Extract GitHub token from file if --github-token or env variable GITHUB_TOKEN is not present (#849)

- Add option `--no-discover-github-token` for disabling this behavior
 - Add new dep gh-token v0.1.0 to crates/bin
 - Extract github-token from git-credentials or gh config if `--github-token` or
    environment variable `GITHUB_TOKEN` is not present.

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

crates/bin/src/args.rs

@@ -1,7 +1,7 @@
 use std::{
     env,
     ffi::OsString,
-    fmt,
+    fmt, fs, iter,
     num::{NonZeroU64, ParseIntError},
     path::PathBuf,
     str::FromStr,
@@ -14,6 +14,7 @@ use binstalk::{
 };
 use clap::{error::ErrorKind, CommandFactory, Parser, ValueEnum};
 use compact_str::CompactString;
+use dirs::home_dir;
 use log::LevelFilter;
 use semver::VersionReq;
 use strum::EnumCount;
@@ -145,6 +146,14 @@ pub struct Args {
     #[clap(help_heading = "Overrides", long, value_delimiter(','))]
     pub disable_strategies: Vec<Strategy>,
 
+    /// If `--github-token` or environment variable `GITHUB_TOKEN` is not
+    /// specified, then cargo-binstall will try to extract github token from
+    /// `$HOME/.git-credentials` or `$HOME/.config/gh/hosts.yml` by default.
+    ///
+    /// This option can be used to disable that behavior.
+    #[clap(help_heading = "Overrides", long)]
+    pub no_discover_github_token: bool,
+
     /// Disable symlinking / versioned updates.
     ///
     /// By default, Binstall will install a binary named `<name>-<version>` in the install path, and
@@ -452,9 +461,52 @@ You cannot use --{option} and specify multiple packages at the same time. Do one
             .exit()
     }
 
+    if opts.github_token.is_none() && !opts.no_discover_github_token {
+        if let Some(github_token) = try_extract_from_git_credentials() {
+            opts.github_token = Some(github_token);
+        } else if let Ok(github_token) = gh_token::get() {
+            opts.github_token = Some(github_token.into());
+        }
+    }
+
     opts
 }
 
+fn try_extract_from_git_credentials() -> Option<CompactString> {
+    home_dir()
+        .map(|mut home| {
+            home.push(".git-credentials");
+            home
+        })
+        .into_iter()
+        .chain(iter::from_fn(|| {
+            let home = env::var_os("XDG_CONFIG_HOME")?;
+            (!home.is_empty()).then(|| {
+                let mut path = PathBuf::from(home);
+                path.push("git/credentials");
+                path
+            })
+        }))
+        .find_map(try_extract_from_git_credentials_from)
+}
+
+fn try_extract_from_git_credentials_from(path: PathBuf) -> Option<CompactString> {
+    fs::read_to_string(path)
+        .ok()?
+        .lines()
+        .find_map(extract_github_token_from_git_credentials_line)
+        .map(CompactString::from)
+}
+
+fn extract_github_token_from_git_credentials_line(line: &str) -> Option<&str> {
+    let cred = line
+        .trim()
+        .strip_prefix("https://")?
+        .strip_suffix("@github.com")?;
+
+    Some(cred.split_once(':')?.1)
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
@@ -463,4 +515,24 @@ mod test {
     fn verify_cli() {
         Args::command().debug_assert()
     }
+
+    const GIT_CREDENTIALS_TEST_CASES: &[(&str, Option<&str>)] = &[
+        // Success
+        ("https://NobodyXu:gho_asdc@github.com", Some("gho_asdc")),
+        (
+            "https://NobodyXu:gho_asdc12dz@github.com",
+            Some("gho_asdc12dz"),
+        ),
+        // Failure
+        ("http://NobodyXu:gho_asdc@github.com", None),
+        ("https://NobodyXu:gho_asdc@gitlab.com", None),
+        ("https://NobodyXugho_asdc@github.com", None),
+    ];
+
+    #[test]
+    fn test_extract_github_token_from_git_credentials_line() {
+        GIT_CREDENTIALS_TEST_CASES.iter().for_each(|(line, res)| {
+            assert_eq!(extract_github_token_from_git_credentials_line(line), *res);
+        })
+    }
 }