Lock RO

benches/benchsuite/benches/resolve.rs

@@ -228,6 +228,7 @@ fn make_config(ws_root: &Path) -> Config {
             false,
             false,
             false,
+            false,
             &Some(target_dir()),
             &[],
             &[],

crates/resolver-tests/tests/resolve.rs

@@ -66,6 +66,7 @@ proptest! {
                 false,
                 false,
                 false,
+                false,
                 &None,
                 &["minimal-versions".to_string()],
                 &[],
@@ -576,6 +577,7 @@ fn test_resolving_minimum_version_with_transitive_deps() {
             false,
             false,
             false,
+            false,
             &None,
             &["minimal-versions".to_string()],
             &[],

src/bin/cargo/cli.rs

@@ -341,6 +341,7 @@ fn config_configure(
     let color = args.value_of("color").or_else(|| global_color.as_deref());
     let frozen = args.is_present("frozen") || global_args.frozen;
     let locked = args.is_present("locked") || global_args.locked;
+    let lock_ro = args.is_present("lock-ro") || global_args.lock_ro;
     let offline = args.is_present("offline") || global_args.offline;
     let mut unstable_flags = global_args.unstable_flags;
     if let Some(values) = args.values_of("unstable-features") {
@@ -356,6 +357,7 @@ fn config_configure(
         color,
         frozen,
         locked,
+        lock_ro,
         offline,
         arg_target_dir,
         &unstable_flags,
@@ -381,6 +383,7 @@ struct GlobalArgs {
     color: Option<String>,
     frozen: bool,
     locked: bool,
+    lock_ro: bool,
     offline: bool,
     unstable_flags: Vec<String>,
     config_args: Vec<String>,
@@ -394,6 +397,7 @@ impl GlobalArgs {
             color: args.value_of("color").map(|s| s.to_string()),
             frozen: args.is_present("frozen"),
             locked: args.is_present("locked"),
+            lock_ro: args.is_present("lock-ro"),
             offline: args.is_present("offline"),
             unstable_flags: args
                 .values_of_lossy("unstable-features")
@@ -470,6 +474,7 @@ See 'cargo help <command>' for more information on a specific command.\n",
         )
         .arg(opt("frozen", "Require Cargo.lock and cache are up to date").global(true))
         .arg(opt("locked", "Require Cargo.lock is up to date").global(true))
+        .arg(opt("lock-ro", "Assume Cargo.lock is read only").global(true))
         .arg(opt("offline", "Run without accessing the network").global(true))
         .arg(
             multi_opt(

src/cargo/core/workspace.rs

@@ -98,6 +98,10 @@ pub struct Workspace<'cfg> {
 
     /// Workspace-level custom metadata
     custom_metadata: Option<toml::Value>,
+
+    // If `true`, then the resolver will not write to `Cargo.lock` files.
+    // This is set by the `--lock-ro` command line flag.
+    is_prevent_lock_write: bool,
 }
 
 // Separate structure for tracking loaded packages (to avoid loading anything
@@ -197,6 +201,7 @@ impl<'cfg> Workspace<'cfg> {
             ignore_lock: false,
             resolve_behavior: ResolveBehavior::V1,
             custom_metadata: None,
+            is_prevent_lock_write: config.lock_ro(),
         }
     }
 
@@ -562,6 +567,10 @@ impl<'cfg> Workspace<'cfg> {
         self.custom_metadata.as_ref()
     }
 
+    pub fn is_prevent_lock_write(&self) -> bool {
+        self.is_prevent_lock_write
+    }
+
     pub fn load_workspace_config(&mut self) -> CargoResult<Option<WorkspaceRootConfig>> {
         // If we didn't find a root, it must mean there is no [workspace] section, and thus no
         // metadata.

src/cargo/ops/resolve.rs

@@ -203,7 +203,7 @@ fn resolve_with_registry<'cfg>(
         true,
     )?;
 
-    if !ws.is_ephemeral() && ws.require_optional_deps() {
+    if !ws.is_ephemeral() && ws.require_optional_deps() && !ws.is_prevent_lock_write() {
         ops::write_pkg_lockfile(ws, &mut resolve)?;
     }
     Ok(resolve)

src/cargo/util/config/mod.rs

@@ -149,6 +149,10 @@ pub struct Config {
     /// `locked` is set if we should not update lock files. If the lock file
     /// is missing, or needs to be updated, an error is produced.
     locked: bool,
+    /// `lock_ro` is set if we should not update lock files. It behaves like
+    /// `locked`, but does not produce an error and silently discards lock
+    /// file changes. Intended for read-only file systems.
+    lock_ro: bool,
     /// `offline` is set if we should never access the network, but otherwise
     /// continue operating if possible.
     offline: bool,
@@ -257,6 +261,7 @@ impl Config {
             extra_verbose: false,
             frozen: false,
             locked: false,
+            lock_ro: false,
             offline: false,
             jobserver: unsafe {
                 if GLOBAL_JOBSERVER.is_null() {
@@ -875,6 +880,7 @@ impl Config {
         color: Option<&str>,
         frozen: bool,
         locked: bool,
+        lock_ro: bool,
         offline: bool,
         target_dir: &Option<PathBuf>,
         unstable_flags: &[String],
@@ -938,6 +944,7 @@ impl Config {
         self.extra_verbose = extra_verbose;
         self.frozen = frozen;
         self.locked = locked;
+        self.lock_ro = lock_ro;
         self.offline = offline
             || self
                 .net_config()
@@ -994,6 +1001,10 @@ impl Config {
         self.locked
     }
 
+    pub fn lock_ro(&self) -> bool {
+        self.lock_ro
+    }
+
     pub fn lock_update_allowed(&self) -> bool {
         !self.frozen && !self.locked
     }

src/doc/man/generated_txt/cargo-bench.txt

@@ -320,6 +320,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-build.txt

@@ -270,6 +270,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-check.txt

@@ -264,6 +264,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-clean.txt

@@ -95,6 +95,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-doc.txt

@@ -235,6 +235,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-fetch.txt

@@ -80,6 +80,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-fix.txt

@@ -337,6 +337,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-generate-lockfile.txt

@@ -56,6 +56,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-install.txt

@@ -235,6 +235,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-metadata.txt

@@ -368,6 +368,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-package.txt

@@ -167,6 +167,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-pkgid.txt

@@ -86,6 +86,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-publish.txt

@@ -134,6 +134,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-run.txt

@@ -180,6 +180,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-rustc.txt

@@ -259,6 +259,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-rustdoc.txt

@@ -251,6 +251,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the

src/doc/man/generated_txt/cargo-test.txt

@@ -334,6 +334,13 @@ OPTIONS
            Cargo.lock file is up-to-date (such as a CI build) or want to avoid
            network access.
 
+       --lock-ro
+           Prevents Cargo from updating the Cargo.lock file. Unlike the
+           --frozen and --locked flags, this flag does not produce an error
+           when the lock file needs to be updated. Instead, the lock file
+           update is transparently discarded. This is intended to allow Cargo
+           to handle read only file systems.
+
        --offline
            Prevents Cargo from accessing the network for any reason. Without
            this flag, Cargo will stop with an error if it needs to access the