dpkg: Normalize instdir by removing trailing '/' and '/.'

This gets rid of several inconsistencies and doubled «/» in syscalls
and output messages.

debian/changelog

@@ -83,6 +83,9 @@ dpkg (1.17.14) UNRELEASED; urgency=low
       the Build-Profiles field in binary packages which can be removed once
       all affected source packages have moved to the new syntax.
     Thanks to Johannes Schauer <j.schauer@email.de>. Closes: #760158
+  * Normalize instdir in dpkg by removing trailing «/» and «/.». This gets
+    rid of several inconsistencies and doubled «/» in syscalls and output
+    messages.
 
   [ Raphaël Hertzog ]
   * Explain better in deb-triggers(5) why interest/activate-noawait should be

src/archives.c

@@ -390,7 +390,6 @@ tarobject_extract(struct tarcontext *tc, struct tar_entry *te,
   case TAR_FILETYPE_HARDLINK:
     varbuf_reset(&hardlinkfn);
     varbuf_add_str(&hardlinkfn, instdir);
-    varbuf_add_char(&hardlinkfn, '/');
     linknode = findnamenode(te->linkname, 0);
     varbuf_add_str(&hardlinkfn,
                    namenodetouse(linknode, tc->pkg, &tc->pkg->available)->name);
@@ -832,7 +831,7 @@ tarobject(void *ctx, struct tar_entry *ti)
     st = &ti->stat;
 
   usenode = namenodetouse(nifd->namenode, tc->pkg, &tc->pkg->available);
-  usename = usenode->name + 1; /* Skip the leading '/'. */
+  usename = usenode->name;
 
   trig_file_activate(usenode, tc->pkg);
 
@@ -1196,16 +1195,14 @@ tar_writeback_barrier(struct fileinlist *files, struct pkginfo *pkg)
 
   for (cfile = files; cfile; cfile = cfile->next) {
     struct filenamenode *usenode;
-    const char *usename;
     int fd;
 
     if (!(cfile->namenode->flags & fnnf_deferred_fsync))
       continue;
 
     usenode = namenodetouse(cfile->namenode, pkg, &pkg->available);
-    usename = usenode->name + 1; /* Skip the leading '/'. */
 
-    setupfnamevbs(usename);
+    setupfnamevbs(usenode->name);
 
     fd = open(fnamenewvb.buf, O_WRONLY);
     if (fd < 0)
@@ -1230,7 +1227,6 @@ tar_deferred_extract(struct fileinlist *files, struct pkginfo *pkg)
 {
   struct fileinlist *cfile;
   struct filenamenode *usenode;
-  const char *usename;
 
   tar_writeback_barrier(files, pkg);
 
@@ -1241,9 +1237,8 @@ tar_deferred_extract(struct fileinlist *files, struct pkginfo *pkg)
       continue;
 
     usenode = namenodetouse(cfile->namenode, pkg, &pkg->available);
-    usename = usenode->name + 1; /* Skip the leading '/'. */
 
-    setupfnamevbs(usename);
+    setupfnamevbs(usenode->name);
 
     if (cfile->namenode->flags & fnnf_deferred_fsync) {
       int fd;
@@ -1646,11 +1641,8 @@ archivefiles(const char *const *argv)
   varbuf_reset(&fnamenewvb);
 
   varbuf_add_str(&fnamevb, instdir);
-  varbuf_add_char(&fnamevb, '/');
   varbuf_add_str(&fnametmpvb, instdir);
-  varbuf_add_char(&fnametmpvb, '/');
   varbuf_add_str(&fnamenewvb, instdir);
-  varbuf_add_char(&fnamenewvb, '/');
   fnameidlu= fnamevb.used;
 
   ensure_diversions();

src/configure.c

@@ -716,8 +716,6 @@ conffderef(struct pkginfo *pkg, struct varbuf *result, const char *in)
 
 	varbuf_reset(result);
 	varbuf_add_str(result, instdir);
-	if (*in != '/')
-		varbuf_add_char(result, '/');
 	varbuf_add_str(result, in);
 	varbuf_end_str(result);
 

src/main.c

@@ -46,6 +46,7 @@
 #include <dpkg/dpkg.h>
 #include <dpkg/dpkg-db.h>
 #include <dpkg/arch.h>
+#include <dpkg/path.h>
 #include <dpkg/subproc.h>
 #include <dpkg/command.h>
 #include <dpkg/options.h>
@@ -343,12 +344,24 @@ set_verify_format(const struct cmdinfo *cip, const char *value)
     badusage(_("unknown verify output format '%s'"), value);
 }
 
+static void
+set_instdir(const struct cmdinfo *cip, const char *value)
+{
+  char *new_instdir;
+
+  new_instdir = m_strdup(value);
+  path_trim_slash_slashdot(new_instdir);
+
+  instdir = new_instdir;
+}
+
 static void
 set_root(const struct cmdinfo *cip, const char *value)
 {
   char *p;
-  instdir= value;
-  m_asprintf(&p, "%s%s", value, ADMINDIR);
+
+  set_instdir(cip, value);
+  m_asprintf(&p, "%s%s", instdir, ADMINDIR);
   admindir= p;
 }
 
@@ -710,7 +723,7 @@ static const struct cmdinfo cmdinfos[]= {
   { "root",              0,   1, NULL,          NULL,      set_root,      0 },
   { "abort-after",       0,   1, &errabort,     NULL,      set_integer,   0 },
   { "admindir",          0,   1, NULL,          &admindir, NULL,          0 },
-  { "instdir",           0,   1, NULL,          &instdir,  NULL,          0 },
+  { "instdir",           0,   1, NULL,          NULL,      set_instdir,   0 },
   { "ignore-depends",    0,   1, NULL,          NULL,      set_ignore_depends, 0 },
   { "force",             0,   2, NULL,          NULL,      set_force,     1 },
   { "refuse",            0,   2, NULL,          NULL,      set_force,     0 },

src/unpack.c

@@ -1084,7 +1084,6 @@ void process_archive(const char *filename) {
 
 	  varbuf_reset(&cfilename);
 	  varbuf_add_str(&cfilename, instdir);
-	  varbuf_add_char(&cfilename, '/');
 	  varbuf_add_str(&cfilename, cfile->namenode->name);
 	  varbuf_end_str(&cfilename);