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authorDenys Vlasenko2017-07-06 19:48:20 +0200
committerDenys Vlasenko2017-07-06 19:48:20 +0200
commit5dad7bdc3bdad8e9934d45301d5a8c51e843cd7b (patch)
treedb493d6ca6cabddcfe3e9a58f33ee712bd1584d4 /shell/hush.c
parent3234045d07c3fb2a9ef8afd02f821158317adbd3 (diff)
downloadbusybox-5dad7bdc3bdad8e9934d45301d5a8c51e843cd7b.zip
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hush: implement negative start in the ${v: -n[:m]} idiom
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'shell/hush.c')
-rw-r--r--shell/hush.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/shell/hush.c b/shell/hush.c
index 64b33cf..f6b50de 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -5619,8 +5619,12 @@ static NOINLINE const char *expand_one_var(char **to_be_freed_pp, char *arg, cha
goto arith_err;
debug_printf_varexp("len:'%s'=%lld\n", exp_word, (long long)len);
if (len >= 0) { /* bash compat: len < 0 is illegal */
- if (beg < 0) /* bash compat */
- beg = 0;
+ if (beg < 0) {
+ /* negative beg counts from the end */
+ beg = (arith_t)strlen(val) + beg;
+ if (beg < 0) /* ${v: -999999} is "" */
+ beg = len = 0;
+ }
debug_printf_varexp("from val:'%s'\n", val);
if (len == 0 || !val || beg >= strlen(val)) {
arith_err: