setup: update error message to be more meaningful

diff --git a/sub-process.c b/sub-process.c
index 92f8aea70aa0bc7654b89bebc3e72b197953e84a..fcc4832c14f3fdbb41bea12142a8fbf167d2aa55 100644 (file)
--- a/sub-process.c
+++ b/sub-process.c
@@ -5,9 +5,10 @@
 #include "sigchain.h"
 #include "pkt-line.h"
 
-int cmd2process_cmp(const struct subprocess_entry *e1,
-                          const struct subprocess_entry *e2,
-                          const void *unused)
+int cmd2process_cmp(const void *unused_cmp_data,
+                   const struct subprocess_entry *e1,
+                   const struct subprocess_entry *e2,
+                   const void *unused_keydata)
 {
        return strcmp(e1->cmd, e2->cmd);
 }
@@ -104,3 +105,107 @@ int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, co
        hashmap_add(hashmap, entry);
        return 0;
 }
+
+static int handshake_version(struct child_process *process,
+                            const char *welcome_prefix, int *versions,
+                            int *chosen_version)
+{
+       int version_scratch;
+       int i;
+       char *line;
+       const char *p;
+
+       if (!chosen_version)
+               chosen_version = &version_scratch;
+
+       if (packet_write_fmt_gently(process->in, "%s-client\n",
+                                   welcome_prefix))
+               return error("Could not write client identification");
+       for (i = 0; versions[i]; i++) {
+               if (packet_write_fmt_gently(process->in, "version=%d\n",
+                                           versions[i]))
+                       return error("Could not write requested version");
+       }
+       if (packet_flush_gently(process->in))
+               return error("Could not write flush packet");
+
+       if (!(line = packet_read_line(process->out, NULL)) ||
+           !skip_prefix(line, welcome_prefix, &p) ||
+           strcmp(p, "-server"))
+               return error("Unexpected line '%s', expected %s-server",
+                            line ? line : "<flush packet>", welcome_prefix);
+       if (!(line = packet_read_line(process->out, NULL)) ||
+           !skip_prefix(line, "version=", &p) ||
+           strtol_i(p, 10, chosen_version))
+               return error("Unexpected line '%s', expected version",
+                            line ? line : "<flush packet>");
+       if ((line = packet_read_line(process->out, NULL)))
+               return error("Unexpected line '%s', expected flush", line);
+
+       /* Check to make sure that the version received is supported */
+       for (i = 0; versions[i]; i++) {
+               if (versions[i] == *chosen_version)
+                       break;
+       }
+       if (!versions[i])
+               return error("Version %d not supported", *chosen_version);
+
+       return 0;
+}
+
+static int handshake_capabilities(struct child_process *process,
+                                 struct subprocess_capability *capabilities,
+                                 unsigned int *supported_capabilities)
+{
+       int i;
+       char *line;
+
+       for (i = 0; capabilities[i].name; i++) {
+               if (packet_write_fmt_gently(process->in, "capability=%s\n",
+                                           capabilities[i].name))
+                       return error("Could not write requested capability");
+       }
+       if (packet_flush_gently(process->in))
+               return error("Could not write flush packet");
+
+       while ((line = packet_read_line(process->out, NULL))) {
+               const char *p;
+               if (!skip_prefix(line, "capability=", &p))
+                       continue;
+
+               for (i = 0;
+                    capabilities[i].name && strcmp(p, capabilities[i].name);
+                    i++)
+                       ;
+               if (capabilities[i].name) {
+                       if (supported_capabilities)
+                               *supported_capabilities |= capabilities[i].flag;
+               } else {
+                       warning("subprocess '%s' requested unsupported capability '%s'",
+                               process->argv[0], p);
+               }
+       }
+
+       return 0;
+}
+
+int subprocess_handshake(struct subprocess_entry *entry,
+                        const char *welcome_prefix,
+                        int *versions,
+                        int *chosen_version,
+                        struct subprocess_capability *capabilities,
+                        unsigned int *supported_capabilities)
+{
+       int retval;
+       struct child_process *process = &entry->process;
+
+       sigchain_push(SIGPIPE, SIG_IGN);
+
+       retval = handshake_version(process, welcome_prefix, versions,
+                                  chosen_version) ||
+                handshake_capabilities(process, capabilities,
+                                       supported_capabilities);
+
+       sigchain_pop(SIGPIPE);
+       return retval;
+}