[FFmpeg-devel] [PATCH v3 2/3] avutil/log: add av_log_set_opts function

[Tobias Rapp]

On 28.03.2018 17:11, wm4 wrote:
> On Wed, 28 Mar 2018 17:03:39 +0200
> Tobias Rapp <t.rapp at noa-archive.com> wrote:
> 
>> Allows to set log level and flag values from string.
>>
>> Signed-off-by: Tobias Rapp <t.rapp at noa-archive.com>
>> ---
>>   doc/APIchanges      |  3 +++
>>   libavutil/log.c     | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   libavutil/log.h     | 16 +++++++++++
>>   libavutil/version.h |  2 +-
>>   4 files changed, 96 insertions(+), 1 deletion(-)
>>
>> diff --git a/doc/APIchanges b/doc/APIchanges
>> index 83c7a40..2d14452 100644
>> --- a/doc/APIchanges
>> +++ b/doc/APIchanges
>> @@ -15,6 +15,9 @@ libavutil:     2017-10-21
>>   
>>   API changes, most recent first:
>>   
>> +2018-03-xx - xxxxxxx - lavu 56.13.100 - log.h
>> +  Add av_log_set_opts().
>> +
>>   2018-03-xx - xxxxxxx - lavc 58.16.100 - avcodec.h
>>     Add FF_SUB_CHARENC_MODE_IGNORE.
>>   
>> diff --git a/libavutil/log.c b/libavutil/log.c
>> index 0a99d01..af32cd6 100644
>> --- a/libavutil/log.c
>> +++ b/libavutil/log.c
>> @@ -34,6 +34,7 @@
>>   #endif
>>   #include <stdarg.h>
>>   #include <stdlib.h>
>> +#include "avassert.h"
>>   #include "avutil.h"
>>   #include "bprint.h"
>>   #include "common.h"
>> @@ -402,6 +403,81 @@ void av_log_set_callback(void (*callback)(void*, int, const char*, va_list))
>>       av_log_callback = callback;
>>   }
>>   
>> +int av_log_set_opts(const char *arg)
>> +{
>> +    const struct { const char *name; int level; } log_levels[] = {
>> +        { "quiet"  , AV_LOG_QUIET   },
>> +        { "panic"  , AV_LOG_PANIC   },
>> +        { "fatal"  , AV_LOG_FATAL   },
>> +        { "error"  , AV_LOG_ERROR   },
>> +        { "warning", AV_LOG_WARNING },
>> +        { "info"   , AV_LOG_INFO    },
>> +        { "verbose", AV_LOG_VERBOSE },
>> +        { "debug"  , AV_LOG_DEBUG   },
>> +        { "trace"  , AV_LOG_TRACE   },
>> +    };
>> +    const char *token;
>> +    char *tail;
>> +    int flags = av_log_get_flags();
>> +    int level = av_log_get_level();
>> +    int cmd, i = 0;
>> +
>> +    av_assert0(arg);
>> +    while (*arg) {
>> +        token = arg;
>> +        if (*token == '+' || *token == '-') {
>> +            cmd = *token++;
>> +        } else {
>> +            cmd = 0;
>> +        }
>> +        if (!i && !cmd) {
>> +            flags = 0;  /* missing relative prefix, build absolute value */
>> +        }
>> +        if (!strncmp(token, "repeat", 6)) {
>> +            if (cmd == '-') {
>> +                flags |= AV_LOG_SKIP_REPEATED;
>> +            } else {
>> +                flags &= ~AV_LOG_SKIP_REPEATED;
>> +            }
>> +            arg = token + 6;
>> +        } else if (!strncmp(token, "level", 5)) {
>> +            if (cmd == '-') {
>> +                flags &= ~AV_LOG_PRINT_LEVEL;
>> +            } else {
>> +                flags |= AV_LOG_PRINT_LEVEL;
>> +            }
>> +            arg = token + 5;
>> +        } else {
>> +            break;
>> +        }
>> +        i++;
>> +    }
>> +    if (!*arg) {
>> +        goto end;
>> +    } else if (*arg == '+') {
>> +        arg++;
>> +    } else if (!i) {
>> +        flags = av_log_get_flags();  /* level value without prefix, reset flags */
>> +    }
>> +
>> +    for (i = 0; i < FF_ARRAY_ELEMS(log_levels); i++) {
>> +        if (!strcmp(arg, log_levels[i].name)) {
>> +            level = log_levels[i].level;
>> +            goto end;
>> +        }
>> +    }
>> +
>> +    level = strtol(arg, &tail, 10);
>> +    if (*tail) {
>> +        return -1;
>> +    }
>> +
>> +end:
>> +    av_log_set_flags(flags);
>> +    av_log_set_level(level);
>> +    return 0;
>> +}
>> +
>>   static void missing_feature_sample(int sample, void *avc, const char *msg,
>>                                      va_list argument_list)
>>   {
>> diff --git a/libavutil/log.h b/libavutil/log.h
>> index d9554e6..97010f7 100644
>> --- a/libavutil/log.h
>> +++ b/libavutil/log.h
>> @@ -356,6 +356,22 @@ void av_log_set_flags(int arg);
>>   int av_log_get_flags(void);
>>   
>>   /**
>> + * Set log flags and level as an option string. Accepts "repeat" and "level"
>> + * flags mapped to AV_LOG_SKIP_REPEATED (inverted) and AV_LOG_PRINT_LEVEL,
>> + * followed by the log level specified either by name ("warning", "info",
>> + * "verbose", etc.) or by number.
>> + *
>> + * When flags are prefixed with "+" or "-" the change is relative to the
>> + * current flags value. When both flags and level are present a "+" separator
>> + * is expected between last flag and before level.
>> + *
>> + * @param  arg  log option string
>> + * @return Returns a negative value if parsing the option string failed,
>> + *         otherwise returns 0.
>> + */
>> +int av_log_set_opts(const char *arg);
>> +
>> +/**
>>    * @}
>>    */
>>   
>> diff --git a/libavutil/version.h b/libavutil/version.h
>> index d3dd2df..296c24b 100644
>> --- a/libavutil/version.h
>> +++ b/libavutil/version.h
>> @@ -79,7 +79,7 @@
>>    */
>>   
>>   #define LIBAVUTIL_VERSION_MAJOR  56
>> -#define LIBAVUTIL_VERSION_MINOR  12
>> +#define LIBAVUTIL_VERSION_MINOR  13
>>   #define LIBAVUTIL_VERSION_MICRO 100
>>   
>>   #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
> 
> Seems like a step backwards. Why can't it stay in the fftools thing?

When v2 of the patch was reviewed in 
http://ffmpeg.org/pipermail/ffmpeg-devel/2018-March/227077.html it was 
suggested to move the code into libavutil so that other applications can 
make use of it. I agree that it can be useful for command-line apps that 
interface with libav* to provide a loglevel option which accepts 
info/verbose/etc. name strings without the need to do an own 
string-to-level parsing.

Regards,
Tobias