/* * freopen.c - open a file and associate a stream with it */ /* $Id$ */ #include #include #include #include #include "loc_incl.h" #define PMODE 0666 /* Do not "optimize" this file to use the open with O_CREAT if the file * does not exist. The reason is given in fopen.c. */ FILE * freopen(const char *name, const char *mode, FILE *stream) { register int i; int rwmode = 0, rwflags = 0; int fd, flags = stream->_flags & (_IONBF | _IOFBF | _IOLBF | _IOMYBUF); (void) fflush(stream); /* ignore errors */ (void) close(fileno(stream)); switch(*mode++) { case 'r': flags |= _IOREAD; rwmode = O_RDONLY; break; case 'w': flags |= _IOWRITE; rwmode = O_WRONLY; rwflags = O_CREAT | O_TRUNC; break; case 'a': flags |= _IOWRITE | _IOAPPEND; rwmode = O_WRONLY; rwflags |= O_APPEND | O_CREAT; break; default: return (FILE *)NULL; } while (*mode) { switch(*mode++) { case 'b': continue; case '+': rwmode = O_RDWR; flags |= _IOREAD | _IOWRITE; continue; /* The sequence may be followed by aditional characters */ default: break; } break; } if ((rwflags & O_TRUNC) || (((fd = open(name, rwmode)) < 0) && (rwflags & O_CREAT))) { if (((fd = creat(name, PMODE)) < 0) && flags | _IOREAD) { (void) close(fd); fd = open(name, rwmode); } } if (fd < 0) { for( i = 0; i < FOPEN_MAX; i++) { if (stream == __iotab[i]) { __iotab[i] = 0; break; } } if (stream != stdin && stream != stdout && stream != stderr) free((void *)stream); return (FILE *)NULL; } stream->_count = 0; stream->_fd = fd; stream->_flags = flags; return stream; }