Re: [Qemu-devel] [PATCH] Add optional dump of default config file paths..

[Anthony Liguori <anthony@codemonkey.ws>]

On 06/14/2010 12:59 PM, john cooper wrote:
> Anthony Liguori wrote:
>    
>> On 06/09/2010 03:05 AM, john cooper wrote:
>>      
>>> This patch adds the ability to determine the build-configured
>>> runtime "config file" paths from the command line.  After
>>> support for cpu model definitions were added to the default
>>> runtime "target-" config file, testing of this feature has
>>> tripped over an unintentionally mis-installed config file
>>> enough to indicate some help is needed resolving such issues.
>>>
>>> As no general "verbose" flag is currently available, specifying
>>> "-readconfig ?" on the command line will maintain the default
>>> (config file) disposition but additionally emit diagnostic info.
>>> This mode is optional, otherwise the existing startup behavior
>>> is identical.
>>>
>>>        
>> I assume this is something requested by libvirt?
>>      
> Not requested by libvirt but rather intended for the qemu
> CLI facing user.  The alternatives of trying to puzzle
> out built-in config file paths via strace or strings when
> config problems surface is rather awkward.  This also
> seems a general need for test of config file related
> functionality.
>    

I wouldn't mind spitting out the ./configure line in qemu -version like 
gcc does.  That has the benefit of being a bit more obviously discoverable.

Regards,

Anthony Liguori

> Thanks,
>
> -john
>
>    
>> I'd prefer we support
>> this via Daniel's capabilities patchset instead of adding yet another
>> hidden help output and having libvirt parse that output.
>>
>> Regards,
>>
>> Anthony Liguori
>>
>>      
>>> Signed-off-by: john cooper<john.cooper@redhat.com>
>>> ---
>>>
>>> diff --git a/qemu-config.c b/qemu-config.c
>>> index 5a4e61b..a490603 100644
>>> --- a/qemu-config.c
>>> +++ b/qemu-config.c
>>> @@ -518,21 +518,29 @@ out:
>>>        return res;
>>>    }
>>>
>>> -int qemu_read_config_file(const char *filename)
>>> +/* attempt to open and parse config file, report problems if vflag
>>> + */
>>> +int qemu_read_config_file(const char *filename, int vflag)
>>>    {
>>>        FILE *f = fopen(filename, "r");
>>> -    int ret;
>>> +    int rv = 0;
>>>
>>>        if (f == NULL) {
>>> -        return -errno;
>>> +        rv = -errno;
>>>        }
>>> -
>>> -    ret = qemu_config_parse(f, vm_config_groups, filename);
>>> -    fclose(f);
>>> -
>>> -    if (ret == 0) {
>>> -        return 0;
>>> -    } else {
>>> -        return -EINVAL;
>>> +    else if (qemu_config_parse(f, vm_config_groups, filename) != 0) {
>>> +        rv = -EINVAL;
>>> +    }
>>> +    else if (vflag) {
>>> +        fprintf(stderr, "read config file %s\n", filename);
>>>        }
>>> +    if (f) {
>>> +        fclose(f);
>>> +    }
>>> +    if (rv&&   vflag) {
>>> +        fprintf(stderr, "can't read config file %s: %s\n",
>>> +                filename, strerror(-rv));
>>> +    }
>>> +    return rv;
>>>    }
>>> +
>>> diff --git a/qemu-config.h b/qemu-config.h
>>> index dca69d4..2e15556 100644
>>> --- a/qemu-config.h
>>> +++ b/qemu-config.h
>>> @@ -23,6 +23,6 @@ void qemu_add_globals(void);
>>>    void qemu_config_write(FILE *fp);
>>>    int qemu_config_parse(FILE *fp, QemuOptsList **lists, const char
>>> *fname);
>>>
>>> -int qemu_read_config_file(const char *filename);
>>> +int qemu_read_config_file(const char *filename, int vflag);
>>>
>>>    #endif /* QEMU_CONFIG_H */
>>> diff --git a/vl.c b/vl.c
>>> index 7121cd0..23c7276 100644
>>> --- a/vl.c
>>> +++ b/vl.c
>>> @@ -2582,6 +2582,7 @@ int main(int argc, char **argv, char **envp)
>>>    #endif
>>>        int show_vnc_port = 0;
>>>        int defconfig = 1;
>>> +    int defconfig_verbose = 0;
>>>
>>>        error_set_progname(argv[0]);
>>>
>>> @@ -2657,6 +2658,10 @@ int main(int argc, char **argv, char **envp)
>>>                case QEMU_OPTION_nodefconfig:
>>>                    defconfig=0;
>>>                    break;
>>> +            case QEMU_OPTION_readconfig:
>>> +                if (!strcmp(optarg, "?"))
>>> +                    defconfig_verbose = 1;
>>> +                break;
>>>                }
>>>            }
>>>        }
>>> @@ -2664,12 +2669,14 @@ int main(int argc, char **argv, char **envp)
>>>        if (defconfig) {
>>>            int ret;
>>>
>>> -        ret = qemu_read_config_file(CONFIG_QEMU_CONFDIR "/qemu.conf");
>>> +        ret = qemu_read_config_file(CONFIG_QEMU_CONFDIR "/qemu.conf",
>>> +                                    defconfig_verbose);
>>>            if (ret<   0&&   ret != -ENOENT) {
>>>                exit(1);
>>>            }
>>>
>>> -        ret = qemu_read_config_file(arch_config_name);
>>> +        ret = qemu_read_config_file(arch_config_name,
>>> +                                    defconfig_verbose);
>>>            if (ret<   0&&   ret != -ENOENT) {
>>>                exit(1);
>>>            }
>>> @@ -3386,15 +3393,9 @@ int main(int argc, char **argv, char **envp)
>>>                    xen_mode = XEN_ATTACH;
>>>                    break;
>>>                case QEMU_OPTION_readconfig:
>>> -                {
>>> -                    int ret = qemu_read_config_file(optarg);
>>> -                    if (ret<   0) {
>>> -                        fprintf(stderr, "read config %s: %s\n", optarg,
>>> -                            strerror(-ret));
>>> -                        exit(1);
>>> -                    }
>>> -                    break;
>>> -                }
>>> +                if (!defconfig_verbose&&
>>> qemu_read_config_file(optarg, 1)<   0)
>>> +                    exit(1);
>>> +                break;
>>>                case QEMU_OPTION_writeconfig:
>>>                    {
>>>                        FILE *fp;
>>>
>>>
>>>        
>>      
>
>