/* * Allocate a file buffer, or switch to unbuffered I/O. * Per the ANSI C standard, ALL tty devices default to line buffered. * * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek * optimisation) right after the fstat() that finds the buffer size. */ void __smakebuf(FILE *fp) { void *p; int flags; size_t size; int couldbetty; if (fp->_flags & __SNBF) { fp->_bf._base = fp->_p = fp->_nbuf; fp->_bf._size = 1; return; } flags = __swhatbuf(fp, &size, &couldbetty); if ((p = malloc(size)) == NULL) { fp->_flags |= __SNBF; fp->_bf._base = fp->_p = fp->_nbuf; fp->_bf._size = 1; return; } __atexit_register_cleanup(_cleanup); flags |= __SMBF; fp->_bf._base = fp->_p = p; fp->_bf._size = size; if (couldbetty && isatty(fp->_file)) flags |= __SLBF; fp->_flags |= flags; }
/* * __sinit() is called whenever stdio's internal variables must be set up. */ void __sinit(void) { _THREAD_PRIVATE_MUTEX(__sinit_mutex); _THREAD_PRIVATE_MUTEX_LOCK(__sinit_mutex); if (__sdidinit) { /* bail out if caller lost the race */ _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex); return; } /* Initialize stdin/stdout/stderr (for the recursive mutex). http://b/18208568. */ for (size_t i = 0; i < 3; ++i) { _FILEEXT_SETUP(__sF+i, __sFext+i); } /* Initialize the pre-allocated (but initially unused) streams. */ for (size_t i = 0; i < FOPEN_MAX - 3; ++i) { _FILEEXT_SETUP(usual+i, usualext+i); } /* make sure we clean up on exit */ __atexit_register_cleanup(_cleanup); /* conservative */ __sdidinit = 1; _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex); }
/* * __sinit() is called whenever stdio's internal variables must be set up. */ void __sinit(void) { _THREAD_PRIVATE_MUTEX(__sinit_mutex); int i; _THREAD_PRIVATE_MUTEX_LOCK(__sinit_mutex); if (__sdidinit) goto out; /* bail out if caller lost the race */ for (i = 0; i < FOPEN_MAX - 3; i++) { _FILEEXT_SETUP(usual+i, usualext+i); } /* make sure we clean up on exit */ __atexit_register_cleanup(_cleanup); /* conservative */ __sdidinit = 1; out: _THREAD_PRIVATE_MUTEX_UNLOCK(__sinit_mutex); }
/* * Set one of the three kinds of buffering, optionally including * a buffer. */ int setvbuf(FILE *fp, char *buf, int mode, size_t size) { int ret, flags; size_t iosize; int ttyflag; /* * Verify arguments. The `int' limit on `size' is due to this * particular implementation. Note, buf and size are ignored * when setting _IONBF. */ if (mode != _IONBF) if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0) return (EOF); /* * Write current buffer, if any. Discard unread input (including * ungetc data), cancel line buffering, and free old buffer if * malloc()ed. We also clear any eof condition, as if this were * a seek. */ ret = 0; (void)__sflush(fp); if (HASUB(fp)) FREEUB(fp); WCIO_FREE(fp); fp->_r = fp->_lbfsize = 0; flags = fp->_flags; if (flags & __SMBF) free((void *)fp->_bf._base); flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF); /* If setting unbuffered mode, skip all the hard work. */ if (mode == _IONBF) goto nbf; /* * Find optimal I/O size for seek optimization. This also returns * a `tty flag' to suggest that we check isatty(fd), but we do not * care since our caller told us how to buffer. */ flags |= __swhatbuf(fp, &iosize, &ttyflag); if (size == 0) { buf = NULL; /* force local allocation */ size = iosize; } /* Allocate buffer if needed. */ if (buf == NULL) { if ((buf = malloc(size)) == NULL) { /* * Unable to honor user's request. We will return * failure, but try again with file system size. */ ret = EOF; if (size != iosize) { size = iosize; buf = malloc(size); } } if (buf == NULL) { /* No luck; switch to unbuffered I/O. */ nbf: fp->_flags = flags | __SNBF; fp->_w = 0; fp->_bf._base = fp->_p = fp->_nbuf; fp->_bf._size = 1; return (ret); } flags |= __SMBF; } /* * Kill any seek optimization if the buffer is not the * right size. * * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)? */ if (size != iosize) flags |= __SNPT; /* * Fix up the FILE fields, and set __cleanup for output flush on * exit (since we are buffered in some way). */ if (mode == _IOLBF) flags |= __SLBF; fp->_flags = flags; fp->_bf._base = fp->_p = (unsigned char *)buf; fp->_bf._size = size; /* fp->_lbfsize is still 0 */ if (flags & __SWR) { /* * Begin or continue writing: see __swsetup(). Note * that __SNBF is impossible (it was handled earlier). */ if (flags & __SLBF) { fp->_w = 0; fp->_lbfsize = -fp->_bf._size; } else fp->_w = size; } else { /* begin/continue reading, or stay in intermediate state */ fp->_w = 0; } __atexit_register_cleanup(_cleanup); return (ret); }