Add environment variables support

src/lib.rs

@@ -77,7 +77,10 @@
 //! reflect the fact that no Pager is active.
 
 #![doc(html_root_url = "https://docs.rs/pager/0.15.0")]
-#![cfg_attr(all(feature = "cargo-clippy", feature = "pedantic"), warn(clippy_pedantic))]
+#![cfg_attr(
+    all(feature = "cargo-clippy", feature = "pedantic"),
+    warn(clippy_pedantic)
+)]
 
 extern crate errno;
 extern crate libc;
@@ -101,6 +104,7 @@ const DEFAULT_PAGER: &str = "more";
 pub struct Pager {
     default_pager: Option<OsString>,
     pager: Option<OsString>,
+    envs: Vec<OsString>,
     on: bool,
     skip_on_notty: bool,
 }
@@ -110,6 +114,7 @@ impl Default for Pager {
         Self {
             default_pager: None,
             pager: env::var_os(DEFAULT_PAGER_ENV),
+            envs: Vec::new(),
             on: true,
             skip_on_notty: true,
         }
@@ -155,6 +160,14 @@ impl Pager {
         }
     }
 
+    /// Launch pager with the specified environment variables
+    pub fn set_pager_envs(self, envs: &[&str]) -> Self {
+        Self {
+            envs: envs.into_iter().map(|x| x.into()).collect(),
+            ..self
+        }
+    }
+
     /// Instructs `Pager` to bypass invoking pager if output is not a `tty`
     #[deprecated(since = "0.14.0", note = "'skip_on_notty' is default now")]
     pub fn skip_on_notty(self) -> Self {
@@ -208,7 +221,11 @@ impl Pager {
                     // I am parent
                     utils::dup2(pager_stdin, libc::STDIN_FILENO);
                     utils::close(main_stdout);
-                    utils::execvp(pager);
+                    if self.envs.is_empty() {
+                        utils::execvp(pager);
+                    } else {
+                        utils::execvpe(pager, &self.envs);
+                    }
                 }
             }
         } else {

src/utils.rs

@@ -32,6 +32,30 @@ pub fn execvp(cmd: &OsString) {
     unsafe { libc::execvp(args[0], args.as_ptr()) };
 }
 
+pub fn execvpe(cmd: &OsString, envs: &[OsString]) {
+    let cstrings = split_string(cmd)
+        .into_iter()
+        .map(osstring2cstring)
+        .collect::<Vec<_>>();
+    let mut args = cstrings.iter().map(|c| c.as_ptr()).collect::<Vec<_>>();
+    args.push(ptr::null());
+
+    let mut cstrings_envs = envs
+        .into_iter()
+        .map(|s| osstring2cstring(s.clone()))
+        .collect::<Vec<_>>();
+    for (mut k, v) in std::env::vars_os() {
+        k.push("=");
+        k.push(v);
+        cstrings_envs.push(osstring2cstring(k));
+    }
+    let mut envs = cstrings_envs.iter().map(|c| c.as_ptr()).collect::<Vec<_>>();
+    envs.push(ptr::null());
+
+    errno::set_errno(errno::Errno(0));
+    unsafe { libc::execvpe(args[0], args.as_ptr(), envs.as_ptr()) };
+}
+
 pub fn dup2(fd1: i32, fd2: i32) {
     assert!(unsafe { libc::dup2(fd1, fd2) } > -1);
 }