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

[john cooper <john.cooper@redhat.com>]

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.

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;
>>
>>    
> 


-- 
john.cooper@redhat.com