[PATCH v4 3/8] convert: Split start_multi_file_filter into two separate functions

[Ben Peart]

To enable future reuse of the filter.<driver>.process infrastructure,
split start_multi_file_filter into two separate parts.

start_multi_file_filter will now only contain the generic logic to
manage the creation and tracking of the child process in a hashmap.

start_multi_file_filter_fn is a protocol specific initialization
function that will negotiate the multi-file-filter interface version
and capabilities.

Signed-off-by: Ben Peart <benpe...@microsoft.com>
---
 convert.c | 63 ++++++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 38 insertions(+), 25 deletions(-)

diff --git a/convert.c b/convert.c
index 793c29ebfd..404757eac9 100644
--- a/convert.c
+++ b/convert.c
@@ -565,35 +565,14 @@ static void stop_multi_file_filter(struct child_process 
*process)
        finish_command(process);
 }
 
-static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, 
const char *cmd)
+static int start_multi_file_filter_fn(struct cmd2process *entry)
 {
        int err;
-       struct cmd2process *entry;
-       struct child_process *process;
-       const char *argv[] = { cmd, NULL };
        struct string_list cap_list = STRING_LIST_INIT_NODUP;
        char *cap_buf;
        const char *cap_name;
-
-       entry = xmalloc(sizeof(*entry));
-       entry->cmd = cmd;
-       entry->supported_capabilities = 0;
-       process = &entry->process;
-
-       child_process_init(process);
-       process->argv = argv;
-       process->use_shell = 1;
-       process->in = -1;
-       process->out = -1;
-       process->clean_on_exit = 1;
-       process->clean_on_exit_handler = stop_multi_file_filter;
-
-       if (start_command(process)) {
-               error("cannot fork to run external filter '%s'", cmd);
-               return NULL;
-       }
-
-       hashmap_entry_init(entry, strhash(cmd));
+       struct child_process *process = &entry->process;
+       const char *cmd = entry->cmd;
 
        sigchain_push(SIGPIPE, SIG_IGN);
 
@@ -642,7 +621,41 @@ static struct cmd2process *start_multi_file_filter(struct 
hashmap *hashmap, cons
 done:
        sigchain_pop(SIGPIPE);
 
-       if (err || errno == EPIPE) {
+       if (err || errno == EPIPE)
+               err = err ? err : errno;
+
+       return err;
+}
+
+static struct cmd2process *start_multi_file_filter(struct hashmap *hashmap, 
const char *cmd)
+{
+       int err;
+       struct cmd2process *entry;
+       struct child_process *process;
+       const char *argv[] = { cmd, NULL };
+
+       entry = xmalloc(sizeof(*entry));
+       entry->cmd = cmd;
+       entry->supported_capabilities = 0;
+       process = &entry->process;
+
+       child_process_init(process);
+       process->argv = argv;
+       process->use_shell = 1;
+       process->in = -1;
+       process->out = -1;
+       process->clean_on_exit = 1;
+       process->clean_on_exit_handler = stop_multi_file_filter;
+
+       if (start_command(process)) {
+               error("cannot fork to run external filter '%s'", cmd);
+               return NULL;
+       }
+
+       hashmap_entry_init(entry, strhash(cmd));
+
+       err = start_multi_file_filter_fn(entry);
+       if (err) {
                error("initialization for external filter '%s' failed", cmd);
                kill_multi_file_filter(hashmap, entry);
                return NULL;
-- 
2.12.1.gvfs.1.18.ge47db72