[PATCH 3/3] handle return values of read, write and fgets

[walter harms]

Am 27.09.2012 16:04, schrieb Denys Vlasenko:
> On Tue, Jul 31, 2012 at 3:15 PM,
> <manuel.f.zerpies at ww.stud.uni-erlangen.de> wrote:
>> From: Manuel Zerpies <manuel.f.zerpies at ww.stud.uni-erlangen.de>
>>
>> Check the return values of read(), write() and fgets().
>>
>> Signed-off-by: Manuel Zerpies <manuel.f.zerpies at ww.stud.uni-erlangen.de>
>> ---
>>  applets/applet_tables.c |    5 ++++-
>>  applets/usage.c         |    7 +++++--
>>  libbb/lineedit.c        |    4 +++-
>>  libbb/xfuncs_printf.c   |    4 +++-
>>  4 files changed, 15 insertions(+), 5 deletions(-)
>>
>> diff --git a/applets/applet_tables.c b/applets/applet_tables.c
>> index 152d5f4..ffd4a82 100644
>> --- a/applets/applet_tables.c
>> +++ b/applets/applet_tables.c
>> @@ -141,8 +141,11 @@ int main(int argc, char **argv)
>>                 line_old[0] = 0;
>>                 fp = fopen(argv[2], "r");
>>                 if (fp) {
>> -                       fgets(line_old, sizeof(line_old), fp);
>> +                       char *c = fgets(line_old, sizeof(line_old), fp);
>>                         fclose(fp);
>> +                       if (c == NULL) {
>> +                               return 1;
>> +                       }
>>                 }
>>                 sprintf(line_new, "#define NUM_APPLETS %u\n", NUM_APPLETS);
>>                 if (strcmp(line_old, line_new) != 0) {
>> diff --git a/applets/usage.c b/applets/usage.c
>> index 94520ff..faa6b27 100644
>> --- a/applets/usage.c
>> +++ b/applets/usage.c
>> @@ -48,8 +48,11 @@ int main(void)
>>         qsort(usage_array,
>>                 num_messages, sizeof(usage_array[0]),
>>                 compare_func);
>> -       for (i = 0; i < num_messages; i++)
>> -               write(STDOUT_FILENO, usage_array[i].usage, strlen(usage_array[i].usage) + 1);
>> +       for (i = 0; i < num_messages; i++) {
>> +               ssize_t r = write(STDOUT_FILENO, usage_array[i].usage, strlen(usage_array[i].usage) + 1);
>> +               if (r < 0)
>> +                       return 1;
>> +       }
> 
> You can also add short write handling.
> And btw, we have tons of printf's all over the place w/o result check,
> want to fix them all? :)
> 

i am a big fan of dprintf() because it si now posix we could use it here ?

re,
 wh



> 
>> diff --git a/libbb/lineedit.c b/libbb/lineedit.c
>> index b89748a..356c7f1 100644
>> --- a/libbb/lineedit.c
>> +++ b/libbb/lineedit.c
>> @@ -2729,7 +2729,9 @@ int FAST_FUNC read_line_input(const char* prompt, char* command, int maxsize)
>>  {
>>         fputs(prompt, stdout);
>>         fflush_all();
>> -       fgets(command, maxsize, stdin);
>> +       char *c = fgets(command, maxsize, stdin);
>> +       if (c == NULL)
>> +               return 0;
> 
> Should return -1 (see libbb.h comment).
> 
>>         return strlen(command);
>>  }
>>
>> diff --git a/libbb/xfuncs_printf.c b/libbb/xfuncs_printf.c
>> index 29c963f..9c76fbb 100644
>> --- a/libbb/xfuncs_printf.c
>> +++ b/libbb/xfuncs_printf.c
>> @@ -590,8 +590,10 @@ void FAST_FUNC generate_uuid(uint8_t *buf)
>>
>>         i = open("/dev/urandom", O_RDONLY);
>>         if (i >= 0) {
>> -               read(i, buf, 16);
>> +               ssize_t r = read(i, buf, 16);
>>                 close(i);
>> +               if (r < 0)
>> +                       return;
> 
> Well, paranoia code below takes care of the possibility
> of read error.
> 
>>         }
>>         /* Paranoia. /dev/urandom may be missing.
>>          * rand() is guaranteed to generate at least [0, 2^15) range,
> 
> 
> 
> commit b2320370be14811459718b9fe418efed75ea3615
> Author: Denys Vlasenko <vda.linux at googlemail.com>
> Date:   Thu Sep 27 16:03:49 2012 +0200
> 
>     lineedit: in !EDITING config, return -1 on fgets error
> 
>     Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
> 
> diff --git a/libbb/lineedit.c b/libbb/lineedit.c
> index 92bea85..dbe6164 100644
> --- a/libbb/lineedit.c
> +++ b/libbb/lineedit.c
> @@ -2729,7 +2729,8 @@ int FAST_FUNC read_line_input(const char*
> prompt, char* command, int maxsize)
>  {
>         fputs(prompt, stdout);
>         fflush_all();
> -       fgets(command, maxsize, stdin);
> +       if (!fgets(command, maxsize, stdin))
> +               return -1;
>         return strlen(command);
>  }
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