FOPEN(3) | Library Functions Manual | FOPEN(3) |
FILE *
fopen(const char * restrict path, const char * restrict mode);
FILE *
fdopen(int fildes, const char *mode);
FILE *
freopen(const char * restrict path, const char * restrict mode, FILE * restrict stream);
The argument mode points to a string beginning with one of the following sequences (Additional characters may follow these sequences.):
r
”r+
”w
”w+
”a
”a+
”Additionally:
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(2) value.
Opening a file with append mode causes all subsequent writes to it to be forced to the then current end of file, regardless of intervening repositioning of the stream.
The fopen() and freopen() functions initially position the stream at the start of the file unless the file is opened with append mode, in which case the stream is initially positioned at the end of the 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. The stream is positioned at the file offset of the file descriptor.
The freopen() function opens the file whose name is the string pointed to by path 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. The primary use of the freopen() function is to change the file associated with a standard text stream (stderr, stdin, or stdout).
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).
FILE *file; int fd; if ((file = fdopen(fd, "r")) != NULL) { /* perform operations on the FILE * */ fclose(file); } else { /* failure, report the error */ close(fd); }
November 14, 2012 | NetBSD 6.1 |