Presently, Valgrind (non-client) code that wants to use the stat

family of syscalls is impossible to write in a way that's portable and
correct.  On some targets (eg x86-linux) you need to do sys_stat64 and
receive the results in a 'struct vki_stat64'.  But on other targets
(eg amd64-linux) neither sys_stat64 nor 'struct vki_stat64' exist.

This commit adds a new type, 'struct vg_stat', which contains 64 bit
fields in all the right places, and makes VG_(stat) and VG_(fstat) use
it.  This means callers to the two functions no longer need to worry
about the is-it-64-bit-clean-or-not question, since these routines
reformat the received data into a'struct vg_stat'.  Kind of like what
glibc must have been doing for decades.

This (indirectly) fixes a bug on x86-linux, in which m_debuginfo would
sometimes fail to read debug info, due to VG_(di_notify_mmap) using
VG_(stat) (hence sys_stat) on the file, which failed, and when in fact
it should have used sys_stat64.  Bug reported and tracked down by
Marc-Oliver Straub.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@8522 a5019735-40e9-0310-863c-91ae7b9d1cf9

1 files changed, 28 insertions, 2 deletions

diff --git a/include/pub_tool_libcfile.h b/include/pub_tool_libcfile.h
index 9e3274b35..81710d4d9 100644
--- a/include/pub_tool_libcfile.h
+++ b/include/pub_tool_libcfile.h
@@ -37,6 +37,32 @@
 
 /* To use this file you must first include pub_tool_vki.h. */
 
+/* Note that VG_(stat) and VG_(fstat) write to a 'struct vg_stat*' and
+   not a 'struct vki_stat*' or a 'struct vki_stat64*'.  'struct
+   vg_stat*' is not the same as either of the vki_ versions.  No
+   specific vki_stat{,64} kernel structure will work and is
+   consistently available on different architectures on Linux, so we
+   have to use this 'struct vg_stat' impedance-matching type
+   instead. */
+struct vg_stat {
+   ULong   st_dev;
+   ULong   st_ino;
+   ULong   st_nlink;
+   UInt    st_mode;
+   UInt    st_uid;
+   UInt    st_gid;
+   ULong   st_rdev;
+   Long    st_size;
+   ULong   st_blksize;
+   ULong   st_blocks;
+   ULong   st_atime;
+   ULong   st_atime_nsec;
+   ULong   st_mtime;
+   ULong   st_mtime_nsec;
+   ULong   st_ctime;
+   ULong   st_ctime_nsec;
+};
+
 extern SysRes VG_(open)   ( const Char* pathname, Int flags, Int mode );
 extern void   VG_(close)  ( Int fd );
 extern Int    VG_(read)   ( Int fd, void* buf, Int count);
@@ -44,8 +70,8 @@ extern Int    VG_(write)  ( Int fd, const void* buf, Int count);
 extern Int    VG_(pipe)   ( Int fd[2] );
 extern OffT   VG_(lseek)  ( Int fd, OffT offset, Int whence );
 
-extern SysRes VG_(stat)   ( Char* file_name, struct vki_stat* buf );
-extern Int    VG_(fstat)  ( Int   fd,        struct vki_stat* buf );
+extern SysRes VG_(stat)   ( Char* file_name, struct vg_stat* buf );
+extern Int    VG_(fstat)  ( Int   fd,        struct vg_stat* buf );
 extern SysRes VG_(dup)    ( Int oldfd );
 extern Int    VG_(rename) ( Char* old_name, Char* new_name );
 extern Int    VG_(unlink) ( Char* file_name );