Accept `file://` URLs for `requirements.txt` et all references (#4145)

## Summary

Closes https://github.com/astral-sh/uv/issues/4124.

crates/requirements-txt/src/lib.rs

@@ -262,6 +262,7 @@ impl RequirementsTxt {
                     read_url_to_string(&requirements_txt, client).await
                 }
             } else {
+                // Ex) `file:///home/ferris/project/requirements.txt`
                 uv_fs::read_to_string_transcode(&requirements_txt)
                     .await
                     .map_err(RequirementsTxtParserError::IO)
@@ -321,6 +322,22 @@ impl RequirementsTxt {
                     let sub_file =
                         if filename.starts_with("http://") || filename.starts_with("https://") {
                             PathBuf::from(filename.as_ref())
+                        } else if filename.starts_with("file://") {
+                            requirements_txt.join(
+                                Url::parse(filename.as_ref())
+                                    .map_err(|err| RequirementsTxtParserError::Url {
+                                        source: err,
+                                        url: filename.to_string(),
+                                        start,
+                                        end,
+                                    })?
+                                    .to_file_path()
+                                    .map_err(|()| RequirementsTxtParserError::FileUrl {
+                                        url: filename.to_string(),
+                                        start,
+                                        end,
+                                    })?,
+                            )
                         } else {
                             requirements_dir.join(filename.as_ref())
                         };
@@ -360,6 +377,22 @@ impl RequirementsTxt {
                     let sub_file =
                         if filename.starts_with("http://") || filename.starts_with("https://") {
                             PathBuf::from(filename.as_ref())
+                        } else if filename.starts_with("file://") {
+                            requirements_txt.join(
+                                Url::parse(filename.as_ref())
+                                    .map_err(|err| RequirementsTxtParserError::Url {
+                                        source: err,
+                                        url: filename.to_string(),
+                                        start,
+                                        end,
+                                    })?
+                                    .to_file_path()
+                                    .map_err(|()| RequirementsTxtParserError::FileUrl {
+                                        url: filename.to_string(),
+                                        start,
+                                        end,
+                                    })?,
+                            )
                         } else {
                             requirements_dir.join(filename.as_ref())
                         };
@@ -815,6 +848,11 @@ pub enum RequirementsTxtParserError {
         start: usize,
         end: usize,
     },
+    FileUrl {
+        url: String,
+        start: usize,
+        end: usize,
+    },
     VerbatimUrl {
         source: pep508_rs::VerbatimUrlError,
         url: String,
@@ -882,6 +920,9 @@ impl Display for RequirementsTxtParserError {
             Self::Url { url, start, .. } => {
                 write!(f, "Invalid URL at position {start}: `{url}`")
             }
+            Self::FileUrl { url, start, .. } => {
+                write!(f, "Invalid file URL at position {start}: `{url}`")
+            }
             Self::VerbatimUrl { source, url } => {
                 write!(f, "Invalid URL: `{url}`: {source}")
             }
@@ -945,6 +986,7 @@ impl std::error::Error for RequirementsTxtParserError {
         match &self {
             Self::IO(err) => err.source(),
             Self::Url { source, .. } => Some(source),
+            Self::FileUrl { .. } => None,
             Self::VerbatimUrl { source, .. } => Some(source),
             Self::UrlConversion(_) => None,
             Self::UnsupportedUrl(_) => None,
@@ -976,6 +1018,13 @@ impl Display for RequirementsTxtFileError {
                     self.file.user_display(),
                 )
             }
+            RequirementsTxtParserError::FileUrl { url, start, .. } => {
+                write!(
+                    f,
+                    "Invalid file URL in `{}` at position {start}: `{url}`",
+                    self.file.user_display(),
+                )
+            }
             RequirementsTxtParserError::VerbatimUrl { url, .. } => {
                 write!(f, "Invalid URL in `{}`: `{url}`", self.file.user_display())
             }

crates/uv/src/cli.rs

@@ -253,15 +253,30 @@ fn parse_index_url(input: &str) -> Result<Maybe<IndexUrl>, String> {
     }
 }
 
+/// Parse a string into a [`PathBuf`]. The string can represent a file, either as a path or a
+/// `file://` URL.
+fn parse_file_path(input: &str) -> Result<PathBuf, String> {
+    if input.starts_with("file://") {
+        let url = match url::Url::from_str(input) {
+            Ok(url) => url,
+            Err(err) => return Err(err.to_string()),
+        };
+        url.to_file_path()
+            .map_err(|()| "invalid file URL".to_string())
+    } else {
+        match PathBuf::from_str(input) {
+            Ok(path) => Ok(path),
+            Err(err) => Err(err.to_string()),
+        }
+    }
+}
+
 /// Parse a string into a [`PathBuf`], mapping the empty string to `None`.
-fn parse_file_path(input: &str) -> Result<Maybe<PathBuf>, String> {
+fn parse_maybe_file_path(input: &str) -> Result<Maybe<PathBuf>, String> {
     if input.is_empty() {
         Ok(Maybe::None)
     } else {
-        match PathBuf::from_str(input) {
+        parse_file_path(input).map(Maybe::Some)
-            Ok(path) => Ok(Maybe::Some(path)),
-            Err(err) => Err(err.to_string()),
-        }
     }
 }
 
@@ -271,7 +286,7 @@ pub(crate) struct PipCompileArgs {
     /// Include all packages listed in the given `requirements.in` files.
     ///
     /// When the path is `-`, then requirements are read from stdin.
-    #[arg(required(true))]
+    #[arg(required(true), value_parser = parse_file_path)]
     pub(crate) src_file: Vec<PathBuf>,
 
     /// Constrain versions using the given requirements files.
@@ -281,7 +296,7 @@ pub(crate) struct PipCompileArgs {
     /// trigger the installation of that package.
     ///
     /// This is equivalent to pip's `--constraint` option.
-    #[arg(long, short, env = "UV_CONSTRAINT", value_delimiter = ' ', value_parser = parse_file_path)]
+    #[arg(long, short, env = "UV_CONSTRAINT", value_delimiter = ' ', value_parser = parse_maybe_file_path)]
     pub(crate) constraint: Vec<Maybe<PathBuf>>,
 
     /// Override versions using the given requirements files.
@@ -293,7 +308,7 @@ pub(crate) struct PipCompileArgs {
     /// While constraints are _additive_, in that they're combined with the requirements of the
     /// constituent packages, overrides are _absolute_, in that they completely replace the
     /// requirements of the constituent packages.
-    #[arg(long)]
+    #[arg(long, value_parser = parse_file_path)]
     pub(crate) r#override: Vec<PathBuf>,
 
     /// Include optional dependencies in the given extra group name; may be provided more than once.
@@ -593,7 +608,7 @@ pub(crate) struct PipCompileArgs {
 #[allow(clippy::struct_excessive_bools)]
 pub(crate) struct PipSyncArgs {
     /// Include all packages listed in the given `requirements.txt` files.
-    #[arg(required(true))]
+    #[arg(required(true), value_parser = parse_file_path)]
     pub(crate) src_file: Vec<PathBuf>,
 
     /// Constrain versions using the given requirements files.
@@ -603,7 +618,7 @@ pub(crate) struct PipSyncArgs {
     /// trigger the installation of that package.
     ///
     /// This is equivalent to pip's `--constraint` option.
-    #[arg(long, short, env = "UV_CONSTRAINT", value_delimiter = ' ', value_parser = parse_file_path)]
+    #[arg(long, short, env = "UV_CONSTRAINT", value_delimiter = ' ', value_parser = parse_maybe_file_path)]
     pub(crate) constraint: Vec<Maybe<PathBuf>>,
 
     /// Reinstall all packages, regardless of whether they're already installed.
@@ -892,7 +907,7 @@ pub(crate) struct PipInstallArgs {
     pub(crate) package: Vec<String>,
 
     /// Install all packages listed in the given requirements files.
-    #[arg(long, short, group = "sources")]
+    #[arg(long, short, group = "sources", value_parser = parse_file_path)]
     pub(crate) requirement: Vec<PathBuf>,
 
     /// Install the editable package based on the provided local file path.
@@ -906,7 +921,7 @@ pub(crate) struct PipInstallArgs {
     /// trigger the installation of that package.
     ///
     /// This is equivalent to pip's `--constraint` option.
-    #[arg(long, short, env = "UV_CONSTRAINT", value_delimiter = ' ', value_parser = parse_file_path)]
+    #[arg(long, short, env = "UV_CONSTRAINT", value_delimiter = ' ', value_parser = parse_maybe_file_path)]
     pub(crate) constraint: Vec<Maybe<PathBuf>>,
 
     /// Override versions using the given requirements files.
@@ -918,7 +933,7 @@ pub(crate) struct PipInstallArgs {
     /// While constraints are _additive_, in that they're combined with the requirements of the
     /// constituent packages, overrides are _absolute_, in that they completely replace the
     /// requirements of the constituent packages.
-    #[arg(long)]
+    #[arg(long, value_parser = parse_file_path)]
     pub(crate) r#override: Vec<PathBuf>,
 
     /// Include optional dependencies in the given extra group name; may be provided more than once.
@@ -1259,7 +1274,7 @@ pub(crate) struct PipUninstallArgs {
     pub(crate) package: Vec<String>,
 
     /// Uninstall all packages listed in the given requirements files.
-    #[arg(long, short, group = "sources")]
+    #[arg(long, short, group = "sources", value_parser = parse_file_path)]
     pub(crate) requirement: Vec<PathBuf>,
 
     /// The Python interpreter from which packages should be uninstalled.

crates/uv/tests/pip_compile.rs

@@ -9629,3 +9629,29 @@ fn dynamic_pyproject_toml() -> Result<()> {
 
     Ok(())
 }
+
+/// Accept `file://` URLs as installation sources.
+#[test]
+fn file_url() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let requirements_txt = context.temp_dir.child("requirements file.txt");
+    requirements_txt.write_str("iniconfig")?;
+
+    let url = Url::from_file_path(requirements_txt.simple_canonicalize()?).expect("valid file URL");
+
+    uv_snapshot!(context.filters(), context.compile().arg(url.to_string()), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2024-03-25T00:00:00Z file://[TEMP_DIR]/requirements%20file.txt
+    iniconfig==2.0.0
+        # via -r requirements file.txt
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    "###);
+
+    Ok(())
+}