code review 3941041: syscall: include all, even duplictate, invented error m...

syscall: include all, even duplictate, invented error messages

Otherwise syscall.Errstr() returns "" for some (EWOULDBLOCK) errors.

[brainman, 2011-01-10 06:20:34]

Hello golang-dev@googlegroups.com,

I'd like you to review this change.

[rsc, 2011-01-11 15:48:05]

Something's not quite right here...

http://codereview.appspot.com/3941041/diff/2001/src/pkg/syscall/mkerrors_wind...
File src/pkg/syscall/mkerrors_windows.sh (left):

http://codereview.appspot.com/3941041/diff/2001/src/pkg/syscall/mkerrors_wind...
src/pkg/syscall/mkerrors_windows.sh:193: if(errors[j].value == e)	// duplicate
value
The fact that deleting this helps 
suggests that the values in errors[j].value
are simply incorrect.  This is an important
loop in general, since duplicate error values
would lead to duplicate entries for a given index
in the [...]string array we're printing.
I suggest changing the printf below to say

  printf("\t%s - APPLICATION_ERROR: \"%s\", /* %d */\n", errors[i].name, buf,
errors[i].value);

to find out why this program thought two errors
with different values had the same value.

[brainman, 2011-01-12 00:02:19]

http://codereview.appspot.com/3941041/diff/2001/src/pkg/syscall/mkerrors_wind...
File src/pkg/syscall/mkerrors_windows.sh (left):

http://codereview.appspot.com/3941041/diff/2001/src/pkg/syscall/mkerrors_wind...
src/pkg/syscall/mkerrors_windows.sh:193: if(errors[j].value == e)	// duplicate
value
On 2011/01/11 15:48:05, rsc wrote:
> ...  This is an important
> loop in general, since duplicate error values
> would lead to duplicate entries for a given index
> in the [...]string array we're printing.

I think you are mistaken. We don't use errors[j].value anywhere in the go code,
the only things we care are: mnemonic error names (EACCES, EADDRINUSE) and their
"unix" error messages (strings returned by strerror). We build a list of const
with mnemonic names, all their values will be unique (we use iota) and won't
relate to correspondent unix values. We also build a list of error messages for
every mnemonic name we introduce, and while some names will refer to the same
error (EAGAIN and EWOULDBLOCK) their values in go will be different. What this
CL fixes, it adds missing error messages (for EWOULDBLOCK and others) - error
messages for EAGAIN and EWOULDBLOCK will be identical, but they will sit in
errors[] array at different indexes.

[rsc, 2011-01-19 19:47:17]

LGTM

[brainman, 2011-01-20 10:24:25]

*** Submitted as http://code.google.com/p/go/source/detail?r=5105b2ff334d ***

syscall: include all, even duplictate, invented error messages

Otherwise syscall.Errstr() returns "" for some (EWOULDBLOCK) errors.

R=rsc
CC=golang-dev
http://codereview.appspot.com/3941041

Committer: Alex Brainman <alex.brainman@gmail.com>