_t limit)
{
char buf1[PATH_MAX], *p1;
char buf2[PATH_MAX], *p2;
@ -72,7 +73,8 @@ c_link(const char *file1, off_t skip1, const char *file2, off_t skip2)
dfound = 0;
byte = 1;
for (p1 = buf1 + skip1, p2 = buf2 + skip2; *p1 && *p2; p1++, p2++) {
for (p1 = buf1 + skip1, p2 = buf2 + skip2;
*p1 && *p2 && (limit == 0 || byte <= limit); p1++, p2++) {
if ((ch = *p1) != *p2) {
if (xflag) {
dfound = 1;

8
usr.bin/cmp/regular.c
View File

@ -60,7 +60,7 @@ static void segv_handler(int);
void
c_regular(int fd1, const char *file1, off_t skip1, off_t len1,
int fd2, const char *file2, off_t skip2, off_t len2)
int fd2, const char *file2, off_t skip2, off_t len2, off_t limit)
{
struct sigaction act, oact;
cap_rights_t rights;
@ -86,15 +86,17 @@ c_regular(int fd1, const char *file1, off_t skip1, off_t len1,
off2 = ROUNDPAGE(skip2);
length = MIN(len1, len2);
if (limit > 0)
length = MIN(length, limit);
if ((m1 = remmap(NULL, fd1, off1)) == NULL) {
c_special(fd1, file1, skip1, fd2, file2, skip2);
c_special(fd1, file1, skip1, fd2, file2, skip2, limit);
return;
}
if ((m2 = remmap(NULL, fd2, off2)) == NULL) {
munmap(m1, MMAP_CHUNK);
c_special(fd1, file1, skip1, fd2, file2, skip2);
c_special(fd1, file1, skip1, fd2, file2, skip2, limit);
return;
}

4
usr.bin/cmp/special.c
View File

@ -49,7 +49,7 @@ __FBSDID("$FreeBSD$");
void
c_special(int fd1, const char *file1, off_t skip1,
int fd2, const char *file2, off_t skip2)
int fd2, const char *file2, off_t skip2, off_t limit)
{
int ch1, ch2;
off_t byte, line;
@ -76,7 +76,7 @@ c_special(int fd1, const char *file1, off_t skip1,
if (getc(fp2) == EOF)
goto eof;
for (byte = line = 1;; ++byte) {
for (byte = line = 1; limit == 0 || byte <= limit; ++byte) {
ch1 = getc(fp1);
ch2 = getc(fp2);
if (ch1 == EOF || ch2 == EOF)

23
usr.bin/cmp/tests/cmp_test2.sh
View File

@ -91,10 +91,33 @@ skipsuff_body()
atf_check -s exit:0 cmp -s a b 1k 1k
}
atf_test_case limit
limit_head()
{
atf_set "descr" "Test cmp(1) -n (limit)"
}
limit_body()
{
echo -n "aaaabbbb" > a
echo -n "aaaaxxxx" > b
atf_check -s exit:1 -o ignore cmp -s a b
atf_check -s exit:0 cmp -sn 4 a b
atf_check -s exit:0 cmp -sn 3 a b
atf_check -s exit:1 -o ignore cmp -sn 5 a b
# Test special, too. The implementation for link is effectively
# identical.
atf_check -s exit:0 -e empty -x "cat a | cmp -sn 4 b -"
atf_check -s exit:0 -e empty -x "cat a | cmp -sn 3 b -"
atf_check -s exit:1 -o ignore -x "cat a | cmp -sn 5 b -"
}
atf_init_test_cases()
{
atf_add_test_case special
atf_add_test_case symlink
atf_add_test_case pr252542
atf_add_test_case skipsuff
atf_add_test_case limit
}