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Retry lookups with larger buffer sizes on ERANGE #38

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Merged
merged 2 commits into from
Oct 7, 2020
Merged

Retry lookups with larger buffer sizes on ERANGE #38

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9ba0446
Retry lookups with larger buffer sizes on ERANGE
Freaky May 20, 2020
43ed211
Defend against overflow, and fix for 1.31
Freaky Aug 17, 2020
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60 changes: 48 additions & 12 deletions src/base.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -322,14 +322,23 @@ unsafe fn members(groups: *mut *mut c_char) -> Vec<OsString> {
/// ```
pub fn get_user_by_uid(uid: uid_t) -> Option<User> {
let mut passwd = unsafe { mem::zeroed::<c_passwd>() };
let mut buf = vec![0; 2048]; // TODO: Retry with larger buffer sizes
let mut buf = vec![0; 2048];
let mut result = ptr::null_mut::<c_passwd>();

#[cfg(feature = "logging")]
debug!("Running getpwuid_r for user #{}", uid);

unsafe {
libc::getpwuid_r(uid, &mut passwd, buf.as_mut_ptr(), buf.len(), &mut result);
loop {
let r = unsafe {
libc::getpwuid_r(uid, &mut passwd, buf.as_mut_ptr(), buf.len(), &mut result)
};

if r != libc::ERANGE {
break;
}

let newsize = buf.len().checked_mul(2)?;
buf.resize(newsize, 0);
}

if result.is_null() {
Expand Down Expand Up @@ -375,14 +384,23 @@ pub fn get_user_by_name<S: AsRef<OsStr> + ?Sized>(username: &S) -> Option<User>
};

let mut passwd = unsafe { mem::zeroed::<c_passwd>() };
let mut buf = vec![0; 2048]; // TODO: Retry with larger buffer sizes
let mut buf = vec![0; 2048];
let mut result = ptr::null_mut::<c_passwd>();

#[cfg(feature = "logging")]
debug!("Running getpwnam_r for user {:?}", username.as_ref());

unsafe {
libc::getpwnam_r(username.as_ptr(), &mut passwd, buf.as_mut_ptr(), buf.len(), &mut result);
loop {
let r = unsafe {
libc::getpwnam_r(username.as_ptr(), &mut passwd, buf.as_mut_ptr(), buf.len(), &mut result)
};

if r != libc::ERANGE {
break;
}

let newsize = buf.len().checked_mul(2)?;
buf.resize(newsize, 0);
}

if result.is_null() {
Expand Down Expand Up @@ -419,14 +437,23 @@ pub fn get_user_by_name<S: AsRef<OsStr> + ?Sized>(username: &S) -> Option<User>
/// ```
pub fn get_group_by_gid(gid: gid_t) -> Option<Group> {
let mut passwd = unsafe { mem::zeroed::<c_group>() };
let mut buf = vec![0; 2048]; // TODO: Retry with larger buffer sizes
let mut buf = vec![0; 2048];
let mut result = ptr::null_mut::<c_group>();

#[cfg(feature = "logging")]
debug!("Running getgruid_r for group #{}", gid);

unsafe {
libc::getgrgid_r(gid, &mut passwd, buf.as_mut_ptr(), buf.len(), &mut result);
loop {
let r = unsafe {
libc::getgrgid_r(gid, &mut passwd, buf.as_mut_ptr(), buf.len(), &mut result)
};

if r != libc::ERANGE {
break;
}

let newsize = buf.len().checked_mul(2)?;
buf.resize(newsize, 0);
}

if result.is_null() {
Expand Down Expand Up @@ -472,14 +499,23 @@ pub fn get_group_by_name<S: AsRef<OsStr> + ?Sized>(groupname: &S) -> Option<Grou
};

let mut group = unsafe { mem::zeroed::<c_group>() };
let mut buf = vec![0; 2048]; // TODO: Retry with larger buffer sizes
let mut buf = vec![0; 2048];
let mut result = ptr::null_mut::<c_group>();

#[cfg(feature = "logging")]
debug!("Running getgrnam_r for group {:?}", groupname.as_ref());

unsafe {
libc::getgrnam_r(groupname.as_ptr(), &mut group, buf.as_mut_ptr(), buf.len(), &mut result);
loop {
let r = unsafe {
libc::getgrnam_r(groupname.as_ptr(), &mut group, buf.as_mut_ptr(), buf.len(), &mut result)
};

if r != libc::ERANGE {
break;
}

let newsize = buf.len().checked_mul(2)?;
buf.resize(newsize, 0);
}

if result.is_null() {
Expand Down