Re: [PATCH v2 1/4] tools: iio: Move printf failure messages to stderr

[Jonathan Cameron]

On 12 July 2015 14:07:15 BST, Hartmut Knaack <knaack.h@xxxxxx> wrote:
>Cristina Georgiana Opriceana schrieb am 12.07.2015 um 13:38:
>> On Sat, Jul 11, 2015 at 12:42 AM, Hartmut Knaack <knaack.h@xxxxxx>
>wrote:
>>> Cristina Opriceana schrieb am 10.07.2015 um 12:56:
>>>> Replace printf error messages with fprintf(stderr, ...) in order
>>>> to ensure consistency and to make faults easier to identify.
>>>> This patch uses coccinelle to detect and apply the changes.
>>>>
>>>
>>> Hi Cristina,
>>> I just had a look at the series. You have all cases I regard
>necessary
>>> covered. There are however a few cases which probably qualify as
>error
>>> messages, too. Please see inline.
>>> However, for my personal taste, this could have been merged all in a
>>> single patch. Especially the third patch should have been included
>in
>>> this one (as during review, people certainly think that you missed
>the
>>> second line, just to find it fixed two patches later).
>> 
>> Hi,
>> 
>> Yes, I could have included all in a single patch, but I tried to
>> automatize this task and build a rather generic semantic patch in
>> coccinelle for the substitutions. Had I included all in one patch,
>the
>> changes with coccinelle wouldn't have been differentiated from the
>> other ones. If that is okay, I think I can merge them in one patch.
>> 
>
>Point taken for making it reproducible. I just like to raise awareness:
>The maintainers are very busy. They have a full time job, respond to
>the
>mailing list, review patches and do all the git magic. That keeps them
>pretty busy, so I would aim to make the maintainers life as easy as
>possible.
>Checking just one patch against some sources can be quicker/easier than
>checking multiple ones. Same goes for applying patches.

Always a balance needing to be struck here.  I always slightly prefer too many patches to too few.

Here however the breaking up doesn't really help with clarity.  I don't feel
 strongly about it though! (Particularly as I can rely on Hartmut's review here to
 cover what was missed and only quickly double check validity of what changed.,)


Jonathan
>Other than that, I just feel strong about the third patch standing
>separate,
>which I don't regard a good idea. Either your script should have been
>extended to catch such cases, or if it is not worth the effort, it
>should
>have been changed by hand. But it should have gone in one pass.
>
>>>> Signed-off-by: Cristina Opriceana <cristina.opriceana@xxxxxxxxx>
>>>> ---
>>>> Changes in v2:
>>>>  - s/failiure/failure
>>>>
>>>>  tools/iio/generic_buffer.c    | 17 ++++++++++-------
>>>>  tools/iio/iio_event_monitor.c |  6 +++---
>>>>  tools/iio/iio_utils.c         | 34
>++++++++++++++++++++--------------
>>>>  3 files changed, 33 insertions(+), 24 deletions(-)
>>>>
>>>> diff --git a/tools/iio/generic_buffer.c
>b/tools/iio/generic_buffer.c
>>>> index 0e73723..2f4e12f 100644
>>>> --- a/tools/iio/generic_buffer.c
>>>> +++ b/tools/iio/generic_buffer.c
>>>> @@ -271,7 +271,7 @@ int main(int argc, char **argv)
>>>>       }
>>>>
>>>>       if (device_name == NULL) {
>>>> -             printf("Device name not set\n");
>>>> +             fprintf(stderr, "Device name not set\n");
>>>>               print_usage();
>>>>               return -1;
>>>>       }
>>>> @@ -279,7 +279,7 @@ int main(int argc, char **argv)
>>>>       /* Find the device requested */
>>>>       dev_num = find_type_by_name(device_name, "iio:device");
>>>>       if (dev_num < 0) {
>>>> -             printf("Failed to find the %s\n", device_name);
>>>> +             fprintf(stderr, "Failed to find the %s\n",
>device_name);
>>>>               return dev_num;
>>>>       }
>>>>
>>>> @@ -307,7 +307,8 @@ int main(int argc, char **argv)
>>>>               /* Verify the trigger exists */
>>>>               trig_num = find_type_by_name(trigger_name,
>"trigger");
>>>>               if (trig_num < 0) {
>>>> -                     printf("Failed to find the trigger %s\n",
>trigger_name);
>>>> +                     fprintf(stderr, "Failed to find the trigger
>%s\n",
>>>> +                             trigger_name);
>>>>                       ret = trig_num;
>>>>                       goto error_free_triggername;
>>>>               }
>>>> @@ -323,7 +324,7 @@ int main(int argc, char **argv)
>>>>        */
>>>>       ret = build_channel_array(dev_dir_name, &channels,
>&num_channels);
>>>>       if (ret) {
>>>> -             printf("Problem reading scan element information\n");
>>>> +             fprintf(stderr, "Problem reading scan element
>information\n");
>>>>               printf("diag %s\n", dev_dir_name);
>>>
>>> My preference would even be to print it all in just one fprintf.
>> 
>> I thought so, also, but the string would go beyond 80 characters and
>> would have to be split which is ugly and brings a warning on it.
>> 
>
>I just gave it a try compile testing:
>		fprintf(stderr, "Problem reading scan element information\n"
>			"diag %s\n", dev_dir_name);
>
>Compiled just fine, and the same format is used in your second patch as
>well.
>
>>>>               goto error_free_triggername;
>>>>       }
>>>> @@ -350,7 +351,8 @@ int main(int argc, char **argv)
>>>>                                                   dev_dir_name,
>>>>                                                   trigger_name);
>>>>               if (ret < 0) {
>>>> -                     printf("Failed to write current_trigger
>file\n");
>>>> +                     fprintf(stderr,
>>>> +                             "Failed to write current_trigger
>file\n");
>>>>                       goto error_free_buf_dir_name;
>>>>               }
>>>>       }
>>>> @@ -382,7 +384,7 @@ int main(int argc, char **argv)
>>>>       fp = open(buffer_access, O_RDONLY | O_NONBLOCK);
>>>>       if (fp == -1) { /* TODO: If it isn't there make the node */
>>>>               ret = -errno;
>>>> -             printf("Failed to open %s\n", buffer_access);
>>>> +             fprintf(stderr, "Failed to open %s\n",
>buffer_access);
>>>>               goto error_free_buffer_access;
>>>>       }
>>>>
>>>
>>> At line 410 we have a block:
>>>                 read_size = read(fp, data, toread * scan_size);
>>>                 if (read_size < 0) {
>>>                         if (errno == EAGAIN) {
>>>                                 printf("nothing available\n");
>>>                                 continue;
>>>
>>> I'm tempted to say,that this should go to stderr, as well. Any
>opinions?
>> 
>> I see it more as an informing note, since the device continues
>looping
>> for data, but it could be considered an error as well.
>
>I thought about the case when stdout gets piped to a data file while
>stderr
>goes into a logfile (or an application reads one data stream while
>checking
>the error stream).
>
>> 
>>>> @@ -431,7 +433,8 @@ int main(int argc, char **argv)
>>>>               ret = write_sysfs_string("trigger/current_trigger",
>>>>                                        dev_dir_name, "NULL");
>>>>               if (ret < 0)
>>>> -                     printf("Failed to write to %s\n",
>dev_dir_name);
>>>> +                     fprintf(stderr, "Failed to write to %s\n",
>>>> +                             dev_dir_name);
>>>>
>>>>  error_close_buffer_access:
>>>>       if (close(fp) == -1)
>>>> diff --git a/tools/iio/iio_event_monitor.c
>b/tools/iio/iio_event_monitor.c
>>>> index 703f4cb..843bc4c 100644
>>>> --- a/tools/iio/iio_event_monitor.c
>>>> +++ b/tools/iio/iio_event_monitor.c
>>>
>>> At line 217:
>>>         if (!event_is_known(event)) {
>>>                 printf("Unknown event: time: %lld, id: %llx\n",
>>>                        event->timestamp, event->id);
>>>
>>>                 return;
>>> Better have this on stderr, as well?
>> 
>> This is more suitable for stderr, indeed.
>> 
>>>> @@ -278,14 +278,14 @@ int main(int argc, char **argv)
>>>>       fd = open(chrdev_name, 0);
>>>>       if (fd == -1) {
>>>>               ret = -errno;
>>>> -             fprintf(stdout, "Failed to open %s\n", chrdev_name);
>>>> +             fprintf(stderr, "Failed to open %s\n", chrdev_name);
>>>>               goto error_free_chrdev_name;
>>>>       }
>>>>
>>>>       ret = ioctl(fd, IIO_GET_EVENT_FD_IOCTL, &event_fd);
>>>>       if (ret == -1 || event_fd == -1) {
>>>>               ret = -errno;
>>>> -             fprintf(stdout, "Failed to retrieve event fd\n");
>>>> +             fprintf(stderr, "Failed to retrieve event fd\n");
>>>>               if (close(fd) == -1)
>>>>                       perror("Failed to close character device
>file");
>>>>
>>>
>>> A similar borderline case as above in line 301:
>>>                 ret = read(event_fd, &event, sizeof(event));
>>>                 if (ret == -1) {
>>>                         if (errno == EAGAIN) {
>>>                                 printf("nothing available\n");
>>>                                 continue;
>>>
>>>> @@ -311,7 +311,7 @@ int main(int argc, char **argv)
>>>>               }
>>>>
>>>>               if (ret != sizeof(event)) {
>>>> -                     printf("Reading event failed!\n");
>>>> +                     fprintf(stderr, "Reading event failed!\n");
>>>>                       ret = -EIO;
>>>>                       break;
>>>>               }
>>>> diff --git a/tools/iio/iio_utils.c b/tools/iio/iio_utils.c
>>>> index 8fb3214..46dfa3f 100644
>>>> --- a/tools/iio/iio_utils.c
>>>> +++ b/tools/iio/iio_utils.c
>>>> @@ -140,7 +140,8 @@ int iioutils_get_type(unsigned *is_signed,
>unsigned *bytes, unsigned *bits_used,
>>>>                       sysfsfp = fopen(filename, "r");
>>>>                       if (sysfsfp == NULL) {
>>>>                               ret = -errno;
>>>> -                             printf("failed to open %s\n",
>filename);
>>>> +                             fprintf(stderr, "failed to open
>%s\n",
>>>> +                                     filename);
>>>>                               goto error_free_filename;
>>>>                       }
>>>>
>>>> @@ -152,7 +153,8 @@ int iioutils_get_type(unsigned *is_signed,
>unsigned *bytes, unsigned *bits_used,
>>>>                                    &padint, shift);
>>>>                       if (ret < 0) {
>>>>                               ret = -errno;
>>>> -                             printf("failed to pass scan type
>description\n");
>>>> +                             fprintf(stderr,
>>>> +                                     "failed to pass scan type
>description\n");
>>>>                               goto error_close_sysfsfp;
>>>>                       } else if (ret != 5) {
>>>>                               ret = -EIO;
>>>> @@ -170,7 +172,8 @@ int iioutils_get_type(unsigned *is_signed,
>unsigned *bytes, unsigned *bits_used,
>>>>                       *is_signed = (signchar == 's');
>>>>                       if (fclose(sysfsfp)) {
>>>>                               ret = -errno;
>>>> -                             printf("Failed to close %s\n",
>filename);
>>>> +                             fprintf(stderr, "Failed to close
>%s\n",
>>>> +                                     filename);
>>>>                               goto error_free_filename;
>>>>                       }
>>>>
>>>> @@ -454,7 +457,8 @@ int build_channel_array(const char *device_dir,
>>>>                       sysfsfp = fopen(filename, "r");
>>>>                       if (sysfsfp == NULL) {
>>>>                               ret = -errno;
>>>> -                             printf("failed to open %s\n",
>filename);
>>>> +                             fprintf(stderr, "failed to open
>%s\n",
>>>> +                                     filename);
>>>>                               free(filename);
>>>>                               goto error_cleanup_array;
>>>>                       }
>>>> @@ -581,11 +585,13 @@ int find_type_by_name(const char *name, const
>char *type)
>>>>                       ret = sscanf(ent->d_name + strlen(type),
>"%d", &number);
>>>>                       if (ret < 0) {
>>>>                               ret = -errno;
>>>> -                             printf("failed to read element
>number\n");
>>>> +                             fprintf(stderr,
>>>> +                                     "failed to read element
>number\n");
>>>>                               goto error_close_dir;
>>>>                       } else if (ret != 1) {
>>>>                               ret = -EIO;
>>>> -                             printf("failed to match element
>number\n");
>>>> +                             fprintf(stderr,
>>>> +                                     "failed to match element
>number\n");
>>>>                               goto error_close_dir;
>>>>                       }
>>>>
>>>> @@ -664,7 +670,7 @@ static int _write_sysfs_int(const char
>*filename, const char *basedir, int val,
>>>>       sysfsfp = fopen(temp, "w");
>>>>       if (sysfsfp == NULL) {
>>>>               ret = -errno;
>>>> -             printf("failed to open %s\n", temp);
>>>> +             fprintf(stderr, "failed to open %s\n", temp);
>>>>               goto error_free;
>>>>       }
>>>>
>>>> @@ -685,7 +691,7 @@ static int _write_sysfs_int(const char
>*filename, const char *basedir, int val,
>>>>               sysfsfp = fopen(temp, "r");
>>>>               if (sysfsfp == NULL) {
>>>>                       ret = -errno;
>>>> -                     printf("failed to open %s\n", temp);
>>>> +                     fprintf(stderr, "failed to open %s\n", temp);
>>>>                       goto error_free;
>>>>               }
>>>>
>>>> @@ -750,7 +756,7 @@ static int _write_sysfs_string(const char
>*filename, const char *basedir,
>>>>       char *temp = malloc(strlen(basedir) + strlen(filename) + 2);
>>>>
>>>>       if (temp == NULL) {
>>>> -             printf("Memory allocation failed\n");
>>>> +             fprintf(stderr, "Memory allocation failed\n");
>>>>               return -ENOMEM;
>>>>       }
>>>>
>>>> @@ -761,7 +767,7 @@ static int _write_sysfs_string(const char
>*filename, const char *basedir,
>>>>       sysfsfp = fopen(temp, "w");
>>>>       if (sysfsfp == NULL) {
>>>>               ret = -errno;
>>>> -             printf("Could not open %s\n", temp);
>>>> +             fprintf(stderr, "Could not open %s\n", temp);
>>>>               goto error_free;
>>>>       }
>>>>
>>>> @@ -782,7 +788,7 @@ static int _write_sysfs_string(const char
>*filename, const char *basedir,
>>>>               sysfsfp = fopen(temp, "r");
>>>>               if (sysfsfp == NULL) {
>>>>                       ret = -errno;
>>>> -                     printf("Could not open file to verify\n");
>>>> +                     fprintf(stderr, "Could not open file to
>verify\n");
>>>>                       goto error_free;
>>>>               }
>>>>
>>>> @@ -856,7 +862,7 @@ int read_sysfs_posint(const char *filename,
>const char *basedir)
>>>>       char *temp = malloc(strlen(basedir) + strlen(filename) + 2);
>>>>
>>>>       if (temp == NULL) {
>>>> -             printf("Memory allocation failed");
>>>> +             fprintf(stderr, "Memory allocation failed");
>>>>               return -ENOMEM;
>>>>       }
>>>>
>>>> @@ -903,7 +909,7 @@ int read_sysfs_float(const char *filename,
>const char *basedir, float *val)
>>>>       char *temp = malloc(strlen(basedir) + strlen(filename) + 2);
>>>>
>>>>       if (temp == NULL) {
>>>> -             printf("Memory allocation failed");
>>>> +             fprintf(stderr, "Memory allocation failed");
>>>>               return -ENOMEM;
>>>>       }
>>>>
>>>> @@ -950,7 +956,7 @@ int read_sysfs_string(const char *filename,
>const char *basedir, char *str)
>>>>       char *temp = malloc(strlen(basedir) + strlen(filename) + 2);
>>>>
>>>>       if (temp == NULL) {
>>>> -             printf("Memory allocation failed");
>>>> +             fprintf(stderr, "Memory allocation failed");
>>>>               return -ENOMEM;
>>>>       }
>>>>
>>>>
>>>
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