No OOM error condition in ga_concat_strings(), concat_fnames(), concat_str()

- xmallocz() is not static anymore. There are many use cases for this function
	 in the codebase and we should start using it.
 - Simpler types in ga_concat_strings()

src/ex_cmds.c

@@ -4022,22 +4022,14 @@ void do_sub(exarg_T *eap)
                   char_u *new_line = concat_str(new_start,
                                                 sub_firstline + copycol);
 
-                  if (new_line == NULL) {
-                    vim_free(orig_line);
-                    orig_line = NULL;
-                  } else {
-                    /* Position the cursor relative to the
-                     * end of the line, the previous
-                     * substitute may have inserted or
-                     * deleted characters before the
-                     * cursor. */
-                    len_change = (int)STRLEN(new_line)
-                                 - (int)STRLEN(orig_line);
+                  // Position the cursor relative to the end of the line, the
+                  // previous substitute may have inserted or deleted characters
+                  // before the cursor.
+                  len_change = (int)STRLEN(new_line) - (int)STRLEN(orig_line);
                   curwin->w_cursor.col += len_change;
                   ml_replace(lnum, new_line, FALSE);
                 }
               }
-              }
 
               search_match_lines = regmatch.endpos[0].lnum
                                    - regmatch.startpos[0].lnum;

src/garray.c

@@ -102,28 +102,26 @@ void ga_remove_duplicate_strings(garray_T *gap)
 ///
 /// @param gap
 ///
-/// @returns NULL when out of memory.
+/// @returns the concatenated strings
 char_u* ga_concat_strings(garray_T *gap)
 {
-  int i;
-  int len = 0;
-  char_u *s;
+  size_t len = 0;
 
-  for (i = 0; i < gap->ga_len; ++i) {
-    len += (int)STRLEN(((char_u **)(gap->ga_data))[i]) + 1;
+  for (int i = 0; i < gap->ga_len; ++i) {
+    len += strlen(((char **)(gap->ga_data))[i]) + 1;
   }
 
-  s = alloc(len + 1);
+  char *s = xmallocz(len);
 
   *s = NUL;
-  for (i = 0; i < gap->ga_len; ++i) {
+  for (int i = 0; i < gap->ga_len; ++i) {
     if (*s != NUL) {
-      STRCAT(s, ",");
+      strcat(s, ",");
     }
-    STRCAT(s, ((char_u **)(gap->ga_data))[i]);
+    strcat(s, ((char **)(gap->ga_data))[i]);
   }
 
-  return s;
+  return (char_u *)s;
 }
 
 /// Concatenate a string to a growarray which contains characters.

src/if_cscope.c

@@ -2161,7 +2161,7 @@ static char *cs_resolve_file(int i, char *name)
       && (strncmp(name, csinfo[i].ppath, strlen(csinfo[i].ppath)) != 0)
       && (name[0] != '/')
       ) {
-    fullname = (char *)alloc(len);
+    fullname = xmalloc(len);
     (void)sprintf(fullname, "%s/%s", csinfo[i].ppath, name);
   } else if (csdir != NULL && csinfo[i].fname != NULL && *csdir != NUL) {
     /* Check for csdir to be non empty to avoid empty path concatenated to

src/main.c

@@ -1433,11 +1433,9 @@ scripterror:
         char_u      *r;
 
         r = concat_fnames(p, path_tail(alist_name(&GARGLIST[0])), TRUE);
-        if (r != NULL) {
         vim_free(p);
         p = r;
       }
-      }
 
 #ifdef USE_FNAME_CASE
       /* Make the case of the file name match the actual file. */

src/memline.c

@@ -1586,18 +1586,12 @@ recover_names (
           tail = make_percent_swname(dir_name, fname_res);
         } else
 #endif
-        {
         tail = path_tail(fname_res);
         tail = concat_fnames(dir_name, tail, TRUE);
-        }
-        if (tail == NULL)
-          num_names = 0;
-        else {
         num_names = recov_file_names(names, tail, FALSE);
         vim_free(tail);
       }
     }
-    }
 
     /* check for out-of-memory */
     for (i = 0; i < num_names; ++i) {
@@ -1709,8 +1703,7 @@ static char_u *make_percent_swname(char_u *dir, char_u *name)
   f = fix_fname(name != NULL ? name : (char_u *) "");
   d = NULL;
   if (f != NULL) {
-    s = alloc((unsigned)(STRLEN(f) + 1));
-    STRCPY(s, f);
+    s = (char_u *)xstrdup((char *)f);
     for (d = s; *d != NUL; mb_ptr_adv(d))
       if (vim_ispathsep(*d))
         *d = '%';
@@ -1855,12 +1848,8 @@ static int recov_file_names(char_u **names, char_u *path, int prepend_dot)
     ++num_names;
   }
 
-  /*
-   * Form the normal swap file name pattern by appending ".sw?".
-   */
+  // Form the normal swap file name pattern by appending ".sw?".
   names[num_names] = concat_fnames(path, (char_u *)".sw?", FALSE);
-  if (names[num_names] == NULL)
-    goto end;
   if (num_names >= 1) {     /* check if we have the same name twice */
     p = names[num_names - 1];
     i = (int)STRLEN(names[num_names - 1]) - (int)STRLEN(names[num_names]);
@@ -3497,16 +3486,12 @@ get_file_in_dir (
       *tail = NUL;
       t = concat_fnames(fname, dname + 2, TRUE);
       *tail = save_char;
-      if (t == NULL)                /* out of memory */
-        retval = NULL;
-      else {
       retval = concat_fnames(t, tail, TRUE);
       vim_free(t);
     }
-    }
-  } else
+  } else {
     retval = concat_fnames(dname, tail, TRUE);
-
+  }
 
   return retval;
 }

src/misc1.c

@@ -3125,11 +3125,11 @@ static char_u *vim_version_dir(char_u *vimdir)
   if (vimdir == NULL || *vimdir == NUL)
     return NULL;
   p = concat_fnames(vimdir, (char_u *)VIM_VERSION_NODOT, TRUE);
-  if (p != NULL && os_isdir(p))
+  if (os_isdir(p))
     return p;
   vim_free(p);
   p = concat_fnames(vimdir, (char_u *)RUNTIME_DIRNAME, TRUE);
-  if (p != NULL && os_isdir(p))
+  if (os_isdir(p))
     return p;
   vim_free(p);
   return NULL;
@@ -3163,13 +3163,10 @@ void vim_setenv(char_u *name, char_u *val)
    */
   if (*val != NUL && STRICMP(name, "VIMRUNTIME") == 0) {
     char_u  *buf = concat_str(val, (char_u *)"/lang");
-
-    if (buf != NULL) {
     bindtextdomain(VIMPACKAGE, (char *)buf);
     vim_free(buf);
   }
 }
-}
 
 
 /*

src/option.c

@@ -5048,7 +5048,6 @@ static char_u *compile_cap_prog(synblock_T *synblock)
   else {
     /* Prepend a ^ so that we only match at one column */
     re = concat_str((char_u *)"^", synblock->b_p_spc);
-    if (re != NULL) {
     synblock->b_cap_prog = vim_regcomp(re, RE_MAGIC);
     vim_free(re);
     if (synblock->b_cap_prog == NULL) {
@@ -5056,7 +5055,6 @@ static char_u *compile_cap_prog(synblock_T *synblock)
       return e_invarg;
     }
   }
-  }
 
   vim_regfree(rp);
   return NULL;

src/path.c

@@ -272,32 +272,26 @@ int vim_fnamencmp(char_u *x, char_u *y, size_t len)
  */
 char_u *concat_fnames(char_u *fname1, char_u *fname2, int sep)
 {
-  char_u  *dest;
+  char_u *dest = xmalloc(STRLEN(fname1) + STRLEN(fname2) + 3);
 
-  dest = alloc((unsigned)(STRLEN(fname1) + STRLEN(fname2) + 3));
-  if (dest != NULL) {
   STRCPY(dest, fname1);
-    if (sep)
+  if (sep) {
     add_pathsep(dest);
-    STRCAT(dest, fname2);
   }
+  STRCAT(dest, fname2);
+
   return dest;
 }
 
 /*
  * Concatenate two strings and return the result in allocated memory.
- * Returns NULL when out of memory.
  */
 char_u *concat_str(char_u *str1, char_u *str2)
 {
-  char_u  *dest;
   size_t l = STRLEN(str1);
-
-  dest = alloc((unsigned)(l + STRLEN(str2) + 1L));
-  if (dest != NULL) {
+  char_u *dest = xmalloc(l + STRLEN(str2) + 1);
   STRCPY(dest, str1);
   STRCPY(dest + l, str2);
-  }
   return dest;
 }
 
@@ -916,8 +910,6 @@ expand_in_path (
 
   paths = ga_concat_strings(&path_ga);
   ga_clear_strings(&path_ga);
-  if (paths == NULL)
-    return 0;
 
   files = globpath(paths, pattern, (flags & EW_ICASE) ? WILD_ICASE : 0);
   vim_free(paths);

src/quickfix.c

@@ -1119,8 +1119,8 @@ static int qf_get_fnum(char_u *directory, char_u *fname)
       slash_adjust(directory);
     slash_adjust(fname);
 #endif
-    if (directory != NULL && !vim_isAbsName(fname)
-        && (ptr = concat_fnames(directory, fname, TRUE)) != NULL) {
+    if (directory != NULL && !vim_isAbsName(fname)) {
+      ptr = concat_fnames(directory, fname, TRUE);
       /*
        * Here we check if the file really exists.
        * This should normally be true, but if make works without
@@ -1280,10 +1280,7 @@ static char_u *qf_guess_filepath(char_u *filename)
     vim_free(fullname);
     fullname = concat_fnames(ds_ptr->dirname, filename, TRUE);
 
-    /* If concat_fnames failed, just go on. The worst thing that can happen
-     * is that we delete the entire stack.
-     */
-    if (fullname != NULL && os_file_exists(fullname))
+    if (os_file_exists(fullname))
       break;
 
     ds_ptr = ds_ptr->next;

src/undo.c

@@ -721,11 +721,11 @@ char_u *u_get_undo_file_name(char_u *buf_ffname, int reading)
       }
     }
 
-    /* When reading check if the file exists. */
-    if (undo_file_name != NULL && (!reading
-                                   || mch_stat((char *)undo_file_name,
-                                       &st) >= 0))
+    // When reading check if the file exists.
+    if (undo_file_name != NULL &&
+        (!reading || mch_stat((char *)undo_file_name, &st) >= 0)) {
       break;
+    }
     vim_free(undo_file_name);
     undo_file_name = NULL;
   }