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June 2003

3 participants
2 discussions

Re: How to override "hidden symbols" from a preloadable object (LD_PRELOAD)
by Alain Knaff 22 Jun '03

22 Jun '03

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 _______________________________________________ zlibc mailing list zlibc(a)tux.org http://www.tux.org/mailman/listinfo/zlibc

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Redhat 8
by Paul Murray 19 Jun '03

19 Jun '03

Base install of RH8 has glibc 2.0 I get a file not found now. Any solution? Works perfectly fine with RH7.2 base install standard glibc on that machine. Help? Paul

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