зеркало из https://github.com/microsoft/git.git
Merge branch 'jk/http-backend-deadlock'
Communication between the HTTP server and http_backend process can lead to a dead-lock when relaying a large ref negotiation request. Diagnose the situation better, and mitigate it by reading such a request first into core (to a reasonable limit). * jk/http-backend-deadlock: http-backend: spool ref negotiation requests to buffer t5551: factor out tag creation http-backend: fix die recursion with custom handler
This commit is contained in:
Junio C Hamano
Коммит
777e75b605
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@ -255,6 +255,15 @@ The GIT_HTTP_EXPORT_ALL environmental variable may be passed to
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'git-http-backend' to bypass the check for the "git-daemon-export-ok"
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file in each repository before allowing export of that repository.
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The `GIT_HTTP_MAX_REQUEST_BUFFER` environment variable (or the
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`http.maxRequestBuffer` config variable) may be set to change the
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largest ref negotiation request that git will handle during a fetch; any
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fetch requiring a larger buffer will not succeed. This value should not
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normally need to be changed, but may be helpful if you are fetching from
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a repository with an extremely large number of refs. The value can be
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specified with a unit (e.g., `100M` for 100 megabytes). The default is
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10 megabytes.
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The backend process sets GIT_COMMITTER_NAME to '$REMOTE_USER' and
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GIT_COMMITTER_EMAIL to '$\{REMOTE_USER}@http.$\{REMOTE_ADDR\}',
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ensuring that any reflogs created by 'git-receive-pack' contain some
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110
http-backend.c
110
http-backend.c
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@ -13,18 +13,20 @@ static const char content_type[] = "Content-Type";
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static const char content_length[] = "Content-Length";
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static const char last_modified[] = "Last-Modified";
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static int getanyfile = 1;
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static unsigned long max_request_buffer = 10 * 1024 * 1024;
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static struct string_list *query_params;
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struct rpc_service {
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const char *name;
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const char *config_name;
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unsigned buffer_input : 1;
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signed enabled : 2;
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};
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static struct rpc_service rpc_service[] = {
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{ "upload-pack", "uploadpack", 1 },
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{ "receive-pack", "receivepack", -1 },
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{ "upload-pack", "uploadpack", 1, 1 },
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{ "receive-pack", "receivepack", 0, -1 },
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};
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static struct string_list *get_parameters(void)
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@ -225,6 +227,7 @@ static void http_config(void)
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struct strbuf var = STRBUF_INIT;
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git_config_get_bool("http.getanyfile", &getanyfile);
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git_config_get_ulong("http.maxrequestbuffer", &max_request_buffer);
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for (i = 0; i < ARRAY_SIZE(rpc_service); i++) {
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struct rpc_service *svc = &rpc_service[i];
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@ -266,9 +269,52 @@ static struct rpc_service *select_service(const char *name)
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return svc;
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}
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static void inflate_request(const char *prog_name, int out)
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/*
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* This is basically strbuf_read(), except that if we
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* hit max_request_buffer we die (we'd rather reject a
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* maliciously large request than chew up infinite memory).
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*/
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static ssize_t read_request(int fd, unsigned char **out)
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{
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size_t len = 0, alloc = 8192;
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unsigned char *buf = xmalloc(alloc);
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if (max_request_buffer < alloc)
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max_request_buffer = alloc;
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while (1) {
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ssize_t cnt;
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cnt = read_in_full(fd, buf + len, alloc - len);
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if (cnt < 0) {
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free(buf);
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return -1;
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}
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/* partial read from read_in_full means we hit EOF */
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len += cnt;
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if (len < alloc) {
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*out = buf;
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return len;
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}
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/* otherwise, grow and try again (if we can) */
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if (alloc == max_request_buffer)
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die("request was larger than our maximum size (%lu);"
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" try setting GIT_HTTP_MAX_REQUEST_BUFFER",
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max_request_buffer);
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alloc = alloc_nr(alloc);
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if (alloc > max_request_buffer)
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alloc = max_request_buffer;
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REALLOC_ARRAY(buf, alloc);
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}
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}
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static void inflate_request(const char *prog_name, int out, int buffer_input)
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{
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git_zstream stream;
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unsigned char *full_request = NULL;
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unsigned char in_buf[8192];
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unsigned char out_buf[8192];
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unsigned long cnt = 0;
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@ -277,11 +323,21 @@ static void inflate_request(const char *prog_name, int out)
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git_inflate_init_gzip_only(&stream);
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while (1) {
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ssize_t n = xread(0, in_buf, sizeof(in_buf));
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ssize_t n;
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if (buffer_input) {
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if (full_request)
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n = 0; /* nothing left to read */
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else
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n = read_request(0, &full_request);
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stream.next_in = full_request;
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} else {
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n = xread(0, in_buf, sizeof(in_buf));
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stream.next_in = in_buf;
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}
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if (n <= 0)
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die("request ended in the middle of the gzip stream");
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stream.next_in = in_buf;
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stream.avail_in = n;
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while (0 < stream.avail_in) {
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@ -307,9 +363,22 @@ static void inflate_request(const char *prog_name, int out)
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done:
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git_inflate_end(&stream);
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close(out);
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free(full_request);
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}
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static void run_service(const char **argv)
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static void copy_request(const char *prog_name, int out)
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{
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unsigned char *buf;
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ssize_t n = read_request(0, &buf);
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if (n < 0)
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die_errno("error reading request body");
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if (write_in_full(out, buf, n) != n)
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die("%s aborted reading request", prog_name);
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close(out);
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free(buf);
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}
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static void run_service(const char **argv, int buffer_input)
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{
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const char *encoding = getenv("HTTP_CONTENT_ENCODING");
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const char *user = getenv("REMOTE_USER");
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@ -334,7 +403,7 @@ static void run_service(const char **argv)
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"GIT_COMMITTER_EMAIL=%s@http.%s", user, host);
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cld.argv = argv;
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if (gzipped_request)
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if (buffer_input || gzipped_request)
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cld.in = -1;
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cld.git_cmd = 1;
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if (start_command(&cld))
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@ -342,7 +411,9 @@ static void run_service(const char **argv)
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close(1);
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if (gzipped_request)
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inflate_request(argv[0], cld.in);
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inflate_request(argv[0], cld.in, buffer_input);
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else if (buffer_input)
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copy_request(argv[0], cld.in);
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else
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close(0);
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@ -392,7 +463,7 @@ static void get_info_refs(char *arg)
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packet_flush(1);
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argv[0] = svc->name;
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run_service(argv);
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run_service(argv, 0);
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} else {
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select_getanyfile();
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@ -496,25 +567,28 @@ static void service_rpc(char *service_name)
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end_headers();
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argv[0] = svc->name;
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run_service(argv);
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run_service(argv, svc->buffer_input);
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strbuf_release(&buf);
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}
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static int dead;
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static NORETURN void die_webcgi(const char *err, va_list params)
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{
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static int dead;
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if (dead <= 1) {
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vreportf("fatal: ", err, params);
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if (!dead) {
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dead = 1;
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http_status(500, "Internal Server Error");
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hdr_nocache();
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end_headers();
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vreportf("fatal: ", err, params);
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}
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exit(0); /* we successfully reported a failure ;-) */
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}
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static int die_webcgi_recursing(void)
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{
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return dead++ > 1;
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}
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static char* getdir(void)
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{
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struct strbuf buf = STRBUF_INIT;
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@ -569,6 +643,7 @@ int main(int argc, char **argv)
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git_extract_argv0_path(argv[0]);
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set_die_routine(die_webcgi);
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set_die_is_recursing_routine(die_webcgi_recursing);
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if (!method)
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die("No REQUEST_METHOD from server");
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@ -619,6 +694,9 @@ int main(int argc, char **argv)
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not_found("Repository not exported: '%s'", dir);
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http_config();
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max_request_buffer = git_env_ulong("GIT_HTTP_MAX_REQUEST_BUFFER",
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max_request_buffer);
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cmd->imp(cmd_arg);
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return 0;
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}
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@ -218,27 +218,35 @@ test_expect_success 'transfer.hiderefs works over smart-http' '
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git -C hidden.git rev-parse --verify b
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'
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test_expect_success 'create 2,000 tags in the repo' '
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(
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cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
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for i in $(test_seq 2000)
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# create an arbitrary number of tags, numbered from tag-$1 to tag-$2
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create_tags () {
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rm -f marks &&
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for i in $(test_seq "$1" "$2")
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do
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echo "commit refs/heads/too-many-refs"
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echo "mark :$i"
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echo "committer git <git@example.com> $i +0000"
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echo "data 0"
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echo "M 644 inline bla.txt"
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echo "data 4"
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echo "bla"
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# don't use here-doc, because it requires a process
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# per loop iteration
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echo "commit refs/heads/too-many-refs-$1" &&
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echo "mark :$i" &&
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echo "committer git <git@example.com> $i +0000" &&
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echo "data 0" &&
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echo "M 644 inline bla.txt" &&
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echo "data 4" &&
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echo "bla" &&
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# make every commit dangling by always
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# rewinding the branch after each commit
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echo "reset refs/heads/too-many-refs"
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echo "from :1"
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echo "reset refs/heads/too-many-refs-$1" &&
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echo "from :$1"
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done | git fast-import --export-marks=marks &&
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# now assign tags to all the dangling commits we created above
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tag=$(perl -e "print \"bla\" x 30") &&
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sed -e "s|^:\([^ ]*\) \(.*\)$|\2 refs/tags/$tag-\1|" <marks >>packed-refs
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}
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test_expect_success 'create 2,000 tags in the repo' '
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(
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cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
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create_tags 1 2000
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)
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'
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@ -259,5 +267,20 @@ test_expect_success 'large fetch-pack requests can be split across POSTs' '
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test_line_count = 2 posts
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'
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test_expect_success EXPENSIVE 'http can handle enormous ref negotiation' '
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(
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cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
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create_tags 2001 50000
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) &&
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git -C too-many-refs fetch -q --tags &&
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(
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cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
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create_tags 50001 100000
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) &&
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git -C too-many-refs fetch -q --tags &&
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git -C too-many-refs for-each-ref refs/tags >tags &&
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test_line_count = 100000 tags
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'
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stop_httpd
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test_done
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