#
cargo/ops/
common_for_install_and_uninstall.rs

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83
    84
    85
    86
    87
    88
    89
    90
    91
    92
    93
    94
    95
    96
    97
    98
    99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155
    156
    157
    158
    159
    160
    161
    162
    163
    164
    165
    166
    167
    168
    169
    170
    171
    172
    173
    174
    175
    176
    177
    178
    179
    180
    181
    182
    183
    184
    185
    186
    187
    188
    189
    190
    191
    192
    193
    194
    195
    196
    197
    198
    199
    200
    201
    202
    203
    204
    205
    206
    207
    208
    209
    210
    211
    212
    213
    214
    215
    216
    217
    218
    219
    220
    221
    222
    223
    224
    225
    226
    227
    228
    229
    230
    231
    232
    233
    234
    235
    236
    237
    238
    239
    240
    241
    242
    243
    244
    245
    246
    247
    248
    249
    250
    251
    252
    253
    254
    255
    256
    257
    258
    259
    260
    261
    262
    263
    264
    265
    266
    267
    268
    269
    270
    271
    272
    273
    274
    275
    276
    277
    278
    279
    280
    281
    282
    283
    284
    285
    286
    287
    288
    289
    290
    291
    292
    293
    294
    295
    296
    297
    298
    299
    300
    301
    302
    303
    304
    305
    306
    307
    308
    309
    310
    311
    312
    313
    314
    315
    316
    317
    318
    319
    320
    321
    322
    323
    324
    325
    326
    327
    328
    329
    330
    331
    332
    333
    334
    335
    336
    337
    338
    339
    340
    341
    342
    343
    344
    345
    346
    347
    348
    349
    350
    351
    352
    353
    354
    355
    356
    357
    358
    359
    360
    361
    362
    363
    364
    365
    366
    367
    368
    369
    370
    371
    372
    373
    374
    375
    376
    377
    378
    379
    380
    381
    382
    383
    384
    385
    386
    387
    388
    389
    390
    391
    392
    393
    394
    395
    396
    397
    398
    399
    400
    401
    402
    403
    404
    405
    406
    407
    408
    409
    410
    411
    412
    413
    414
    415
    416
    417
    418
    419
    420
    421
    422
    423
    424
    425
    426
    427
    428
    429
    430
    431
    432
    433
    434
    435
    436
    437
    438
    439
    440
    441
    442
    443
    444
    445
    446
    447
    448
    449
    450
    451
    452
    453
    454
    455
    456
    457
    458
    459
    460
    461
    462
    463
    464
    465
    466
    467
    468
    469
    470
    471
    472
    473
    474
    475
    476
    477
    478
    479
    480
    481
    482
    483
    484
    485
    486
    487
    488
    489
    490
    491
    492
    493
    494
    495
    496
    497
    498
    499
    500
    501
    502
    503
    504
    505
    506
    507
    508
    509
    510
    511
    512
    513
    514
    515
    516
    517
    518
    519
    520
    521
    522
    523
    524
    525
    526
    527
    528
    529
    530
    531
    532
    533
    534
    535
    536
    537
    538
    539
    540
    541
    542
    543
    544
    545
    546
    547
    548
    549
    550
    551
    552
    553
    554
    555
    556
    557
    558
    559
    560
    561
    562
    563
    564
    565
    566
    567
    568
    569
    570
    571
    572
    573
    574
    575
    576
    577
    578
    579
    580
    581
    582
    583
    584
    585
    586
    587
    588
    589
    590
    591
    592
    593
    594
    595
    596
    597
    598
    599
    600
    601
    602
    603
    604
    605
    606
    607
    608
    609
    610
    611
    612
    613
    614
    615
    616
    617
    618
    619
    620
    621
    622
    623
    624
    625
    626
    627
    628
    629
    630
    631
    632
    633
    634
    635
    636
    637
    638
    639
    640
    641
    642
    643
    644
    645
    646
    647
    648
    649
    650
    651
    652
    653
    654
    655
    656
    657
    658
    659
    660
    661
    662
    663
    664
    665
    666
    667
    668
    669
    670
    671
    672
    673
    674
    675
    676
    677
    678
    679
    680
    681
    682
    683
    684
    685
    686
    687
    688
    689
    690
    691
    692
    693
    694
    695
    696
    697
    698
    699
    700
    701
    702
    703
    704
    705
    706
    707
    708
    709
    710
    711
    712
    713
    714
    715
    716
    717
    718
    719
    720
    721
    722
    723
    724
    725
    726
    727
    728
    729
    730
    731
    732
    733
    734
    735
    736
    737
    738
    739
    740
    741
    742
    743
    744
    745
    746
    747
    748
    749
    750
    751
    752
    753
    754
    755
    756
    757
    758
    759
    760
    761
    762
    763
    764
    765
    766
    767
    768
    769
    770
    771
    772
    773
    774
    775
    776
    777
    778
    779
    780
    781
    782
    783
    784
    785
    786
    787
    788
    789
    790
    791
    792
    793
    794
    795
    796
    797
    798
    799
    800
    801
    802
    803
    804
    805
    806
    807
    808
    809
    810
    811
    812

    use std::collections::{btree_map, BTreeMap, BTreeSet};
    use std::env;
    use std::io::prelude::*;
    use std::io::SeekFrom;
    use std::path::{Path, PathBuf};
    use std::rc::Rc;
    use std::task::Poll;

    use anyhow::{bail, format_err, Context as _};
    use cargo_util::paths;
    use cargo_util_schemas::core::PartialVersion;
    use ops::FilterRule;
    use serde::{Deserialize, Serialize};

    use crate::core::compiler::{DirtyReason, Freshness};
    use crate::core::Target;
    use crate::core::{Dependency, FeatureValue, Package, PackageId, SourceId};
    use crate::ops::{self, CompileFilter, CompileOptions};
    use crate::sources::source::QueryKind;
    use crate::sources::source::Source;
    use crate::sources::PathSource;
    use crate::util::cache_lock::CacheLockMode;
    use crate::util::errors::CargoResult;
    use crate::util::GlobalContext;
    use crate::util::{FileLock, Filesystem};

    /// On-disk tracking for which package installed which binary.
    ///
    /// v1 is an older style, v2 is a new style that tracks more information, and
    /// is both backwards and forwards compatible. Cargo keeps both files in sync,
    /// updating both v1 and v2 at the same time. Additionally, if it detects
    /// changes in v1 that are not in v2 (such as when an older version of Cargo
    /// is used), it will automatically propagate those changes to v2.
    ///
    /// This maintains a filesystem lock, preventing other instances of Cargo from
    /// modifying at the same time. Drop the value to unlock.
    ///
    /// It is intended that v1 should be retained for a while during a longish
    /// transition period, and then v1 can be removed.
    pub struct InstallTracker {
        v1: CrateListingV1,
        v2: CrateListingV2,
        v1_lock: FileLock,
        v2_lock: FileLock,
    }

    /// Tracking information for the set of installed packages.
    #[derive(Default, Deserialize, Serialize)]
    struct CrateListingV2 {
        /// Map of every installed package.
        installs: BTreeMap<PackageId, InstallInfo>,
        /// Forwards compatibility. Unknown keys from future versions of Cargo
        /// will be stored here and retained when the file is saved.
        #[serde(flatten)]
        other: BTreeMap<String, serde_json::Value>,
    }

    /// Tracking information for the installation of a single package.
    ///
    /// This tracks the settings that were used when the package was installed.
    /// Future attempts to install the same package will check these settings to
    /// determine if it needs to be rebuilt/reinstalled. If nothing has changed,
    /// then Cargo will inform the user that it is "up to date".
    ///
    /// This is only used for the v2 format.
    #[derive(Debug, Deserialize, Serialize)]
    struct InstallInfo {
        /// Version requested via `--version`.
        /// None if `--version` not specified. Currently not used, possibly may be
        /// used in the future.
        version_req: Option<String>,
        /// Set of binary names installed.
        bins: BTreeSet<String>,
        /// Set of features explicitly enabled.
        features: BTreeSet<String>,
        all_features: bool,
        no_default_features: bool,
        /// Either "debug" or "release".
        profile: String,
        /// The installation target.
        /// Either the host or the value specified in `--target`.
        /// None if unknown (when loading from v1).
        target: Option<String>,
        /// Output of `rustc -V`.
        /// None if unknown (when loading from v1).
        /// Currently not used, possibly may be used in the future.
        rustc: Option<String>,
        /// Forwards compatibility.
        #[serde(flatten)]
        other: BTreeMap<String, serde_json::Value>,
    }

    /// Tracking information for the set of installed packages.
    #[derive(Default, Deserialize, Serialize)]
    pub struct CrateListingV1 {
        /// Map of installed package id to the set of binary names for that package.
        v1: BTreeMap<PackageId, BTreeSet<String>>,
    }

    impl InstallTracker {
        /// Create an `InstallTracker` from information on disk.
        pub fn load(gctx: &GlobalContext, root: &Filesystem) -> CargoResult<InstallTracker> {
            let v1_lock =
                root.open_rw_exclusive_create(Path::new(".crates.toml"), gctx, "crate metadata")?;
            let v2_lock =
                root.open_rw_exclusive_create(Path::new(".crates2.json"), gctx, "crate metadata")?;

            let v1 = (|| -> CargoResult<_> {
                let mut contents = String::new();
                v1_lock.file().read_to_string(&mut contents)?;
                if contents.is_empty() {
                    Ok(CrateListingV1::default())
                } else {
                    Ok(toml::from_str(&contents).context("invalid TOML found for metadata")?)
                }
            })()
            .with_context(|| {
                format!(
                    "failed to parse crate metadata at `{}`",
                    v1_lock.path().to_string_lossy()
                )
            })?;

            let v2 = (|| -> CargoResult<_> {
                let mut contents = String::new();
                v2_lock.file().read_to_string(&mut contents)?;
                let mut v2 = if contents.is_empty() {
                    CrateListingV2::default()
                } else {
                    serde_json::from_str(&contents).context("invalid JSON found for metadata")?
                };
                v2.sync_v1(&v1);
                Ok(v2)
            })()
            .with_context(|| {
                format!(
                    "failed to parse crate metadata at `{}`",
                    v2_lock.path().to_string_lossy()
                )
            })?;

            Ok(InstallTracker {
                v1,
                v2,
                v1_lock,
                v2_lock,
            })
        }

        /// Checks if the given package should be built, and checks if executables
        /// already exist in the destination directory.
        ///
        /// Returns a tuple `(freshness, map)`. `freshness` indicates if the
        /// package should be built (`Dirty`) or if it is already up-to-date
        /// (`Fresh`) and should be skipped. The map maps binary names to the
        /// `PackageId` that installed it (which is `None` if not known).
        ///
        /// If there are no duplicates, then it will be considered `Dirty` (i.e.,
        /// it is OK to build/install).
        ///
        /// `force=true` will always be considered `Dirty` (i.e., it will always
        /// be rebuilt/reinstalled).
        ///
        /// Returns an error if there is a duplicate and `--force` is not used.
        pub fn check_upgrade(
            &self,
            dst: &Path,
            pkg: &Package,
            force: bool,
            opts: &CompileOptions,
            target: &str,
            _rustc: &str,
        ) -> CargoResult<(Freshness, BTreeMap<String, Option<PackageId>>)> {
            let exes = exe_names(pkg, &opts.filter);
            // Check if any tracked exe's are already installed.
            let duplicates = self.find_duplicates(dst, &exes);
            if force || duplicates.is_empty() {
                return Ok((Freshness::Dirty(DirtyReason::Forced), duplicates));
            }
            // Check if all duplicates come from packages of the same name. If
            // there are duplicates from other packages, then --force will be
            // required.
            //
            // There may be multiple matching duplicates if different versions of
            // the same package installed different binaries.
            //
            // This does not check the source_id in order to allow the user to
            // switch between different sources. For example, installing from git,
            // and then switching to the official crates.io release or vice-versa.
            // If the source_id were included, then the user would get possibly
            // confusing errors like "package `foo 1.0.0` is already installed"
            // and the change of source may not be obvious why it fails.
            let matching_duplicates: Vec<PackageId> = duplicates
                .values()
                .filter_map(|v| match v {
                    Some(dupe_pkg_id) if dupe_pkg_id.name() == pkg.name() => Some(*dupe_pkg_id),
                    _ => None,
                })
                .collect();

            // If both sets are the same length, that means all duplicates come
            // from packages with the same name.
            if matching_duplicates.len() == duplicates.len() {
                // Determine if it is dirty or fresh.
                let source_id = pkg.package_id().source_id();
                if source_id.is_path() {
                    // `cargo install --path ...` is always rebuilt.
                    return Ok((Freshness::Dirty(DirtyReason::Forced), duplicates));
                }
                let is_up_to_date = |dupe_pkg_id| {
                    let info = self
                        .v2
                        .installs
                        .get(dupe_pkg_id)
                        .expect("dupes must be in sync");
                    let precise_equal = if source_id.is_git() {
                        // Git sources must have the exact same hash to be
                        // considered "fresh".
                        dupe_pkg_id.source_id().has_same_precise_as(source_id)
                    } else {
                        true
                    };

                    dupe_pkg_id.version() == pkg.version()
                        && dupe_pkg_id.source_id() == source_id
                        && precise_equal
                        && info.is_up_to_date(opts, target, &exes)
                };
                if matching_duplicates.iter().all(is_up_to_date) {
                    Ok((Freshness::Fresh, duplicates))
                } else {
                    Ok((Freshness::Dirty(DirtyReason::Forced), duplicates))
                }
            } else {
                // Format the error message.
                let mut msg = String::new();
                for (bin, p) in duplicates.iter() {
                    msg.push_str(&format!("binary `{}` already exists in destination", bin));
                    if let Some(p) = p.as_ref() {
                        msg.push_str(&format!(" as part of `{}`\n", p));
                    } else {
                        msg.push('\n');
                    }
                }
                msg.push_str("Add --force to overwrite");
                bail!("{}", msg);
            }
        }

        /// Check if any executables are already installed.
        ///
        /// Returns a map of duplicates, the key is the executable name and the
        /// value is the `PackageId` that is already installed. The `PackageId` is
        /// None if it is an untracked executable.
        fn find_duplicates(
            &self,
            dst: &Path,
            exes: &BTreeSet<String>,
        ) -> BTreeMap<String, Option<PackageId>> {
            exes.iter()
                .filter_map(|name| {
                    if !dst.join(&name).exists() {
                        None
                    } else {
                        let p = self.v2.package_for_bin(name);
                        Some((name.clone(), p))
                    }
                })
                .collect()
        }

        /// Mark that a package was installed.
        pub fn mark_installed(
            &mut self,
            package: &Package,
            bins: &BTreeSet<String>,
            version_req: Option<String>,
            opts: &CompileOptions,
            target: &str,
            rustc: &str,
        ) {
            self.v2
                .mark_installed(package, bins, version_req, opts, target, rustc);
            self.v1.mark_installed(package, bins);
        }

        /// Save tracking information to disk.
        pub fn save(&self) -> CargoResult<()> {
            self.v1.save(&self.v1_lock).with_context(|| {
                format!(
                    "failed to write crate metadata at `{}`",
                    self.v1_lock.path().to_string_lossy()
                )
            })?;

            self.v2.save(&self.v2_lock).with_context(|| {
                format!(
                    "failed to write crate metadata at `{}`",
                    self.v2_lock.path().to_string_lossy()
                )
            })?;
            Ok(())
        }

        /// Iterator of all installed binaries.
        /// Items are `(pkg_id, bins)` where `bins` is the set of binaries that
        /// package installed.
        pub fn all_installed_bins(&self) -> impl Iterator<Item = (&PackageId, &BTreeSet<String>)> {
            self.v1.v1.iter()
        }

        /// Set of binaries installed by a particular package.
        /// Returns None if the package is not installed.
        pub fn installed_bins(&self, pkg_id: PackageId) -> Option<&BTreeSet<String>> {
            self.v1.v1.get(&pkg_id)
        }

        /// Remove a package from the tracker.
        pub fn remove(&mut self, pkg_id: PackageId, bins: &BTreeSet<String>) {
            self.v1.remove(pkg_id, bins);
            self.v2.remove(pkg_id, bins);
        }

        /// Remove a bin after it successfully had been removed in disk and then save the tracker at last.
        pub fn remove_bin_then_save(
            &mut self,
            pkg_id: PackageId,
            bin: &str,
            bin_path: &PathBuf,
        ) -> CargoResult<()> {
            paths::remove_file(bin_path)?;
            self.v1.remove_bin(pkg_id, bin);
            self.v2.remove_bin(pkg_id, bin);
            self.save()?;
            Ok(())
        }
    }

    impl CrateListingV1 {
        fn mark_installed(&mut self, pkg: &Package, bins: &BTreeSet<String>) {
            // Remove bins from any other packages.
            for other_bins in self.v1.values_mut() {
                for bin in bins {
                    other_bins.remove(bin);
                }
            }
            // Remove entries where `bins` is empty.
            let to_remove = self
                .v1
                .iter()
                .filter_map(|(&p, set)| if set.is_empty() { Some(p) } else { None })
                .collect::<Vec<_>>();
            for p in to_remove.iter() {
                self.v1.remove(p);
            }
            // Add these bins.
            self.v1
                .entry(pkg.package_id())
                .or_insert_with(BTreeSet::new)
                .append(&mut bins.clone());
        }

        fn remove(&mut self, pkg_id: PackageId, bins: &BTreeSet<String>) {
            let mut installed = match self.v1.entry(pkg_id) {
                btree_map::Entry::Occupied(e) => e,
                btree_map::Entry::Vacant(..) => panic!("v1 unexpected missing `{}`", pkg_id),
            };

            for bin in bins {
                installed.get_mut().remove(bin);
            }
            if installed.get().is_empty() {
                installed.remove();
            }
        }

        fn remove_bin(&mut self, pkg_id: PackageId, bin: &str) {
            let mut installed = match self.v1.entry(pkg_id) {
                btree_map::Entry::Occupied(e) => e,
                btree_map::Entry::Vacant(..) => panic!("v1 unexpected missing `{}`", pkg_id),
            };
            installed.get_mut().remove(bin);
            if installed.get().is_empty() {
                installed.remove();
            }
        }

        fn save(&self, lock: &FileLock) -> CargoResult<()> {
            let mut file = lock.file();
            file.seek(SeekFrom::Start(0))?;
            file.set_len(0)?;
            let data = toml::to_string_pretty(self)?;
            file.write_all(data.as_bytes())?;
            Ok(())
        }
    }

    impl CrateListingV2 {
        /// Incorporate any changes from v1 into self.
        /// This handles the initial upgrade to v2, *and* handles the case
        /// where v2 is in use, and a v1 update is made, then v2 is used again.
        /// i.e., `cargo +new install foo ; cargo +old install bar ; cargo +new install bar`
        /// For now, v1 is the source of truth, so its values are trusted over v2.
        fn sync_v1(&mut self, v1: &CrateListingV1) {
            // Make the `bins` entries the same.
            for (pkg_id, bins) in &v1.v1 {
                self.installs
                    .entry(*pkg_id)
                    .and_modify(|info| info.bins = bins.clone())
                    .or_insert_with(|| InstallInfo::from_v1(bins));
            }
            // Remove any packages that aren't present in v1.
            let to_remove: Vec<_> = self
                .installs
                .keys()
                .filter(|pkg_id| !v1.v1.contains_key(pkg_id))
                .cloned()
                .collect();
            for pkg_id in to_remove {
                self.installs.remove(&pkg_id);
            }
        }

        fn package_for_bin(&self, bin_name: &str) -> Option<PackageId> {
            self.installs
                .iter()
                .find(|(_, info)| info.bins.contains(bin_name))
                .map(|(pkg_id, _)| *pkg_id)
        }

        fn mark_installed(
            &mut self,
            pkg: &Package,
            bins: &BTreeSet<String>,
            version_req: Option<String>,
            opts: &CompileOptions,
            target: &str,
            rustc: &str,
        ) {
            // Remove bins from any other packages.
            for info in &mut self.installs.values_mut() {
                for bin in bins {
                    info.bins.remove(bin);
                }
            }
            // Remove entries where `bins` is empty.
            let to_remove = self
                .installs
                .iter()
                .filter_map(|(&p, info)| if info.bins.is_empty() { Some(p) } else { None })
                .collect::<Vec<_>>();
            for p in to_remove.iter() {
                self.installs.remove(p);
            }
            // Add these bins.
            if let Some(info) = self.installs.get_mut(&pkg.package_id()) {
                info.bins.append(&mut bins.clone());
                info.version_req = version_req;
                info.features = feature_set(&opts.cli_features.features);
                info.all_features = opts.cli_features.all_features;
                info.no_default_features = !opts.cli_features.uses_default_features;
                info.profile = opts.build_config.requested_profile.to_string();
                info.target = Some(target.to_string());
                info.rustc = Some(rustc.to_string());
            } else {
                self.installs.insert(
                    pkg.package_id(),
                    InstallInfo {
                        version_req,
                        bins: bins.clone(),
                        features: feature_set(&opts.cli_features.features),
                        all_features: opts.cli_features.all_features,
                        no_default_features: !opts.cli_features.uses_default_features,
                        profile: opts.build_config.requested_profile.to_string(),
                        target: Some(target.to_string()),
                        rustc: Some(rustc.to_string()),
                        other: BTreeMap::new(),
                    },
                );
            }
        }

        fn remove(&mut self, pkg_id: PackageId, bins: &BTreeSet<String>) {
            let mut info_entry = match self.installs.entry(pkg_id) {
                btree_map::Entry::Occupied(e) => e,
                btree_map::Entry::Vacant(..) => panic!("v2 unexpected missing `{}`", pkg_id),
            };

            for bin in bins {
                info_entry.get_mut().bins.remove(bin);
            }
            if info_entry.get().bins.is_empty() {
                info_entry.remove();
            }
        }

        fn remove_bin(&mut self, pkg_id: PackageId, bin: &str) {
            let mut info_entry = match self.installs.entry(pkg_id) {
                btree_map::Entry::Occupied(e) => e,
                btree_map::Entry::Vacant(..) => panic!("v1 unexpected missing `{}`", pkg_id),
            };
            info_entry.get_mut().bins.remove(bin);
            if info_entry.get().bins.is_empty() {
                info_entry.remove();
            }
        }

        fn save(&self, lock: &FileLock) -> CargoResult<()> {
            let mut file = lock.file();
            file.seek(SeekFrom::Start(0))?;
            file.set_len(0)?;
            let data = serde_json::to_string(self)?;
            file.write_all(data.as_bytes())?;
            Ok(())
        }
    }

    impl InstallInfo {
        fn from_v1(set: &BTreeSet<String>) -> InstallInfo {
            InstallInfo {
                version_req: None,
                bins: set.clone(),
                features: BTreeSet::new(),
                all_features: false,
                no_default_features: false,
                profile: "release".to_string(),
                target: None,
                rustc: None,
                other: BTreeMap::new(),
            }
        }

        /// Determine if this installation is "up to date", or if it needs to be reinstalled.
        ///
        /// This does not do Package/Source/Version checking.
        fn is_up_to_date(&self, opts: &CompileOptions, target: &str, exes: &BTreeSet<String>) -> bool {
            self.features == feature_set(&opts.cli_features.features)
                && self.all_features == opts.cli_features.all_features
                && self.no_default_features != opts.cli_features.uses_default_features
                && self.profile.as_str() == opts.build_config.requested_profile.as_str()
                && (self.target.is_none() || self.target.as_deref() == Some(target))
                && &self.bins == exes
        }
    }

    /// Determines the root directory where installation is done.
    pub fn resolve_root(flag: Option<&str>, gctx: &GlobalContext) -> CargoResult<Filesystem> {
        let config_root = gctx.get_path("install.root")?;
        Ok(flag
            .map(PathBuf::from)
            .or_else(|| gctx.get_env_os("CARGO_INSTALL_ROOT").map(PathBuf::from))
            .or_else(move || config_root.map(|v| v.val))
            .map(Filesystem::new)
            .unwrap_or_else(|| gctx.home().clone()))
    }

    /// Determines the `PathSource` from a `SourceId`.
    pub fn path_source(source_id: SourceId, gctx: &GlobalContext) -> CargoResult<PathSource<'_>> {
        let path = source_id
            .url()
            .to_file_path()
            .map_err(|()| format_err!("path sources must have a valid path"))?;
        Ok(PathSource::new(&path, source_id, gctx))
    }

    /// Gets a Package based on command-line requirements.
    pub fn select_dep_pkg<T>(
        source: &mut T,
        dep: Dependency,
        gctx: &GlobalContext,
        needs_update: bool,
        current_rust_version: Option<&PartialVersion>,
    ) -> CargoResult<Package>
    where
        T: Source,
    {
        // This operation may involve updating some sources or making a few queries
        // which may involve frobbing caches, as a result make sure we synchronize
        // with other global Cargos
        let _lock = gctx.acquire_package_cache_lock(CacheLockMode::DownloadExclusive)?;

        if needs_update {
            source.invalidate_cache();
        }

        let deps = loop {
            match source.query_vec(&dep, QueryKind::Exact)? {
                Poll::Ready(deps) => break deps,
                Poll::Pending => source.block_until_ready()?,
            }
        };
        match deps
            .iter()
            .map(|s| s.as_summary())
            .max_by_key(|p| p.package_id())
        {
            Some(summary) => {
                if let (Some(current), Some(msrv)) = (current_rust_version, summary.rust_version()) {
                    if !msrv.is_compatible_with(current) {
                        let name = summary.name();
                        let ver = summary.version();
                        let extra = if dep.source_id().is_registry() {
                            // Match any version, not just the selected
                            let msrv_dep =
                                Dependency::parse(dep.package_name(), None, dep.source_id())?;
                            let msrv_deps = loop {
                                match source.query_vec(&msrv_dep, QueryKind::Exact)? {
                                    Poll::Ready(deps) => break deps,
                                    Poll::Pending => source.block_until_ready()?,
                                }
                            };
                            if let Some(alt) = msrv_deps
                                .iter()
                                .map(|s| s.as_summary())
                                .filter(|summary| {
                                    summary
                                        .rust_version()
                                        .map(|msrv| msrv.is_compatible_with(current))
                                        .unwrap_or(true)
                                })
                                .max_by_key(|s| s.package_id())
                            {
                                if let Some(rust_version) = alt.rust_version() {
                                    format!(
                                        "\n`{name} {}` supports rustc {rust_version}",
                                        alt.version()
                                    )
                                } else {
                                    format!(
                                        "\n`{name} {}` has an unspecified minimum rustc version",
                                        alt.version()
                                    )
                                }
                            } else {
                                String::new()
                            }
                        } else {
                            String::new()
                        };
                        bail!("\
    cannot install package `{name} {ver}`, it requires rustc {msrv} or newer, while the currently active rustc version is {current}{extra}"
    )
                    }
                }
                let pkg = Box::new(source).download_now(summary.package_id(), gctx)?;
                Ok(pkg)
            }
            None => {
                let is_yanked: bool = if dep.version_req().is_exact() {
                    let version: String = dep.version_req().to_string();
                    if let Ok(pkg_id) =
                        PackageId::try_new(dep.package_name(), &version[1..], source.source_id())
                    {
                        source.invalidate_cache();
                        loop {
                            match source.is_yanked(pkg_id) {
                                Poll::Ready(Ok(is_yanked)) => break is_yanked,
                                Poll::Ready(Err(_)) => break false,
                                Poll::Pending => source.block_until_ready()?,
                            }
                        }
                    } else {
                        false
                    }
                } else {
                    false
                };
                if is_yanked {
                    bail!(
                        "cannot install package `{}`, it has been yanked from {}",
                        dep.package_name(),
                        source.source_id()
                    )
                } else {
                    bail!(
                        "could not find `{}` in {} with version `{}`",
                        dep.package_name(),
                        source.source_id(),
                        dep.version_req(),
                    )
                }
            }
        }
    }

    pub fn select_pkg<T, F>(
        source: &mut T,
        dep: Option<Dependency>,
        mut list_all: F,
        gctx: &GlobalContext,
        current_rust_version: Option<&PartialVersion>,
    ) -> CargoResult<Package>
    where
        T: Source,
        F: FnMut(&mut T) -> CargoResult<Vec<Package>>,
    {
        // This operation may involve updating some sources or making a few queries
        // which may involve frobbing caches, as a result make sure we synchronize
        // with other global Cargos
        let _lock = gctx.acquire_package_cache_lock(CacheLockMode::DownloadExclusive)?;

        source.invalidate_cache();

        return if let Some(dep) = dep {
            select_dep_pkg(source, dep, gctx, false, current_rust_version)
        } else {
            let candidates = list_all(source)?;
            let binaries = candidates
                .iter()
                .filter(|cand| cand.targets().iter().filter(|t| t.is_bin()).count() > 0);
            let examples = candidates
                .iter()
                .filter(|cand| cand.targets().iter().filter(|t| t.is_example()).count() > 0);
            let git_url = source.source_id().url().to_string();
            let pkg = match one(binaries, |v| multi_err("binaries", &git_url, v))? {
                Some(p) => p,
                None => match one(examples, |v| multi_err("examples", &git_url, v))? {
                    Some(p) => p,
                    None => bail!(
                        "no packages found with binaries or \
                             examples"
                    ),
                },
            };
            Ok(pkg.clone())
        };

        fn multi_err(kind: &str, git_url: &str, mut pkgs: Vec<&Package>) -> String {
            pkgs.sort_unstable_by_key(|a| a.name());
            let first_pkg = pkgs[0];
            format!(
                "multiple packages with {} found: {}. When installing a git repository, \
                cargo will always search the entire repo for any Cargo.toml.\n\
                Please specify a package, e.g. `cargo install --git {} {}`.",
                kind,
                pkgs.iter()
                    .map(|p| p.name().as_str())
                    .collect::<Vec<_>>()
                    .join(", "),
                git_url,
                first_pkg.name()
            )
        }
    }

    /// Get one element from the iterator.
    /// Returns None if none left.
    /// Returns error if there is more than one item in the iterator.
    fn one<I, F>(mut i: I, f: F) -> CargoResult<Option<I::Item>>
    where
        I: Iterator,
        F: FnOnce(Vec<I::Item>) -> String,
    {
        match (i.next(), i.next()) {
            (Some(i1), Some(i2)) => {
                let mut v = vec![i1, i2];
                v.extend(i);
                Err(format_err!("{}", f(v)))
            }
            (Some(i), None) => Ok(Some(i)),
            (None, _) => Ok(None),
        }
    }

    /// Helper to convert features to a `BTreeSet`.
    fn feature_set(features: &Rc<BTreeSet<FeatureValue>>) -> BTreeSet<String> {
        features.iter().map(|s| s.to_string()).collect()
    }

    /// Helper to get the executable names from a filter.
    pub fn exe_names(pkg: &Package, filter: &ops::CompileFilter) -> BTreeSet<String> {
        let to_exe = |name| format!("{}{}", name, env::consts::EXE_SUFFIX);
        match filter {
            CompileFilter::Default { .. } => pkg
                .targets()
                .iter()
                .filter(|t| t.is_bin())
                .map(|t| to_exe(t.name()))
                .collect(),
            CompileFilter::Only {
                all_targets: true, ..
            } => pkg
                .targets()
                .iter()
                .filter(|target| target.is_executable())
                .map(|target| to_exe(target.name()))
                .collect(),
            CompileFilter::Only {
                ref bins,
                ref examples,
                ..
            } => {
                let collect = |rule: &_, f: fn(&Target) -> _| match rule {
                    FilterRule::All => pkg
                        .targets()
                        .iter()
                        .filter(|t| f(t))
                        .map(|t| t.name().into())
                        .collect(),
                    FilterRule::Just(targets) => targets.clone(),
                };
                let all_bins = collect(bins, Target::is_bin);
                let all_examples = collect(examples, Target::is_exe_example);

                all_bins
                    .iter()
                    .chain(all_examples.iter())
                    .map(|name| to_exe(name))
                    .collect()
            }
        }
    }