gcc.c: Fix commentary describing %g, %u, %U, and %O.

d
        * gcc.c: Fix commentary describing %g, %u, %U, and %O.
        * gcc.c (do_spec_1): Fix support for %O so the
        temporary file name made for it the first time
        gets reused subsequently.

From-SVN: r21450

diff --git a/gcc/gcc.c b/gcc/gcc.c
index a1d2632e2598c2a5280eb26b1901dd20322b22cd..1787d0f1c93205fe1410aa474648d1cf340b78f4 100644 (file)
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -281,12 +281,30 @@ or with constant text in a single argument.
  %b     substitute the basename of the input file being processed.
        This is the substring up to (and not including) the last period
        and not including the directory.
- %g     substitute the temporary-file-name-base.  This is a string chosen
-       once per compilation.  Different temporary file names are made by
-       concatenation of constant strings on the end, as in `%g.s'.
-       %g also has the same effect of %d.
- %u    like %g, but make the temporary file name unique.
- %U    returns the last file name generated with %u.
+ %gSUFFIX
+       substitute a file name that has suffix SUFFIX and is chosen
+       once per compilation, and mark the argument a la %d.  To reduce
+       exposure to denial-of-service attacks, the file name is now
+       chosen in a way that is hard to predict even when previously
+       chosen file names are known.  For example, `%g.s ... %g.o ... %g.s'
+       might turn into `ccUVUUAU.s ccXYAXZ12.o ccUVUUAU.s'.  SUFFIX matches
+       the regexp "[.A-Za-z]*" or the special string "%O", which is
+       treated exactly as if %O had been pre-processed.  Previously, %g
+       was simply substituted with a file name chosen once per compilation,
+       without regard to any appended suffix (which was therefore treated
+       just like ordinary text), making such attacks more likely to succeed.
+ %uSUFFIX
+       like %g, but generates a new temporary file name even if %uSUFFIX
+       was already seen.
+ %USUFFIX
+       substitutes the last file name generated with %uSUFFIX, generating a
+       new one if there is no such last file name.  In the absence of any
+       %uSUFFIX, this is just like %gSUFFIX, except they don't share
+       the same suffix "space", so `%g.s ... %U.s ... %g.s ... %U.s'
+       would involve the generation of two distinct file names, one
+       for each `%g.s' and another for each `%U.s'.  Previously, %U was
+       simply substituted with a file name chosen for the previous %u,
+       without regard to any appended suffix.
  %d    marks the argument containing or following the %d as a
        temporary file name, so that that file will be deleted if CC exits
        successfully.  Unlike %g, this contributes no text to the argument.
@@ -303,7 +321,13 @@ or with constant text in a single argument.
        Input files whose names have no recognized suffix are not compiled
        at all, but they are included among the output files, so they will
        be linked.
- %O    substitutes the suffix for object files.
+ %O    substitutes the suffix for object files.  Note that this is
+       handled specially when it immediately follows %g, %u, or %U,
+       because of the need for those to form complete file names.  The
+       handling is such that %O is treated exactly as if it had already
+       been substituted, except that %g, %u, and %U do not currently
+       support additional SUFFIX characters following %O as they would
+       following, for example, `.o'.
  %p    substitutes the standard macro predefinitions for the
        current target machine.  Use this when running cpp.
  %P    like %p, but puts `__' before and after the name of each macro.
@@ -3620,16 +3644,30 @@ do_spec_1 (spec, inswitch, soft_matched_part)
                   That matters for the names of object files.
                   In 2.4, do something about that.  */
                struct temp_name *t;
+               int suffix_length;
                char *suffix = p;
-               while (*p == '.' || ISALPHA (*p)
-                      || (p[0] == '%' && p[1] == 'O'))
-                 p++;
+
+               if (p[0] == '%' && p[1] == 'O')
+                 {
+                   /* We don't support extra suffix characters after %O.  */
+                   if (*p == '.' || ISALPHA (*p))
+                     abort ();
+                   suffix = OBJECT_SUFFIX;
+                   suffix_length = strlen (OBJECT_SUFFIX);
+                   p += 2;
+                 }
+               else
+                 {
+                   while (*p == '.' || ISALPHA (*p))
+                     p++;
+                   suffix_length = p - suffix;
+                 }
 
                /* See if we already have an association of %g/%u/%U and
                   suffix.  */
                for (t = temp_names; t; t = t->next)
-                 if (t->length == p - suffix
-                     && strncmp (t->suffix, suffix, p - suffix) == 0
+                 if (t->length == suffix_length
+                     && strncmp (t->suffix, suffix, suffix_length) == 0
                      && t->unique == (c != 'g'))
                    break;
 
@@ -3642,21 +3680,10 @@ do_spec_1 (spec, inswitch, soft_matched_part)
                        t->next = temp_names;
                        temp_names = t;
                      }
-                   if (strncmp (suffix, "%O", 2) == 0)
-                     {
-                       t->length = strlen(OBJECT_SUFFIX);
-                       t->suffix = save_string (OBJECT_SUFFIX,
-                                                strlen(OBJECT_SUFFIX));
-                       t->unique = (c != 'g');
-                       temp_filename = make_temp_file (OBJECT_SUFFIX);
-                     }
-                   else
-                     {
-                       t->length = p - suffix;
-                       t->suffix = save_string (suffix, p - suffix);
-                       t->unique = (c != 'g');
-                       temp_filename = make_temp_file (t->suffix);
-                     }
+                   t->length = suffix_length;
+                   t->suffix = save_string (suffix, suffix_length);
+                   t->unique = (c != 'g');
+                   temp_filename = make_temp_file (t->suffix);
                    temp_filename_length = strlen (temp_filename);
                    t->filename = temp_filename;
                    t->filename_length = temp_filename_length;