use skip_prefix to avoid repeated calculations

In some cases, we use starts_with to check for a prefix, and
then use an already-calculated prefix length to advance a
pointer past the prefix. There are no magic numbers or
duplicated strings here, but we can still make the code
simpler and more obvious by using skip_prefix.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/help.c b/help.c
index 79e800714780568009f66787aa25079ec6b81fac..f31f29ac421e224a59726fc1f2dfc16d92faad0f 100644 (file)
--- a/help.c
+++ b/help.c
@@ -129,7 +129,6 @@ static void list_commands_in_dir(struct cmdnames *cmds,
                                         const char *path,
                                         const char *prefix)
 {
-       int prefix_len;
        DIR *dir = opendir(path);
        struct dirent *de;
        struct strbuf buf = STRBUF_INIT;
@@ -139,15 +138,15 @@ static void list_commands_in_dir(struct cmdnames *cmds,
                return;
        if (!prefix)
                prefix = "git-";
-       prefix_len = strlen(prefix);
 
        strbuf_addf(&buf, "%s/", path);
        len = buf.len;
 
        while ((de = readdir(dir)) != NULL) {
+               const char *ent;
                int entlen;
 
-               if (!starts_with(de->d_name, prefix))
+               if (!skip_prefix(de->d_name, prefix, &ent))
                        continue;
 
                strbuf_setlen(&buf, len);
@@ -155,11 +154,11 @@ static void list_commands_in_dir(struct cmdnames *cmds,
                if (!is_executable(buf.buf))
                        continue;
 
-               entlen = strlen(de->d_name) - prefix_len;
-               if (has_extension(de->d_name, ".exe"))
+               entlen = strlen(ent);
+               if (has_extension(ent, ".exe"))
                        entlen -= 4;
 
-               add_cmdname(cmds, de->d_name + prefix_len, entlen);
+               add_cmdname(cmds, ent, entlen);
        }
        closedir(dir);
        strbuf_release(&buf);

diff --git a/http.c b/http.c
index 2b4f6a357c39f3685107da3cf63a9891470a6de9..f04621e61d157478f4100dc710118e1bd8634c70 100644 (file)
--- a/http.c
+++ b/http.c
@@ -1087,11 +1087,10 @@ static int update_url_from_redirect(struct strbuf *base,
        if (!strcmp(asked, got->buf))
                return 0;
 
-       if (!starts_with(asked, base->buf))
+       if (!skip_prefix(asked, base->buf, &tail))
                die("BUG: update_url_from_redirect: %s is not a superset of %s",
                    asked, base->buf);
 
-       tail = asked + base->len;
        tail_len = strlen(tail);
 
        if (got->len < tail_len ||