-/* Fmemopen implementation.
- Copyright (C) 2000, 2002, 2005, 2006 Free Software Foundation, Inc.
+/* fmemopen implementation.
+ Copyright (C) 2015-2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
- Contributed by Hanno Mueller, kontakt@hanno.de, 2000.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
- 02111-1307 USA. */
-
-/*
- * fmemopen() - "my" version of a string stream
- * Hanno Mueller, kontakt@hanno.de
- *
- *
- * I needed fmemopen() for an application that I currently work on,
- * but couldn't find it in libio. The following snippet of code is an
- * attempt to implement what glibc's documentation describes.
- *
- *
- *
- * I already see some potential problems:
- *
- * - I never used the "original" fmemopen(). I am sure that "my"
- * fmemopen() behaves differently than the original version.
- *
- * - The documentation doesn't say wether a string stream allows
- * seeks. I checked the old fmemopen implementation in glibc's stdio
- * directory, wasn't quite able to see what is going on in that
- * source, but as far as I understand there was no seek there. For
- * my application, I needed fseek() and ftell(), so it's here.
- *
- * - "append" mode and fseek(p, SEEK_END) have two different ideas
- * about the "end" of the stream.
- *
- * As described in the documentation, when opening the file in
- * "append" mode, the position pointer will be set to the first null
- * character of the string buffer (yet the buffer may already
- * contain more data). For fseek(), the last byte of the buffer is
- * used as the end of the stream.
- *
- * - It is unclear to me what the documentation tries to say when it
- * explains what happens when you use fmemopen with a NULL
- * buffer.
- *
- * Quote: "fmemopen [then] allocates an array SIZE bytes long. This
- * is really only useful if you are going to write things to the
- * buffer and then read them back in again."
- *
- * What does that mean if the original fmemopen() did not allow
- * seeking? How do you read what you just wrote without seeking back
- * to the beginning of the stream?
- *
- * - I think there should be a second version of fmemopen() that does
- * not add null characters for each write. (At least in my
- * application, I am not actually using strings but binary data and
- * so I don't need the stream to add null characters on its own.)
- */
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* fmemopen() from 2.22 and forward works as defined by POSIX. It also
+ provides an older symbol, version 2.2.5, that behaves different regarding
+ SEEK_END (libio/oldfmemopen.c). */
+
#include <errno.h>
#include <libio.h>
typedef struct fmemopen_cookie_struct fmemopen_cookie_t;
struct fmemopen_cookie_struct
{
- char *buffer;
- int mybuffer;
- size_t size;
- _IO_off64_t pos;
- size_t maxpos;
+ char *buffer; /* memory buffer. */
+ int mybuffer; /* allocated my buffer? */
+ int append; /* buffer open for append? */
+ size_t size; /* buffer length in bytes. */
+ _IO_off64_t pos; /* current position at the buffer. */
+ size_t maxpos; /* max position in buffer. */
};
static ssize_t
fmemopen_read (void *cookie, char *b, size_t s)
{
- fmemopen_cookie_t *c;
-
- c = (fmemopen_cookie_t *) cookie;
+ fmemopen_cookie_t *c = (fmemopen_cookie_t *) cookie;
- if (c->pos + s > c->size)
+ if (c->pos + s > c->maxpos)
{
- if ((size_t) c->pos == c->size)
+ if ((size_t) c->pos == c->maxpos)
return 0;
s = c->size - c->pos;
}
static ssize_t
fmemopen_write (void *cookie, const char *b, size_t s)
{
- fmemopen_cookie_t *c;
+ fmemopen_cookie_t *c = (fmemopen_cookie_t *) cookie;;
+ _IO_off64_t pos = c->append ? c->maxpos : c->pos;
int addnullc;
- c = (fmemopen_cookie_t *) cookie;
-
- addnullc = s == 0 || b[s - 1] != '\0';
+ addnullc = (s == 0 || b[s - 1] != '\0');
- if (c->pos + s + addnullc > c->size)
+ if (pos + s + addnullc > c->size)
{
- if ((size_t) (c->pos + addnullc) == c->size)
+ if ((size_t) (c->pos + addnullc) >= c->size)
{
__set_errno (ENOSPC);
return 0;
}
- s = c->size - c->pos - addnullc;
+ s = c->size - pos - addnullc;
}
- memcpy (&(c->buffer[c->pos]), b, s);
+ memcpy (&(c->buffer[pos]), b, s);
- c->pos += s;
- if ((size_t) c->pos > c->maxpos)
+ pos += s;
+ if ((size_t) pos > c->maxpos)
{
- c->maxpos = c->pos;
+ c->maxpos = pos;
if (addnullc)
c->buffer[c->maxpos] = '\0';
}
fmemopen_seek (void *cookie, _IO_off64_t *p, int w)
{
_IO_off64_t np;
- fmemopen_cookie_t *c;
-
- c = (fmemopen_cookie_t *) cookie;
+ fmemopen_cookie_t *c = (fmemopen_cookie_t *) cookie;
switch (w)
{
break;
case SEEK_END:
- np = c->maxpos - *p;
+ np = c->maxpos + *p;
break;
default:
static int
fmemopen_close (void *cookie)
{
- fmemopen_cookie_t *c;
-
- c = (fmemopen_cookie_t *) cookie;
+ fmemopen_cookie_t *c = (fmemopen_cookie_t *) cookie;
if (c->mybuffer)
free (c->buffer);
FILE *
-fmemopen (void *buf, size_t len, const char *mode)
+__fmemopen (void *buf, size_t len, const char *mode)
{
cookie_io_functions_t iof;
fmemopen_cookie_t *c;
+ FILE *result;
- if (__builtin_expect (len == 0, 0))
- {
- einval:
- __set_errno (EINVAL);
- return NULL;
- }
-
- c = (fmemopen_cookie_t *) malloc (sizeof (fmemopen_cookie_t));
+ c = (fmemopen_cookie_t *) calloc (sizeof (fmemopen_cookie_t), 1);
if (c == NULL)
return NULL;
}
else
{
- if (__builtin_expect ((uintptr_t) len > -(uintptr_t) buf, 0))
+ if (__glibc_unlikely ((uintptr_t) len > -(uintptr_t) buf))
{
free (c);
- goto einval;
+ __set_errno (EINVAL);
+ return NULL;
}
c->buffer = buf;
+
+ /* POSIX states that w+ mode should truncate the buffer. */
+ if (mode[0] == 'w' && mode[1] == '+')
+ c->buffer[0] = '\0';
+
+ if (mode[0] == 'a')
+ c->maxpos = strnlen (c->buffer, len);
}
- c->size = len;
- if (mode[0] == 'w')
- c->buffer[0] = '\0';
+ /* Mode | starting position (cookie::pos) | size (cookie::size)
+ ------ |----------------------------------|-----------------------------
+ read | beginning of the buffer | size argument
+ write | beginning of the buffer | zero
+ append | first null or size buffer + 1 | first null or size argument
+ */
- c->maxpos = strlen (c->buffer);
+ c->size = len;
+
+ if (mode[0] == 'r')
+ c->maxpos = len;
- if (mode[0] == 'a')
+ c->append = mode[0] == 'a';
+ if (c->append)
c->pos = c->maxpos;
else
c->pos = 0;
iof.seek = fmemopen_seek;
iof.close = fmemopen_close;
- return _IO_fopencookie (c, mode, iof);
+ result = _IO_fopencookie (c, mode, iof);
+ if (__glibc_unlikely (result == NULL))
+ {
+ if (c->mybuffer)
+ free (c->buffer);
+
+ free (c);
+ }
+
+ return result;
}
+libc_hidden_def (__fmemopen)
+versioned_symbol (libc, __fmemopen, fmemopen, GLIBC_2_22);
projects / thirdparty / glibc.git / blobdiff