hush: speed up ${x//\*/|} too

function                                             old     new   delta
expand_one_var                                      2502    2544     +42

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 6d472337f..87fc2f445 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -6472,16 +6472,21 @@ static arith_t expand_and_evaluate_arith(const char *arg, const char **errmsg_p)
 /* ${var/[/]pattern[/repl]} helpers */
 static char *strstr_pattern(char *val, const char *pattern, int *size)
 {
-        int sz = strcspn(pattern, "*?[\\");
-        if (pattern[sz] == '\0') {
+        int first_escaped = (pattern[0] == '\\' && pattern[1]);
+        /* "first_escaped" trick allows to treat e.g. "\*no_glob_chars"
+         * as literal too (as it is semi-common, and easy to accomodate
+         * by just using str + 1).
+         */
+        int sz = strcspn(pattern + first_escaped * 2, "*?[\\");
+        if ((pattern + first_escaped * 2)[sz] == '\0') {
                 /* Optimization for trivial patterns.
                  * Testcase for very slow replace (performs about 22k replaces):
                  * x=::::::::::::::::::::::
                  * x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;echo ${#x}
                  * echo "${x//:/|}"
                  */
-                *size = sz;
-                return strstr(val, pattern);
+                *size = sz + first_escaped;
+                return strstr(val, pattern + first_escaped);
         }
 
         while (1) {