http: use strbufs instead of fixed buffers

We keep the names of incoming packs and objects in fixed
PATH_MAX-size buffers, and snprintf() into them. This is
unlikely to end up with truncated filenames, but it is
possible (especially on systems where PATH_MAX is shorter
than actual paths can be). Let's switch to using strbufs,
which makes the question go away entirely.

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

diff --git a/http.c b/http.c
index a5bd5d62c22c054f82b9971fc1f320c643f1d6fb..fc5fff90a776ca7e93dc151836c1e0a4c4e7c179 100644 (file)
--- a/http.c
+++ b/http.c
@@ -2087,6 +2087,7 @@ void release_http_pack_request(struct http_pack_request *preq)
                preq->packfile = NULL;
        }
        preq->slot = NULL;
+       strbuf_release(&preq->tmpfile);
        free(preq->url);
        free(preq);
 }
@@ -2109,19 +2110,19 @@ int finish_http_pack_request(struct http_pack_request *preq)
                lst = &((*lst)->next);
        *lst = (*lst)->next;
 
-       if (!strip_suffix(preq->tmpfile, ".pack.temp", &len))
+       if (!strip_suffix(preq->tmpfile.buf, ".pack.temp", &len))
                die("BUG: pack tmpfile does not end in .pack.temp?");
-       tmp_idx = xstrfmt("%.*s.idx.temp", (int)len, preq->tmpfile);
+       tmp_idx = xstrfmt("%.*s.idx.temp", (int)len, preq->tmpfile.buf);
 
        argv_array_push(&ip.args, "index-pack");
        argv_array_pushl(&ip.args, "-o", tmp_idx, NULL);
-       argv_array_push(&ip.args, preq->tmpfile);
+       argv_array_push(&ip.args, preq->tmpfile.buf);
        ip.git_cmd = 1;
        ip.no_stdin = 1;
        ip.no_stdout = 1;
 
        if (run_command(&ip)) {
-               unlink(preq->tmpfile);
+               unlink(preq->tmpfile.buf);
                unlink(tmp_idx);
                free(tmp_idx);
                return -1;
@@ -2129,7 +2130,7 @@ int finish_http_pack_request(struct http_pack_request *preq)
 
        unlink(sha1_pack_index_name(p->sha1));
 
-       if (finalize_object_file(preq->tmpfile, sha1_pack_name(p->sha1))
+       if (finalize_object_file(preq->tmpfile.buf, sha1_pack_name(p->sha1))
         || finalize_object_file(tmp_idx, sha1_pack_index_name(p->sha1))) {
                free(tmp_idx);
                return -1;
@@ -2148,6 +2149,7 @@ struct http_pack_request *new_http_pack_request(
        struct http_pack_request *preq;
 
        preq = xcalloc(1, sizeof(*preq));
+       strbuf_init(&preq->tmpfile, 0);
        preq->target = target;
 
        end_url_with_slash(&buf, base_url);
@@ -2155,12 +2157,11 @@ struct http_pack_request *new_http_pack_request(
                sha1_to_hex(target->sha1));
        preq->url = strbuf_detach(&buf, NULL);
 
-       snprintf(preq->tmpfile, sizeof(preq->tmpfile), "%s.temp",
-               sha1_pack_name(target->sha1));
-       preq->packfile = fopen(preq->tmpfile, "a");
+       strbuf_addf(&preq->tmpfile, "%s.temp", sha1_pack_name(target->sha1));
+       preq->packfile = fopen(preq->tmpfile.buf, "a");
        if (!preq->packfile) {
                error("Unable to open local file %s for pack",
-                     preq->tmpfile);
+                     preq->tmpfile.buf);
                goto abort;
        }
 
@@ -2187,6 +2188,7 @@ struct http_pack_request *new_http_pack_request(
        return preq;
 
 abort:
+       strbuf_release(&preq->tmpfile);
        free(preq->url);
        free(preq);
        return NULL;
@@ -2237,7 +2239,7 @@ struct http_object_request *new_http_object_request(const char *base_url,
 {
        char *hex = sha1_to_hex(sha1);
        struct strbuf filename = STRBUF_INIT;
-       char prevfile[PATH_MAX];
+       struct strbuf prevfile = STRBUF_INIT;
        int prevlocal;
        char prev_buf[PREV_BUF_SIZE];
        ssize_t prev_read = 0;
@@ -2245,40 +2247,41 @@ struct http_object_request *new_http_object_request(const char *base_url,
        struct http_object_request *freq;
 
        freq = xcalloc(1, sizeof(*freq));
+       strbuf_init(&freq->tmpfile, 0);
        hashcpy(freq->sha1, sha1);
        freq->localfile = -1;
 
        sha1_file_name(&filename, sha1);
-       snprintf(freq->tmpfile, sizeof(freq->tmpfile),
-                "%s.temp", filename.buf);
+       strbuf_addf(&freq->tmpfile, "%s.temp", filename.buf);
 
-       snprintf(prevfile, sizeof(prevfile), "%s.prev", filename.buf);
-       unlink_or_warn(prevfile);
-       rename(freq->tmpfile, prevfile);
-       unlink_or_warn(freq->tmpfile);
+       strbuf_addf(&prevfile, "%s.prev", filename.buf);
+       unlink_or_warn(prevfile.buf);
+       rename(freq->tmpfile.buf, prevfile.buf);
+       unlink_or_warn(freq->tmpfile.buf);
        strbuf_release(&filename);
 
        if (freq->localfile != -1)
                error("fd leakage in start: %d", freq->localfile);
-       freq->localfile = open(freq->tmpfile,
+       freq->localfile = open(freq->tmpfile.buf,
                               O_WRONLY | O_CREAT | O_EXCL, 0666);
        /*
         * This could have failed due to the "lazy directory creation";
         * try to mkdir the last path component.
         */
        if (freq->localfile < 0 && errno == ENOENT) {
-               char *dir = strrchr(freq->tmpfile, '/');
+               char *dir = strrchr(freq->tmpfile.buf, '/');
                if (dir) {
                        *dir = 0;
-                       mkdir(freq->tmpfile, 0777);
+                       mkdir(freq->tmpfile.buf, 0777);
                        *dir = '/';
                }
-               freq->localfile = open(freq->tmpfile,
+               freq->localfile = open(freq->tmpfile.buf,
                                       O_WRONLY | O_CREAT | O_EXCL, 0666);
        }
 
        if (freq->localfile < 0) {
-               error_errno("Couldn't create temporary file %s", freq->tmpfile);
+               error_errno("Couldn't create temporary file %s",
+                           freq->tmpfile.buf);
                goto abort;
        }
 
@@ -2292,7 +2295,7 @@ struct http_object_request *new_http_object_request(const char *base_url,
         * If a previous temp file is present, process what was already
         * fetched.
         */
-       prevlocal = open(prevfile, O_RDONLY);
+       prevlocal = open(prevfile.buf, O_RDONLY);
        if (prevlocal != -1) {
                do {
                        prev_read = xread(prevlocal, prev_buf, PREV_BUF_SIZE);
@@ -2309,7 +2312,8 @@ struct http_object_request *new_http_object_request(const char *base_url,
                } while (prev_read > 0);
                close(prevlocal);
        }
-       unlink_or_warn(prevfile);
+       unlink_or_warn(prevfile.buf);
+       strbuf_release(&prevfile);
 
        /*
         * Reset inflate/SHA1 if there was an error reading the previous temp
@@ -2324,7 +2328,7 @@ struct http_object_request *new_http_object_request(const char *base_url,
                        lseek(freq->localfile, 0, SEEK_SET);
                        if (ftruncate(freq->localfile, 0) < 0) {
                                error_errno("Couldn't truncate temporary file %s",
-                                           freq->tmpfile);
+                                           freq->tmpfile.buf);
                                goto abort;
                        }
                }
@@ -2354,6 +2358,7 @@ struct http_object_request *new_http_object_request(const char *base_url,
        return freq;
 
 abort:
+       strbuf_release(&prevfile);
        free(freq->url);
        free(freq);
        return NULL;
@@ -2381,25 +2386,25 @@ int finish_http_object_request(struct http_object_request *freq)
        if (freq->http_code == 416) {
                warning("requested range invalid; we may already have all the data.");
        } else if (freq->curl_result != CURLE_OK) {
-               if (stat(freq->tmpfile, &st) == 0)
+               if (stat(freq->tmpfile.buf, &st) == 0)
                        if (st.st_size == 0)
-                               unlink_or_warn(freq->tmpfile);
+                               unlink_or_warn(freq->tmpfile.buf);
                return -1;
        }
 
        git_inflate_end(&freq->stream);
        git_SHA1_Final(freq->real_sha1, &freq->c);
        if (freq->zret != Z_STREAM_END) {
-               unlink_or_warn(freq->tmpfile);
+               unlink_or_warn(freq->tmpfile.buf);
                return -1;
        }
        if (hashcmp(freq->sha1, freq->real_sha1)) {
-               unlink_or_warn(freq->tmpfile);
+               unlink_or_warn(freq->tmpfile.buf);
                return -1;
        }
 
        sha1_file_name(&filename, freq->sha1);
-       freq->rename = finalize_object_file(freq->tmpfile, filename.buf);
+       freq->rename = finalize_object_file(freq->tmpfile.buf, filename.buf);
        strbuf_release(&filename);
 
        return freq->rename;
@@ -2407,7 +2412,7 @@ int finish_http_object_request(struct http_object_request *freq)
 
 void abort_http_object_request(struct http_object_request *freq)
 {
-       unlink_or_warn(freq->tmpfile);
+       unlink_or_warn(freq->tmpfile.buf);
 
        release_http_object_request(freq);
 }
@@ -2427,4 +2432,5 @@ void release_http_object_request(struct http_object_request *freq)
                release_active_slot(freq->slot);
                freq->slot = NULL;
        }
+       strbuf_release(&freq->tmpfile);
 }

diff --git a/http.h b/http.h
index f7bd3b26b0da70e44402579e4912a1b20dcef16e..d9379f9cb268af704cbf1362ff8bad1956bc8505 100644 (file)
--- a/http.h
+++ b/http.h
@@ -200,7 +200,7 @@ struct http_pack_request {
        struct packed_git *target;
        struct packed_git **lst;
        FILE *packfile;
-       char tmpfile[PATH_MAX];
+       struct strbuf tmpfile;
        struct active_request_slot *slot;
 };
 
@@ -212,7 +212,7 @@ extern void release_http_pack_request(struct http_pack_request *preq);
 /* Helpers for fetching object */
 struct http_object_request {
        char *url;
-       char tmpfile[PATH_MAX];
+       struct strbuf tmpfile;
        int localfile;
        CURLcode curl_result;
        char errorstr[CURL_ERROR_SIZE];