#491 check return codes everywhere

[Randolf Schultz]

Some checks for return codes are missing.

Examples:
Would you like to add more error handling for return values from "sscanf"
like in the function "ay_read_unistring" and from "fprintf" in the function
"ay_write_header"?
http://ayam.cvs.sourceforge.net/ayam/ayam/src/aycore/read.c?revision=1.32&v
iew=markup
http://ayam.cvs.sourceforge.net/ayam/ayam/src/aycore/write.c?revision=1.12&
view=markup

[Markus Elfring]

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I suggest to avoid all unchecked function calls.

Can you imagine that the file output will fail in a reproducible way?

[Randolf Schultz]

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Greetings,

yes, that is why ay_write_scene() is checking errno and
ferror(fileptr) after all objects have been written.
In the case of a full disk, the most likely cause of
a failed write, this should be sufficient (tested on
Linux).
If there is a way to create a mangled Ayam scene file
using normal user input without those checks raising
a visible error message: please tell.

best regards,
Randolf

[Markus Elfring]

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I read your source code in a way that your check that happens after all output should be performed may be too late because parts of the execution of the instruction "ay_write_header(fileptr);" (line 331) failed earlier.
Would you like to detect every error situation as early as possible?