enable building a source package by name and version

If a package is specified by name, it is downloaded inside the chroot
using the embedded deb-src uris. sbuild implements this natively,
pbuilder does not implement this yet, but there is #988419 and
mmdebstrap can make it work.

4 files changed, 42 insertions, 5 deletions

diff --git a/mdbp/build_schema.json b/mdbp/build_schema.json
index d971f0d..e7c203c 100644
--- a/mdbp/build_schema.json
+++ b/mdbp/build_schema.json
@@ -31,6 +31,21 @@
             "description": "a mapping of checksum algorithms to the expected values"
           }
         }
+      }, {
+        "required": [ "sourcename" ],
+        "additionalProperties": false,
+        "properties": {
+          "sourcename": {
+            "type": "string",
+            "pattern": "^[a-z0-9][a-z0-9.+-]*$",
+            "description": "name of a source package to fetch from the configured distribution"
+          },
+          "version": {
+            "type": "string",
+            "pattern": "^([0-9]+:)?[a-zA-Z0-9.+~-]+$",
+            "description": "request a particular version of the source package"
+          }
+        }
       } ]
     },
     "distribution": {
diff --git a/mdbp/mmdebstrap.py b/mdbp/mmdebstrap.py
index 62d3195..0a7dba4 100644
--- a/mdbp/mmdebstrap.py
+++ b/mdbp/mmdebstrap.py
@@ -3,6 +3,7 @@
 """mdbp backend using mmdebstrap"""
 
 import argparse
+import contextlib
 import ctypes
 import ctypes.util
 import functools
@@ -67,10 +68,20 @@ def hook_main(buildjsonfilename: str, chrootname: str) -> None:
     if "dscpath" in build["input"]:
         dscpath = fullbuildpath.parent / \
                 pathlib.PurePath(build["input"]["dscpath"]).name
-    else:
+    elif "dscuri" in build["input"]:
         dscpath = download_dsc(build["input"], fullbuildpath.parent)
     priv_drop(["chown", "-R", "build:build", "."],
                chroot=chroot, chdir=buildpath.parent)
+    apt_get = ["apt-get", "--yes", "-oAPT::Keep-Downloaded-Packages=false"]
+    if "sourcename" in build["input"]:
+        sourcename = build["input"]["sourcename"]
+        with contextlib.suppress(KeyError):
+            sourcename += "=" + build["input"]["version"]
+        priv_drop([*apt_get, "--only-source", "--download-only", "source",
+                   sourcename],
+                  chroot=chroot, chdir=buildpath.parent, setuid="build")
+        [dscpath] = fullbuildpath.parent.glob(build["input"]["sourcename"] +
+                                              "_*.dsc")
     priv_drop(["dpkg-source", "--no-check", "--extract", dscpath.name,
                buildpath.name],
               setuid="build", chroot=chroot, chdir=buildpath.parent)
@@ -78,7 +89,6 @@ def hook_main(buildjsonfilename: str, chrootname: str) -> None:
         path.unlink()
     hostarch = build.get("hostarch") or build.get("buildarch") or \
             native_architecture()
-    apt_get = ["apt-get", "--yes", "-oAPT::Keep-Downloaded-Packages=false"]
     cmd = [*apt_get, "build-dep", "--host-architecture", hostarch,
            *dict(any=["--arch-only"],
                  all=["--indep-only"]).get(build.get("type"), ()),
@@ -182,6 +192,8 @@ def main() -> None:
         build["distribution"],
         "/dev/null",
         args.mirror,
+        *(["deb-src %s %s main" % (args.mirror, build["distribution"])]
+          if "sourcename" in build["input"] else ()),
         *build.get("extrarepositories", ()),
     ]
     proc = subprocess.Popen(cmd,
diff --git a/mdbp/pbuilder.py b/mdbp/pbuilder.py
index a5f734a..7208152 100644
--- a/mdbp/pbuilder.py
+++ b/mdbp/pbuilder.py
@@ -18,6 +18,8 @@ def main() -> None:
     args = parser.parse_args()
     build = args.buildjson
 
+    if "sourcename" in build["input"]:
+        raise ValueError("building a source package by name is not supported")
     enablelog = build["output"].get("log", True)
     if build.get("lintian", {}).get("run"):
         raise ValueError("running lintian not supported")
diff --git a/mdbp/sbuild.py b/mdbp/sbuild.py
index ef6b67d..defd0bc 100644
--- a/mdbp/sbuild.py
+++ b/mdbp/sbuild.py
@@ -75,11 +75,19 @@ def main() -> None:
         sbc["external_commands"]["finished-build-commands"] = \
                 ["mv /etc/resolv.conf.disabled /etc/resolv.conf"]
 
-    with tempfile.NamedTemporaryFile(mode="w") as sbuildconf, \
-         get_dsc(build) as dscpath:
+    with contextlib.ExitStack() as stack:
+        sbuildconf = stack.enter_context(tempfile.NamedTemporaryFile(mode="w"))
         sbuildconf.write(perl_conf(sbc))
         sbuildconf.flush()
-        proc = subprocess.Popen(["sbuild", str(dscpath.absolute())],
+
+        try:
+            thing = build["input"]["sourcename"]
+            with contextlib.suppress(KeyError):
+                thing += "_" + build["input"]["version"]
+        except KeyError:
+            thing = str(stack.enter_context(get_dsc(build)).absolute())
+
+        proc = subprocess.Popen(["sbuild", thing],
                                 env=dict(SBUILD_CONFIG=sbuildconf.name,
                                          PATH="/usr/bin:/bin"),
                                 cwd=build["output"]["directory"],