1berry/MariaDB-server
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Bug#52134 performance schema file io, symlink in path

Browse Source 
Backport from mysql-next-mr (5.6) to mysql-trunk (5.5)
This commit is contained in:
Marc Alff 2010-07-15 19:25:03 -06:00
parent c92a6ea8ea
commit edf7865437
1 changed files with 48 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
storage/perfschema/pfs_instr.cc
View File

@ -829,7 +829,7 @@ find_or_create_file(PFS_thread *thread, PFS_file_class *klass,
- it fits into pfs->m_filename
- it is safe to use mysys apis to normalize the file name.
*/
memcpy(safe_buffer, filename, FN_REFLEN - 2);
memcpy(safe_buffer, filename, FN_REFLEN - 1);
safe_buffer[FN_REFLEN - 1]= 0;
safe_filename= safe_buffer;
}
@ -840,16 +840,58 @@ find_or_create_file(PFS_thread *thread, PFS_file_class *klass,
Normalize the file name to avoid duplicates when using aliases:
- absolute or relative paths
- symbolic links
Names are resolved as follows:
- /real/path/to/real_file ==> same
- /path/with/link/to/real_file ==> /real/path/to/real_file
- real_file ==> /real/path/to/real_file
- ./real_file ==> /real/path/to/real_file
- /real/path/to/sym_link ==> same
- /path/with/link/to/sym_link ==> /real/path/to/sym_link
- sym_link ==> /real/path/to/sym_link
- ./sym_link ==> /real/path/to/sym_link
When the last component of a file is a symbolic link,
the last component is *not* resolved, so that all file io
operations on a link (create, read, write, delete) are counted
against the link itself, not the target file.
Resolving the name would lead to create counted against the link,
and read/write/delete counted against the target, leading to
incoherent results and instrumentation leaks.
Also note that, when creating files, this name resolution
works properly for files that do not exist (yet) on the file system.
*/
char buffer[FN_REFLEN];
char dirbuffer[FN_REFLEN];
size_t dirlen;
const char *normalized_filename;
int normalized_length;
/*
Ignore errors, the file may not exist.
my_realpath always provide a best effort result in buffer.
*/
(void) my_realpath(buffer, safe_filename, MYF(0));
dirlen= dirname_length(safe_filename);
if (dirlen == 0)
{
dirbuffer[0]= FN_CURLIB;
dirbuffer[1]= FN_LIBCHAR;
dirbuffer[2]= '\0';
}
else
{
memcpy(dirbuffer, safe_filename, dirlen);
dirbuffer[dirlen]= '\0';
}
if (my_realpath(buffer, dirbuffer, MYF(0)) != 0)
{
file_lost++;
return NULL;
}
/* Append the unresolved file name to the resolved path */
char *ptr= buffer + strlen(buffer);
char *buf_end= &buffer[sizeof(buffer)-1];
if (buf_end > ptr)
*ptr++= FN_LIBCHAR;
if (buf_end > ptr)
strncpy(ptr, safe_filename + dirlen, buf_end - ptr);
*buf_end= '\0';
normalized_filename= buffer;
normalized_length= strlen(normalized_filename);