FIO45-C. Never expect write() to terminate the writing process at a NULL character

The POSIX standard defines the write() interface as follows [1].

ssize_t write (int filedes, const void *buffer, size_t size);

The write function writes up to size bytes from buffer to the file with descriptor filedes. The data in buffer is not necessarily a character string and a null character is output like any other character.

The definition does not state that the write() function will stop copying characters into the file if a null character is encountered. Therefore, when writing a C string in to a file using the write() function, always use the size of the string plus 1 (for the null character) as the size parameter.

Noncompliant Code Example

Compliant Code Example

References

[1] http://www.gnu.org/software/libc/manual/html_node/I_002fO-Primitives.html#I_002fO-Primitives