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tail: fix "tail -r" for piped input that begins with '\n'

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A subtle logic bug, probably introduced in r311895, caused tail to print the
first two lines of piped input in forward order, if the very first character
was a newline.

PR:		222671
Reported by:	Jim Long <freebsd-bugzilla@umpquanet.com>, pprocacci@gmail.com
MFC after:	3 weeks
Sponsored by:	Spectra Logic Corp
This commit is contained in:
Alan Somers 2018-02-19 22:09:49 +00:00
parent 88126356cf
commit d23662ec2e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=329606
2 changed files with 49 additions and 2 deletions
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7
usr.bin/tail/reverse.c
View File

@ -257,10 +257,13 @@ r_buf(FILE *fp, const char *fn)
if ((*p == '\n') || start) {
struct bfelem *tr;
if (start && llen)
if (llen && start && *p != '\n')
WR(p, llen + 1);
else if (llen)
else if (llen) {
WR(p + 1, llen);
if (start && *p == '\n')
WR(p, 1);
}
tr = TAILQ_NEXT(tl, entries);
llen = 0;
if (tr != NULL) {

44
usr.bin/tail/tests/tail_test.sh
View File

@ -83,6 +83,49 @@ HERE
atf_check cmp expectfile outpipe
}
# Regression test for PR 222671
# https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=222671
atf_test_case pipe_leading_newline_r
pipe_leading_newline_r_head()
{
atf_set "descr" "Reverse a pipe whose first character is a newline"
}
pipe_leading_newline_r_body()
{
cat > expectfile << HERE
3
2
1
HERE
printf '\n1\n2\n3\n' | tail -r > outfile
printf '\n1\n2\n3\n' | tail -r > outpipe
atf_check cmp expectfile outfile
atf_check cmp expectfile outpipe
}
atf_test_case file_rc28
file_rc28_head()
{
atf_set "descr" "Reverse a file and display the last 28 characters"
}
file_rc28_body()
{
cat > infile <<HERE
This is the first line
This is the second line
This is the third line
HERE
cat > expectfile << HERE
This is the third line
line
HERE
tail -rc28 infile > outfile
tail -rc28 < infile > outpipe
atf_check cmp expectfile outfile
atf_check cmp expectfile outpipe
}
atf_test_case file_rc28
file_rc28_head()
{
@ -235,6 +278,7 @@ atf_init_test_cases()
atf_add_test_case file_r
atf_add_test_case file_rc28
atf_add_test_case file_rn2
atf_add_test_case pipe_leading_newline_r
# The longfile tests are designed to exercise behavior in r_buf(),
# which operates on 128KB blocks
atf_add_test_case longfile_r