fetch: create status table using strbuf

When we fetch from a remote, we print a status table like:

  From url
   * [new branch]   foo -> origin/foo

We create this table in a static buffer using sprintf. If
the remote refnames are long, they can overflow this buffer
and smash the stack.

Instead, let's use a strbuf to build the string.

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

diff --git a/builtin/fetch.c b/builtin/fetch.c
index 93c99385a95e6ab525fa64c1dbb70d5d4ca103ba..4f4af2a6999d6c3d80a602faf79aa554e430a44d 100644 (file)
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -239,23 +239,23 @@ static int s_update_ref(const char *action,
 
 static int update_local_ref(struct ref *ref,
                            const char *remote,
-                           char *display)
+                           struct strbuf *display)
 {
        struct commit *current = NULL, *updated;
        enum object_type type;
        struct branch *current_branch = branch_get(NULL);
        const char *pretty_ref = prettify_refname(ref->name);
 
-       *display = 0;
        type = sha1_object_info(ref->new_sha1, NULL);
        if (type < 0)
                die(_("object %s not found"), sha1_to_hex(ref->new_sha1));
 
        if (!hashcmp(ref->old_sha1, ref->new_sha1)) {
                if (verbosity > 0)
-                       sprintf(display, "= %-*s %-*s -> %s", TRANSPORT_SUMMARY_WIDTH,
-                               _("[up to date]"), REFCOL_WIDTH, remote,
-                               pretty_ref);
+                       strbuf_addf(display, "= %-*s %-*s -> %s",
+                                   TRANSPORT_SUMMARY_WIDTH,
+                                   _("[up to date]"), REFCOL_WIDTH,
+                                   remote, pretty_ref);
                return 0;
        }
 
@@ -267,9 +267,10 @@ static int update_local_ref(struct ref *ref,
                 * If this is the head, and it's not okay to update
                 * the head, and the old value of the head isn't empty...
                 */
-               sprintf(display, _("! %-*s %-*s -> %s  (can't fetch in current branch)"),
-                       TRANSPORT_SUMMARY_WIDTH, _("[rejected]"), REFCOL_WIDTH, remote,
-                       pretty_ref);
+               strbuf_addf(display,
+                           _("! %-*s %-*s -> %s  (can't fetch in current branch)"),
+                           TRANSPORT_SUMMARY_WIDTH, _("[rejected]"),
+                           REFCOL_WIDTH, remote, pretty_ref);
                return 1;
        }
 
@@ -277,9 +278,11 @@ static int update_local_ref(struct ref *ref,
            !prefixcmp(ref->name, "refs/tags/")) {
                int r;
                r = s_update_ref("updating tag", ref, 0);
-               sprintf(display, "%c %-*s %-*s -> %s%s", r ? '!' : '-',
-                       TRANSPORT_SUMMARY_WIDTH, _("[tag update]"), REFCOL_WIDTH, remote,
-                       pretty_ref, r ? _("  (unable to update local ref)") : "");
+               strbuf_addf(display, "%c %-*s %-*s -> %s%s",
+                           r ? '!' : '-',
+                           TRANSPORT_SUMMARY_WIDTH, _("[tag update]"),
+                           REFCOL_WIDTH, remote, pretty_ref,
+                           r ? _("  (unable to update local ref)") : "");
                return r;
        }
 
@@ -302,9 +305,11 @@ static int update_local_ref(struct ref *ref,
                }
 
                r = s_update_ref(msg, ref, 0);
-               sprintf(display, "%c %-*s %-*s -> %s%s", r ? '!' : '*',
-                       TRANSPORT_SUMMARY_WIDTH, what, REFCOL_WIDTH, remote, pretty_ref,
-                       r ? _("  (unable to update local ref)") : "");
+               strbuf_addf(display, "%c %-*s %-*s -> %s%s",
+                           r ? '!' : '*',
+                           TRANSPORT_SUMMARY_WIDTH, what,
+                           REFCOL_WIDTH, remote, pretty_ref,
+                           r ? _("  (unable to update local ref)") : "");
                return r;
        }
 
@@ -318,9 +323,11 @@ static int update_local_ref(struct ref *ref,
                    (recurse_submodules != RECURSE_SUBMODULES_ON))
                        check_for_new_submodule_commits(ref->new_sha1);
                r = s_update_ref("fast-forward", ref, 1);
-               sprintf(display, "%c %-*s %-*s -> %s%s", r ? '!' : ' ',
-                       TRANSPORT_SUMMARY_WIDTH, quickref, REFCOL_WIDTH, remote,
-                       pretty_ref, r ? _("  (unable to update local ref)") : "");
+               strbuf_addf(display, "%c %-*s %-*s -> %s%s",
+                           r ? '!' : ' ',
+                           TRANSPORT_SUMMARY_WIDTH, quickref,
+                           REFCOL_WIDTH, remote, pretty_ref,
+                           r ? _("  (unable to update local ref)") : "");
                return r;
        } else if (force || ref->force) {
                char quickref[84];
@@ -332,15 +339,17 @@ static int update_local_ref(struct ref *ref,
                    (recurse_submodules != RECURSE_SUBMODULES_ON))
                        check_for_new_submodule_commits(ref->new_sha1);
                r = s_update_ref("forced-update", ref, 1);
-               sprintf(display, "%c %-*s %-*s -> %s  (%s)", r ? '!' : '+',
-                       TRANSPORT_SUMMARY_WIDTH, quickref, REFCOL_WIDTH, remote,
-                       pretty_ref,
-                       r ? _("unable to update local ref") : _("forced update"));
+               strbuf_addf(display, "%c %-*s %-*s -> %s  (%s)",
+                           r ? '!' : '+',
+                           TRANSPORT_SUMMARY_WIDTH, quickref,
+                           REFCOL_WIDTH, remote, pretty_ref,
+                           r ? _("unable to update local ref") : _("forced update"));
                return r;
        } else {
-               sprintf(display, "! %-*s %-*s -> %s  %s",
-                       TRANSPORT_SUMMARY_WIDTH, _("[rejected]"), REFCOL_WIDTH, remote,
-                       pretty_ref, _("(non-fast-forward)"));
+               strbuf_addf(display, "! %-*s %-*s -> %s  %s",
+                           TRANSPORT_SUMMARY_WIDTH, _("[rejected]"),
+                           REFCOL_WIDTH, remote, pretty_ref,
+                           _("(non-fast-forward)"));
                return 1;
        }
 }
@@ -350,8 +359,8 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
 {
        FILE *fp;
        struct commit *commit;
-       int url_len, i, note_len, shown_url = 0, rc = 0;
-       char note[1024];
+       int url_len, i, shown_url = 0, rc = 0;
+       struct strbuf note = STRBUF_INIT;
        const char *what, *kind;
        struct ref *rm;
        char *url, *filename = dry_run ? "/dev/null" : git_path("FETCH_HEAD");
@@ -407,19 +416,17 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
                if (4 < i && !strncmp(".git", url + i - 3, 4))
                        url_len = i - 3;
 
-               note_len = 0;
+               strbuf_reset(&note);
                if (*what) {
                        if (*kind)
-                               note_len += sprintf(note + note_len, "%s ",
-                                                   kind);
-                       note_len += sprintf(note + note_len, "'%s' of ", what);
+                               strbuf_addf(&note, "%s ", kind);
+                       strbuf_addf(&note, "'%s' of ", what);
                }
-               note[note_len] = '\0';
                fprintf(fp, "%s\t%s\t%s",
                        sha1_to_hex(commit ? commit->object.sha1 :
                                    rm->old_sha1),
                        rm->merge ? "" : "not-for-merge",
-                       note);
+                       note.buf);
                for (i = 0; i < url_len; ++i)
                        if ('\n' == url[i])
                                fputs("\\n", fp);
@@ -427,21 +434,24 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
                                fputc(url[i], fp);
                fputc('\n', fp);
 
+               strbuf_reset(&note);
                if (ref) {
-                       rc |= update_local_ref(ref, what, note);
+                       rc |= update_local_ref(ref, what, &note);
                        free(ref);
                } else
-                       sprintf(note, "* %-*s %-*s -> FETCH_HEAD",
-                               TRANSPORT_SUMMARY_WIDTH, *kind ? kind : "branch",
-                                REFCOL_WIDTH, *what ? what : "HEAD");
-               if (*note) {
+                       strbuf_addf(&note, "* %-*s %-*s -> FETCH_HEAD",
+                                   TRANSPORT_SUMMARY_WIDTH,
+                                   *kind ? kind : "branch",
+                                   REFCOL_WIDTH,
+                                   *what ? what : "HEAD");
+               if (note.len) {
                        if (verbosity >= 0 && !shown_url) {
                                fprintf(stderr, _("From %.*s\n"),
                                                url_len, url);
                                shown_url = 1;
                        }
                        if (verbosity >= 0)
-                               fprintf(stderr, " %s\n", note);
+                               fprintf(stderr, " %s\n", note.buf);
                }
        }
        free(url);
@@ -450,6 +460,7 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
                error(_("some local refs could not be updated; try running\n"
                      " 'git remote prune %s' to remove any old, conflicting "
                      "branches"), remote_name);
+       strbuf_release(&note);
        return rc;
 }