posixGetUserInfo
TODO this reads /etc/passwd. But sometimes the user/id mapping is in something else
like NIS, AD, etc. See man nss or look at an strace for id myuser.
Function parameters
Parameters
- name:[]const u8
Type definitions in this namespace
Types
- ArgIteratorWindows
- Iterator that implements the Windows command-line parsing algorithm.
- ArgIteratorGeneralOptions
- Optional parameters for `ArgIteratorGeneral`
- ArgIterator
- Cross-platform command line argument iterator.
Functions in this namespace
Functions
- getCwd
- The result is a slice of `out_buffer`, from index `0`.
- getCwdAlloc
- Caller must free the returned memory.
- getEnvMap
- Returns a snapshot of the environment variables of the current process.
- getEnvVarOwned
- Caller must free returned memory.
- hasEnvVarConstant
- On Windows, `key` must be valid WTF-8.
- hasNonEmptyEnvVarConstant
- On Windows, `key` must be valid WTF-8.
- parseEnvVarInt
- Parses an environment variable as an integer.
- hasEnvVar
- On Windows, if `key` is not valid [WTF-8](https://simonsapin.github.io/wtf-8/),
- hasNonEmptyEnvVar
- On Windows, if `key` is not valid [WTF-8](https://simonsapin.github.io/wtf-8/),
- getenvW
- Windows-only.
- ArgIteratorGeneral
- A general Iterator to parse a string into a set of arguments
- args
- Holds the command-line arguments, with the program name as the first entry.
- argsWithAllocator
- You must deinitialize iterator's internal buffers by calling `deinit` when done.
- argsAlloc
- Caller must call argsFree on result.
- getUserInfo
- POSIX function which gets a uid from username.
- posixGetUserInfo
- TODO this reads /etc/passwd.
- execv
- Replaces the current process image with the executed process.
- execve
- Replaces the current process image with the executed process.
- totalSystemMemory
- Returns the total system memory, in bytes as a u64.
- cleanExit
- Indicate that we are now terminating with a successful exit code.
- raiseFileDescriptorLimit
- Raise the open file descriptor limit.
- createEnvironFromMap
- Creates a null-delimited environment variable block in the format
- createEnvironFromExisting
- Creates a null-delimited environment variable block in the format
- createWindowsEnvBlock
- Caller must free result.
- fatal
- Logs an error and then terminates the process with exit code 1.
Error sets in this namespace
Error Sets
Tells whether calling the `execv` or `execve` functions will be a compile error.
Values
Source
Implementation
pub fn posixGetUserInfo(name: []const u8) !UserInfo {
const file = try std.fs.openFileAbsolute("/etc/passwd", .{});
defer file.close();
const reader = file.deprecatedReader();
const State = enum {
Start,
WaitForNextLine,
SkipPassword,
ReadUserId,
ReadGroupId,
};
var buf: [std.heap.page_size_min]u8 = undefined;
var name_index: usize = 0;
var state = State.Start;
var uid: posix.uid_t = 0;
var gid: posix.gid_t = 0;
while (true) {
const amt_read = try reader.read(buf[0..]);
for (buf[0..amt_read]) |byte| {
switch (state) {
.Start => switch (byte) {
':' => {
state = if (name_index == name.len) State.SkipPassword else State.WaitForNextLine;
},
'\n' => return error.CorruptPasswordFile,
else => {
if (name_index == name.len or name[name_index] != byte) {
state = .WaitForNextLine;
}
name_index += 1;
},
},
.WaitForNextLine => switch (byte) {
'\n' => {
name_index = 0;
state = .Start;
},
else => continue,
},
.SkipPassword => switch (byte) {
'\n' => return error.CorruptPasswordFile,
':' => {
state = .ReadUserId;
},
else => continue,
},
.ReadUserId => switch (byte) {
':' => {
state = .ReadGroupId;
},
'\n' => return error.CorruptPasswordFile,
else => {
const digit = switch (byte) {
'0'...'9' => byte - '0',
else => return error.CorruptPasswordFile,
};
{
const ov = @mulWithOverflow(uid, 10);
if (ov[1] != 0) return error.CorruptPasswordFile;
uid = ov[0];
}
{
const ov = @addWithOverflow(uid, digit);
if (ov[1] != 0) return error.CorruptPasswordFile;
uid = ov[0];
}
},
},
.ReadGroupId => switch (byte) {
'\n', ':' => {
return UserInfo{
.uid = uid,
.gid = gid,
};
},
else => {
const digit = switch (byte) {
'0'...'9' => byte - '0',
else => return error.CorruptPasswordFile,
};
{
const ov = @mulWithOverflow(gid, 10);
if (ov[1] != 0) return error.CorruptPasswordFile;
gid = ov[0];
}
{
const ov = @addWithOverflow(gid, digit);
if (ov[1] != 0) return error.CorruptPasswordFile;
gid = ov[0];
}
},
},
}
}
if (amt_read < buf.len) return error.UserNotFound;
}
}