The fmemopen implementation does not account the file position correctly in
append mode. The following example shows the failure:
===
int main ()
{
char buf[10] = "test";
FILE *fp = fmemopen (buf, 10, "a+");
fseek (fp, 0, SEEK_SET);
int gr;
if ((gr = getc (fp)) != 't' ||
(gr = getc (fp)) != 'e' ||
(gr = getc (fp)) != 's' ||
(gr = getc (fp)) != 't' ||
(gr = getc (fp)) != EOF)
{
printf ("%s: getc failed returned %i\n", __FUNCTION__, gr);
return 1;
}
return 0;
}
===
This is due both how read and write operation update the buffer position,
taking in consideration buffer lenght instead of maximum position defined
by the open mode. This patch fixes it and also fixes fseek not returning
EINVAL for invalid whence modes.
Tested on x86_64 and i686.
[BZ #20012]
* libio/fmemopen.c (fmemopen_read): Use buffer maximum position, not
length to calculate the buffer to read.
(fmemopen_write): Set the buffer position based on bytes written.
(fmemopen_seek): Return EINVAL for invalid whence modes.
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.
Joseph Myers
Adhemerval Zanella
Adhemerval Zanella