Input Interface

Overview

The input functions present an interface similar to the stdio functions on top of different underlying input sources. More…

// typedefs

typedef struct _snd_input snd_input_t;

// enums

enum snd_input_type_t;

// global functions

int
snd_input_stdio_open(
    snd_input_t** inputp,
    const char* file,
    const char* mode
);

int
snd_input_stdio_attach(
    snd_input_t** inputp,
    FILE* fp,
    int _close
);

int
snd_input_buffer_open(
    snd_input_t** inputp,
    const char* buffer,
    ssize_t size
);

int
snd_input_close(snd_input_t* input);

int
snd_input_scanf(
    snd_input_t* input,
    const char* format,
    ...
);

char*
snd_input_gets(
    snd_input_t* input,
    char* str,
    size_t size
);

int
snd_input_getc(snd_input_t* input);

int
snd_input_ungetc(
    snd_input_t* input,
    int c
);

Detailed Documentation

The input functions present an interface similar to the stdio functions on top of different underlying input sources.

The snd_config_load function uses such an input handle to be able to load configurations not only from standard files but also from other sources, e.g. from memory buffers.

Typedefs

typedef struct _snd_input snd_input_t

Internal structure for an input object.

The ALSA library uses a pointer to this structure as a handle to an input object. Applications don’t access its contents directly.

Global Functions

int
snd_input_stdio_open(
    snd_input_t** inputp,
    const char* file,
    const char* mode
)

Creates a new input object reading from a file.

Parameters:

inputp The functions puts the pointer to the new input object at the address specified by inputp.
file The name of the file to read from.
mode The open mode, like fopen(3).

Returns:

Zero if successful, otherwise a negative error code.

int
snd_input_stdio_attach(
    snd_input_t** inputp,
    FILE* fp,
    int _close
)

Creates a new input object using an existing stdio FILE pointer.

Parameters:

inputp The function puts the pointer to the new input object at the address specified by inputp.
fp The FILE pointer to read from. Reading begins at the current file position.
_close Close flag. Set this to 1 if snd_input_close should close fp by calling fclose.

Returns:

Zero if successful, otherwise a negative error code.

int
snd_input_buffer_open(
    snd_input_t** inputp,
    const char* buffer,
    ssize_t size
)

Creates a new input object from a memory buffer.

This functions creates a copy of the input buffer, so the application is not required to preserve the buffer after this function has been called.

Parameters:

inputp The function puts the pointer to the new input object at the address specified by inputp.
buf Address of the input buffer.
size Size of the input buffer.

Returns:

Zero if successful, otherwise a negative error code.

int
snd_input_close(snd_input_t* input)

Closes an input handle.

Parameters:

input The input handle to be closed.

Returns:

Zero if successful, otherwise a negative error code.

int
snd_input_scanf(
    snd_input_t* input,
    const char* format,
    ...
)

Reads formatted input (like fscanf(3)) from an input handle.

Bug Reading from a memory buffer doesn’t work.

Parameters:

input The input handle.
format Format string in fscanf format.
Other fscanf arguments.

Returns:

The number of input items assigned, or EOF.

char*
snd_input_gets(
    snd_input_t* input,
    char* str,
    size_t size
)

Reads a line from an input handle (like fgets(3)).

Like fgets, the returned string is zero-terminated, and contains the new-line character '\n' if the line fits into the buffer.

Parameters:

input The input handle.
str Address of the destination buffer.
size The size of the destination buffer.

Returns:

Pointer to the buffer if successful, otherwise NULL.

int
snd_input_getc(snd_input_t* input)

Reads a character from an input handle (like fgetc(3)).

Parameters:

input The input handle.

Returns:

The character read, or EOF on end of file or error.

int
snd_input_ungetc(
    snd_input_t* input,
    int c
)

Puts the last character read back to an input handle (like ungetc(3)).

Parameters:

input The input handle.
c The character to push back.

Returns:

The character pushed back, or EOF on error.