std: implement `hostname` by joboet · Pull Request #146937 · rust-lang/rust

joboet · 2025-09-23T15:10:47Z

Resolves rust-lang/libs-team#330
Tracking issue: #135142

This is based on #135141, but I've reimplemented the UNIX version, which now:

uses sysconf(_SC_HOST_NAME_MAX) as an initial buffer length
returns OutOfMemory if the Vec allocation fails
retries the operation if it detects that the name returned by gethostname was truncated

Additionally, as part of the rebase, I had to move some WinSock abstractions (initialisation and error access) to sys::pal so that they can be accessed from sys::net::hostname.

CC @orowith2os (and thank you for your work!)

rustbot · 2025-09-23T15:10:52Z

r? @Mark-Simulacrum

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library/std/src/sys/net/hostname/windows.rs

Mark-Simulacrum

r=me with nit fixed

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Mark-Simulacrum · 2025-09-28T18:03:15Z

library/std/src/sys/net/hostname/unix.rs

+                }
+            }
+            // As `buf.capacity()` is always positive (as Rust allocations cannot
+            // be larger than `isize::MAX` bytes), the only way `EINVAL` can be


buf.capacity() is a usize, so saying it's "always positive" feels confusing to me. I'm not sure what relevance isize has here.

gethostname documents that EINVAL is returned if size is negative (even though it is an unsigned integer). I've changed the comment to mention only isize::MAX.

joboet · 2025-09-29T08:28:15Z

I've rephrased the comment and also changed the Windows version to use cvt instead of cvt_gai (it makes no functional difference, but cvt_gai is kind of getaddrinfo-specific).

Mark-Simulacrum · 2025-09-29T11:57:45Z

@bors r+

bors · 2025-09-29T11:57:48Z

📌 Commit 97333f8 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

std: implement `hostname` Resolves rust-lang/libs-team#330 Tracking issue: rust-lang#135142 This is based on rust-lang#135141, but I've reimplemented the UNIX version, which now: * uses `sysconf(_SC_HOST_NAME_MAX)` as an initial buffer length * returns `OutOfMemory` if the `Vec` allocation fails * retries the operation if it detects that the name returned by `gethostname` was truncated Additionally, as part of the rebase, I had to move some WinSock abstractions (initialisation and error access) to `sys::pal` so that they can be accessed from `sys::net::hostname`. CC `@orowith2os` (and thank you for your work!)

Rollup of 6 pull requests Successful merges: - #143613 (Fix backtraces with `-C panic=abort` on linux; emit unwind tables by default) - #146937 (std: implement `hostname`) - #147040 (mbe: macro_check: Fix function comments referencing non-existent parameters) - #147131 (Use MirPatch in simplify_branches.) - #147133 (Remove one loop in `extract_cfg_from_attrs`) - #147150 (Emit allocator attributes for allocator shim) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 5 pull requests Successful merges: - #146937 (std: implement `hostname`) - #147040 (mbe: macro_check: Fix function comments referencing non-existent parameters) - #147131 (Use MirPatch in simplify_branches.) - #147133 (Remove one loop in `extract_cfg_from_attrs`) - #147150 (Emit allocator attributes for allocator shim) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #146937 - joboet:gethostname, r=Mark-Simulacrum std: implement `hostname` Resolves rust-lang/libs-team#330 Tracking issue: #135142 This is based on #135141, but I've reimplemented the UNIX version, which now: * uses `sysconf(_SC_HOST_NAME_MAX)` as an initial buffer length * returns `OutOfMemory` if the `Vec` allocation fails * retries the operation if it detects that the name returned by `gethostname` was truncated Additionally, as part of the rebase, I had to move some WinSock abstractions (initialisation and error access) to `sys::pal` so that they can be accessed from `sys::net::hostname`. CC ``@orowith2os`` (and thank you for your work!)

…boet Fix broken STD build for ESP-IDF PRs rust-lang#147162 and rust-lang#146937 did [broke](https://github.com/esp-rs/esp-idf-sys/actions/runs/18151791720/job/51663969786) the STD build for `target_os = "espidf"` because that target [does not have neither a `gethostname`, not a `libc::_SC_HOST_NAME_MAX` by default](espressif/esp-idf#14849). While there is a [3rd party component for this syscall](https://components.espressif.com/components/espressif/sock_utils/versions/0.2.2/readme) in the ESP-IDF component registry, I don't think we should use it, because it does not come with ESP-IDF by default. Therefore, the one-liner fix just re-routes ESP-IDF into the `unsupported` branch.

Rollup merge of #147213 - ivmarkov:fix-hostname-espidf, r=joboet Fix broken STD build for ESP-IDF PRs #147162 and #146937 did [broke](https://github.com/esp-rs/esp-idf-sys/actions/runs/18151791720/job/51663969786) the STD build for `target_os = "espidf"` because that target [does not have neither a `gethostname`, not a `libc::_SC_HOST_NAME_MAX` by default](espressif/esp-idf#14849). While there is a [3rd party component for this syscall](https://components.espressif.com/components/espressif/sock_utils/versions/0.2.2/readme) in the ESP-IDF component registry, I don't think we should use it, because it does not come with ESP-IDF by default. Therefore, the one-liner fix just re-routes ESP-IDF into the `unsupported` branch.

std: implement `hostname` Resolves rust-lang/libs-team#330 Tracking issue: rust-lang#135142 This is based on rust-lang#135141, but I've reimplemented the UNIX version, which now: * uses `sysconf(_SC_HOST_NAME_MAX)` as an initial buffer length * returns `OutOfMemory` if the `Vec` allocation fails * retries the operation if it detects that the name returned by `gethostname` was truncated Additionally, as part of the rebase, I had to move some WinSock abstractions (initialisation and error access) to `sys::pal` so that they can be accessed from `sys::net::hostname`. CC ``@orowith2os`` (and thank you for your work!)

…boet Fix broken STD build for ESP-IDF PRs rust-lang#147162 and rust-lang#146937 did [broke](https://github.com/esp-rs/esp-idf-sys/actions/runs/18151791720/job/51663969786) the STD build for `target_os = "espidf"` because that target [does not have neither a `gethostname`, not a `libc::_SC_HOST_NAME_MAX` by default](espressif/esp-idf#14849). While there is a [3rd party component for this syscall](https://components.espressif.com/components/espressif/sock_utils/versions/0.2.2/readme) in the ESP-IDF component registry, I don't think we should use it, because it does not come with ESP-IDF by default. Therefore, the one-liner fix just re-routes ESP-IDF into the `unsupported` branch.

rustbot assigned Mark-Simulacrum Sep 23, 2025

rustbot added O-windows Operating system: Windows S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Sep 23, 2025

std: move WinSock abstractions to sys::pal

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joboet force-pushed the gethostname branch from 4d8cd7a to 2d450d6 Compare September 23, 2025 15:15

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joboet force-pushed the gethostname branch from 2d450d6 to 1c8e9f9 Compare September 23, 2025 15:26

camsteffen reviewed Sep 23, 2025

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camsteffen reviewed Sep 23, 2025

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joboet added the O-unix Operating system: Unix-like label Sep 23, 2025

joboet force-pushed the gethostname branch from 1c8e9f9 to 5a7dfbc Compare September 23, 2025 18:51

Mark-Simulacrum requested changes Sep 28, 2025

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 28, 2025

std: implement hostname

97333f8

joboet force-pushed the gethostname branch from 5a7dfbc to 97333f8 Compare September 29, 2025 08:25

joboet added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 29, 2025

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 29, 2025

matthiaskrgr mentioned this pull request Sep 29, 2025

Rollup of 6 pull requests #147158

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matthiaskrgr mentioned this pull request Sep 29, 2025

Rollup of 5 pull requests #147162

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bors merged commit 8223831 into rust-lang:master Sep 30, 2025
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rustbot added this to the 1.92.0 milestone Sep 30, 2025

ivmarkov mentioned this pull request Oct 1, 2025

Fix broken STD build for ESP-IDF #147213

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folkertdev mentioned this pull request Oct 7, 2025

Rust nightly doesn't build on armv7-sony-vita-newlibeabihf #147437

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FenrirWolf mentioned this pull request Nov 3, 2025

Add missing constants from unistd.h for newlib targets rust-lang/libc#4811

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tbu- mentioned this pull request Dec 11, 2025

std: net: Add function to return the system hostname #135141

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std: implement `hostname`#146937

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