use PATH_MAX instead of magic number

User on OpenMPI list wanted to create a 259 character file.  shared file
pointer name construction used the magic '256' value to construct a full
path to the hidden shared file pointer file.  PATH_MAX already exists
for this purpose, so use it.

While there, found a few spots checking/setting PATH_MAX, so do that in
one place

Closes #2212
Signed-off-by: Ken Raffenetti <raffenet@mcs.anl.gov>

src/mpi/romio/adio/common/ad_fstype.c

@@ -137,10 +137,6 @@ Output Parameters:
 */
 #ifdef ROMIO_NEEDS_ADIOPARENTDIR
 
-#ifndef PATH_MAX
-#define PATH_MAX 65535
-#endif
-
 /* In a strict ANSI environment, S_ISLNK may not be defined.  Fix that
    here.  We assume that S_ISLNK is *always* defined as a macro.  If
    that is not universally true, then add a test to the romio

src/mpi/romio/adio/common/shfp_fname.c

@@ -21,8 +21,11 @@
    store the shared file pointer. The shared-file-pointer file is a 
    hidden file in the same directory as the real file being accessed.
    If the real file is /tmp/thakur/testfile, the shared-file-pointer
-   file will be /tmp/thakur/.testfile.shfp.xxxx, where xxxx is
-   a random number. This file is created only if the shared
+   file will be /tmp/thakur/.testfile.shfp.yyy.xxxx, where yyy
+   is rank 0's process id and xxxx is a random number. If the
+   underlying file system supports shared file pointers
+   (PVFS does not, for example), the file name is always
+   constructed. This file is created only if the shared
    file pointer functions are used and is deleted when the real
    file is closed. */
 
@@ -33,14 +36,14 @@ void ADIOI_Shfp_fname(ADIO_File fd, int rank, int *error_code)
     char *slash, *ptr, tmp[128];
     int pid = 0;
 
-    fd->shared_fp_fname = (char *) ADIOI_Malloc(256);
+    fd->shared_fp_fname = (char *) ADIOI_Malloc(PATH_MAX);
 
     if (!rank) {
         srand(time(NULL));
         i = rand();
 	pid = (int)getpid();
 	
-	if (ADIOI_Strncpy(fd->shared_fp_fname, fd->filename, 256)) {
+	if (ADIOI_Strncpy(fd->shared_fp_fname, fd->filename, PATH_MAX)) {
 	    *error_code = ADIOI_Err_create_code("ADIOI_Shfp_fname",
 		    fd->filename, ENAMETOOLONG);
 	    return;
@@ -57,7 +60,7 @@ void ADIOI_Shfp_fname(ADIO_File fd, int rank, int *error_code)
 			fd->filename, ENAMETOOLONG);
 		return;
 	    }
-	    if (ADIOI_Strncpy(fd->shared_fp_fname + 1, fd->filename, 255)) {
+	    if (ADIOI_Strncpy(fd->shared_fp_fname + 1, fd->filename, PATH_MAX-1)) {
 		*error_code = ADIOI_Err_create_code("ADIOI_Shfp_fname",
 			fd->filename, ENAMETOOLONG);
 		return;
@@ -76,7 +79,7 @@ void ADIOI_Shfp_fname(ADIO_File fd, int rank, int *error_code)
 		return;
 	    }
 	    /* ok to cast: file names bounded by PATH_MAX and NAME_MAX */
-	    len = (int) (256 - (slash+2 - fd->shared_fp_fname));
+	    len = (int) (PATH_MAX - (slash+2 - fd->shared_fp_fname));
 	    if (ADIOI_Strncpy(slash + 2, ptr + 1, len)) {
 		*error_code = ADIOI_Err_create_code("ADIOI_Shfp_fname",
 			ptr + 1, ENAMETOOLONG);
@@ -86,7 +89,7 @@ void ADIOI_Shfp_fname(ADIO_File fd, int rank, int *error_code)
 	    
 	ADIOI_Snprintf(tmp, 128, ".shfp.%d.%d", pid, i);
 	/* ADIOI_Strnapp will return non-zero if truncated.  That's ok */
-	ADIOI_Strnapp(fd->shared_fp_fname, tmp, 256);
+	ADIOI_Strnapp(fd->shared_fp_fname, tmp, PATH_MAX);
 	
 	len = (int)strlen(fd->shared_fp_fname);
 	MPI_Bcast(&len, 1, MPI_INT, 0, fd->comm);

src/mpi/romio/adio/common/system_hints.c

@@ -28,10 +28,6 @@
 #include <io.h>
 #endif
 
-#ifndef PATH_MAX
-#define PATH_MAX 65535
-#endif
-
 /*#define SYSHINT_DEBUG 1  */
 
 #define ROMIO_HINT_DEFAULT_CFG "/etc/romio-hints"

src/mpi/romio/adio/include/adioi.h

@@ -1034,7 +1034,13 @@ typedef struct wcThreadFuncData {
 void *ADIOI_IO_Thread_Func(void *vptr_args);
 
 
+#ifdef HAVE_LIMITS_H
+#include <limits.h>
+#endif
 
+#ifndef PATH_MAX
+#define PATH_MAX 65535
+#endif
 
 #endif