[PATCH v2] sub-process: print the cmd when a capability is unsupported

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.

Helped-by: Lars Schneider [off-list ref]
Signed-off-by: Christian Couder <redacted>
---
Change since previous version:

   - Use process->argv[0] instead of adding a new parameter to
     handshake_capabilities(), thanks to Lars.

  sub-process.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sub-process.c b/sub-process.c
index 6edb97c1c6..6ccfaaba99 100644
--- a/sub-process.c
+++ b/sub-process.c

@@ -184,8 +184,8 @@ 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'",
+				process->argv[0], p);
  		}
  	}
  

On 16 Aug 2017, at 14:40, Christian Couder [off-list ref] wrote:

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.

Helped-by: Lars Schneider [off-list ref]
Signed-off-by: Christian Couder <redacted>
---
Change since previous version:

 - Use process->argv[0] instead of adding a new parameter to
   handshake_capabilities(), thanks to Lars.

sub-process.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sub-process.c b/sub-process.c
index 6edb97c1c6..6ccfaaba99 100644
--- a/sub-process.c
+++ b/sub-process.c

@@ -184,8 +184,8 @@ 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'",
+				process->argv[0], p);
		}
	}

-- 
2.14.1.146.g7de11f915a