Don't misinterpret blank configuration entries as sentinels

Configuration table entries not defined by builtin and custom
configuration files remain blank.  They get misinterpreted as sentinel
in tables that use one.  Affected are tables product, ship-chr,
plane-chr, land-chr and nuke-chr.  Tables item, sect-chr and
infrastructure are immune despite using a sentinel, because omitting
entries is not permitted there.

Code relying on the sentinel fails to pick up entries after the first
blank one.  They don't get set up correctly, they're invisible to
build and show, and not recognized as symbolic selector values (the
frg in ship ?type=frg).  xdump is fine, because it doesn't rely on
sentinels.  It dumps blank entries normally.

The bugs don't bite in the stock game, because the builtin
configuration files are all dense.

The sentinels are all null strings.  Set them to "" in the affected
tables' oninit callback.  Fix up code iterating over the tables to
ignore such entries.  This is precisely the code relying on sentinels,
plus xdump's xdvisible().

src/lib/commands/xdump.c

@@ -37,6 +37,7 @@
 #include "empobj.h"
 #include "news.h"
 #include "optlist.h"
+#include "product.h"
 #include "version.h"
 #include "xdump.h"
 
@@ -52,6 +53,7 @@ xdvisible(int type, void *p)
     struct lonstr *lp = p;
     struct natstr *natp;
     int tlev;
+    char *name;
 
     switch (type) {
     case EF_SECTOR:
@@ -84,19 +86,27 @@ xdvisible(int type, void *p)
     case EF_TRADE:
     case EF_COMM:
 	return gp->own != 0;
+    case EF_PRODUCT:
+	return ((struct pchrstr *)p)->p_sname[0] != 0;
     case EF_SHIP_CHR:
 	tlev = ((struct mchrstr *)p)->m_tech;
+	name = ((struct mchrstr *)p)->m_name;
 	goto tech;
     case EF_PLANE_CHR:
 	tlev = ((struct plchrstr *)p)->pl_tech;
+	name = ((struct plchrstr *)p)->pl_name;
 	goto tech;
     case EF_LAND_CHR:
 	tlev = ((struct lchrstr *)p)->l_tech;
+	name = ((struct lchrstr *)p)->l_name;
     tech:
 	natp = getnatp(player->cnum);
+	if (!name[0])
+	    return 0;
 	return player->god || tlev <= (int)(1.25 * natp->nat_level[NAT_TLEV]);
     case EF_NUKE_CHR:
 	tlev = ((struct nchrstr *)p)->n_tech;
+	name = ((struct nchrstr *)p)->n_name;
 	if (drnuke_const > MIN_DRNUKE_CONST) {
 	    natp = getnatp(player->cnum);
 	    if (tlev > (int)((int)(1.25 * natp->nat_level[NAT_RLEV])

src/lib/common/ef_verify.c

@@ -226,6 +226,8 @@ ef_verify(void)
 
     /* Special checks */
     for (i = 0; pchr[i].p_sname; i++) {
+	if (!pchr[i].p_sname[0])
+	    continue;
 	if ((pchr[i].p_type >= 0) == (pchr[i].p_level >= 0)) {
 	    fprintf(stderr,
 		"Config %s uid %d field level doesn't match field type\n",

src/lib/common/filetable.c

@@ -62,6 +62,11 @@ static void nuk_oninit(void *);
 static void nat_oninit(void *);
 static void realm_oninit(void *);
 static void game_oninit(void *);
+static void pchr_oninit(void *);
+static void mchr_oninit(void *);
+static void plchr_oninit(void *);
+static void lchr_oninit(void *);
+static void nchr_oninit(void *);
 
 /* Number of elements in ARRAY.  */
 #define SZ(array) (sizeof(array) / sizeof((array)[0]))
@@ -192,17 +197,17 @@ struct empfile empfile[] = {
     {EF_ITEM, "item", "item.config", ichr_ca, EF_BAD,
      ARRAY_CACHE(ichr, EFF_CFG), NULL, NULL, NULL, NULL},
     {EF_PRODUCT, "product", "product.config", pchr_ca, EF_BAD,
-     ARRAY_CACHE(pchr, EFF_CFG), NULL, NULL, NULL, NULL},
+     ARRAY_CACHE(pchr, EFF_CFG), pchr_oninit, NULL, NULL, NULL},
     {EF_SECTOR_CHR, "sect-chr", "sect.config", dchr_ca, EF_BAD,
      ARRAY_CACHE(dchr, EFF_CFG), NULL, NULL, NULL, NULL},
     {EF_SHIP_CHR, "ship-chr", "ship.config", mchr_ca, EF_BAD,
-     ARRAY_CACHE(mchr, EFF_CFG), NULL, NULL, NULL, NULL},
+     ARRAY_CACHE(mchr, EFF_CFG), mchr_oninit, NULL, NULL, NULL},
     {EF_PLANE_CHR, "plane-chr", "plane.config", plchr_ca, EF_BAD,
-     ARRAY_CACHE(plchr, EFF_CFG), NULL, NULL, NULL, NULL},
+     ARRAY_CACHE(plchr, EFF_CFG), plchr_oninit, NULL, NULL, NULL},
     {EF_LAND_CHR, "land-chr", "land.config", lchr_ca, EF_BAD,
-     ARRAY_CACHE(lchr, EFF_CFG), NULL, NULL, NULL, NULL},
+     ARRAY_CACHE(lchr, EFF_CFG), lchr_oninit, NULL, NULL, NULL},
     {EF_NUKE_CHR, "nuke-chr", "nuke.config", nchr_ca, EF_BAD,
-     ARRAY_CACHE(nchr, EFF_CFG), NULL, NULL, NULL, NULL},
+     ARRAY_CACHE(nchr, EFF_CFG), nchr_oninit, NULL, NULL, NULL},
     {EF_NEWS_CHR, "news-chr", NULL, rpt_ca, EF_BAD,
      ARRAY_TABLE(rpt, N_MAX_VERB + 1, EFF_CFG), NULL, NULL, NULL, NULL},
     {EF_INFRASTRUCTURE, "infrastructure", "infra.config", intrchr_ca, EF_BAD,
@@ -329,6 +334,36 @@ game_oninit(void *ptr)
     ((struct gamestr *)ptr)->game_turn = 1;
 }
 
+static void
+pchr_oninit(void *ptr)
+{
+    ((struct pchrstr *)ptr)->p_sname = "";
+}
+
+static void
+mchr_oninit(void *ptr)
+{
+    ((struct mchrstr *)ptr)->m_name = "";
+}
+
+static void
+plchr_oninit(void *ptr)
+{
+    ((struct plchrstr *)ptr)->pl_name = "";
+}
+
+static void
+lchr_oninit(void *ptr)
+{
+    ((struct lchrstr *)ptr)->l_name = "";
+}
+
+static void
+nchr_oninit(void *ptr)
+{
+    ((struct nchrstr *)ptr)->n_name = "";
+}
+
 static void
 ef_fix_size(struct empfile *ep, int n)
 {

src/lib/common/stmtch.c

@@ -40,6 +40,7 @@
  * several.
  * Each array element has a pointer to its name stored at offset OFFS.
  * Search stops when this name is a null pointer.
+ * It ignores elements with an empty name.
  * NEEDLE is compared to element names with mineq(NEEDLE, NAME).
  * SIZE gives the size of an array element.
  */
@@ -54,6 +55,8 @@ stmtch(char *needle, void *haystack, ptrdiff_t offs, size_t size)
 	name = *(char **)((char *)haystack + i * size + offs);
 	if (!name)
 	    break;
+	if (!*name)
+	    continue;
 	switch (mineq(needle, name)) {
 	case ME_MISMATCH:
 	    break;

src/lib/common/xundump.c

@@ -43,7 +43,6 @@
  * - Normalize terminology: table/rows/columns or file/records/fields
  * - Loading tables with NSC_STRING elements more than once leaks memory
  * TODO:
- * - Check EFF_CFG tables are dense
  * - Symbolic array indexes
  * - Option to treat missing and unknown fields as warning, not error
  * TODO, but hardly worth the effort:

src/lib/global/init.c

@@ -60,6 +60,8 @@ init_mchr(void)
     struct mchrstr *mp;
 
     for (mp = mchr; mp->m_name; mp++) {
+	if (!mp->m_name[0])
+	    continue;
 	if (mp->m_nplanes && !(mp->m_flags & M_MSL || mp->m_flags & M_FLY))
 	    mp->m_flags |= M_MSL;
     }
@@ -71,6 +73,8 @@ init_plchr(void)
     struct plchrstr *pp;
 
     for (pp = plchr; pp->pl_name; pp++) {
+	if (!pp->pl_name[0])
+	    continue;
 	if (pp->pl_flags & P_M)
 	    pp->pl_flags |= P_V;
     }
@@ -81,7 +85,9 @@ init_pchr(void)
 {
     struct pchrstr *p;
 
-    for (p = pchr; p->p_name; p++) {
+    for (p = pchr; p->p_sname; p++) {
+	if (!p->p_sname[0])
+	    continue;
 	if (opt_GO_RENEW) {
 	    if (p->p_type == I_DUST || p->p_type == I_OIL)
 		p->p_nrdep = 0;

src/lib/subs/show.c

@@ -79,6 +79,8 @@ make_mchr_index(struct chr_index chridx[], int tlev)
 
     n = 0;
     for (i = 0; mchr[i].m_name; i++) {
+	if (!mchr[i].m_name[0])
+	    continue;
 	if (mchr[i].m_tech > tlev)
 	    continue;
 	if ((mchr[i].m_flags & M_TRADE) && !opt_TRADESHIPS)
@@ -100,6 +102,8 @@ make_plchr_index(struct chr_index chridx[], int tlev)
 
     n = 0;
     for (i = 0; plchr[i].pl_name; i++) {
+	if (!plchr[i].pl_name[0])
+	    continue;
 	if (plchr[i].pl_tech > tlev)
 	    continue;
 	chridx[n].type = i;
@@ -119,6 +123,8 @@ make_lchr_index(struct chr_index chridx[], int tlev)
 
     n = 0;
     for (i = 0; lchr[i].l_name; i++) {
+	if (!lchr[i].l_name[0])
+	    continue;
 	if (lchr[i].l_tech > tlev)
 	    continue;
 	if ((lchr[i].l_flags & L_SPY) && !opt_LANDSPIES)
@@ -140,6 +146,8 @@ make_nchr_index(struct chr_index chridx[], int tlev)
 
     n = 0;
     for (i = 0; nchr[i].n_name; i++) {
+	if (!nchr[i].n_name[0])
+	    continue;
 	if (nchr[i].n_tech > tlev)
 	    continue;
 	chridx[n].type = i;
@@ -506,6 +514,8 @@ show_product(int tlev)
     pr("product    cost  raw materials  reso dep  level p.e.\n");
 
     for (pp = pchr; pp->p_sname; pp++) {
+	if (!pp->p_sname[0])
+	    continue;
 	pr("%7.7s %c  $%-3d ",
 	   pp->p_sname,
 	   pp->p_type < 0 ? ' ' : ichr[pp->p_type].i_mnem,