feat(std): emulate flock for solaris via fcntl

Upstream Solaris flock emulation to libstd from cargo.

This is borrowed from
https://github.com/rust-lang/cargo/blob/3b379fcc541b39321a7758552d37e5e0cc4277b9/src/cargo/util/flock.rs#L502-L536
which was implemented by an Oracle employee.
The code has been in cargo since 2022-12.

Python's `fcntl.flock` emulates like this as well:
https://github.com/python/cpython/blob/c919d02edecfe9d75fe374756fb8aa1db8d95f55/Modules/fcntlmodule.c#L337-L400

We did the same thing in
https://github.com/rust-lang/rust/blob/0d0f4eac8b98133e5da6d3604d86a8f3b5a67844/compiler/rustc_data_structures/src/flock/unix.rs#L13-L39

2 files changed, 70 insertions, 0 deletions

diff --git a/library/std/src/fs/tests.rs b/library/std/src/fs/tests.rs
index f4431cedd18..f8dfb0d6334 100644
--- a/library/std/src/fs/tests.rs
+++ b/library/std/src/fs/tests.rs
@@ -226,6 +226,7 @@ fn file_test_io_seek_and_write() {
     target_os = "freebsd",
     target_os = "linux",
     target_os = "netbsd",
+    target_os = "solaris",
     target_vendor = "apple",
 ))]
 fn file_lock_multiple_shared() {
@@ -249,6 +250,7 @@ fn file_lock_multiple_shared() {
     target_os = "freebsd",
     target_os = "linux",
     target_os = "netbsd",
+    target_os = "solaris",
     target_vendor = "apple",
 ))]
 fn file_lock_blocking() {
@@ -273,6 +275,7 @@ fn file_lock_blocking() {
     target_os = "freebsd",
     target_os = "linux",
     target_os = "netbsd",
+    target_os = "solaris",
     target_vendor = "apple",
 ))]
 fn file_lock_drop() {
@@ -294,6 +297,7 @@ fn file_lock_drop() {
     target_os = "freebsd",
     target_os = "linux",
     target_os = "netbsd",
+    target_os = "solaris",
     target_vendor = "apple",
 ))]
 fn file_lock_dup() {
diff --git a/library/std/src/sys/fs/unix.rs b/library/std/src/sys/fs/unix.rs
index 3b525406223..dfd6ce56a76 100644
--- a/library/std/src/sys/fs/unix.rs
+++ b/library/std/src/sys/fs/unix.rs
@@ -1293,6 +1293,15 @@ impl File {
         return Ok(());
     }
 
+    #[cfg(target_os = "solaris")]
+    pub fn lock(&self) -> io::Result<()> {
+        let mut flock: libc::flock = unsafe { mem::zeroed() };
+        flock.l_type = libc::F_WRLCK as libc::c_short;
+        flock.l_whence = libc::SEEK_SET as libc::c_short;
+        cvt(unsafe { libc::fcntl(self.as_raw_fd(), libc::F_SETLKW, &flock) })?;
+        Ok(())
+    }
+
     #[cfg(not(any(
         target_os = "freebsd",
         target_os = "fuchsia",
@@ -1300,6 +1309,7 @@ impl File {
         target_os = "netbsd",
         target_os = "openbsd",
         target_os = "cygwin",
+        target_os = "solaris",
         target_vendor = "apple",
     )))]
     pub fn lock(&self) -> io::Result<()> {
@@ -1320,6 +1330,15 @@ impl File {
         return Ok(());
     }
 
+    #[cfg(target_os = "solaris")]
+    pub fn lock_shared(&self) -> io::Result<()> {
+        let mut flock: libc::flock = unsafe { mem::zeroed() };
+        flock.l_type = libc::F_RDLCK as libc::c_short;
+        flock.l_whence = libc::SEEK_SET as libc::c_short;
+        cvt(unsafe { libc::fcntl(self.as_raw_fd(), libc::F_SETLKW, &flock) })?;
+        Ok(())
+    }
+
     #[cfg(not(any(
         target_os = "freebsd",
         target_os = "fuchsia",
@@ -1327,6 +1346,7 @@ impl File {
         target_os = "netbsd",
         target_os = "openbsd",
         target_os = "cygwin",
+        target_os = "solaris",
         target_vendor = "apple",
     )))]
     pub fn lock_shared(&self) -> io::Result<()> {
@@ -1355,6 +1375,23 @@ impl File {
         }
     }
 
+    #[cfg(target_os = "solaris")]
+    pub fn try_lock(&self) -> Result<(), TryLockError> {
+        let mut flock: libc::flock = unsafe { mem::zeroed() };
+        flock.l_type = libc::F_WRLCK as libc::c_short;
+        flock.l_whence = libc::SEEK_SET as libc::c_short;
+        let result = cvt(unsafe { libc::fcntl(self.as_raw_fd(), libc::F_SETLK, &flock) });
+        if let Err(err) = result {
+            if err.kind() == io::ErrorKind::WouldBlock {
+                Err(TryLockError::WouldBlock)
+            } else {
+                Err(TryLockError::Error(err))
+            }
+        } else {
+            Ok(())
+        }
+    }
+
     #[cfg(not(any(
         target_os = "freebsd",
         target_os = "fuchsia",
@@ -1362,6 +1399,7 @@ impl File {
         target_os = "netbsd",
         target_os = "openbsd",
         target_os = "cygwin",
+        target_os = "solaris",
         target_vendor = "apple",
     )))]
     pub fn try_lock(&self) -> Result<(), TryLockError> {
@@ -1393,6 +1431,23 @@ impl File {
         }
     }
 
+    #[cfg(target_os = "solaris")]
+    pub fn try_lock_shared(&self) -> Result<(), TryLockError> {
+        let mut flock: libc::flock = unsafe { mem::zeroed() };
+        flock.l_type = libc::F_RDLCK as libc::c_short;
+        flock.l_whence = libc::SEEK_SET as libc::c_short;
+        let result = cvt(unsafe { libc::fcntl(self.as_raw_fd(), libc::F_SETLK, &flock) });
+        if let Err(err) = result {
+            if err.kind() == io::ErrorKind::WouldBlock {
+                Err(TryLockError::WouldBlock)
+            } else {
+                Err(TryLockError::Error(err))
+            }
+        } else {
+            Ok(())
+        }
+    }
+
     #[cfg(not(any(
         target_os = "freebsd",
         target_os = "fuchsia",
@@ -1400,6 +1455,7 @@ impl File {
         target_os = "netbsd",
         target_os = "openbsd",
         target_os = "cygwin",
+        target_os = "solaris",
         target_vendor = "apple",
     )))]
     pub fn try_lock_shared(&self) -> Result<(), TryLockError> {
@@ -1423,6 +1479,15 @@ impl File {
         return Ok(());
     }
 
+    #[cfg(target_os = "solaris")]
+    pub fn unlock(&self) -> io::Result<()> {
+        let mut flock: libc::flock = unsafe { mem::zeroed() };
+        flock.l_type = libc::F_UNLCK as libc::c_short;
+        flock.l_whence = libc::SEEK_SET as libc::c_short;
+        cvt(unsafe { libc::fcntl(self.as_raw_fd(), libc::F_SETLKW, &flock) })?;
+        Ok(())
+    }
+
     #[cfg(not(any(
         target_os = "freebsd",
         target_os = "fuchsia",
@@ -1430,6 +1495,7 @@ impl File {
         target_os = "netbsd",
         target_os = "openbsd",
         target_os = "cygwin",
+        target_os = "solaris",
         target_vendor = "apple",
     )))]
     pub fn unlock(&self) -> io::Result<()> {