[PATCH] sub-process: print the cmd when a capability is unsupported

[Christian Couder]

In handshake_capabilities() we use warning() when a capability
is not supported, so the exit code of the function is 0 and no
further error is shown. This is a problem because the warning
message doesn't tell us which subprocess cmd failed.

On the contrary if we cannot write a packet from this function,
we use error() and then subprocess_start() outputs:

    initialization for subprocess '<cmd>' failed

so we can know which subprocess cmd failed.

Let's improve the warning() message, so that we can know which
subprocess cmd failed.

Signed-off-by: Christian Couder <chrisc...@tuxfamily.org>
---
 sub-process.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/sub-process.c b/sub-process.c
index 6edb97c1c6..6b133f8dce 100644
--- a/sub-process.c
+++ b/sub-process.c
@@ -158,7 +158,8 @@ static int handshake_version(struct child_process *process,
 
 static int handshake_capabilities(struct child_process *process,
                                  struct subprocess_capability *capabilities,
-                                 unsigned int *supported_capabilities)
+                                 unsigned int *supported_capabilities,
+                                 const char *cmd)
 {
        int i;
        char *line;
@@ -184,8 +185,8 @@ static int handshake_capabilities(struct child_process 
*process,
                        if (supported_capabilities)
                                *supported_capabilities |= capabilities[i].flag;
                } else {
-                       warning("external filter requested unsupported filter 
capability '%s'",
-                               p);
+                       warning("subprocess '%s' requested unsupported 
capability '%s'",
+                               cmd, p);
                }
        }
 
@@ -206,8 +207,10 @@ int subprocess_handshake(struct subprocess_entry *entry,
 
        retval = handshake_version(process, welcome_prefix, versions,
                                   chosen_version) ||
-                handshake_capabilities(process, capabilities,
-                                       supported_capabilities);
+                handshake_capabilities(process,
+                                       capabilities,
+                                       supported_capabilities,
+                                       entry->cmd);
 
        sigchain_pop(SIGPIPE);
        return retval;
-- 
2.14.1.187.gd6d46550f4