Ruby  3.4.0dev (2024-11-05 revision 348a53415339076afc4a02fcd09f3ae36e9c4c61)
Macros | Functions | Variables
io.h File Reference

(348a53415339076afc4a02fcd09f3ae36e9c4c61)

Public APIs related to rb_cIO. More...

#include "ruby/internal/dllexport.h"
#include "ruby/internal/value.h"
Include dependency graph for io.h:
This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Macros

#define rb_defout   rb_stdout
 
#define RB_RESERVED_FD_P(fd)   rb_reserved_fd_p(fd)
 Just another name of rb_reserved_fd_p. More...
 

Functions

VALUE rb_io_write (VALUE io, VALUE str)
 Writes the given string to the given IO. More...
 
VALUE rb_io_gets (VALUE io)
 Reads a "line" from the given IO. More...
 
VALUE rb_io_getbyte (VALUE io)
 Reads a byte from the given IO. More...
 
VALUE rb_io_ungetc (VALUE io, VALUE c)
 "Unget"s a string. More...
 
VALUE rb_io_ungetbyte (VALUE io, VALUE b)
 Identical to rb_io_ungetc(), except it doesn't take the encoding of the passed IO into account. More...
 
VALUE rb_io_close (VALUE io)
 Closes the IO. More...
 
VALUE rb_io_flush (VALUE io)
 Flushes any buffered data within the passed IO to the underlying operating system. More...
 
VALUE rb_io_eof (VALUE io)
 Queries if the passed IO is at the end of file. More...
 
VALUE rb_io_binmode (VALUE io)
 Sets the binmode. More...
 
VALUE rb_io_ascii8bit_binmode (VALUE io)
 Forces no conversions be applied to the passed IO. More...
 
VALUE rb_io_addstr (VALUE io, VALUE str)
 Identical to rb_io_write(), except it always returns the passed IO. More...
 
VALUE rb_io_printf (int argc, const VALUE *argv, VALUE io)
 This is a rb_f_sprintf() + rb_io_write() combo. More...
 
VALUE rb_io_print (int argc, const VALUE *argv, VALUE io)
 Iterates over the passed array to apply rb_io_write() individually. More...
 
VALUE rb_io_puts (int argc, const VALUE *argv, VALUE io)
 Iterates over the passed array to apply rb_io_write() individually. More...
 
VALUE rb_io_fdopen (int fd, int flags, const char *path)
 Creates an IO instance whose backend is the given file descriptor. More...
 
VALUE rb_file_open (const char *fname, const char *fmode)
 Opens a file located at the given path. More...
 
VALUE rb_file_open_str (VALUE fname, const char *fmode)
 Identical to rb_file_open(), except it takes the pathname as a Ruby's string instead of C's. More...
 
VALUE rb_gets (void)
 Much like rb_io_gets(), but it reads from the mysterious ARGF object. More...
 
void rb_write_error (const char *str)
 Writes the given error message to somewhere applicable. More...
 
void rb_write_error2 (const char *str, long len)
 Identical to rb_write_error(), except it additionally takes the message's length. More...
 
void rb_close_before_exec (int lowfd, int maxhint, VALUE noclose_fds)
 Closes everything. More...
 
int rb_pipe (int *pipes)
 This is an rb_cloexec_pipe() + rb_update_max_fd() combo. More...
 
int rb_reserved_fd_p (int fd)
 Queries if the given FD is reserved or not. More...
 
int rb_cloexec_open (const char *pathname, int flags, mode_t mode)
 Opens a file that closes on exec. More...
 
int rb_cloexec_dup (int oldfd)
 Identical to rb_cloexec_fcntl_dupfd(), except it implies minfd is 3. More...
 
int rb_cloexec_dup2 (int oldfd, int newfd)
 Identical to rb_cloexec_dup(), except you can specify the destination file descriptor. More...
 
int rb_cloexec_pipe (int fildes[2])
 Opens a pipe with closing on exec. More...
 
int rb_cloexec_fcntl_dupfd (int fd, int minfd)
 Duplicates a file descriptor with closing on exec. More...
 
void rb_update_max_fd (int fd)
 Informs the interpreter that the passed fd can be the max. More...
 
void rb_fd_fix_cloexec (int fd)
 Sets or clears the close-on-exec flag of the passed file descriptor to the desired state. More...
 

Variables

VALUE rb_fs
 The field separator character for inputs, or the $;. More...
 
VALUE rb_output_fs
 The field separator character for outputs, or the $,. More...
 
VALUE rb_rs
 The record separator character for inputs, or the $/. More...
 
VALUE rb_default_rs
 This is the default value of rb_rs, i.e. More...
 
VALUE rb_output_rs
 The record separator character for outputs, or the $\. More...
 

Detailed Description

Public APIs related to rb_cIO.

Author
Ruby developers ruby-.nosp@m.core.nosp@m.@ruby.nosp@m.-lan.nosp@m.g.org
Warning
Symbols prefixed with either RBIMPL or rbimpl are implementation details. Don't take them as canon. They could rapidly appear then vanish. The name (path) of this header file is also an implementation detail. Do not expect it to persist at the place it is now. Developers are free to move it anywhere anytime at will.
Note
To ruby-core: remember that this header can be possibly recursively included from extension libraries written in C++. Do not expect for instance __VA_ARGS__ is always available. We assume C99 for ruby itself but we don't assume languages of extension libraries. They could be written in C++98.

Definition in file io.h.

Macro Definition Documentation

◆ rb_defout

#define rb_defout   rb_stdout
Deprecated:
This macro once was a thing in the old days, but makes no sense any longer today.

Exists here for backwards compatibility only. You can safely forget about it.

Definition at line 37 of file io.h.

◆ RB_RESERVED_FD_P

#define RB_RESERVED_FD_P (   fd)    rb_reserved_fd_p(fd)

Just another name of rb_reserved_fd_p.

Definition at line 556 of file io.h.

Function Documentation

◆ rb_cloexec_dup()

int rb_cloexec_dup ( int  oldfd)

Identical to rb_cloexec_fcntl_dupfd(), except it implies minfd is 3.

Parameters
[in]oldfdFile descriptor to duplicate.
Return values
-1dup2(2) failed for some reason.
otherwiseAn allocated new file descriptor.
Note
This function does not raise.

Definition at line 367 of file io.c.

◆ rb_cloexec_dup2()

int rb_cloexec_dup2 ( int  oldfd,
int  newfd 
)

Identical to rb_cloexec_dup(), except you can specify the destination file descriptor.

If the destination is already squatted by another file descriptor that gets silently closed without any warnings. (This is a spec requested by POSIX.)

Parameters
[in]oldfdFile descriptor to duplicate.
[in]newfdReturn value destination.
Return values
-1dup2(2) failed for some reason.
newfdAn allocated new file descriptor.
Postcondition
Whatever sat at newfd gets closed with no notifications.
In case return value is -1 newfd is untouched.
Note
This function does not raise.

Definition at line 374 of file io.c.

◆ rb_cloexec_fcntl_dupfd()

int rb_cloexec_fcntl_dupfd ( int  fd,
int  minfd 
)

Duplicates a file descriptor with closing on exec.

In case of POSIX environments, a child process inherits its parent's opened file descriptors. Which is nowadays considered as one of the UNIX mistakes. This function duplicates a file descriptor as dup(2) does, but additionally instructs the operating system that we don't want the duplicated FD be seen from child processes.

Parameters
[in]fdFile descriptor to duplicate.
[in]minfdMinimum allowed FD to return.
Return values
-1dup(2) failed for some reason.
otherwiseAn allocated new file descriptor.
Note
This function does not raise.

minfd is handy when for instance STDERR is closed but you don't want to use fd 2.

Definition at line 461 of file io.c.

Referenced by rb_cloexec_dup().

◆ rb_cloexec_open()

int rb_cloexec_open ( const char *  pathname,
int  flags,
mode_t  mode 
)

Opens a file that closes on exec.

In case of POSIX environments, a child process inherits its parent's opened file descriptors. Which is nowadays considered as one of the UNIX mistakes. This function opens a file descriptor as open(2) does, but additionally instructs the operating system that we don't want it be seen from child processes.

Parameters
[in]pathnameFile path to open.
[in]flagsOpen mode, as in open(2).
[in]modeFile mode, in case of O_CREAT.
Return values
-1open(2) failed for some reason.
otherwiseAn allocated new file descriptor.
Note
This function does not raise.

Definition at line 328 of file io.c.

◆ rb_cloexec_pipe()

int rb_cloexec_pipe ( int  fildes[2])

Opens a pipe with closing on exec.

In case of POSIX environments, a child process inherits its parent's opened file descriptors. Which is nowadays considered as one of the UNIX mistakes. This function opens a pipe as pipe(2) does, but additionally instructs the operating system that we don't want the duplicated FDs be seen from child processes.

Parameters
[out]fildesReturn buffer. Must at least hold 2 elements.
Return values
0Successful creation of a pipe.
-1Failure in underlying system call(s).
Postcondition
pipes is filled with file descriptors.
errno is set on failure.

Definition at line 427 of file io.c.

Referenced by rb_pipe().

◆ rb_close_before_exec()

void rb_close_before_exec ( int  lowfd,
int  maxhint,
VALUE  noclose_fds 
)

Closes everything.

In case of POSIX environments, a child process inherits its parent's opened file descriptors. Which is nowadays considered as one of the UNIX mistakes. This function closes such inherited file descriptors. When your C extension needs to have a child process, don't forget to call this from your child process right before exec.

Parameters
[in]lowfdLower bound of FDs (you want STDIN to remain, no?).
[in]maxhintHint of max FDs.
[in]noclose_fdsA hash, whose keys are an allowlist.

◆ rb_fd_fix_cloexec()

void rb_fd_fix_cloexec ( int  fd)

Sets or clears the close-on-exec flag of the passed file descriptor to the desired state.

STDIN, STDOUT, STDERR are the exceptional file descriptors that shall remain open. All others are to be closed on exec. When a C extension library opens a file descriptor using anything other than rb_cloexec_open() etc., that file descriptor shall experience this function.

Parameters
[in]fdAn open file descriptor.

Definition at line 298 of file io.c.

◆ rb_file_open()

VALUE rb_file_open ( const char *  fname,
const char *  fmode 
)

Opens a file located at the given path.

fmode is a C string that represents the open mode. It can be one of:

  • r (means O_RDONLY),
  • w (means O_WRONLY | O_TRUNC | O_CREAT),
  • a (means O_WRONLY | O_APPEND | O_CREAT),

Followed by zero or more combinations of:

  • b (means _O_BINARY),
  • t (means _O_TEXT),
  • + (means O_RDWR),
  • x (means O_TRUNC), or
  • :[BOM|]enc[:enc] (see below).

This last one specifies external (and internal if any) encodings, respectively. If optional BOM| is specified and the specified external encoding is capable of expressing BOMs, opening file's contents' byte order is auto-detected using the mechanism.

So for instance, fmode of "rt|BOM:utf-16le:utf-8" specifies that...

  • the physical representation of the contents of the file is in UTF-16;
  • honours its BOM but assumes little endian if absent;
  • opens the file for reading;
  • what is read is converted into UTF-8;
  • with newlines cannibalised to \n.
Parameters
[in]fnamePath to open.
[in]fmodeMode specifier much like fopen(3).
Exceptions
rb_eArgErrorfmode contradicted (e.g. "bt").
rb_eSystemCallErroropen(2) failed for some reason.
Returns
An instance of rb_cIO.

Definition at line 7233 of file io.c.

◆ rb_file_open_str()

VALUE rb_file_open_str ( VALUE  fname,
const char *  fmode 
)

Identical to rb_file_open(), except it takes the pathname as a Ruby's string instead of C's.

In case the passed Ruby object is a non-String it tries to call #to_path.

Parameters
[in]fnamePath to open.
[in]fmodeMode specifier much like fopen(3).
Exceptions
rb_eTypeErrorfname is not a String.
rb_eEncCompatErrorfname is not ASCII-compatible.
rb_eArgErrorfmode contradicted (e.g. "bt").
rb_eSystemCallErroropen(2) failed for some reason.
Returns
An instance of rb_cIO.

Definition at line 7226 of file io.c.

◆ rb_gets()

VALUE rb_gets ( void  )

Much like rb_io_gets(), but it reads from the mysterious ARGF object.

ARGF in this context can be seen as a virtual IO which concatenates contents of the files passed to the process via the ARGV, or just STDIN if there are no such files.

Unlike rb_io_gets() this function sets $_.

Exceptions
rb_eFrozenErrorARGF resorts to STDIN but it is frozen.
Return values
RUBY_QnilARGF is at EOF.
otherwiseAn instance of rb_cString.
Postcondition
ARGF is read.
$_ is set.

Definition at line 10364 of file io.c.

◆ rb_io_addstr()

VALUE rb_io_addstr ( VALUE  io,
VALUE  str 
)

Identical to rb_io_write(), except it always returns the passed IO.

Parameters
[out]ioAn IO, opened for writing.
[in]strA String-like object to write to io.
Exceptions
rb_eIOErrorio isn't opened for writing.
rb_eFrozenErrorio is frozen.
rb_eTypeErrorNo conversion from str to String.
rb_eSystemCallErrorwrite(2) failed.
Returns
The passed io.
Postcondition
str is written to io.
Note
This function blocks.

Definition at line 2342 of file io.c.

◆ rb_io_ascii8bit_binmode()

VALUE rb_io_ascii8bit_binmode ( VALUE  io)

Forces no conversions be applied to the passed IO.

Unlike rb_io_binmode(), this cancels any newline conversions as well as encoding conversions. Any texts read/written through the IO will be the verbatim binary contents.

Parameters
[out]ioTarget IO to modify.
Exceptions
rb_eFrozenErrorio is frozen.
Returns
The passed io.
Postcondition
io is in binmode. Both external/internal encoding are set to rb_ascii8bit_encoding().
Note
This is the implementation of IO#binmode.

Definition at line 6342 of file io.c.

◆ rb_io_binmode()

VALUE rb_io_binmode ( VALUE  io)

Sets the binmode.

This operation nullifies the effect of textmode (newline conversion from "\r\n" to "\n" or vice versa). Note that it doesn't stop character encodings conversions. For instance an IO created using:

File.open(
"/dev/urandom",
textmode: true,
external_encoding: Encoding::GB18030,
internal_encoding: Encoding::Windows_31J)

has both newline and character conversions. If you pass such IO to this function, only the textmode:true part is cancelled. Texts read through the IO would still be encoded in Windows-31J; texts written to the IO will be encoded in GB18030.

Parameters
[out]ioTarget IO to modify.
Exceptions
rb_eFrozenErrorio is frozen.
Returns
The passed io.
Postcondition
io is in binmode.
Note
There is no equivalent operation in Ruby. You can do this only in C.

Definition at line 6296 of file io.c.

◆ rb_io_close()

VALUE rb_io_close ( VALUE  io)

Closes the IO.

Any buffered contents are flushed to the operating system. Any future operations against the IO would raise rb_eIOError. In case the io was created using IO.popen, it also sets the $?.

Parameters
[out]ioTarget IO to close.
Returns
Always returns RUBY_Qnil.
Postcondition
$? is set in case IO is a pipe.
No operations are possible against io any further.
Note
This can block to flush the contents.
This can wake other threads up, especially those who are select()-ing the passed IO.
Multiple invocations of this function over the same IO again and again is not an error, since Ruby 2.3.

Definition at line 5716 of file io.c.

Referenced by rb_gets().

◆ rb_io_eof()

VALUE rb_io_eof ( VALUE  io)

Queries if the passed IO is at the end of file.

"The end of file" here mans that there are no more data to read. This function blocks until the read buffer is filled in, and if that operation reached the end of file, it still returns RUBY_Qfalse (because there are data yet in that buffer). It returns RUBY_Qtrue once after the buffer is cleared.

Parameters
[in,out]ioTarget io to query.
Exceptions
rb_eIOErrorio is not opened for reading.
rb_eFrozenErrorio is frozen.
Return values
RUBY_QfalseThere are things yet to be read.
RUBY_Qtrue"The end of file" situation.

Definition at line 2687 of file io.c.

◆ rb_io_fdopen()

VALUE rb_io_fdopen ( int  fd,
int  flags,
const char *  path 
)

Creates an IO instance whose backend is the given file descriptor.

C extension libraries sometimes have file descriptors created elsewhere (maybe deep inside of another shared library), which they want ruby programs to handle. This function is handy for such situations.

Parameters
[in]fdTarget file descriptor.
[in]flagsFlags, e.g. O_CREAT|O_EXCL
[in]pathThe path of the file that backs fd, for diagnostics.
Returns
An allocated instance of rb_cIO with the autoclose flag set.
Note
Leave path NULL if you don't know.

Definition at line 9295 of file io.c.

◆ rb_io_flush()

VALUE rb_io_flush ( VALUE  io)

Flushes any buffered data within the passed IO to the underlying operating system.

Parameters
[out]ioTarget IO to flush.
Exceptions
rb_eIOErrorio is closed.
rb_eFrozenErrorio is frozen.
rb_eSystemCallErrorwrite(2) failed for some reason.
Returns
The passed io.
Postcondition
io's buffers are empty.
Note
This operation also discards the read buffer. Should basically be harmless, but in an esoteric situation like when user pushed something different from what was read using ungetc, this operation in fact changes the behaviour of the io.
Buffering is difficult. This operation flushes the data from our userspace to the kernel, but that doesn't always mean you can expect them stored persistently onto your hard drive.

Definition at line 2398 of file io.c.

Referenced by rb_io_getbyte().

◆ rb_io_getbyte()

VALUE rb_io_getbyte ( VALUE  io)

Reads a byte from the given IO.

Note
In Ruby a "byte" always means an 8 bit integer ranging from 0 to 255 inclusive.
Parameters
[in,out]ioAn IO, opened for reading.
Exceptions
rb_eIOErrorio is not opened for reading.
rb_eFrozenErrorio is frozen.
Return values
RUBY_Qnilio is at EOF.
otherwiseAn instance of rb_cInteger.
Postcondition
io is read.

Definition at line 5035 of file io.c.

◆ rb_io_gets()

VALUE rb_io_gets ( VALUE  io)

Reads a "line" from the given IO.

A line here means a chunk of characters which is terminated by either "\n" or an EOF.

Parameters
[in,out]ioAn IO, opened for reading.
Exceptions
rb_eIOErrorio isn't opened for reading.
rb_eFrozenErrorio is frozen.
Return values
RUBY_Qnilio is at EOF.
otherwiseAn instance of rb_cString.
Postcondition
io is read.
Note
Unlike IO#gets it doesn't set $_.
Unlike IO#gets it doesn't consider $/.

Definition at line 4260 of file io.c.

Referenced by rb_gets().

◆ rb_io_print()

VALUE rb_io_print ( int  argc,
const VALUE argv,
VALUE  io 
)

Iterates over the passed array to apply rb_io_write() individually.

If there is $,, this function inserts the string in middle of each iterations. If there is $\, this function appends the string at the end. If the array is empty, this function outputs $_.

Parameters
[in]argcNumber of objects of argv.
[in]argvAn array of strings to display.
[out]ioAn IO, opened for writing.
Exceptions
rb_eIOErrorio isn't opened for writing.
rb_eFrozenErrorio is frozen.
rb_eTypeErrorNo conversion from str to String.
rb_eSystemCallErrorwrite(2) failed.
Returns
Always returns RUBY_Qnil.
Postcondition
argv is written to io.
Note
This function blocks.
This function calls rb_io_write() multiple times. Which means, it is not an atomic operation. Outputs from multiple threads can interleave.

Definition at line 8690 of file io.c.

◆ rb_io_printf()

VALUE rb_io_printf ( int  argc,
const VALUE argv,
VALUE  io 
)

This is a rb_f_sprintf() + rb_io_write() combo.

Parameters
[in]argcNumber of objects of argv.
[in]argvA format string followed by its arguments.
[out]ioAn IO, opened for writing.
Exceptions
rb_eIOErrorio isn't opened for writing.
rb_eFrozenErrorio is frozen.
rb_eTypeErrorNo conversion from str to String.
rb_eSystemCallErrorwrite(2) failed.
Returns
Always returns RUBY_Qnil.
Postcondition
argv is formatted, then written to io.
Note
This function blocks.

Definition at line 8564 of file io.c.

◆ rb_io_puts()

VALUE rb_io_puts ( int  argc,
const VALUE argv,
VALUE  io 
)

Iterates over the passed array to apply rb_io_write() individually.

Unlike rb_io_print(), this function prints a newline per each element. It also flattens the passed array (OTOH rb_io_print() just resorts to rb_ary_to_s()).

Parameters
[in]argcNumber of objects of argv.
[in]argvAn array of strings to display.
[out]ioAn IO, opened for writing.
Exceptions
rb_eIOErrorio isn't opened for writing.
rb_eFrozenErrorio is frozen.
rb_eTypeErrorNo conversion from str to String.
rb_eSystemCallErrorwrite(2) failed.
Returns
Always returns RUBY_Qnil.
Postcondition
argv is written to io.
Note
This function blocks.
This function calls rb_io_write() multiple times. Which means, it is not an atomic operation. Outputs from multiple threads can interleave.

Definition at line 8922 of file io.c.

Referenced by rb_f_abort().

◆ rb_io_ungetbyte()

VALUE rb_io_ungetbyte ( VALUE  io,
VALUE  b 
)

Identical to rb_io_ungetc(), except it doesn't take the encoding of the passed IO into account.

When an integer is passed, it just casts that value to C's unsigned char, and pushes that back.

Parameters
[out]ioAn IO, opened for reading.
[in]bEither a String, or an Integer.
Exceptions
rb_eIOErrorio is not opened for reading.
rb_eFrozenErrorio is frozen.
rb_eTypeErrorNo conversion from b to rb_cString.
Returns
Always returns RUBY_Qnil.

Definition at line 5129 of file io.c.

◆ rb_io_ungetc()

VALUE rb_io_ungetc ( VALUE  io,
VALUE  c 
)

"Unget"s a string.

This function pushes back the passed string onto the passed IO, such that a subsequent buffered read will return it. If the passed content is in fact an integer, a single character string of that codepoint of the encoding of the IO will be pushed back instead.

It might be counter-intuitive but this function can push back multiple characters at once. Also this function can be called multiple times on a same IO. Also a "character" can be wider than a byte, depending on the encoding of the IO.

Parameters
[out]ioAn IO, opened for reading.
[in]cEither a String, or an Integer.
Exceptions
rb_eIOErrorio is not opened for reading.
rb_eFrozenErrorio is frozen.
rb_eTypeErrorNo conversion from c to rb_cString.
Returns
Always returns RUBY_Qnil.

Definition at line 5193 of file io.c.

◆ rb_io_write()

VALUE rb_io_write ( VALUE  io,
VALUE  str 
)

Writes the given string to the given IO.

Parameters
[out]ioAn IO, opened for writing.
[in]strA String-like object to write to io.
Exceptions
rb_eIOErrorio isn't opened for writing.
rb_eFrozenErrorio is frozen.
rb_eTypeErrorNo conversion from str to String.
rb_eSystemCallErrorwrite(2) failed for some reason.
Returns
The number of bytes written to the io.
Postcondition
str (up to the length of return value) is written to io.
Note
This function blocks.
Partial write is a thing. It must be at least questionable not to check the return value.

Definition at line 2294 of file io.c.

Referenced by rb_io_addstr(), rb_io_print(), rb_io_printf(), rb_io_puts(), and rb_write_error2().

◆ rb_pipe()

int rb_pipe ( int *  pipes)

This is an rb_cloexec_pipe() + rb_update_max_fd() combo.

Parameters
[out]pipesReturn buffer. Must at least hold 2 elements.
Return values
0Successful creation of a pipe.
-1Failure in underlying system call(s).
Postcondition
pipes is filled with file descriptors.
errno is set on failure.

Definition at line 7343 of file io.c.

◆ rb_reserved_fd_p()

int rb_reserved_fd_p ( int  fd)

Queries if the given FD is reserved or not.

Occasionally Ruby interpreter opens files for its own purposes. Use this function to prevent touching such behind-the-scene descriptors.

Parameters
[in]fdTarget file descriptor.
Return values
1fd is reserved.
0Otherwise.

◆ rb_update_max_fd()

void rb_update_max_fd ( int  fd)

Informs the interpreter that the passed fd can be the max.

This information is used from rb_close_before_exec().

Parameters
[in]fdAn open FD, which can be large.

Definition at line 248 of file io.c.

Referenced by rb_fd_fix_cloexec(), rb_io_open_descriptor(), and rb_pipe().

◆ rb_write_error()

void rb_write_error ( const char *  str)

Writes the given error message to somewhere applicable.

On Windows it goes to the console. On POSIX environments it goes to the standard error.

Warning
IT IS A BAD IDEA to use this function form your C extensions. It is often annoying when GUI applications write to consoles; users don't want to look at there. Programmers also want to control the cause of the message itself, like by rescuing an exception. Just let ruby handle errors. That must be better than going your own way.
Parameters
[in]strError message to display.
Postcondition
str is written to somewhere.

Definition at line 9119 of file io.c.

◆ rb_write_error2()

void rb_write_error2 ( const char *  str,
long  len 
)

Identical to rb_write_error(), except it additionally takes the message's length.

Necessary when you want to handle wide characters.

Parameters
[in]strError message to display.
[in]lenLength of str, in bytes.
Postcondition
str is written to somewhere.

Definition at line 9099 of file io.c.

Referenced by rb_write_error().

Variable Documentation

◆ rb_default_rs

VALUE rb_default_rs
extern

This is the default value of rb_rs, i.e.

"\n". It seems it has always been just a newline string since the beginning. Not sure why C codes has to use this, given there is no way for ruby programs to interface.

Also it has not been deprecated for unknown reasons.

Definition at line 207 of file io.c.

Referenced by rb_gets(), rb_io_gets(), and rb_io_puts().

◆ rb_fs

VALUE rb_fs
extern

The field separator character for inputs, or the $;.

This affects how String#split works. You can set this via the -F command line option. You can also assign arbitrary ruby objects programmatically, but it makes best sense for you to assign a regular expression here.

Definition at line 649 of file string.c.

◆ rb_output_fs

VALUE rb_output_fs
extern

The field separator character for outputs, or the $,.

This affects how Array#join works.

Deprecated:
Assigning anything other than RUBY_Qnil to this variable is deprecated.

Definition at line 204 of file io.c.

Referenced by rb_io_print().

◆ rb_output_rs

VALUE rb_output_rs
extern

The record separator character for outputs, or the $\.

This affects how IO#print works.

Deprecated:
Assigning anything other than RUBY_Qnil to this variable is deprecated.

Definition at line 206 of file io.c.

Referenced by rb_io_print().

◆ rb_rs

VALUE rb_rs
extern

The record separator character for inputs, or the $/.

This affects how IO#gets works. You can set this via the -0 command line option.

Deprecated:
Assigning anything other than RUBY_Qnil to this variable is deprecated.

Definition at line 205 of file io.c.

Referenced by rb_gets().