read / write - glibc

Split from the chapter glibc: stdio and Formatted I/O into the per-function layout; see the method page and the glibc ledger for coverage status.

Signature – ssize_t read(int fd, void *buf, size_t count); ssize_t write(int fd, const void *buf, size_t count);

Libc side – pure translation: bytes on success, 0 = EOF for read, -1+errno on failure. Short counts are not errors and the caller loops (manual, Input and Output Primitives). Both are cancellation points in glibc; write’s data may land even when it reports EINTR-style failure. read is the primitive underneath every stream input function (manual). Syscall semantics, EIO on background terminal reads, and EAGAIN aliasing are in the syscall chapter read/write entries.