Expose getpwuid #1140
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Expose getpwuid #1140
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asomers
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Oct 20, 2019
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I wonder if the range checking should be moved into getpwduid itself, instead of being done on every access. What do you think?
| /// | ||
| /// See also [getpwuid(2)](https://pubs.opengroup.org/onlinepubs/9699919799/functions/getpwuid.html) | ||
| pub fn getpwuid(uid: Uid) -> Result<Option<Passwd>> { | ||
| let mut inner: libc::passwd = unsafe { mem::zeroed() }; |
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This should use mem::MaybeUninit instead of mem::zeroed.
| /// See also [getpwuid(2)](https://pubs.opengroup.org/onlinepubs/9699919799/functions/getpwuid.html) | ||
| pub fn getpwuid(uid: Uid) -> Result<Option<Passwd>> { | ||
| let mut inner: libc::passwd = unsafe { mem::zeroed() }; | ||
| let mut result = ptr::null_mut(); |
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result, too, should use MaybeUninit.
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| #[test] | ||
| fn test_passwd() -> nix::Result<()> { | ||
| let passwd = getpwuid(getuid())? |
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Test functions should all return ().
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You should probably look at #1139. It overlaps with this one. |
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I'm going to close this PR, because I like #1139's approach better. It solves the same problem but in a different way. |
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Implement
getpwuid_r, which loads thepasswdentry for a givenUid, allowing you to find the user's name, shell, homedir, etc.I did not know what to do about the string ownership model. It returns us a
structfull of*const c_charpointers, which supposedly point to our buffer. I wrote new code to check these, to some extent, then trustCStrto do the rest. I did this because I couldn't find any other code innixthat did this (which must exist, someone point it out so I can slap my forehead), and to defer the cost of the checks to the time of use, i.e. so if you only want thename, you don't have to pay to check theshell.The code should be safe without the extra checks, if the system follows the rules, and I have no reason to believe otherwise; perhaps just deleting the extra checks is reasonable?
Also not handled: dynamically increasing the buffer size if the function returns that the buffer is too small.
GETPW_R_SIZE_MAXis1024on Ubuntu 19.10 / 5.3 / amd64.