[PATCH] grep: fix infinite loop in -o
Colin Watson
cjwatson at ubuntu.com
Thu Aug 19 13:50:52 UTC 2010
If the supplied pattern matches the empty string at the start of a line,
then 'grep -o' would loop forever.
Originally reported as
https://bugs.launchpad.net/ubuntu/+source/busybox/+bug/619817.
Signed-off-by: Colin Watson <cjwatson at ubuntu.com>
---
findutils/grep.c | 20 +++++++++++++-------
testsuite/grep.tests | 4 ++++
2 files changed, 17 insertions(+), 7 deletions(-)
diff --git a/findutils/grep.c b/findutils/grep.c
index 688ea6a..7545ade 100644
--- a/findutils/grep.c
+++ b/findutils/grep.c
@@ -463,13 +463,19 @@ static int grep_file(FILE *file)
} else while (1) {
unsigned end = gl->matched_range.rm_eo;
char old = line[end];
- line[end] = '\0';
- print_line(line + gl->matched_range.rm_so,
- end - gl->matched_range.rm_so,
- linenum, ':');
- if (old == '\0')
- break;
- line[end] = old;
+ if (gl->matched_range.rm_so == gl->matched_range.rm_eo) {
+ end++;
+ if (line[end] == '\0')
+ break;
+ } else {
+ line[end] = '\0';
+ print_line(line + gl->matched_range.rm_so,
+ end - gl->matched_range.rm_so,
+ linenum, ':');
+ if (old == '\0')
+ break;
+ line[end] = old;
+ }
#if !ENABLE_EXTRA_COMPAT
if (regexec(&gl->compiled_regex, line + end,
1, &gl->matched_range, REG_NOTBOL) != 0)
diff --git a/testsuite/grep.tests b/testsuite/grep.tests
index 520a184..ad99257 100755
--- a/testsuite/grep.tests
+++ b/testsuite/grep.tests
@@ -98,5 +98,9 @@ testing "grep -o does not loop forever" \
'grep -o "[^/]*$"' \
"test\n" \
"" "/var/test\n"
+testing "grep -o does not loop forever on zero-length match at ^" \
+ 'grep -o "" | head -n1' \
+ "" \
+ "" "test\n"
exit $FAILCOUNT
--
1.7.1
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