Use mkdtemp and path_make_temp_template instead of tempnam and tmpnam

Those two functions are deprecated, produce warnings at link time,
and should not be used as they are cause of possible race conditions.

As a side effect we don't need to ensure the path is not existing as
mkdtemp has done that for us, which slightly simplifies the code.

debian/changelog

@@ -108,6 +108,9 @@ dpkg (1.15.6) UNRELEASED; urgency=low
   * Update debian/copyright.
   * Use Debian instead of ‘Debian GNU/Linux’ when referring to the
     distribution.
+  * On dpkg --no-act with --install, --unpack or --record-avail, and
+    dpkg-deb --info or --field use mkdtemp() to create a temporary directory
+    instead of insecure tempnam() or tmpnam() functions.
 
   [ Modestas Vainius ]
   * Implement symbol patterns (Closes: #563752). From now on, it is possible to

dpkg-deb/info.c

@@ -41,6 +41,7 @@
 #include <dpkg/dpkg-db.h>
 #include <dpkg/pkg-format.h>
 #include <dpkg/buffer.h>
+#include <dpkg/path.h>
 #include <dpkg/subproc.h>
 #include <dpkg/myopt.h>
 
@@ -69,21 +70,15 @@ static void info_prepare(const char *const **argvp,
                          const char **directoryp,
                          int admininfo) {
   char *dbuf;
-  pid_t c1;
   
   *debarp= *(*argvp)++;
   if (!*debarp) badusage(_("--%s needs a .deb filename argument"),cipaction->olong);
-  /* This creates a temporary directory, so ignore the warning. */
-  if ((dbuf= tempnam(NULL,"dpkg")) == NULL)
-    ohshite(_("failed to make temporary directoryname"));
+
+  dbuf = mkdtemp(path_make_temp_template("dpkg"));
+  if (!dbuf)
+    ohshite(_("failed to create temporary directory"));
   *directoryp= dbuf;
 
-  c1 = subproc_fork();
-  if (!c1) {
-    execlp(RM, "rm", "-rf", dbuf, NULL);
-    ohshite(_("failed to exec rm -rf"));
-  }
-  subproc_wait_check(c1, "rm -rf", 0);
   push_cleanup(cu_info_prepare, -1, NULL, 0, 1, (void *)dbuf);
   extracthalf(*debarp, dbuf, "mx", admininfo);
 }

src/processarc.c

@@ -40,6 +40,7 @@
 #include <dpkg/i18n.h>
 #include <dpkg/dpkg.h>
 #include <dpkg/dpkg-db.h>
+#include <dpkg/path.h>
 #include <dpkg/buffer.h>
 #include <dpkg/subproc.h>
 #include <dpkg/tarfn.h>
@@ -88,7 +89,6 @@ void process_archive(const char *filename) {
    * variables had better still exist ...
    */
   static int p1[2];
-  static char cidirtmpnambuf[L_tmpnam+100];
   static char *cidirbuf = NULL, *reasmbuf = NULL;
   static struct fileinlist *newconffiles, *newfileslist;
   static enum pkgstatus oldversionstatus;
@@ -186,10 +186,14 @@ void process_archive(const char *filename) {
     
 
   if (f_noact) {
-    cidir= cidirtmpnambuf;
-    /* We use tmpnam here, not to get a unique filename, but to get a unique directory. */
-    if (!tmpnam(cidir)) ohshite(_("unable to get unique filename for control info"));
+    if (!cidirbuf)
+      free(cidirbuf);
+    cidir = cidirbuf = mkdtemp(path_make_temp_template("dpkg"));
+    if (!cidir)
+      ohshite(_("unable to create temporary directory"));
     strcat(cidir,"/");
+
+    cidirrest = cidir + strlen(cidir);
   } else {
     /* We want it to be on the same filesystem so that we can
      * use rename(2) to install the postinst &c.
@@ -199,12 +203,14 @@ void process_archive(const char *filename) {
     cidir= cidirbuf;
     strcpy(cidir,admindir);
     strcat(cidir, "/" CONTROLDIRTMP);
-  }
-  cidirrest= cidir + strlen(cidir);
 
-  assert(*cidir && cidirrest[-1] == '/');
-  cidirrest[-1] = '\0';
-  ensure_pathname_nonexisting(cidir); cidirrest[-1]= '/';
+    cidirrest = cidir + strlen(cidir);
+
+    assert(*cidir && cidirrest[-1] == '/');
+    cidirrest[-1] = '\0';
+    ensure_pathname_nonexisting(cidir);
+    cidirrest[-1] = '/';
+  }
   
   push_cleanup(cu_cidir, ~0, NULL, 0, 2, (void *)cidir, (void *)cidirrest);
   c1 = subproc_fork();