165 lines
4.3 KiB
C++
165 lines
4.3 KiB
C++
#include "profiles.hh"
|
||
#include "store-api.hh"
|
||
#include "util.hh"
|
||
|
||
#include <sys/types.h>
|
||
#include <sys/stat.h>
|
||
#include <unistd.h>
|
||
#include <errno.h>
|
||
#include <stdio.h>
|
||
|
||
|
||
namespace nix {
|
||
|
||
|
||
static bool cmpGensByNumber(const Generation & a, const Generation & b)
|
||
{
|
||
return a.number < b.number;
|
||
}
|
||
|
||
|
||
/* Parse a generation name of the format
|
||
`<profilename>-<number>-link'. */
|
||
static int parseName(const string & profileName, const string & name)
|
||
{
|
||
if (string(name, 0, profileName.size() + 1) != profileName + "-") return -1;
|
||
string s = string(name, profileName.size() + 1);
|
||
string::size_type p = s.find("-link");
|
||
if (p == string::npos) return -1;
|
||
int n;
|
||
if (string2Int(string(s, 0, p), n) && n >= 0)
|
||
return n;
|
||
else
|
||
return -1;
|
||
}
|
||
|
||
|
||
|
||
Generations findGenerations(Path profile, int & curGen)
|
||
{
|
||
Generations gens;
|
||
|
||
Path profileDir = dirOf(profile);
|
||
string profileName = baseNameOf(profile);
|
||
|
||
for (auto & i : readDirectory(profileDir)) {
|
||
int n;
|
||
if ((n = parseName(profileName, i.name)) != -1) {
|
||
Generation gen;
|
||
gen.path = profileDir + "/" + i.name;
|
||
gen.number = n;
|
||
struct stat st;
|
||
if (lstat(gen.path.c_str(), &st) != 0)
|
||
throw SysError(format("statting ‘%1%’") % gen.path);
|
||
gen.creationTime = st.st_mtime;
|
||
gens.push_back(gen);
|
||
}
|
||
}
|
||
|
||
gens.sort(cmpGensByNumber);
|
||
|
||
curGen = pathExists(profile)
|
||
? parseName(profileName, readLink(profile))
|
||
: -1;
|
||
|
||
return gens;
|
||
}
|
||
|
||
|
||
static void makeName(const Path & profile, unsigned int num,
|
||
Path & outLink)
|
||
{
|
||
Path prefix = (format("%1%-%2%") % profile % num).str();
|
||
outLink = prefix + "-link";
|
||
}
|
||
|
||
|
||
Path createGeneration(Path profile, Path outPath)
|
||
{
|
||
/* The new generation number should be higher than old the
|
||
previous ones. */
|
||
int dummy;
|
||
Generations gens = findGenerations(profile, dummy);
|
||
|
||
unsigned int num;
|
||
if (gens.size() > 0) {
|
||
Generation last = gens.back();
|
||
|
||
if (readLink(last.path) == outPath) {
|
||
/* We only create a new generation symlink if it differs
|
||
from the last one.
|
||
|
||
This helps keeping gratuitous installs/rebuilds from piling
|
||
up uncontrolled numbers of generations, cluttering up the
|
||
UI like grub. */
|
||
return last.path;
|
||
}
|
||
|
||
num = gens.back().number;
|
||
} else {
|
||
num = 0;
|
||
}
|
||
|
||
/* Create the new generation. Note that addPermRoot() blocks if
|
||
the garbage collector is running to prevent the stuff we've
|
||
built from moving from the temporary roots (which the GC knows)
|
||
to the permanent roots (of which the GC would have a stale
|
||
view). If we didn't do it this way, the GC might remove the
|
||
user environment etc. we've just built. */
|
||
Path generation;
|
||
makeName(profile, num + 1, generation);
|
||
addPermRoot(*store, outPath, generation, false, true);
|
||
|
||
return generation;
|
||
}
|
||
|
||
|
||
static void removeFile(const Path & path)
|
||
{
|
||
if (remove(path.c_str()) == -1)
|
||
throw SysError(format("cannot unlink ‘%1%’") % path);
|
||
}
|
||
|
||
|
||
void deleteGeneration(const Path & profile, unsigned int gen)
|
||
{
|
||
Path generation;
|
||
makeName(profile, gen, generation);
|
||
removeFile(generation);
|
||
}
|
||
|
||
|
||
void switchLink(Path link, Path target)
|
||
{
|
||
/* Hacky. */
|
||
if (dirOf(target) == dirOf(link)) target = baseNameOf(target);
|
||
|
||
Path tmp = canonPath(dirOf(link) + "/.new_" + baseNameOf(link));
|
||
createSymlink(target, tmp);
|
||
/* The rename() system call is supposed to be essentially atomic
|
||
on Unix. That is, if we have links `current -> X' and
|
||
`new_current -> Y', and we rename new_current to current, a
|
||
process accessing current will see X or Y, but never a
|
||
file-not-found or other error condition. This is sufficient to
|
||
atomically switch user environments. */
|
||
if (rename(tmp.c_str(), link.c_str()) != 0)
|
||
throw SysError(format("renaming ‘%1%’ to ‘%2%’") % tmp % link);
|
||
}
|
||
|
||
|
||
void lockProfile(PathLocks & lock, const Path & profile)
|
||
{
|
||
lock.lockPaths(singleton<PathSet>(profile),
|
||
(format("waiting for lock on profile ‘%1%’") % profile).str());
|
||
lock.setDeletion(true);
|
||
}
|
||
|
||
|
||
string optimisticLockProfile(const Path & profile)
|
||
{
|
||
return pathExists(profile) ? readLink(profile) : "";
|
||
}
|
||
|
||
|
||
}
|