Remove OOM checks: suggested changes in review

- Replace a vim_strsave/free pair with xrealloc
 - Use xmallocz() in some places
 - Use xrealloc() and forget about the NULL pointer case
 - Remove invalid comment
 - Remove unnecessary checks
 - Replace a complicated xmalloc/STRCPY/free code chunk code with xrealloc()
 - Replace a vim_strsave/free code chunk with xrealloc()

src/nvim/eval.c

@@ -9592,9 +9592,8 @@ static void f_getcmdpos(typval_T *argvars, typval_T *rettv)
 static void f_getcmdtype(typval_T *argvars, typval_T *rettv)
 {
   rettv->v_type = VAR_STRING;
-  rettv->vval.v_string = xmalloc(2);
+  rettv->vval.v_string = xmallocz(1);
   rettv->vval.v_string[0] = get_cmdline_type();
-  rettv->vval.v_string[1] = NUL;
 }
 
 /*
@@ -12124,8 +12123,6 @@ static void f_readfile(typval_T *argvars, typval_T *rettv)
     if (start < p) {
       /* There's part of a line in buf, store it in "prev". */
       if (p - start + prevlen >= prevsize) {
-        /* need bigger "prev" buffer */
-        char_u *newprev;
 
         /* A common use case is ordinary text files and "prev" gets a
          * fragment of a line, so the first allocation is made
@@ -12138,8 +12135,7 @@ static void f_readfile(typval_T *argvars, typval_T *rettv)
           long growmin  = (long)((p - start) * 2 + prevlen);
           prevsize = grow50pc > growmin ? grow50pc : growmin;
         }
-        newprev = (prev == NULL) ? xmalloc(prevsize) : xrealloc(prev, prevsize);
-        prev = newprev;
+        prev = xrealloc(prev, prevsize);
       }
       /* Add the line part to end of "prev". */
       memmove(prev + prevlen, start, p - start);
@@ -12398,10 +12394,9 @@ static void f_repeat(typval_T *argvars, typval_T *rettv)
     if (len <= 0)
       return;
 
-    char_u *r = xmalloc(len + 1);
+    char_u *r = xmallocz(len);
     for (int i = 0; i < n; i++)
       memmove(r + i * slen, p, (size_t)slen);
-    r[len] = NUL;
 
     rettv->vval.v_string = r;
   }
@@ -15708,7 +15703,7 @@ static char_u *make_expanded_name(char_u *in_start, char_u *expr_start, char_u *
   temp_result = eval_to_string(expr_start + 1, &nextcmd, FALSE);
   if (temp_result != NULL && nextcmd == NULL) {
     retval = xmalloc(STRLEN(temp_result) + (expr_start - in_start)
-                              + (in_end - expr_end) + 1);
+                     + (in_end - expr_end) + 1);
     STRCPY(retval, in_start);
     STRCAT(retval, temp_result);
     STRCAT(retval, expr_end + 1);

src/nvim/ex_getln.c

@@ -1986,7 +1986,7 @@ static void alloc_cmdbuff(int len)
   else
     len += 20;
 
-  ccline.cmdbuff = xmalloc(len);      /* caller should check for out-of-memory */
+  ccline.cmdbuff = xmalloc(len);
   ccline.cmdbufflen = len;
 }
 
@@ -2179,10 +2179,7 @@ void put_on_cmdline(char_u *str, int len, int redraw)
   if (len < 0)
     len = (int)STRLEN(str);
 
-  /* Check if ccline.cmdbuff needs to be longer */
-  if (ccline.cmdlen + len + 1 >= ccline.cmdbufflen) {
-    realloc_cmdbuff(ccline.cmdlen + len + 1);
-  }
+  realloc_cmdbuff(ccline.cmdlen + len + 1);
 
   if (!ccline.overstrike) {
     memmove(ccline.cmdbuff + ccline.cmdpos + len,

src/nvim/quickfix.c

@@ -719,13 +719,10 @@ restofline:
         if (qfprev == NULL)
           goto error2;
         if (*errmsg && !multiignore) {
-          len = (int)STRLEN(qfprev->qf_text);
-          ptr = xmalloc(len + STRLEN(errmsg) + 2);
-          STRCPY(ptr, qfprev->qf_text);
-          free(qfprev->qf_text);
-          qfprev->qf_text = ptr;
-          *(ptr += len) = '\n';
-          STRCPY(++ptr, errmsg);
+          size_t len = STRLEN(qfprev->qf_text);
+          qfprev->qf_text = xrealloc(qfprev->qf_text, len + STRLEN(errmsg) + 2);
+          qfprev->qf_text[len] = '\n';
+          STRCPY(qfprev->qf_text + len + 1, errmsg);
         }
         if (qfprev->qf_nr == -1)
           qfprev->qf_nr = enr;

src/nvim/screen.c

@@ -4691,10 +4691,7 @@ win_redr_status_matches (
   if (matches == NULL)          /* interrupted completion? */
     return;
 
-  if (has_mbyte)
-    buf = xmalloc(Columns * MB_MAXBYTES + 1);
-  else
-    buf = xmalloc(Columns + 1);
+  buf = xmalloc(has_mbyte ? Columns * MB_MAXBYTES + 1 : Columns + 1);
 
   if (match == -1) {    /* don't show match but original text */
     match = 0;

src/nvim/term.c

@@ -4304,14 +4304,9 @@ replace_termcodes (
   }
   result[dlen] = NUL;
 
-  /*
-   * Copy the new string to allocated memory.
-   * If this fails, just return from.
-   */
-  *bufp = vim_strsave(result);
-  from = *bufp;
-  free(result);
-  return from;
+  *bufp = xrealloc(result, dlen + 1);
+
+  return *bufp;
 }
 
 /*