fdopen(3c) [opensolaris man page]
fdopen(3C) Standard C Library Functions fdopen(3C) NAME
fdopen - associate a stream with a file descriptor SYNOPSIS
#include <stdio.h> FILE *fdopen(int fildes, const char *mode); DESCRIPTION
The fdopen() function associates a stream with a file descriptor fildes. The mode argument is a character string having one of the following values: r or rb Open a file for reading. w or wb Open a file for writing. a or ab Open a file for writing at end of file. r+, rb+ or r+b Open a file for update (reading and writing). w+, wb+ or w+b Open a file for update (reading and writing). a+, ab+ or a+b Open a file for update (reading and writing) at end of file. The meaning of these flags is exactly as specified for the fopen(3C) function, except that modes beginning with w do not cause truncation of the file. A trailing F character can also be included in the mode argument as described in fopen(3C) to enable extended FILE facility. The mode of the stream must be allowed by the file access mode of the open file. The file position indicator associated with the new stream is set to the position indicated by the file offset associated with the file descriptor. The fdopen() function preserves the offset maximum previously set for the open file description corresponding to fildes. The error and end-of-file indicators for the stream are cleared. The fdopen() function may cause the st_atime field of the underlying file to be marked for update. If fildes refers to a shared memory object, the result of the fdopen() function is unspecified. RETURN VALUES
Upon successful completion, fdopen() returns a pointer to a stream. Otherwise, a null pointer is returned and errno is set to indicate the error. The fdopen() function may fail and not set errno if there are no free stdio streams. ERRORS
The fdopen() function may fail if: EBADF The fildes argument is not a valid file descriptor. EINVAL The mode argument is not a valid mode. EMFILE {FOPEN_MAX} streams are currently open in the calling process. {STREAM_MAX} streams are currently open in the calling process. ENOMEM There is insufficient space to allocate a buffer. USAGE
A process is allowed to have at least {FOPEN_MAX} stdio streams open at a time. For 32-bit applications, however, the underlying ABIs for- merly required that no file descriptor used to access the file underlying a stdio stream have a value greater than 255. To maintain binary compatibility with earlier Solaris releases, this limit still constrains 32-bit applications. File descriptors are obtained from calls like open(2), dup(2), creat(2) or pipe(2), which open files but do not return streams. Streams are necessary input for almost all of the standard I/O library functions. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |See below. | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ The F character in the mode argument is Evolving. In all other respects this function is Standard. SEE ALSO
creat(2), dup(2), open(2), pipe(2), fclose(3C), fopen(3C), attributes(5), standards(5) SunOS 5.11 18 Apr 2006 fdopen(3C)
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FOPEN(3) BSD Library Functions Manual FOPEN(3) NAME
fdopen, fopen, freopen -- stream open functions LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <stdio.h> FILE * fdopen(int fildes, const char *mode); FILE * fopen(const char *restrict filename, const char *restrict mode); FILE * freopen(const char *restrict filename, const char *restrict mode, FILE *restrict stream); DESCRIPTION
The fopen() function opens the file whose name is the string pointed to by filename and associates a stream with it. The argument mode points to a string beginning with one of the following sequences (Additional characters may follow these sequences.): ``r'' Open text file for reading. The stream is positioned at the beginning of the file. ``r+'' Open for reading and writing. The stream is positioned at the beginning of the file. ``w'' Truncate file to zero length or create text file for writing. The stream is positioned at the beginning of the file. ``w+'' Open for reading and writing. The file is created if it does not exist, otherwise it is truncated. The stream is positioned at the beginning of the file. ``a'' Open for writing. The file is created if it does not exist. The stream is positioned at the end of the file. Subsequent writes to the file will always end up at the then current end of file, irrespective of any intervening fseek(3) or similar. ``a+'' Open for reading and writing. The file is created if it does not exist. The stream is positioned at the end of the file. Subse- quent writes to the file will always end up at the then current end of file, irrespective of any intervening fseek(3) or similar. The mode string can also include the letter ``b'' either as a third character or as a character between the characters in any of the two- character strings described above. This is strictly for compatibility with ISO/IEC 9899:1990 (``ISO C90'') and has no effect; the ``b'' is ignored. Finally, as an extension to the standards (and thus may not be portable), mode string may end with the letter ``x'', which insists on creat- ing a new file when used with ``w'' or ``a''. If path exists, then an error is returned (this is the equivalent of specifying O_EXCL with open(2)). Any created files will have mode "S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH" (0666), as modified by the process' umask value (see umask(2)). Reads and writes may be intermixed on read/write streams in any order, and do not require an intermediate seek as in previous versions of stdio. This is not portable to other systems, however; ANSI C requires that a file positioning function intervene between output and input, unless an input operation encounters end-of-file. The fdopen() function associates a stream with the existing file descriptor, fildes. The mode of the stream must be compatible with the mode of the file descriptor. When the stream is closed via fclose(3), fildes is closed also. The freopen() function opens the file whose name is the string pointed to by filename and associates the stream pointed to by stream with it. The original stream (if it exists) is closed. The mode argument is used just as in the fopen() function. If the filename argument is NULL, freopen() attempts to re-open the file associated with stream with a new mode. The new mode must be com- patible with the mode that the stream was originally opened with: o Streams originally opened with mode ``r'' can only be reopened with that same mode. o Streams originally opened with mode ``a'' can be reopened with the same mode, or mode ``w''. o Streams originally opened with mode ``w'' can be reopened with the same mode, or mode ``a''. o Streams originally opened with mode ``r+'', ``w+'', or ``a+'' can be reopened with any mode. The primary use of the freopen() function is to change the file associated with a standard text stream (stderr, stdin, or stdout). RETURN VALUES
Upon successful completion fopen(), fdopen(), and freopen() return a FILE pointer. Otherwise, NULL is returned and the global variable errno is set to indicate the error. ERRORS
[EINVAL] The mode argument to fopen(), fdopen(), or freopen() was invalid. The fopen(), fdopen() and freopen() functions may also fail and set errno for any of the errors specified for the routine malloc(3). The fopen() function may also fail and set errno for any of the errors specified for the routine open(2). The fdopen() function may also fail and set errno for any of the errors specified for the routine fcntl(2). The freopen() function may also fail and set errno for any of the errors specified for the routines open(2), fclose(3) and fflush(3). SEE ALSO
open(2), fclose(3), fileno(3), fseek(3), funopen(3) STANDARDS
The fopen() and freopen() functions conform to ISO/IEC 9899:1990 (``ISO C90''). The fdopen() function conforms to IEEE Std 1003.1-1988 (``POSIX.1''). BSD
January 26, 2003 BSD