Change VG_(mkstemp) such that

(a) the 2nd argument must not be NULL
    This was true anyhow and requiring it allows us to simplify the function
    by eliminating the local buffer.
(b) the memory pointed to by the 2nd argument is always initialised
    In the past the output file name was not initialised in case VG_(open)
    failed 10 times in a row. The call sites in m_main.c and m_gdbserver/target.c
    were reading the uninitialised filename unconditionally. This was spotted
    by IBM's BEAM checker.
Fix call sites, eliminate some magic constants along the way.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14706

coregrind/m_debuginfo/readpdb.c

@@ -2415,7 +2415,8 @@ HChar* ML_(find_name_of_pdb_file)( const HChar* pename )
    /* This is a giant kludge, of the kind "you did WTF?!?", but it
       works. */
    Bool   do_cleanup = False;
-   HChar  tmpname[VG_(mkstemp_fullname_bufsz)(50-1)], tmpnameroot[50];
+   HChar  tmpnameroot[50];     // large enough
+   HChar  tmpname[VG_(mkstemp_fullname_bufsz)(sizeof tmpnameroot - 1)];
    Int    fd, r;
    HChar* res = NULL;
 
@@ -2429,7 +2430,7 @@ HChar* ML_(find_name_of_pdb_file)( const HChar* pename )
    fd = VG_(mkstemp)( tmpnameroot, tmpname );
    if (fd == -1) {
       VG_(message)(Vg_UserMsg,
-                   "Find PDB file: Can't create /tmp file %s\n", tmpname);
+                   "Find PDB file: Can't create temporary file %s\n", tmpname);
       goto out;
    }
    do_cleanup = True;

coregrind/m_gdbserver/target.c

@@ -558,11 +558,14 @@ static Bool getplatformoffset (SizeT *result)
    // lm_modid_offset is a magic offset, retrieved using an external program.
 
    if (!getplatformoffset_called) {
+      getplatformoffset_called = True;
       const HChar *platform = VG_PLATFORM;
       const HChar *cmdformat = "%s/%s-%s -o %s";
       const HChar *getoff = "getoff";
       HChar outfile[VG_(mkstemp_fullname_bufsz) (VG_(strlen)(getoff))];
       Int fd = VG_(mkstemp) (getoff, outfile);
+      if (fd == -1)
+         return False;
       HChar cmd[ VG_(strlen)(cmdformat)
                  + VG_(strlen)(VG_(libdir)) - 2
                  + VG_(strlen)(getoff)      - 2
@@ -617,7 +620,6 @@ static Bool getplatformoffset (SizeT *result)
       ret = VG_(unlink)( outfile );
       if (ret != 0)
          VG_(umsg) ("error: could not unlink %s\n", outfile);
-      getplatformoffset_called = True;
    }
 
    *result = lm_modid_offset;

coregrind/m_libcfile.c

@@ -760,13 +760,13 @@ SizeT VG_(mkstemp_fullname_bufsz) ( SizeT part_of_name_len )
 
 Int VG_(mkstemp) ( const HChar* part_of_name, /*OUT*/HChar* fullname )
 {
-   HChar  buf[VG_(mkstemp_fullname_bufsz)(VG_(strlen)(part_of_name))];
-   Int    n, tries, fd;
+   Int    n, tries;
    UInt   seed;
    SysRes sres;
    const HChar *tmpdir;
 
    vg_assert(part_of_name);
+   vg_assert(fullname);
    n = VG_(strlen)(part_of_name);
    vg_assert(n > 0 && n < 100);
 
@@ -779,23 +779,20 @@ Int VG_(mkstemp) ( const HChar* part_of_name, /*OUT*/HChar* fullname )
    while (True) {
       if (tries++ > 10) 
          return -1;
-      VG_(sprintf)( buf, mkstemp_format,
+      VG_(sprintf)( fullname, mkstemp_format,
                     tmpdir, part_of_name, VG_(random)( &seed ));
       if (0)
-         VG_(printf)("VG_(mkstemp): trying: %s\n", buf);
+         VG_(printf)("VG_(mkstemp): trying: %s\n", fullname);
 
-      sres = VG_(open)(buf,
+      sres = VG_(open)(fullname,
                        VKI_O_CREAT|VKI_O_RDWR|VKI_O_EXCL|VKI_O_TRUNC,
                        VKI_S_IRUSR|VKI_S_IWUSR);
       if (sr_isError(sres)) {
-         VG_(umsg)("VG_(mkstemp): failed to create temp file: %s\n", buf);
+         VG_(umsg)("VG_(mkstemp): failed to create temp file: %s\n", fullname);
          continue;
       }
       /* VG_(safe_fd) doesn't return if it fails. */
-      fd = VG_(safe_fd)( sr_Res(sres) );
-      if (fullname)
-         VG_(strcpy)( fullname, buf );
-      return fd;
+      return VG_(safe_fd)( sr_Res(sres) );
    }
    /* NOTREACHED */
 }

coregrind/m_main.c

@@ -1893,7 +1893,8 @@ Int valgrind_main ( Int argc, HChar **argv, HChar **envp )
    VG_(cl_auxv_fd) = -1;
 #else
    if (!need_help) {
-      HChar  buf[50], buf2[VG_(mkstemp_fullname_bufsz)(50-1)];
+      HChar  buf[50];   // large enough
+      HChar  buf2[VG_(mkstemp_fullname_bufsz)(sizeof buf - 1)];
       HChar  nul[1];
       Int    fd, r;
       const HChar* exename;

coregrind/pub_core_libcfile.h

@@ -95,8 +95,8 @@ extern SysRes VG_(pread) ( Int fd, void* buf, Int count, OffT offset );
 extern SizeT VG_(mkstemp_fullname_bufsz) ( SizeT part_of_name_len );
 
 /* Create and open (-rw------) a tmp file name incorporating said arg.
-   Returns -1 on failure, else the fd of the file.  If fullname is
-   non-NULL, the file's name is written into it.  The number of bytes written
+   Returns -1 on failure, else the fd of the file.  The file name is
+   written to the memory pointed to be fullname. The number of bytes written
    is equal to VG_(mkstemp_fullname_bufsz)(VG_(strlen)(part_of_name)). */
 extern Int VG_(mkstemp) ( const HChar* part_of_name, /*OUT*/HChar* fullname );