>It is not strictly an error to read/write less than the requested amount, >but you will find that a lot of applications don't handle this correctly. I'd give it a slightly different nuance. It's not an error, and it's a reasonable thing to do, but there is value in not doing it. POSIX and its predecessors back to the beginning of Unix say read()/write() don't have to transfer the full count (they must transfer at least one byte). The main reason for this choice is that it may require more resources (e.g. a memory buffer) than the system can allocate to do the whole request at once. Programs that assume a full transfer are fairly common, but are universally regarded as either broken or just lazy, and when it does cause a problem, it is far more common to fix the application than the kernel. Most application programs access files via libc's fread/fwrite, which don't have partial transfers. GNU libc does handle partial (kernel) reads and writes correctly. I'd be surprised if someone can name a major application that doesn't. -- Bryan Henderson IBM Almaden Research Center San Jose CA Filesystems - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
