Any news on this libc_hidden_def issue?
Thx,
Alain
On Thursday 29 May 2003 12:20, Alain Knaff wrote:
Hello,
I'm the author of zlibc (http://zlibc.linux.lu), which is a preloadable object that allows applications to transparently read compressed data. No recompilation or relinking necessary.
It works by overriding a number of key system calls (or rather, their libc entry points), such as open, stat, etc. in such a way that they check for .gz files if the file requested by the application did not exist, and then spawning a gunzip to uncompress the file.
This has worked fine since the a.out days, until glibc-2.2, but recently broke in the glibc 2.3.
From what I've seen, the reason for the problem are the libc_hidden_def macros which are now used throughout glibc. Their goal apparently is to make sure that libc functions (such as fopen or fopen64) only call libc's own functions (such as open), and to completely ignore any functions brought by LD_PRELOADed objects. As you can imagine, this breaks zlibc big time. Fopen will no longer call zlibc's "open" that checks for compressed files.
Do you know of any method to have fopen still use the open supplied by zlibc? Or is it now considered "bad etiquette" to attempt to override libc's internal functions?
Thanks for any ideas,
Alain
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