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Questions tagged [glibc]

The GNU C library is used as the C library in the GNU system and most systems with the Linux kernel. It defines the "system calls" and other basic facilities such as open, malloc, printf, exit, etc.

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Why does glibc's strlen need to be so complicated to run quickly?

I was looking through the strlen code here and I was wondering if the optimizations used in the code are really needed? For example, why wouldn't something like the following work equally good or better? unsigned long strlen(char s[]) { unsigned…
user11954200
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Multiple glibc libraries on a single host

My linux (SLES-8) server currently has glibc-2.2.5-235, but I have a program which won't work on this version and requires glibc-2.3.3. Is it possible to have multiple glibcs installed on the same host? This is the error I get when I run my program…
dogbane
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How can I link to a specific glibc version?

When I compile something on my Ubuntu Lucid 10.04 PC it gets linked against glibc. Lucid uses 2.11 of glibc. When I run this binary on another PC with an older glibc, the command fails saying there's no glibc 2.11... As far as I know glibc uses…
falstaff
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Using C++ library in C code

I have a C++ library that provides various classes for managing data. I have the source code for the library. I want to extend the C++ API to support C function calls so that the library can be used with C code and C++ code at the same time. I'm…
Misha M
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difference between gcc -D_FORTIFY_SOURCE=1 and -D_FORTIFY_SOURCE=2

Can someone point out the difference between gcc -D_FORTIFY_SOURCE=1 and -D_FORTIFY_SOURCE=2? I guess =2 is more secure? I haven't been able to find a list which lists differences point by point. I have also read that -D_FORTIFY_SOURCE=2 should be…
Frank Meerkötter
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Why is statically linking glibc discouraged?

Most of the sources online state that you can statically link glibc, but discourage from doing so; e.g. centos package repo: The glibc-static package contains the C library static libraries for -static linking. You don't need these, unless you…
pzelasko
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Compiling without libc

I want to compile my C-code without the (g)libc. How can I deactivate it and which functions depend on it? I tried -nostdlib but it doesn't help: The code is compilable and runs, but I can still find the name of the libc in the hexdump of my…
u149796
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Is there a best practice on setting up glibc on docker alpine linux base image?

Is there a best practice on setting up glibc on docker alpine linux base image with correct paths so any spawned process can correctly reference the location of the installed libc libraries?
kai
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Linux static linking is dead?

In fact, -static gcc flag on Linux doesn't work now. Let me cite from the GNU libc FAQ: 2.22. Even statically linked programs need some shared libraries which is not acceptable for me. What can I do? {AJ} NSS (for details just type `info libc…
Shcheklein
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Check glibc version for a particular gcc compiler

I have two gcc compilers installed on my system, one is gcc 4.1.2 (default) and the other is gcc 4.4.4. How can I check the libc version used by gcc 4.4.4, because /lib/libc.so.6 shows the glibc used by gcc 4.1.2, since it is the default compiler.
MetallicPriest
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Why is this code using strlen heavily 6.5x slower with GCC optimizations enabled?

I wanted to benchmark glibc's strlen function for some reason and found out it apparently performs much slower with optimizations enabled in GCC and I have no idea why. Here's my code: #include #include #include…
Display Name
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How to upgrade glibc on Debian?

I heard I can do it using apt-get install libc6, but I need to add something to /etc/apt/sources.list to receive the newest glibc version. What should I do?
antpetr89
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Will malloc implementations return free-ed memory back to the system?

I have a long-living application with frequent memory allocation-deallocation. Will any malloc implementation return freed memory back to the system? What is, in this respect, the behavior of: ptmalloc 1, 2 (glibc default) or 3 dlmalloc tcmalloc…
osgx
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What is GLIBC? What is it used for?

I was searching for the source code of the C standard libraries. What I mean with it is, for example, how are cos, abs, printf, scanf, fopen, and all the other standard C functions written, I mean to see their source code. So while searching for…
user1261015
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Does standard c library provides linked list etc. data structures?

Do standard C library implementations, especially glibc (the GNU C Library) provide linked lists, stack et al. data structures, or do we have to roll our own? Thanks.
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