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authorAdhemerval Zanella <azanella@linux.vnet.ibm.com>2014-06-09 16:19:25 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.com>2015-07-08 12:07:21 -0300
commitfdb7d390dd0d96e4a8239c46f3aa64598b90842b (patch)
treeadab2a28bad088043828d25b5c6bf83a5612fba7 /libio/fmemopen.c
parent1c1e3125206ef810dc7282023f6267a33b486233 (diff)
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libio: fmemopen rewrite to POSIX compliance
This patch added a new fmemopen version, for glibc 2.22, that aims to be POSIX complaint. It fixes some long-stading glibc fmemopen issues, such as: * it changes the way fseek with SEEK_END works on fmemopen to seek relative to buffer size instead of first '\0'. This is default mode and 'b' opening mode does not change internal behavior (bz#6544). * fix apending opening mode to use as start position either first null byte of len specified in function call (bz#13152 and #13151). * remove binary option 'b' and internal different handling (bz#12836) * fix seek/SEE_END with negative values (bz#14292). A compatibility symbol is provided to with old behavior for older symbols version (2.2.5). * include/stdio.h (fmemopen): Remove hidden prototype. (__fmemopen): Add new hidden prototype. * libio/Makefile: Add oldfmemopen object. * libio/Versions [GLIBC_2.22]: Add new fmemopen symbol. * libio/fmemopen.c (__fmemopen): Function rewrite to be POSIX compliance. * libio/oldfmemopen.c: New file: old fmemopen implementation for symbol compatibility. * stdio-common/Makefile [tests]: Add new tst-fmemopen3. * stdio-common/psiginfo.c [psiginfo]: Call __fmemopen instead of fmemopen. * stdio-common/tst-fmemopen3.c: New file: more fmemopen tests, focus on append and read mode. * sysdeps/unix/sysv/linux/aarch64/libc.abilist [GLIBC_2.22]: Add fmemopen. * sysdeps/unix/sysv/linux/alpha/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/arm/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/i386/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/ia64/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/microblaze/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/sh/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/x86_64/64/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/hppa/libc.abilist [GLIBC_2.22]: Likewise. * sysdeps/unix/sysv/linux/nios2/libc.abilist [GLIBC_2.22]: Likewise.
Diffstat (limited to 'libio/fmemopen.c')
-rw-r--r--libio/fmemopen.c140
1 files changed, 47 insertions, 93 deletions
diff --git a/libio/fmemopen.c b/libio/fmemopen.c
index 06e5ab8002..e6e6a49f76 100644
--- a/libio/fmemopen.c
+++ b/libio/fmemopen.c
@@ -1,7 +1,6 @@
-/* Fmemopen implementation.
- Copyright (C) 2000-2015 Free Software Foundation, Inc.
+/* fmemopen implementation.
+ Copyright (C) 2015 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
@@ -17,54 +16,10 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-/*
- * 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.)
- */
+/* 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>
@@ -79,25 +34,23 @@
typedef struct fmemopen_cookie_struct fmemopen_cookie_t;
struct fmemopen_cookie_struct
{
- char *buffer;
- int mybuffer;
- int binmode;
- 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;
}
@@ -115,29 +68,28 @@ fmemopen_read (void *cookie, char *b, size_t s)
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 = c->binmode == 0 && (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)
{
__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';
}
@@ -150,9 +102,7 @@ static int
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)
{
@@ -165,7 +115,7 @@ fmemopen_seek (void *cookie, _IO_off64_t *p, int w)
break;
case SEEK_END:
- np = (c->binmode ? c->size : c->maxpos) - *p;
+ np = c->maxpos + *p;
break;
default:
@@ -184,9 +134,7 @@ fmemopen_seek (void *cookie, _IO_off64_t *p, int w)
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);
@@ -197,18 +145,11 @@ fmemopen_close (void *cookie)
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;
- if (__glibc_unlikely (len == 0))
- {
- einval:
- __set_errno (EINVAL);
- return NULL;
- }
-
c = (fmemopen_cookie_t *) malloc (sizeof (fmemopen_cookie_t));
if (c == NULL)
return NULL;
@@ -231,26 +172,38 @@ fmemopen (void *buf, size_t len, const char *mode)
if (__glibc_unlikely ((uintptr_t) len > -(uintptr_t) buf))
{
free (c);
- goto einval;
+ __set_errno (EINVAL);
+ return NULL;
}
c->buffer = buf;
- if (mode[0] == 'w')
+ /* POSIX states that w+ mode should truncate the buffer. */
+ if (mode[0] == 'w' && mode[1] == '+')
c->buffer[0] = '\0';
c->maxpos = strnlen (c->buffer, len);
}
+
+ /* 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->size = len;
- if (mode[0] == 'a')
+ if (mode[0] == 'r')
+ c->maxpos = len;
+
+ c->append = mode[0] == 'a';
+ if (c->append)
c->pos = c->maxpos;
else
c->pos = 0;
- c->binmode = mode[0] != '\0' && mode[1] == 'b';
-
iof.read = fmemopen_read;
iof.write = fmemopen_write;
iof.seek = fmemopen_seek;
@@ -258,4 +211,5 @@ fmemopen (void *buf, size_t len, const char *mode)
return _IO_fopencookie (c, mode, iof);
}
-libc_hidden_def (fmemopen)
+libc_hidden_def (__fmemopen)
+versioned_symbol (libc, __fmemopen, fmemopen, GLIBC_2_22);