Bound optalias_check's output buffers (thread their sizes)

optalias_check() wrote into caller-provided char* buffers with unchecked ops:
the param0 case did strcpybuff/strcatbuff of command+param into return_argv[0],
which can exceed the buffer, and the syntax-error paths sprintf()'d an option
name into return_error -- which is only 256 bytes in the config-file caller, so
a long option overflows it. Both are the overflow the audit flagged.

Thread return_argv_size and return_error_size through the (internal,
non-exported) signature; copy with strlcpybuff/strlcatbuff and format with
snprintf, so an over-long value aborts/truncates instead of overrunning. Update
both callers to pass their real sizes.

Leaves the shared cmdl_ins macro (the cmdl_* family wants its block size
threaded too -- a separate cleanup).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/htsalias.c

@@ -266,7 +266,9 @@ const char *hts_optalias[][4] = {
   return value: number of arguments treated (0 if error)
 */
 int optalias_check(int argc, const char *const *argv, int n_arg,
-                   int *return_argc, char **return_argv, char *return_error) {
+                   int *return_argc, char **return_argv,
+                   size_t return_argv_size, char *return_error,
+                   size_t return_error_size) {
   return_error[0] = '\0';
   *return_argc = 1;
   if (argv[n_arg][0] == '-')
@@ -323,9 +325,10 @@ int optalias_check(int argc, const char *const *argv, int n_arg,
           /* Copy parameters? */
           if (need_param == 2) {
             if ((n_arg + 1 >= argc) || (argv[n_arg + 1][0] == '-')) {   /* no supplemental parameter */
-              sprintf(return_error,
-                      "Syntax error:\n\tOption %s needs to be followed by a parameter: %s <param>\n\t%s\n",
-                      command, command, _NOT_NULL(optalias_help(command)));
+              snprintf(return_error, return_error_size,
+                       "Syntax error:\n\tOption %s needs to be followed by a "
+                       "parameter: %s <param>\n\t%s\n",
+                       command, command, _NOT_NULL(optalias_help(command)));
               return 0;
             }
             strcpybuff(param, argv[n_arg + 1]);
@@ -338,35 +341,36 @@ int optalias_check(int argc, const char *const *argv, int n_arg,
 
         /* Must be alone (-P /tmp) */
         if (strcmp(hts_optalias[pos][2], "param1") == 0) {
-          strcpybuff(return_argv[0], command);
-          strcpybuff(return_argv[1], param);
+          strlcpybuff(return_argv[0], command, return_argv_size);
+          strlcpybuff(return_argv[1], param, return_argv_size);
           *return_argc = 2;     /* 2 parameters returned */
         }
         /* Alone with parameter (+*.gif) */
         else if (strcmp(hts_optalias[pos][2], "param0") == 0) {
           /* Command */
-          strcpybuff(return_argv[0], command);
-          strcatbuff(return_argv[0], param);
+          strlcpybuff(return_argv[0], command, return_argv_size);
+          strlcatbuff(return_argv[0], param, return_argv_size);
         }
         /* Together (-c8) */
         else {
           /* Command */
-          strcpybuff(return_argv[0], command);
+          strlcpybuff(return_argv[0], command, return_argv_size);
           /* Parameters accepted */
           if (strncmp(hts_optalias[pos][2], "param", 5) == 0) {
             /* --cache=off or --index=on */
             if (strcmp(param, "off") == 0)
-              strcatbuff(return_argv[0], "0");
+              strlcatbuff(return_argv[0], "0", return_argv_size);
             else if (strcmp(param, "on") == 0) {
               // on is the default
               // strcatbuff(return_argv[0],"1");
             } else
-              strcatbuff(return_argv[0], param);
+              strlcatbuff(return_argv[0], param, return_argv_size);
           }
           *return_argc = 1;     /* 1 parameter returned */
         }
       } else {
-        sprintf(return_error, "Unknown option: %s\n", command);
+        snprintf(return_error, return_error_size, "Unknown option: %s\n",
+                 command);
         return 0;
       }
       return need_param;
@@ -380,15 +384,16 @@ int optalias_check(int argc, const char *const *argv, int n_arg,
       if ((strcmp(hts_optalias[pos][2], "param1") == 0)
           || (strcmp(hts_optalias[pos][2], "param0") == 0)) {
         if ((n_arg + 1 >= argc) || (argv[n_arg + 1][0] == '-')) {       /* no supplemental parameter */
-          sprintf(return_error,
-                  "Syntax error:\n\tOption %s needs to be followed by a parameter: %s <param>\n\t%s\n",
-                  argv[n_arg], argv[n_arg],
-                  _NOT_NULL(optalias_help(argv[n_arg])));
+          snprintf(return_error, return_error_size,
+                   "Syntax error:\n\tOption %s needs to be followed by a "
+                   "parameter: %s <param>\n\t%s\n",
+                   argv[n_arg], argv[n_arg],
+                   _NOT_NULL(optalias_help(argv[n_arg])));
           return 0;
         }
         /* Copy parameters */
-        strcpybuff(return_argv[0], argv[n_arg]);
-        strcpybuff(return_argv[1], argv[n_arg + 1]);
+        strlcpybuff(return_argv[0], argv[n_arg], return_argv_size);
+        strlcpybuff(return_argv[1], argv[n_arg + 1], return_argv_size);
         /* And return */
         *return_argc = 2;       /* 2 parameters returned */
         return 2;               /* 2 parameters used */
@@ -397,7 +402,7 @@ int optalias_check(int argc, const char *const *argv, int n_arg,
   }
 
   /* Copy and return other unknown option */
-  strcpybuff(return_argv[0], argv[n_arg]);
+  strlcpybuff(return_argv[0], argv[n_arg], return_argv_size);
   return 1;
 }
 
@@ -524,9 +529,10 @@ int optinclude_file(const char *name, int *argc, char **argv, char *x_argvblk,
             strcatbuff(_tmp_argv[0], a);
             strcpybuff(_tmp_argv[1], b);
 
-            result =
-              optalias_check(2, (const char *const *) tmp_argv, 0, &return_argc,
-                             (tmp_argv + 2), return_error);
+            result = optalias_check(2, (const char *const *) tmp_argv, 0,
+                                    &return_argc, (tmp_argv + 2),
+                                    sizeof(_tmp_argv[0]), return_error,
+                                    sizeof(return_error));
             if (!result) {
               printf("%s\n", return_error);
             } else {

src/htsalias.h

@@ -38,7 +38,9 @@ Please visit our Website: http://www.httrack.com
 #ifdef HTS_INTERNAL_BYTECODE
 extern const char *hts_optalias[][4];
 int optalias_check(int argc, const char *const *argv, int n_arg,
-                   int *return_argc, char **return_argv, char *return_error);
+                   int *return_argc, char **return_argv,
+                   size_t return_argv_size, char *return_error,
+                   size_t return_error_size);
 int optalias_find(const char *token);
 const char *optalias_help(const char *token);
 int optreal_find(const char *token);

src/htscoremain.c

@@ -211,6 +211,10 @@ static int string_safety_selftests(void) {
     htsbuff_cpy(&b, "xyz");             /* reset */
     if (strcmp(htsbuff_str(&b), "xyz") != 0 || b.len != 3)
       return 1;
+
+    htsbuff_catc(&b, '!'); /* single character */
+    if (strcmp(htsbuff_str(&b), "xyz!") != 0 || b.len != 4)
+      return 1;
   }
 
   /* boundary: filling to exactly cap-1 must succeed (one more aborts, which the
@@ -381,10 +385,10 @@ static int hts_main_internal(int argc, char **argv, httrackp * opt) {
       /* Vérifier argv[] non vide */
       if (strnotempty(argv[na])) {
 
-        /* Vérifier Commande (alias) */
-        result =
-          optalias_check(argc, (const char *const *) argv, na, &tmp_argc,
-                         (char **) tmp_argv, tmp_error);
+        /* Resolve an option alias, if any */
+        result = optalias_check(argc, (const char *const *) argv, na, &tmp_argc,
+                                (char **) tmp_argv, sizeof(_tmp_argv[0]),
+                                tmp_error, sizeof(tmp_error));
         if (!result) {
           HTS_PANIC_PRINTF(tmp_error);
           htsmain_free();

src/htslib.c

@@ -1660,138 +1660,107 @@ void treathead(t_cookie * cookie, const char *adr, const char *fil, htsblk * ret
   }
 }
 
-// transforme le message statuscode en chaîne
-HTSEXT_API void infostatuscode(char *msg, int statuscode) {
+// HTTP status code -> reason phrase (per RFC), or NULL if unknown.
+HTSEXT_API const char *infostatuscode_const(int statuscode) {
+  // O(1) dispatch (the compiler builds a jump table); the phrases are static.
   switch (statuscode) {
-    // Erreurs HTTP, selon RFC
   case 100:
-    strcpybuff(msg, "Continue");
-    break;
+    return "Continue";
   case 101:
-    strcpybuff(msg, "Switching Protocols");
-    break;
+    return "Switching Protocols";
   case 200:
-    strcpybuff(msg, "OK");
-    break;
+    return "OK";
   case 201:
-    strcpybuff(msg, "Created");
-    break;
+    return "Created";
   case 202:
-    strcpybuff(msg, "Accepted");
-    break;
+    return "Accepted";
   case 203:
-    strcpybuff(msg, "Non-Authoritative Information");
-    break;
+    return "Non-Authoritative Information";
   case 204:
-    strcpybuff(msg, "No Content");
-    break;
+    return "No Content";
   case 205:
-    strcpybuff(msg, "Reset Content");
-    break;
+    return "Reset Content";
   case 206:
-    strcpybuff(msg, "Partial Content");
-    break;
+    return "Partial Content";
   case 300:
-    strcpybuff(msg, "Multiple Choices");
-    break;
+    return "Multiple Choices";
   case 301:
-    strcpybuff(msg, "Moved Permanently");
-    break;
+    return "Moved Permanently";
   case 302:
-    strcpybuff(msg, "Moved Temporarily");
-    break;
+    return "Moved Temporarily";
   case 303:
-    strcpybuff(msg, "See Other");
-    break;
+    return "See Other";
   case 304:
-    strcpybuff(msg, "Not Modified");
-    break;
+    return "Not Modified";
   case 305:
-    strcpybuff(msg, "Use Proxy");
-    break;
+    return "Use Proxy";
   case 306:
-    strcpybuff(msg, "Undefined 306 error");
-    break;
+    return "Undefined 306 error";
   case 307:
-    strcpybuff(msg, "Temporary Redirect");
-    break;
+    return "Temporary Redirect";
   case 400:
-    strcpybuff(msg, "Bad Request");
-    break;
+    return "Bad Request";
   case 401:
-    strcpybuff(msg, "Unauthorized");
-    break;
+    return "Unauthorized";
   case 402:
-    strcpybuff(msg, "Payment Required");
-    break;
+    return "Payment Required";
   case 403:
-    strcpybuff(msg, "Forbidden");
-    break;
+    return "Forbidden";
   case 404:
-    strcpybuff(msg, "Not Found");
-    break;
+    return "Not Found";
   case 405:
-    strcpybuff(msg, "Method Not Allowed");
-    break;
+    return "Method Not Allowed";
   case 406:
-    strcpybuff(msg, "Not Acceptable");
-    break;
+    return "Not Acceptable";
   case 407:
-    strcpybuff(msg, "Proxy Authentication Required");
-    break;
+    return "Proxy Authentication Required";
   case 408:
-    strcpybuff(msg, "Request Time-out");
-    break;
+    return "Request Time-out";
   case 409:
-    strcpybuff(msg, "Conflict");
-    break;
+    return "Conflict";
   case 410:
-    strcpybuff(msg, "Gone");
-    break;
+    return "Gone";
   case 411:
-    strcpybuff(msg, "Length Required");
-    break;
+    return "Length Required";
   case 412:
-    strcpybuff(msg, "Precondition Failed");
-    break;
+    return "Precondition Failed";
   case 413:
-    strcpybuff(msg, "Request Entity Too Large");
-    break;
+    return "Request Entity Too Large";
   case 414:
-    strcpybuff(msg, "Request-URI Too Large");
-    break;
+    return "Request-URI Too Large";
   case 415:
-    strcpybuff(msg, "Unsupported Media Type");
-    break;
+    return "Unsupported Media Type";
   case 416:
-    strcpybuff(msg, "Requested Range Not Satisfiable");
-    break;
+    return "Requested Range Not Satisfiable";
   case 417:
-    strcpybuff(msg, "Expectation Failed");
-    break;
+    return "Expectation Failed";
   case 500:
-    strcpybuff(msg, "Internal Server Error");
-    break;
+    return "Internal Server Error";
   case 501:
-    strcpybuff(msg, "Not Implemented");
-    break;
+    return "Not Implemented";
   case 502:
-    strcpybuff(msg, "Bad Gateway");
-    break;
+    return "Bad Gateway";
   case 503:
-    strcpybuff(msg, "Service Unavailable");
-    break;
+    return "Service Unavailable";
   case 504:
-    strcpybuff(msg, "Gateway Time-out");
-    break;
+    return "Gateway Time-out";
   case 505:
-    strcpybuff(msg, "HTTP Version Not Supported");
-    break;
-    //
+    return "HTTP Version Not Supported";
   default:
-    if (strnotempty(msg) == 0)
-      strcpybuff(msg, "Unknown error");
-    break;
+    return NULL;
+  }
+}
+
+// Write the status code's reason phrase into msg. For an unknown code, keep any
+// caller-provided message, otherwise fall back to a default. Callers provide a
+// buffer of at least 64 bytes (the longest reason phrase is 31).
+HTSEXT_API void infostatuscode(char *msg, int statuscode) {
+  const char *const text = infostatuscode_const(statuscode);
+
+  if (text != NULL) {
+    strlcpybuff(msg, text, 64);
+  } else if (strnotempty(msg) == 0) {
+    strlcpybuff(msg, "Unknown error", 64);
   }
 }
 

src/htsname.c

@@ -767,7 +767,7 @@ int url_savename(lien_adrfilsave *const afs,
   // ajouter nom du site éventuellement en premier
   if (opt->savename_type == -1) {       // utiliser savename_userdef! (%h%p/%n%q.%t)
     const char *a = StringBuff(opt->savename_userdef);
-    char *b = afs->save;
+    htsbuff sb = htsbuff_array(afs->save);
 
     /*char *nom_pos=NULL,*dot_pos=NULL;  // Position nom et point */
     char tok;
@@ -787,17 +787,16 @@ int url_savename(lien_adrfilsave *const afs,
        }
      */
 
-    // Construire nom
-    while((*a) && (((int) (b - afs->save)) < HTS_URLMAXSIZE)) {      // parser, et pas trop long..
+    // build the name
+    while ((*a) && (sb.len < HTS_URLMAXSIZE)) { // parse, but not too long
       if (*a == '%') {
         int short_ver = 0;
 
         a++;
-        if (*a == 's') {
+        if (*a == 's') { // '%s...' selects the short (8.3) form
           short_ver = 1;
           a++;
         }
-        *b = '\0';
         switch (tok = *a++) {
         case '[':              // %[param:prefix_if_not_empty:suffix_if_not_empty:empty_replacement:notfound_replacement]
           if (strchr(a, ']')) {
@@ -834,8 +833,7 @@ int url_savename(lien_adrfilsave *const afs,
               }
               if (cp) {
                 c = cp + strlen(name[0]);       /* jumps "param=" */
-                strcpybuff(b, name[1]); /* prefix */
-                b += strlen(b);
+                htsbuff_cat(&sb, name[1]);      /* prefix */
                 if (*c != '\0' && *c != '&') {
                   char *d = name[0];
 
@@ -846,110 +844,90 @@ int url_savename(lien_adrfilsave *const afs,
                   *d = '\0';
                   d = unescape_http(catbuff, sizeof(catbuff), name[0]);
                   if (d && *d) {
-                    strcpybuff(b, d);   /* value */
-                    b += strlen(b);
+                    htsbuff_cat(&sb, d); /* value */
                   } else {
-                    strcpybuff(b, name[3]);     /* empty replacement if any */
-                    b += strlen(b);
+                    htsbuff_cat(&sb, name[3]); /* empty replacement if any */
                   }
                 } else {
-                  strcpybuff(b, name[3]);       /* empty replacement if any */
-                  b += strlen(b);
+                  htsbuff_cat(&sb, name[3]); /* empty replacement if any */
                 }
-                strcpybuff(b, name[2]); /* suffix */
-                b += strlen(b);
+                htsbuff_cat(&sb, name[2]); /* suffix */
               } else {
-                strcpybuff(b, name[4]); /* not found replacement if any */
-                b += strlen(b);
+                htsbuff_cat(&sb, name[4]); /* not found replacement if any */
               }
             } else {
-              strcpybuff(b, name[4]);   /* not found replacement if any */
-              b += strlen(b);
+              htsbuff_cat(&sb, name[4]); /* not found replacement if any */
             }
           }
           break;
         case '%':
-          *b++ = '%';
+          htsbuff_catc(&sb, '%');
           break;
-        case 'n':              // nom sans ext
-          *b = '\0';
+        case 'n': // name without extension
           if (dot_pos) {
-            if (!short_ver)     // Noms longs
-              strncatbuff(b, nom_pos, (int) (dot_pos - nom_pos));
+            if (!short_ver)
+              htsbuff_catn(&sb, nom_pos, (int) (dot_pos - nom_pos));
             else
-              strncatbuff(b, nom_pos, min((int) (dot_pos - nom_pos), 8));
+              htsbuff_catn(&sb, nom_pos, min((int) (dot_pos - nom_pos), 8));
           } else {
-            if (!short_ver)     // Noms longs
-              strcpybuff(b, nom_pos);
+            if (!short_ver)
+              htsbuff_cat(&sb, nom_pos);
             else
-              strncatbuff(b, nom_pos, 8);
+              htsbuff_catn(&sb, nom_pos, 8);
           }
-          b += strlen(b);       // pointer à la fin
           break;
-        case 'N':              // nom avec ext
-          // RECOPIE NOM + EXT
-          *b = '\0';
+        case 'N': // name with extension
           if (dot_pos) {
-            if (!short_ver)     // Noms longs
-              strncatbuff(b, nom_pos, (int) (dot_pos - nom_pos));
+            if (!short_ver)
+              htsbuff_catn(&sb, nom_pos, (int) (dot_pos - nom_pos));
             else
-              strncatbuff(b, nom_pos, min((int) (dot_pos - nom_pos), 8));
+              htsbuff_catn(&sb, nom_pos, min((int) (dot_pos - nom_pos), 8));
           } else {
-            if (!short_ver)     // Noms longs
-              strcpybuff(b, nom_pos);
+            if (!short_ver)
+              htsbuff_cat(&sb, nom_pos);
             else
-              strncatbuff(b, nom_pos, 8);
+              htsbuff_catn(&sb, nom_pos, 8);
           }
-          b += strlen(b);       // pointer à la fin
-          *b = '.';
-          ++b;
-          // RECOPIE NOM + EXT
-          *b = '\0';
+          htsbuff_catc(&sb, '.');
           if (dot_pos) {
-            if (!short_ver)     // Noms longs
-              strcpybuff(b, dot_pos + 1);
+            if (!short_ver)
+              htsbuff_cat(&sb, dot_pos + 1);
             else
-              strncatbuff(b, dot_pos + 1, 3);
+              htsbuff_catn(&sb, dot_pos + 1, 3);
           } else {
-            if (!short_ver)     // Noms longs
-              strcpybuff(b, DEFAULT_EXT + 1);   // pas de..
+            if (!short_ver)
+              htsbuff_cat(&sb, DEFAULT_EXT + 1); // skip the leading dot
             else
-              strcpybuff(b, DEFAULT_EXT_SHORT + 1);     // pas de..
+              htsbuff_cat(&sb, DEFAULT_EXT_SHORT + 1); // skip the leading dot
           }
-          b += strlen(b);       // pointer à la fin
-          //
           break;
-        case 't':              // ext
-          *b = '\0';
+        case 't': // extension
           if (dot_pos) {
-            if (!short_ver)     // Noms longs
-              strcpybuff(b, dot_pos + 1);
+            if (!short_ver)
+              htsbuff_cat(&sb, dot_pos + 1);
             else
-              strncatbuff(b, dot_pos + 1, 3);
+              htsbuff_catn(&sb, dot_pos + 1, 3);
           } else {
-            if (!short_ver)     // Noms longs
-              strcpybuff(b, DEFAULT_EXT + 1);   // pas de..
+            if (!short_ver)
+              htsbuff_cat(&sb, DEFAULT_EXT + 1); // skip the leading dot
             else
-              strcpybuff(b, DEFAULT_EXT_SHORT + 1);     // pas de..
+              htsbuff_cat(&sb, DEFAULT_EXT_SHORT + 1); // skip the leading dot
           }
-          b += strlen(b);       // pointer à la fin
           break;
-        case 'p':              // path sans dernier /
-          *b = '\0';
-          if (nom_pos != fil + 1) {     // pas: /index.html (chemin nul)
-            if (!short_ver) {   // Noms longs
-              strncatbuff(b, fil, (int) (nom_pos - fil) - 1);
+        case 'p': // path without trailing /
+          if (nom_pos !=
+              fil + 1) { // skip when the path is empty (e.g. /index.html)
+            if (!short_ver) {
+              htsbuff_catn(&sb, fil, (int) (nom_pos - fil) - 1);
             } else {
               char BIGSTK pth[HTS_URLMAXSIZE * 2], n83[HTS_URLMAXSIZE * 2];
 
               pth[0] = n83[0] = '\0';
-              //
               strncatbuff(pth, fil, (int) (nom_pos - fil) - 1);
               long_to_83(opt->savename_83, n83, pth);
-              strcpybuff(b, n83);
+              htsbuff_cat(&sb, n83);
             }
           }
-          b += strlen(b);       // pointer à la fin
           break;
         case 'h':              // host (IDNA decoded if suitable)
           // IDNA / RFC 3492 (Punycode) handling for HTTP(s)
@@ -957,62 +935,50 @@ int url_savename(lien_adrfilsave *const afs,
             DECLARE_ADR(final_adr);
 
             /* Copy address */
-            *b = '\0';
             if (!short_ver)
-              strcpybuff(b, final_adr);
+              htsbuff_cat(&sb, final_adr);
             else
-              strcpybuff(b, final_adr);
+              htsbuff_cat(&sb, final_adr);
 
             /* release */
             RELEASE_ADR();
           }
-          b += strlen(b);       // pointer à la fin
           break;
-        case 'H':              // host, raw (old mode)
-          *b = '\0';
+        case 'H': // host, raw (old mode)
           if (protocol == PROTOCOL_FILE) {
-            if (!short_ver)     // Noms longs
-              strcpybuff(b, "localhost");
+            if (!short_ver)
+              htsbuff_cat(&sb, "localhost");
             else
-              strcpybuff(b, "local");
+              htsbuff_cat(&sb, "local");
           } else {
-            if (!short_ver)     // Noms longs
-              strcpybuff(b, print_adr);
+            if (!short_ver)
+              htsbuff_cat(&sb, print_adr);
             else
-              strncatbuff(b, print_adr, 8);
+              htsbuff_catn(&sb, print_adr, 8);
           }
-          b += strlen(b);       // pointer à la fin
           break;
-        case 'M':              /* host/address?query MD5 (128-bits) */
-          *b = '\0';
-          {
-            char digest[32 + 2];
-            char BIGSTK buff[HTS_URLMAXSIZE * 2];
+        case 'M': /* host/address?query MD5 (128-bits) */
+        {
+          char digest[32 + 2];
+          char BIGSTK buff[HTS_URLMAXSIZE * 2];
 
-            digest[0] = buff[0] = '\0';
-            strcpybuff(buff, adr);
-            strcatbuff(buff, fil_complete);
-            domd5mem(buff, strlen(buff), digest, 1);
-            strcpybuff(b, digest);
-          }
-          b += strlen(b);       // pointer à la fin
-          break;
+          digest[0] = buff[0] = '\0';
+          strcpybuff(buff, adr);
+          strcatbuff(buff, fil_complete);
+          domd5mem(buff, strlen(buff), digest, 1);
+          htsbuff_cat(&sb, digest);
+        } break;
         case 'Q':
-        case 'q':              /* query MD5 (128-bits/16-bits) 
-                                   GENERATED ONLY IF query string exists! */
-          {
-            char md5[32 + 2];
+        case 'q': /* query MD5 (128-bits/16-bits)
+                      GENERATED ONLY IF query string exists! */
+        {
+          char md5[32 + 2];
 
-            *b = '\0';
-            strncatbuff(b, url_md5(md5, fil_complete), (tok == 'Q') ? 32 : 4);
-            b += strlen(b);     // pointer à la fin
-          }
-          break;
+          htsbuff_catn(&sb, url_md5(md5, fil_complete), (tok == 'Q') ? 32 : 4);
+        } break;
         case 'r':
         case 'R':              // protocol
-          *b = '\0';
-          strcatbuff(b, protocol_str[protocol]);
-          b += strlen(b);       // pointer à la fin
+          htsbuff_cat(&sb, protocol_str[protocol]);
           break;
 
           /* Patch by Juan Fco Rodriguez to get the full query string */
@@ -1021,19 +987,17 @@ int url_savename(lien_adrfilsave *const afs,
             char *d = strchr(fil_complete, '?');
 
             if (d != NULL) {
-              strcatbuff(b, d);
-              b += strlen(b);
+              htsbuff_cat(&sb, d);
             }
           }
           break;
 
         }
       } else
-        *b++ = *a++;
+        htsbuff_catc(&sb, *a++);
     }
-    *b++ = '\0';
     //
-    // Types prédéfinis
+    // predefined types
     //
 
   }

src/htssafe.h

@@ -351,6 +351,13 @@ static HTS_INLINE HTS_UNUSED void htsbuff_cat(htsbuff *b, const char *s) {
   htsbuff_catn(b, s, (size_t) -1);
 }
 
+/** Append a single character (including '\0' as data). Aborts on overflow. */
+static HTS_INLINE HTS_UNUSED void htsbuff_catc(htsbuff *b, char c) {
+  assertf__(1 < b->cap - b->len, "htsbuff append overflow", __FILE__, __LINE__);
+  b->buf[b->len++] = c;
+  b->buf[b->len] = '\0';
+}
+
 /** Reset content to s. Aborts on overflow. */
 static HTS_INLINE HTS_UNUSED void htsbuff_cpy(htsbuff *b, const char *s) {
   b->len = 0;

src/httrack-library.h

@@ -193,6 +193,7 @@ HTSEXT_API int structcheck(const char *path);
 HTSEXT_API int structcheck_utf8(const char *path);
 HTSEXT_API int dir_exists(const char *path);
 HTSEXT_API void infostatuscode(char *msg, int statuscode);
+HTSEXT_API const char *infostatuscode_const(int statuscode);
 HTSEXT_API TStamp mtime_local(void);
 HTSEXT_API void qsec2str(char *st, TStamp t);
 HTSEXT_API char *int2char(strc_int2bytes2 * strc, int n);