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Get __pthread_get_minstack at runtime with dlsym #23631

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Merged
merged 3 commits into from
Mar 24, 2015
Merged

Get __pthread_get_minstack at runtime with dlsym #23631

merged 3 commits into from
Mar 24, 2015

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andersk
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@andersk andersk commented Mar 23, 2015

Linking __pthread_get_minstack, even weakly, was causing Debian’s dpkg-shlibdeps to detect an unnecessarily strict versioned dependency on libc6.

Closes #23628.

@andersk
Get __pthread_get_minstack at runtime with dlsym
0090e01 
Linking __pthread_get_minstack, even weakly, was causing Debian’s
dpkg-shlibdeps to detect an unnecessarily strict versioned dependency
on libc6.

Closes rust-lang#23628.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
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r? @pcwalton

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tamird
tamird reviewed Mar 23, 2015
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src/libstd/sys/unix/thread.rs
#[cfg(target_os = "linux")]
fn min_stack_size(attr: *const libc::pthread_attr_t) -> libc::size_t {
type F = unsafe extern "C" fn(*const libc::pthread_attr_t) -> libc::size_t;
extern {
#[linkage = "extern_weak"]
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since you're removing this could you merge the mac os implementation into this?

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I’m not a Mac user; does Rust use glibc on Mac? I figured we shouldn’t waste time looking up __pthread_get_minstack on non-glibc.

(But yeah, I should update the comment below, if nothing else.)

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i guess i'm not sure, just going by this comment: https://github.com/rust-lang/rust/blob/master/src/libstd/sys/unix/thread.rs#L335

andersk added 2 commits March 23, 2015 03:48
@andersk
min_stack_size: update non-Linux implementation comment
b6641c1 
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
@andersk
min_stack_size: clarify both reasons to use dlsym
737bb30 
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
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We currently actually have a two other of these sorts of extern_weak symbols, but is this the only problematic one? They are:

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andersk commented Mar 23, 2015

Those two are less problematic because they aren’t GLIBC_PRIVATE. They cause dependencies on libc6 (>= 2.12) and libc6 (>= 2.18), respectively. So you might be spuriously prevented from using the package with a much older libc6, but you’ll always be able to use it with a newer one.

 Looking up symbol __cxa_thread_atexit_impl@GLIBC_2.18
 Found in symbols file of libc.so.6 (minver: 2.18, dep: libc6 #MINVER#)
 Looking up symbol pthread_setname_np@GLIBC_2.12
 Found in symbols file of libpthread.so.0 (minver: 2.12, dep: libc6 #MINVER#)

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Ah well it looks like pthread_setname_np is going away anyway, and we can probably apply the same treatment to __cxa_thread_atexit_impl later on if we really need to.

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@bors: r+ 737bb30

alexcrichton added a commit to alexcrichton/rust that referenced this pull request Mar 23, 2015
@alexcrichton
rollup merge of rust-lang#23631: andersk/minstack-dlsym
28fcdc0 
Linking `__pthread_get_minstack`, even weakly, was causing Debian’s `dpkg-shlibdeps` to detect an unnecessarily strict versioned dependency on libc6.

Closes rust-lang#23628.
@bors bors merged commit 737bb30 into rust-lang:master Mar 24, 2015
@andersk andersk deleted the minstack-dlsym branch March 28, 2015 23:36
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Use of __pthread_get_minstack leads to unnecessarily strict libc6 versioned dependency on Debian
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@andersk @rust-highfive @alexcrichton @tamird @pcwalton @bors