Is it possible to get location of dependent libraries from within code
I want to load some dependent libraries from my program with dlopen function. Is it possible to know actual location of these libraries?
eg, ldd shows all dependent libraries with paths in system. How does it work? Is it possible to get paths to correspondent libraries I need to load with dlopen via some call from my C++ code?
c++ linux shared-libraries executable
asked Jan 3 at 10:25
dojo_userdojo_user
135
add a comment |
I want to load some dependent libraries from my program with dlopen function. Is it possible to know actual location of these libraries?
eg, ldd shows all dependent libraries with paths in system. How does it work? Is it possible to get paths to correspondent libraries I need to load with dlopen via some call from my C++ code?
c++ linux shared-libraries executable
asked Jan 3 at 10:25
dojo_userdojo_user
135
Is it an "installed" library you're trying to load?
– YSC
Jan 3 at 10:26
ldd uses LD_LIBRARY_PATH to get the path to the required libraries, for dlopen, it can be anywhere on the filesystem.
– Matthieu Brucher
Jan 3 at 10:28
yup it is. For example it could be some sort of runtime libs(eg nvidia cuda) that I need at certain time not always.
– dojo_user
Jan 3 at 10:28
add a comment |
I want to load some dependent libraries from my program with dlopen function. Is it possible to know actual location of these libraries?
eg, ldd shows all dependent libraries with paths in system. How does it work? Is it possible to get paths to correspondent libraries I need to load with dlopen via some call from my C++ code?
c++ linux shared-libraries executable
asked Jan 3 at 10:25
dojo_userdojo_user
135
I want to load some dependent libraries from my program with dlopen function. Is it possible to know actual location of these libraries?
eg, ldd shows all dependent libraries with paths in system. How does it work? Is it possible to get paths to correspondent libraries I need to load with dlopen via some call from my C++ code?
c++ linux shared-libraries executable
c++ linux shared-libraries executable
asked Jan 3 at 10:25
dojo_userdojo_user
135
asked Jan 3 at 10:25
dojo_userdojo_user
135
asked Jan 3 at 10:25
dojo_userdojo_user
135
asked Jan 3 at 10:25
dojo_userdojo_user
135
asked Jan 3 at 10:25
dojo_userdojo_user
135
135
Is it an "installed" library you're trying to load?
– YSC
Jan 3 at 10:26
ldd uses LD_LIBRARY_PATH to get the path to the required libraries, for dlopen, it can be anywhere on the filesystem.
– Matthieu Brucher
Jan 3 at 10:28
yup it is. For example it could be some sort of runtime libs(eg nvidia cuda) that I need at certain time not always.
– dojo_user
Jan 3 at 10:28
add a comment |
Is it an "installed" library you're trying to load?
– YSC
Jan 3 at 10:26
ldd uses LD_LIBRARY_PATH to get the path to the required libraries, for dlopen, it can be anywhere on the filesystem.
– Matthieu Brucher
Jan 3 at 10:28
yup it is. For example it could be some sort of runtime libs(eg nvidia cuda) that I need at certain time not always.
– dojo_user
Jan 3 at 10:28
Is it an "installed" library you're trying to load?
– YSC
Jan 3 at 10:26
Is it an "installed" library you're trying to load?
– YSC
Jan 3 at 10:26
ldd uses LD_LIBRARY_PATH to get the path to the required libraries, for dlopen, it can be anywhere on the filesystem.
– Matthieu Brucher
Jan 3 at 10:28
ldd uses LD_LIBRARY_PATH to get the path to the required libraries, for dlopen, it can be anywhere on the filesystem.
– Matthieu Brucher
Jan 3 at 10:28
yup it is. For example it could be some sort of runtime libs(eg nvidia cuda) that I need at certain time not always.
– dojo_user
Jan 3 at 10:28
yup it is. For example it could be some sort of runtime libs(eg nvidia cuda) that I need at certain time not always.
– dojo_user
Jan 3 at 10:28
add a comment |
1 Answer
1
active
oldest
votes
From man dlopen one can read:
The function dlopen() loads the dynamic library file named by the null-terminated string filename and returns an opaque "handle" for the dynamic library. If filename is NULL, then the returned handle is for the main program. If filename contains a slash ("/"), then it is interpreted as a (relative or absolute) pathname. Otherwise, the dynamic linker searches for the library as follows (see ld.so(8) for further details):
(ELF only) If the executable file for the calling program contains a DT_RPATH tag, and does not contain a DT_RUNPATH tag, then the directories listed in the DT_RPATH tag are searched.
If, at the time that the program was started, the environment variable
LD_LIBRARY_PATHwas defined to contain a colon-separated list of directories, then these are searched. (As a security measure this variable is ignored for set-user-ID and set-group-ID programs.)
(ELF only) If the executable file for the calling program contains a DT_RUNPATH tag, then the directories listed in that tag are searched.
The cache file
/etc/ld.so.cache(maintained by ldconfig(8)) is checked to see whether it contains an entry for filename.
The directories
/liband/usr/libare searched (in that order).
So, if the desired library is "installed", a simple dlopen("foobar.so", flag) will do.
answered Jan 3 at 10:30
YSCYSC
25.3k557112
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f54020383%2fis-it-possible-to-get-location-of-dependent-libraries-from-within-code%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
From man dlopen one can read:
The function dlopen() loads the dynamic library file named by the null-terminated string filename and returns an opaque "handle" for the dynamic library. If filename is NULL, then the returned handle is for the main program. If filename contains a slash ("/"), then it is interpreted as a (relative or absolute) pathname. Otherwise, the dynamic linker searches for the library as follows (see ld.so(8) for further details):
(ELF only) If the executable file for the calling program contains a DT_RPATH tag, and does not contain a DT_RUNPATH tag, then the directories listed in the DT_RPATH tag are searched.
If, at the time that the program was started, the environment variable
LD_LIBRARY_PATHwas defined to contain a colon-separated list of directories, then these are searched. (As a security measure this variable is ignored for set-user-ID and set-group-ID programs.)
(ELF only) If the executable file for the calling program contains a DT_RUNPATH tag, then the directories listed in that tag are searched.
The cache file
/etc/ld.so.cache(maintained by ldconfig(8)) is checked to see whether it contains an entry for filename.
The directories
/liband/usr/libare searched (in that order).
So, if the desired library is "installed", a simple dlopen("foobar.so", flag) will do.
answered Jan 3 at 10:30
YSCYSC
25.3k557112
add a comment |
From man dlopen one can read:
The function dlopen() loads the dynamic library file named by the null-terminated string filename and returns an opaque "handle" for the dynamic library. If filename is NULL, then the returned handle is for the main program. If filename contains a slash ("/"), then it is interpreted as a (relative or absolute) pathname. Otherwise, the dynamic linker searches for the library as follows (see ld.so(8) for further details):
(ELF only) If the executable file for the calling program contains a DT_RPATH tag, and does not contain a DT_RUNPATH tag, then the directories listed in the DT_RPATH tag are searched.
If, at the time that the program was started, the environment variable
LD_LIBRARY_PATHwas defined to contain a colon-separated list of directories, then these are searched. (As a security measure this variable is ignored for set-user-ID and set-group-ID programs.)
(ELF only) If the executable file for the calling program contains a DT_RUNPATH tag, then the directories listed in that tag are searched.
The cache file
/etc/ld.so.cache(maintained by ldconfig(8)) is checked to see whether it contains an entry for filename.
The directories
/liband/usr/libare searched (in that order).
So, if the desired library is "installed", a simple dlopen("foobar.so", flag) will do.
answered Jan 3 at 10:30
YSCYSC
25.3k557112
add a comment |
From man dlopen one can read:
The function dlopen() loads the dynamic library file named by the null-terminated string filename and returns an opaque "handle" for the dynamic library. If filename is NULL, then the returned handle is for the main program. If filename contains a slash ("/"), then it is interpreted as a (relative or absolute) pathname. Otherwise, the dynamic linker searches for the library as follows (see ld.so(8) for further details):
(ELF only) If the executable file for the calling program contains a DT_RPATH tag, and does not contain a DT_RUNPATH tag, then the directories listed in the DT_RPATH tag are searched.
If, at the time that the program was started, the environment variable
LD_LIBRARY_PATHwas defined to contain a colon-separated list of directories, then these are searched. (As a security measure this variable is ignored for set-user-ID and set-group-ID programs.)
(ELF only) If the executable file for the calling program contains a DT_RUNPATH tag, then the directories listed in that tag are searched.
The cache file
/etc/ld.so.cache(maintained by ldconfig(8)) is checked to see whether it contains an entry for filename.
The directories
/liband/usr/libare searched (in that order).
So, if the desired library is "installed", a simple dlopen("foobar.so", flag) will do.
answered Jan 3 at 10:30
YSCYSC
25.3k557112
From man dlopen one can read:
The function dlopen() loads the dynamic library file named by the null-terminated string filename and returns an opaque "handle" for the dynamic library. If filename is NULL, then the returned handle is for the main program. If filename contains a slash ("/"), then it is interpreted as a (relative or absolute) pathname. Otherwise, the dynamic linker searches for the library as follows (see ld.so(8) for further details):
(ELF only) If the executable file for the calling program contains a DT_RPATH tag, and does not contain a DT_RUNPATH tag, then the directories listed in the DT_RPATH tag are searched.
If, at the time that the program was started, the environment variable
LD_LIBRARY_PATHwas defined to contain a colon-separated list of directories, then these are searched. (As a security measure this variable is ignored for set-user-ID and set-group-ID programs.)
(ELF only) If the executable file for the calling program contains a DT_RUNPATH tag, then the directories listed in that tag are searched.
The cache file
/etc/ld.so.cache(maintained by ldconfig(8)) is checked to see whether it contains an entry for filename.
The directories
/liband/usr/libare searched (in that order).
So, if the desired library is "installed", a simple dlopen("foobar.so", flag) will do.
answered Jan 3 at 10:30
YSCYSC
25.3k557112
answered Jan 3 at 10:30
YSCYSC
25.3k557112
answered Jan 3 at 10:30
YSCYSC
25.3k557112
answered Jan 3 at 10:30
YSCYSC
25.3k557112
25.3k557112
add a comment |
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f54020383%2fis-it-possible-to-get-location-of-dependent-libraries-from-within-code%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Is it an "installed" library you're trying to load?
– YSC
Jan 3 at 10:26
ldd uses LD_LIBRARY_PATH to get the path to the required libraries, for dlopen, it can be anywhere on the filesystem.
– Matthieu Brucher
Jan 3 at 10:28
yup it is. For example it could be some sort of runtime libs(eg nvidia cuda) that I need at certain time not always.
– dojo_user
Jan 3 at 10:28