job.rs 78.6%

77 of 98 lines run, 10 of 12 functions · run #202 on main · run missed

//! What a job's sandbox needs from inside, in either tier: its
//! environment, its program found in its own `PATH`, the usual `/dev`
//! links and `lo`. Compiled into `flow-init` (tier 2, the microVM's PID 1)
//! and into `flow` itself (tier 1, the syscall sandbox), so both start a
//! job the same way.

pub const PATH: &str = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin";

/// The file `program` names: itself when it holds a `/`, otherwise the first
/// executable regular file of that name in `path`'s directories.
pub fn resolve_program(program: &str, path: &str) -> Option<String> {
    use std::os::unix::fs::PermissionsExt;
    if program.is_empty() {
        return None;
    }
    if program.contains('/') {
        return Some(program.to_string());
    }
    path.split(':')
        .filter(|d| !d.is_empty())
        .map(|d| format!("{d}/{program}"))
        .find(|p| std::fs::metadata(p).is_ok_and(|m| m.is_file() && m.permissions().mode() & 0o111 != 0))
}

/// A job's environment: `PATH` and `HOME=/tmp` by default, then the
/// image's own (`/etc/flow/env`, written by `flow rootfs import --env`),
/// then the job's (its sandbox's and its own, already merged by the host).
/// Later ones win, so a pipeline can always set `PATH`.
pub fn job_env(image: Option<&str>, job: &[(String, String)]) -> std::collections::BTreeMap<String, String> {
    let mut env = std::collections::BTreeMap::new();
    env.insert("PATH".to_string(), PATH.to_string());
    env.insert("HOME".to_string(), "/tmp".to_string());
    for line in image.unwrap_or("").lines() {
        if let Some((k, v)) = line.split_once('=') {
            if !k.is_empty() {
                env.insert(k.to_string(), v.to_string());
            }
        }
    }
    for (k, v) in job {
        env.insert(k.clone(), v.clone());
    }
    env
}

/// The links every Linux system has under /dev and devtmpfs does not
/// make: `/dev/fd` (bash's process substitution, `<(…)`) and the standard
/// streams, all through the job's own /proc.
pub fn dev_links(dev: &str) -> Result<(), String> {
    for (name, target) in DEV_LINKS {
        let link = format!("{dev}/{name}");
        if std::fs::symlink_metadata(&link).is_err() {
            std::os::unix::fs::symlink(target, &link).map_err(|e| format!("link {link}: {e}"))?;
        }
    }
    Ok(())
}

const DEV_LINKS: [(&str, &str); 4] =
    [("fd", "/proc/self/fd"), ("stdin", "/proc/self/fd/0"), ("stdout", "/proc/self/fd/1"), ("stderr", "/proc/self/fd/2")];

/// Set `lo` up; the kernel gives it 127.0.0.1 and ::1 itself.
pub fn loopback_up() -> Result<(), String> {
    let fd = unsafe { libc::socket(libc::AF_INET, libc::SOCK_DGRAM | libc::SOCK_CLOEXEC, 0) };
    if fd < 0 {
        return Err(format!("socket for lo: {}", std::io::Error::last_os_error()));
    }
    let mut req: libc::ifreq = unsafe { std::mem::zeroed() };
    for (i, b) in b"lo".iter().enumerate() {
        req.ifr_name[i] = *b as libc::c_char;
    }
    let ok = unsafe {
        // `as _`: the request's type differs between libcs (Android's is c_int).
        libc::ioctl(fd, libc::SIOCGIFFLAGS as _, &mut req) == 0 && {
            req.ifr_ifru.ifru_flags |= libc::IFF_UP as libc::c_short;
            libc::ioctl(fd, libc::SIOCSIFFLAGS as _, &req) == 0
        }
    };
    let err = std::io::Error::last_os_error();
    unsafe { libc::close(fd) };
    if !ok {
        return Err(format!("bring up lo: {err}"));
    }
    Ok(())
}

#[cfg(test)]
mod tests {
    use super::{dev_links, job_env, resolve_program};

    #[test]
    fn the_image_environment_sits_under_the_jobs() {
        let image = "PATH=/opt/llvm-mos/bin:/usr/bin:/bin\nX16EMU=/opt/x16emu\nnot a line\n";
        let env = job_env(Some(image), &[("X16EMU".into(), "/job".into()), ("LANG".into(), "C".into())]);
        assert_eq!(env["PATH"], "/opt/llvm-mos/bin:/usr/bin:/bin", "the image's PATH replaces the default");
        assert_eq!(env["X16EMU"], "/job", "the job's value wins");
        assert_eq!(env["HOME"], "/tmp");
        assert_eq!(env["LANG"], "C");
        assert_eq!(job_env(None, &[])["PATH"], super::PATH);
    }

    #[test]
    fn dev_gets_the_usual_links_once() {
        let dir = std::env::temp_dir().join(format!("flow-init-dev-{}", std::process::id()));
        let _ = std::fs::remove_dir_all(&dir);
        std::fs::create_dir_all(&dir).unwrap();
        let d = dir.to_str().unwrap();
        dev_links(d).unwrap();
        dev_links(d).unwrap();
        assert_eq!(std::fs::read_link(dir.join("fd")).unwrap(), std::path::Path::new("/proc/self/fd"));
        assert_eq!(std::fs::read_link(dir.join("stdout")).unwrap(), std::path::Path::new("/proc/self/fd/1"));
        // Through the host's /proc, the link works as in a job.
        assert!(dir.join("fd").join("0").exists() || !std::path::Path::new("/proc/self/fd/0").exists());
        std::fs::remove_dir_all(&dir).unwrap();
    }

    use std::os::unix::fs::PermissionsExt;

    #[test]
    fn programs_are_found_in_the_jobs_path() {
        let dir = std::env::temp_dir().join(format!("flow-init-test-{}", std::process::id()));
        let (a, b) = (dir.join("a"), dir.join("b"));
        std::fs::create_dir_all(&a).unwrap();
        std::fs::create_dir_all(&b).unwrap();
        std::fs::write(a.join("tool"), "not executable").unwrap();
        std::fs::write(b.join("tool"), "#!/bin/sh\n").unwrap();
        std::fs::set_permissions(b.join("tool"), std::fs::Permissions::from_mode(0o755)).unwrap();
        std::fs::create_dir_all(a.join("dir")).unwrap();
        let path = format!("{}::{}", a.display(), b.display());
        assert_eq!(resolve_program("tool", &path), Some(format!("{}/tool", b.display())), "skips a file that is not executable");
        assert_eq!(resolve_program("dir", &path), None, "and directories");
        assert_eq!(resolve_program("missing", &path), None);
        assert_eq!(resolve_program("./x", &path).as_deref(), Some("./x"), "a path is used as given");
        assert_eq!(resolve_program("", &path), None);
        std::fs::remove_dir_all(&dir).unwrap();
    }
}

1		//! What a job's sandbox needs from inside, in either tier: its
2		//! environment, its program found in its own `PATH`, the usual `/dev`
3		//! links and `lo`. Compiled into `flow-init` (tier 2, the microVM's PID 1)
4		//! and into `flow` itself (tier 1, the syscall sandbox), so both start a
5		//! job the same way.
6
7		pub const PATH: &str = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin";
8
9		/// The file `program` names: itself when it holds a `/`, otherwise the first
10		/// executable regular file of that name in `path`'s directories.
11	5×	pub fn resolve_program(program: &str, path: &str) -> Option<String> {
12		use std::os::unix::fs::PermissionsExt;
13	5×	if program.is_empty() {
14	1×	return None;
15	4×	}
16	4×	if program.contains('/') {
17	1×	return Some(program.to_string());
18	3×	}
19	3×	path.split(':')
20	9×	.filter(\|d\| !d.is_empty())
21	6×	.map(\|d\| format!("{d}/{program}"))
22	6×	.find(\|p\| std::fs::metadata(p).is_ok_and(\|m\| m.is_file() && m.permissions().mode() & 0o111 != 0))
23	5×	}
24
25		/// A job's environment: `PATH` and `HOME=/tmp` by default, then the
26		/// image's own (`/etc/flow/env`, written by `flow rootfs import --env`),
27		/// then the job's (its sandbox's and its own, already merged by the host).
28		/// Later ones win, so a pipeline can always set `PATH`.
29	2×	pub fn job_env(image: Option<&str>, job: &[(String, String)]) -> std::collections::BTreeMap<String, String> {
30	2×	let mut env = std::collections::BTreeMap::new();
31	2×	env.insert("PATH".to_string(), PATH.to_string());
32	2×	env.insert("HOME".to_string(), "/tmp".to_string());
33	3×	for line in image.unwrap_or("").lines() {
34	3×	if let Some((k, v)) = line.split_once('=') {
35	2×	if !k.is_empty() {
36	2×	env.insert(k.to_string(), v.to_string());
37	2×	}
38	1×	}
39		}
40	2×	for (k, v) in job {
41	2×	env.insert(k.clone(), v.clone());
42	2×	}
43	2×	env
44	2×	}
45
46		/// The links every Linux system has under /dev and devtmpfs does not
47		/// make: `/dev/fd` (bash's process substitution, `<(…)`) and the standard
48		/// streams, all through the job's own /proc.
49	2×	pub fn dev_links(dev: &str) -> Result<(), String> {
50	8×	for (name, target) in DEV_LINKS {
51	8×	let link = format!("{dev}/{name}");
52	8×	if std::fs::symlink_metadata(&link).is_err() {
53	4×	std::os::unix::fs::symlink(target, &link).map_err(\|e\| format!("link {link}: {e}"))?;
54	4×	}
55		}
56	2×	Ok(())
57	2×	}
58
59		const DEV_LINKS: [(&str, &str); 4] =
60		[("fd", "/proc/self/fd"), ("stdin", "/proc/self/fd/0"), ("stdout", "/proc/self/fd/1"), ("stderr", "/proc/self/fd/2")];
61
62		/// Set `lo` up; the kernel gives it 127.0.0.1 and ::1 itself.
63	0×	pub fn loopback_up() -> Result<(), String> {
64	0×	let fd = unsafe { libc::socket(libc::AF_INET, libc::SOCK_DGRAM \| libc::SOCK_CLOEXEC, 0) };
65	0×	if fd < 0 {
66	0×	return Err(format!("socket for lo: {}", std::io::Error::last_os_error()));
67	0×	}
68	0×	let mut req: libc::ifreq = unsafe { std::mem::zeroed() };
69	0×	for (i, b) in b"lo".iter().enumerate() {
70	0×	req.ifr_name[i] = *b as libc::c_char;
71	0×	}
72	0×	let ok = unsafe {
73		// `as _`: the request's type differs between libcs (Android's is c_int).
74	0×	libc::ioctl(fd, libc::SIOCGIFFLAGS as _, &mut req) == 0 && {
75	0×	req.ifr_ifru.ifru_flags \|= libc::IFF_UP as libc::c_short;
76	0×	libc::ioctl(fd, libc::SIOCSIFFLAGS as _, &req) == 0
77		}
78		};
79	0×	let err = std::io::Error::last_os_error();
80	0×	unsafe { libc::close(fd) };
81	0×	if !ok {
82	0×	return Err(format!("bring up lo: {err}"));
83	0×	}
84	0×	Ok(())
85	0×	}
86
87		#[cfg(test)]
88		mod tests {
89		use super::{dev_links, job_env, resolve_program};
90
91		#[test]
92	1×	fn the_image_environment_sits_under_the_jobs() {
93	1×	let image = "PATH=/opt/llvm-mos/bin:/usr/bin:/bin\nX16EMU=/opt/x16emu\nnot a line\n";
94	1×	let env = job_env(Some(image), &[("X16EMU".into(), "/job".into()), ("LANG".into(), "C".into())]);
95	1×	assert_eq!(env["PATH"], "/opt/llvm-mos/bin:/usr/bin:/bin", "the image's PATH replaces the default");
96	1×	assert_eq!(env["X16EMU"], "/job", "the job's value wins");
97	1×	assert_eq!(env["HOME"], "/tmp");
98	1×	assert_eq!(env["LANG"], "C");
99	1×	assert_eq!(job_env(None, &[])["PATH"], super::PATH);
100	1×	}
101
102		#[test]
103	1×	fn dev_gets_the_usual_links_once() {
104	1×	let dir = std::env::temp_dir().join(format!("flow-init-dev-{}", std::process::id()));
105	1×	let _ = std::fs::remove_dir_all(&dir);
106	1×	std::fs::create_dir_all(&dir).unwrap();
107	1×	let d = dir.to_str().unwrap();
108	1×	dev_links(d).unwrap();
109	1×	dev_links(d).unwrap();
110	1×	assert_eq!(std::fs::read_link(dir.join("fd")).unwrap(), std::path::Path::new("/proc/self/fd"));
111	1×	assert_eq!(std::fs::read_link(dir.join("stdout")).unwrap(), std::path::Path::new("/proc/self/fd/1"));
112		// Through the host's /proc, the link works as in a job.
113	1×	assert!(dir.join("fd").join("0").exists() \|\| !std::path::Path::new("/proc/self/fd/0").exists());
114	1×	std::fs::remove_dir_all(&dir).unwrap();
115	1×	}
116
117		use std::os::unix::fs::PermissionsExt;
118
119		#[test]
120	1×	fn programs_are_found_in_the_jobs_path() {
121	1×	let dir = std::env::temp_dir().join(format!("flow-init-test-{}", std::process::id()));
122	1×	let (a, b) = (dir.join("a"), dir.join("b"));
123	1×	std::fs::create_dir_all(&a).unwrap();
124	1×	std::fs::create_dir_all(&b).unwrap();
125	1×	std::fs::write(a.join("tool"), "not executable").unwrap();
126	1×	std::fs::write(b.join("tool"), "#!/bin/sh\n").unwrap();
127	1×	std::fs::set_permissions(b.join("tool"), std::fs::Permissions::from_mode(0o755)).unwrap();
128	1×	std::fs::create_dir_all(a.join("dir")).unwrap();
129	1×	let path = format!("{}::{}", a.display(), b.display());
130	1×	assert_eq!(resolve_program("tool", &path), Some(format!("{}/tool", b.display())), "skips a file that is not executable");
131	1×	assert_eq!(resolve_program("dir", &path), None, "and directories");
132	1×	assert_eq!(resolve_program("missing", &path), None);
133	1×	assert_eq!(resolve_program("./x", &path).as_deref(), Some("./x"), "a path is used as given");
134	1×	assert_eq!(resolve_program("", &path), None);
135	1×	std::fs::remove_dir_all(&dir).unwrap();
136	1×	}
137		}

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Coverage / crates/flow-init/src/job.rs 78.6%

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