| Message ID | xmqqv9owa6cw.fsf@gitster-ct.c.googlers.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | C: use skip-prefix to avoid hardcoded string length | expand |
On Mon, Jan 27, 2020 at 02:21:03PM -0800, Junio C Hamano wrote: > We often skip an optional prefix in a string with a hardcoded > constant, e.g. > > if (starts_with(string, "prefix")) > string += 6; > > which is less error prone when written > > skip_prefix(string, "prefix", &string); All of these look obviously correct, because you've introduced new temporary variables to replace the computed values. But... > diff --git a/builtin/reflog.c b/builtin/reflog.c > index 4d3430900d..51ffd74945 100644 > --- a/builtin/reflog.c > +++ b/builtin/reflog.c > @@ -560,15 +560,17 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix) > > for (i = 1; i < argc; i++) { > const char *arg = argv[i]; > + const char *valptr; > + > if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n")) > flags |= EXPIRE_REFLOGS_DRY_RUN; > - else if (starts_with(arg, "--expire=")) { > - if (parse_expiry_date(arg + 9, &cb.cmd.expire_total)) > + else if (skip_prefix(arg, "--expire=", &valptr)) { > + if (parse_expiry_date(valptr, &cb.cmd.expire_total)) > die(_("'%s' is not a valid timestamp"), arg); > explicit_expiry |= EXPIRE_TOTAL; > } In this case, I think the die message in the context could be improved to show "valptr". At which point you might as well do: else if (skip_prefix(arg, "--expire=", &arg)) { > - else if (starts_with(arg, "--expire-unreachable=")) { > - if (parse_expiry_date(arg + 21, &cb.cmd.expire_unreachable)) > + else if (skip_prefix(arg, "--expire-unreachable=", &valptr)) { > + if (parse_expiry_date(valptr, &cb.cmd.expire_unreachable)) > die(_("'%s' is not a valid timestamp"), arg); > explicit_expiry |= EXPIRE_UNREACH; > } Ditto here. -Peff
Jeff King <peff@peff.net> writes: >> + else if (skip_prefix(arg, "--expire=", &valptr)) { >> + if (parse_expiry_date(valptr, &cb.cmd.expire_total)) >> die(_("'%s' is not a valid timestamp"), arg); >> explicit_expiry |= EXPIRE_TOTAL; >> } > > In this case, I think the die message in the context could be improved > to show "valptr". At which point you might as well do: > > else if (skip_prefix(arg, "--expire=", &arg)) { The version that loses "to which parameter did I give malformed timestamp?" information was what I originally have written, and then I added a new valptr variable to avoid the information loss and message change. But thinking about it again, git frotz --expire=tea --expire-unreachable=tee would say "I don't know 'tee'" and then the user can go back and see to which one the misspelt version went, and if the user did git frotz --expire=tee --expire-unreachable=tee and got "I don't know 'tee'", then it also is OK to give that without saying it is about --expire or --expire-unreachable; they are both wrong ;-) So, I guess it probably is a good idea to skip the option name in the error message (we might have to adjust some tests, though). Thanks. >> - else if (starts_with(arg, "--expire-unreachable=")) { >> - if (parse_expiry_date(arg + 21, &cb.cmd.expire_unreachable)) >> + else if (skip_prefix(arg, "--expire-unreachable=", &valptr)) { >> + if (parse_expiry_date(valptr, &cb.cmd.expire_unreachable)) >> die(_("'%s' is not a valid timestamp"), arg); >> explicit_expiry |= EXPIRE_UNREACH; >> } > > Ditto here. > > -Peff
diff --git a/builtin/fast-export.c b/builtin/fast-export.c index dbec4df92b..164406fdd4 100644 --- a/builtin/fast-export.c +++ b/builtin/fast-export.c @@ -870,8 +870,7 @@ static void handle_tag(const char *name, struct tag *tag) printf("reset %s\nfrom %s\n\n", name, oid_to_hex(&null_oid)); } - if (starts_with(name, "refs/tags/")) - name += 10; + skip_prefix(name, "refs/tags/", &name); printf("tag %s\n", name); if (mark_tags) { mark_next_object(&tag->object); diff --git a/builtin/reflog.c b/builtin/reflog.c index 4d3430900d..51ffd74945 100644 --- a/builtin/reflog.c +++ b/builtin/reflog.c @@ -560,15 +560,17 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix) for (i = 1; i < argc; i++) { const char *arg = argv[i]; + const char *valptr; + if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n")) flags |= EXPIRE_REFLOGS_DRY_RUN; - else if (starts_with(arg, "--expire=")) { - if (parse_expiry_date(arg + 9, &cb.cmd.expire_total)) + else if (skip_prefix(arg, "--expire=", &valptr)) { + if (parse_expiry_date(valptr, &cb.cmd.expire_total)) die(_("'%s' is not a valid timestamp"), arg); explicit_expiry |= EXPIRE_TOTAL; } - else if (starts_with(arg, "--expire-unreachable=")) { - if (parse_expiry_date(arg + 21, &cb.cmd.expire_unreachable)) + else if (skip_prefix(arg, "--expire-unreachable=", &valptr)) { + if (parse_expiry_date(valptr, &cb.cmd.expire_unreachable)) die(_("'%s' is not a valid timestamp"), arg); explicit_expiry |= EXPIRE_UNREACH; } diff --git a/notes.c b/notes.c index 0c79964c26..a0349fa778 100644 --- a/notes.c +++ b/notes.c @@ -1279,10 +1279,8 @@ static void format_note(struct notes_tree *t, const struct object_id *object_oid if (!ref || !strcmp(ref, GIT_NOTES_DEFAULT_REF)) { strbuf_addstr(sb, "\nNotes:\n"); } else { - if (starts_with(ref, "refs/")) - ref += 5; - if (starts_with(ref, "notes/")) - ref += 6; + skip_prefix(ref, "refs/", &ref); + skip_prefix(ref, "notes/", &ref); strbuf_addf(sb, "\nNotes (%s):\n", ref); } } diff --git a/parse-options.c b/parse-options.c index 60fae3ad21..e8c04109ba 100644 --- a/parse-options.c +++ b/parse-options.c @@ -357,8 +357,7 @@ static enum parse_opt_result parse_long_opt( } /* negated? */ if (!starts_with(arg, "no-")) { - if (starts_with(long_name, "no-")) { - long_name += 3; + if (skip_prefix(long_name, "no-", &long_name)) { opt_flags |= OPT_UNSET; goto again; } diff --git a/refs/files-backend.c b/refs/files-backend.c index 0ea66a28b6..561c33ac8a 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -465,8 +465,7 @@ static int files_read_raw_ref(struct ref_store *ref_store, close(fd); strbuf_rtrim(&sb_contents); buf = sb_contents.buf; - if (starts_with(buf, "ref:")) { - buf += 4; + if (skip_prefix(buf, "ref:", &buf)) { while (isspace(*buf)) buf++; diff --git a/remote-curl.c b/remote-curl.c index 350d92a074..8eb96152f5 100644 --- a/remote-curl.c +++ b/remote-curl.c @@ -1255,8 +1255,9 @@ static void parse_push(struct strbuf *buf) int ret; do { - if (starts_with(buf->buf, "push ")) - argv_array_push(&specs, buf->buf + 5); + const char *arg; + if (skip_prefix(buf->buf, "push ", &arg)) + argv_array_push(&specs, arg); else die(_("http transport does not support %s"), buf->buf); diff --git a/sha1-name.c b/sha1-name.c index 200eb373ad..75d1c32606 100644 --- a/sha1-name.c +++ b/sha1-name.c @@ -908,14 +908,9 @@ static int get_oid_basic(struct repository *r, const char *str, int len, real_ref, flags, at_time, nth, oid, NULL, &co_time, &co_tz, &co_cnt)) { if (!len) { - if (starts_with(real_ref, "refs/heads/")) { - str = real_ref + 11; - len = strlen(real_ref + 11); - } else { - /* detached HEAD */ + if (!skip_prefix(real_ref, "refs/heads/", &str)) str = "HEAD"; - len = 4; - } + len = strlen(str); } if (at_time) { if (!(flags & GET_OID_QUIETLY)) { diff --git a/transport-helper.c b/transport-helper.c index 413d9d873e..20a7185ec4 100644 --- a/transport-helper.c +++ b/transport-helper.c @@ -404,11 +404,12 @@ static int fetch_with_fetch(struct transport *transport, sendline(data, &buf); while (1) { + const char *name; + if (recvline(data, &buf)) exit(128); - if (starts_with(buf.buf, "lock ")) { - const char *name = buf.buf + 5; + if (skip_prefix(buf.buf, "lock ", &name)) { if (transport->pack_lockfile) warning(_("%s also locked %s"), data->name, name); else
We often skip an optional prefix in a string with a hardcoded constant, e.g. if (starts_with(string, "prefix")) string += 6; which is less error prone when written skip_prefix(string, "prefix", &string); Signed-off-by: Junio C Hamano <gitster@pobox.com> --- builtin/fast-export.c | 3 +-- builtin/reflog.c | 10 ++++++---- notes.c | 6 ++---- parse-options.c | 3 +-- refs/files-backend.c | 3 +-- remote-curl.c | 5 +++-- sha1-name.c | 9 ++------- transport-helper.c | 5 +++-- 8 files changed, 19 insertions(+), 25 deletions(-)