From 6909c20e69f08d256360dd29e50eacd02f49dfb8 Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Sat, 12 Sep 2020 16:57:14 +0300
Subject: Exit with status 2 for recoverable errors

---
 bpkg/bpkg.cli        | 15 ++++++++++++++-
 bpkg/bpkg.cxx        |  7 +++++++
 bpkg/diagnostics.hxx |  5 +++++
 bpkg/rep-fetch.cxx   | 35 ++++++++++++++++++++++-------------
 4 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/bpkg/bpkg.cli b/bpkg/bpkg.cli
index b1c0a00..4975db7 100644
--- a/bpkg/bpkg.cli
+++ b/bpkg/bpkg.cli
@@ -322,6 +322,19 @@ namespace bpkg
 
   "\h|EXIT STATUS|
 
-  Non-zero exit status is returned in case of an error.
+  \dl|
+
+  \li|\cb{0}
+
+  Success.|
+
+  \li|\cb{1}
+
+  Fatal error.|
+
+  \li|\cb{2}
+
+  Recoverable error which is likely to disappear if the command is
+  re-executed.||
   "
 }
diff --git a/bpkg/bpkg.cxx b/bpkg/bpkg.cxx
index ffc91ab..7aba553 100644
--- a/bpkg/bpkg.cxx
+++ b/bpkg/bpkg.cxx
@@ -517,6 +517,13 @@ try
     assert (false);
     fail << "unhandled command";
   }
+  // Derived from failed and so needs to be caught first.
+  //
+  catch (const recoverable&)
+  {
+    r = 2;
+    break;
+  }
   catch (const failed&)
   {
     r = 1;
diff --git a/bpkg/diagnostics.hxx b/bpkg/diagnostics.hxx
index d11ab0b..925b080 100644
--- a/bpkg/diagnostics.hxx
+++ b/bpkg/diagnostics.hxx
@@ -21,6 +21,11 @@ namespace bpkg
   //
   class failed: public std::exception {};
 
+  // As above but needs to be used for recoverable errors which are likely to
+  // disappear on the command retry.
+  //
+  class recoverable: public failed {};
+
   // Print process commmand line. If the number of elements is specified
   // (or the second version is used), then it will print the piped multi-
   // process command line, if present. In this case, the expected format
diff --git a/bpkg/rep-fetch.cxx b/bpkg/rep-fetch.cxx
index b58ef2c..3239421 100644
--- a/bpkg/rep-fetch.cxx
+++ b/bpkg/rep-fetch.cxx
@@ -85,10 +85,14 @@ namespace bpkg
     pkg_package_manifests& pms (pmc.first);
 
     if (rmc.second != pms.sha256sum)
-      fail << "repositories manifest file checksum mismatch for "
-           << rl.canonical_name () <<
+    {
+      error << "repositories manifest file checksum mismatch for "
+            << rl.canonical_name () <<
         info << "try again";
 
+      throw recoverable ();
+    }
+
     fr.packages = move (pms);
 
     if (a)
@@ -97,10 +101,14 @@ namespace bpkg
         pkg_fetch_signature (co, rl, true /* ignore_unknown */));
 
       if (sm.sha256sum != pmc.second)
-        fail << "packages manifest file checksum mismatch for "
-             << rl.canonical_name () <<
+      {
+        error << "packages manifest file checksum mismatch for "
+              << rl.canonical_name () <<
           info << "try again";
 
+        throw recoverable ();
+      }
+
       assert (cert != nullptr);
       authenticate_repository (co, conf, cert_pem, *cert, sm, rl);
     }
@@ -911,12 +919,12 @@ namespace bpkg
               info << r1 << " has " << *pm.sha256sum <<
               info << r2 << " has " << *p->sha256sum;
 
-            // If we fetch all the repositories then the mismatch is definitely
-            // caused by the broken repository. Otherwise, it may also happen
-            // due to the old available package that is not wiped out yet.
-            // Thus, we advice the user to perform the full fetch, unless the
-            // filesystem state is already changed and so this advice will be
-            // given anyway (see rep_fetch() for details).
+            // If we fetch all the repositories then the mismatch is
+            // definitely caused by the broken repository. Otherwise, it may
+            // also happen due to the old available package that is not wiped
+            // out yet.  Thus, we advice the user to perform the full fetch,
+            // unless the filesystem state is already changed and so this
+            // advice will be given anyway (see rep_fetch() for details).
             //
             if (full_fetch)
               dr << info << "consider reporting this to the repository "
@@ -969,15 +977,16 @@ namespace bpkg
     // otherwise.
     //
     // Note that we can end up with a repository dependency cycle via
-    // prerequisites. Thus we register the repository before recursing into its
-    // dependencies.
+    // prerequisites. Thus we register the repository before recursing into
+    // its dependencies.
     //
     if (!fetched_repositories.insert (r).second) // Is already fetched.
     {
       // Authenticate the repository use by the dependent, if required.
       //
       // Note that we only need to authenticate the certificate but not the
-      // repository that was already fetched (and so is already authenticated).
+      // repository that was already fetched (and so is already
+      // authenticated).
       //
       if (need_auth (co, r->location))
         authenticate_certificate (co,
-- 
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