phoenix-rtos-doc / libc / functions / f / fgetc.part-impl.md

fgetc

Synopsis

#include <stdio.h>

int fgetc(FILE *stream);

Status

Partially implemented

Conformance

IEEE Std 1003.1-2017

Description

If the end-of-file indicator for the input stream pointed to by stream is not set and a next byte is present, the fgetc() function shall obtain the next byte as an unsigned char converted to an int, from the input stream pointed to by stream, and advance the associated file position indicator for the stream (if defined). Since fgetc() operates on bytes, reading a character consisting of multiple bytes (or "a multibyte character") may require multiple calls to fgetc().

The fgetc() function may mark the last data access timestamp of the file associated with stream for update. The last data access timestamp shall be marked for update by the first successful execution of fgetc(), fgets(), fread(), fscanf(), getc(), getchar(), getdelim(), getline(), gets(), or scanf() using stream that returns data not supplied by a prior call to ungetc().

Return value

Upon successful completion, fgetc() shall return the next byte from the input stream pointed to by stream. If the end-of-file indicator for the stream is set, or if the stream is at end-of-file, the end-of-file indicator for the stream shall be set and fgetc() shall return EOF. If a read error occurs, the error indicator for the stream shall be set, fgetc() shall return EOF and shall set errno to indicate the error.

Errors

The fgetc() function shall fail if data needs to be read and:

EAGAIN - The O_NONBLOCK flag is set for the file descriptor underlying stream and the thread would be delayed in the fgetc() operation.
EBADF - The file descriptor underlying stream is not a valid file descriptor open for reading.
EINTR - The read operation was terminated due to the receipt of a signal, and no data was transferred.
EIO - A physical I/O error has occurred, or the process is in a background process group attempting to read from its controlling terminal, and either the calling thread is blocking SIGTTIN or the process is ignoring SIGTTIN or the process group of the process is orphaned. This error may also be generated for implementation-defined reasons.
EOVERFLOW - The file is a regular file and an attempt was made to read at or beyond the offset maximum associated with the corresponding stream.

The fgetc() function may fail if:

ENOMEM - Insufficient storage space is available.
ENXIO - A request was made of a nonexistent device, or the request was outside the capabilities of the device.

Tests

Untested

Known bugs

None