Add remote helper debug mode

Remote helpers deadlock easily, so support debug mode which shows the
interaction steps.

Signed-off-by: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/transport-helper.c b/transport-helper.c
index 11f3d7ec52893dcdee127d8493f1897c6c091b31..a721dc25beb31350f6fc64f7446b340f83c707c8 100644 (file)
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -8,6 +8,8 @@
 #include "quote.h"
 #include "remote.h"
 
+static int debug;
+
 struct helper_data
 {
        const char *name;
@@ -22,6 +24,45 @@ struct helper_data
        int refspec_nr;
 };
 
+static void sendline(struct helper_data *helper, struct strbuf *buffer)
+{
+       if (debug)
+               fprintf(stderr, "Debug: Remote helper: -> %s", buffer->buf);
+       if (write_in_full(helper->helper->in, buffer->buf, buffer->len)
+               != buffer->len)
+               die_errno("Full write to remote helper failed");
+}
+
+static int recvline(struct helper_data *helper, struct strbuf *buffer)
+{
+       strbuf_reset(buffer);
+       if (debug)
+               fprintf(stderr, "Debug: Remote helper: Waiting...\n");
+       if (strbuf_getline(buffer, helper->out, '\n') == EOF) {
+               if (debug)
+                       fprintf(stderr, "Debug: Remote helper quit.\n");
+               exit(128);
+       }
+
+       if (debug)
+               fprintf(stderr, "Debug: Remote helper: <- %s\n", buffer->buf);
+       return 0;
+}
+
+static void xchgline(struct helper_data *helper, struct strbuf *buffer)
+{
+       sendline(helper, buffer);
+       recvline(helper, buffer);
+}
+
+static void write_constant(int fd, const char *str)
+{
+       if (debug)
+               fprintf(stderr, "Debug: Remote helper: -> %s", str);
+       if (write_in_full(fd, str, strlen(str)) != strlen(str))
+               die_errno("Full write to remote helper failed");
+}
+
 static struct child_process *get_helper(struct transport *transport)
 {
        struct helper_data *data = transport->data;
@@ -48,15 +89,16 @@ static struct child_process *get_helper(struct transport *transport)
                die("Unable to run helper: git %s", helper->argv[0]);
        data->helper = helper;
 
-       write_str_in_full(helper->in, "capabilities\n");
+       write_constant(helper->in, "capabilities\n");
 
        data->out = xfdopen(helper->out, "r");
        while (1) {
-               if (strbuf_getline(&buf, data->out, '\n') == EOF)
-                       exit(128); /* child died, message supplied already */
+               recvline(data, &buf);
 
                if (!*buf.buf)
                        break;
+               if (debug)
+                       fprintf(stderr, "Debug: Got cap %s\n", buf.buf);
                if (!strcmp(buf.buf, "fetch"))
                        data->fetch = 1;
                if (!strcmp(buf.buf, "option"))
@@ -82,14 +124,21 @@ static struct child_process *get_helper(struct transport *transport)
                free(refspecs);
        }
        strbuf_release(&buf);
+       if (debug)
+               fprintf(stderr, "Debug: Capabilities complete.\n");
        return data->helper;
 }
 
 static int disconnect_helper(struct transport *transport)
 {
        struct helper_data *data = transport->data;
+       struct strbuf buf = STRBUF_INIT;
+
        if (data->helper) {
-               write_str_in_full(data->helper->in, "\n");
+               if (debug)
+                       fprintf(stderr, "Debug: Disconnecting.\n");
+               strbuf_addf(&buf, "\n");
+               sendline(data, &buf);
                close(data->helper->in);
                fclose(data->out);
                finish_command(data->helper);
@@ -117,10 +166,11 @@ static int set_helper_option(struct transport *transport,
                          const char *name, const char *value)
 {
        struct helper_data *data = transport->data;
-       struct child_process *helper = get_helper(transport);
        struct strbuf buf = STRBUF_INIT;
        int i, ret, is_bool = 0;
 
+       get_helper(transport);
+
        if (!data->option)
                return 1;
 
@@ -143,12 +193,7 @@ static int set_helper_option(struct transport *transport,
                quote_c_style(value, &buf, NULL, 0);
        strbuf_addch(&buf, '\n');
 
-       if (write_in_full(helper->in, buf.buf, buf.len) != buf.len)
-               die_errno("cannot send option to %s", data->name);
-
-       strbuf_reset(&buf);
-       if (strbuf_getline(&buf, data->out, '\n') == EOF)
-               exit(128); /* child died, message supplied already */
+       xchgline(data, &buf);
 
        if (!strcmp(buf.buf, "ok"))
                ret = 0;
@@ -208,13 +253,10 @@ static int fetch_with_fetch(struct transport *transport,
        }
 
        strbuf_addch(&buf, '\n');
-       if (write_in_full(data->helper->in, buf.buf, buf.len) != buf.len)
-               die_errno("cannot send fetch to %s", data->name);
+       sendline(data, &buf);
 
        while (1) {
-               strbuf_reset(&buf);
-               if (strbuf_getline(&buf, data->out, '\n') == EOF)
-                       exit(128); /* child died, message supplied already */
+               recvline(data, &buf);
 
                if (!prefixcmp(buf.buf, "lock ")) {
                        const char *name = buf.buf + 5;
@@ -249,12 +291,13 @@ static int fetch_with_import(struct transport *transport,
                             int nr_heads, struct ref **to_fetch)
 {
        struct child_process fastimport;
-       struct child_process *helper = get_helper(transport);
        struct helper_data *data = transport->data;
        int i;
        struct ref *posn;
        struct strbuf buf = STRBUF_INIT;
 
+       get_helper(transport);
+
        if (get_importer(transport, &fastimport))
                die("Couldn't run fast-import");
 
@@ -264,7 +307,7 @@ static int fetch_with_import(struct transport *transport,
                        continue;
 
                strbuf_addf(&buf, "import %s\n", posn->name);
-               write_in_full(helper->in, buf.buf, buf.len);
+               sendline(data, &buf);
                strbuf_reset(&buf);
        }
        disconnect_helper(transport);
@@ -369,17 +412,14 @@ static int push_refs(struct transport *transport,
        }
 
        strbuf_addch(&buf, '\n');
-       if (write_in_full(helper->in, buf.buf, buf.len) != buf.len)
-               exit(128);
+       sendline(data, &buf);
 
        ref = remote_refs;
        while (1) {
                char *refname, *msg;
                int status;
 
-               strbuf_reset(&buf);
-               if (strbuf_getline(&buf, data->out, '\n') == EOF)
-                       exit(128); /* child died, message supplied already */
+               recvline(data, &buf);
                if (!buf.len)
                        break;
 
@@ -471,8 +511,7 @@ static struct ref *get_refs_list(struct transport *transport, int for_push)
 
        while (1) {
                char *eov, *eon;
-               if (strbuf_getline(&buf, data->out, '\n') == EOF)
-                       exit(128); /* child died, message supplied already */
+               recvline(data, &buf);
 
                if (!*buf.buf)
                        break;
@@ -497,6 +536,8 @@ static struct ref *get_refs_list(struct transport *transport, int for_push)
                }
                tail = &((*tail)->next);
        }
+       if (debug)
+               fprintf(stderr, "Debug: Read ref listing.\n");
        strbuf_release(&buf);
 
        for (posn = ret; posn; posn = posn->next)
@@ -510,6 +551,9 @@ int transport_helper_init(struct transport *transport, const char *name)
        struct helper_data *data = xcalloc(sizeof(*data), 1);
        data->name = name;
 
+       if (getenv("GIT_TRANSPORT_HELPER_DEBUG"))
+               debug = 1;
+
        transport->data = data;
        transport->set_option = set_helper_option;
        transport->get_refs_list = get_refs_list;