pactest: make more resiliant to missing files

Add a bunch of guards around function calls like open() and stat() to ensure
we are not going to get ourselves a python error. This made implementing and
testing the new upgrade045 pactest much easier, as its whole purpose was to
create a dead symlink and debug a segfault of pacman (which caused no DB
entries to be written) to support the previously checked in fix for FS#9235
(commit 0c2206f542ce6df2606586d43f190cd5a423fb13). Both of these cases are
now non-fatal in pactest.

Signed-off-by: Dan McGee <dan@archlinux.org>

pactest/pmdb.py

@@ -119,7 +119,10 @@ class pmdb:
 
         # desc
         filename = os.path.join(path, "desc")
-        fd = file(filename, "r")
+        if not os.path.isfile(filename):
+            print "invalid db entry found (desc missing) for pkg", pkgname
+            return None
+        fd = open(filename, "r")
         while 1:
             line = fd.readline()
             if not line:
@@ -158,7 +161,10 @@ class pmdb:
 
         # files
         filename = os.path.join(path, "files")
-        fd = file(filename, "r")
+        if not os.path.isfile(filename):
+            print "invalid db entry found (files missing) for pkg", pkgname
+            return None
+        fd = open(filename, "r")
         while 1:
             line = fd.readline()
             if not line:
@@ -177,6 +183,9 @@ class pmdb:
 
         # depends
         filename = os.path.join(path, "depends")
+        if not os.path.isfile(filename):
+            print "invalid db entry found (depends missing) for pkg", pkgname
+            return None
         fd = file(filename, "r")
         while 1:
             line = fd.readline()

pactest/tests/upgrade045.py

@@ -0,0 +1,16 @@
+self.description = "FS#9235"
+
+lp = pmpkg("foo")
+lp.files = ["etc/foo.cfg -> etc/foo.cfg"]
+lp.backup = ["etc/foo.cfg"]
+self.addpkg2db("local", lp)
+
+p1 = pmpkg("foo", "1.0-2")
+p1.files = ["etc/foo.cfg*"]
+p1.backup = ["etc/foo.cfg"]
+self.addpkg(p1)
+
+self.args = "-U %s" % p1.filename()
+
+self.addrule("PKG_VERSION=foo|1.0-2")
+self.addrule("FILE_EXIST=etc/foo.cfg")

pactest/util.py

@@ -196,6 +196,9 @@ def mkcfgfile(filename, root, option, db):
 def getmd5sum(filename):
     """
     """
+    if not os.path.isfile(filename):
+        print "file %s does not exist!" % filename
+        return ""
     fd = open(filename, "rb")
     checksum = md5.new()
     while 1:
@@ -223,6 +226,9 @@ def mkmd5sum(data):
 def getmtime(filename):
     """
     """
+    if not os.path.exists(filename):
+        print "path %s does not exist!" % filename
+        return 0, 0, 0
     st = os.stat(filename)
     return st[stat.ST_ATIME], st[stat.ST_MTIME], st[stat.ST_CTIME]