Prefer xpalloc to doubling buffers by hand

* src/lread.c (grow_read_buffer): New function, which uses xpalloc.
(read1): Use it for simplicity.
* src/macros.c (store_kbd_macro_char):
* src/minibuf.c (read_minibuf_noninteractive):
* src/term.c (encode_terminal_code):
* src/xrdb.c (magic_db):
Prefer xpalloc to growing buffers by hand.
This doesn’t fix any bugs, but simplifies the code a bit.

5 files changed, 24 insertions, 38 deletions

diff --git a/src/lread.c b/src/lread.c
index 7c891f9954f..c4456f37f6d 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -2120,6 +2120,15 @@ read0 (Lisp_Object readcharfun)
 static ptrdiff_t read_buffer_size;
 static char *read_buffer;
 
+/* Grow the read buffer by at least MAX_MULTIBYTE_LENGTH bytes.  */
+
+static void
+grow_read_buffer (void)
+{
+  read_buffer = xpalloc (read_buffer, &read_buffer_size,
+			 MAX_MULTIBYTE_LENGTH, -1, 1);
+}
+
 /* Read a \-escape sequence, assuming we already read the `\'.
    If the escape sequence forces unibyte, return eight-bit char.  */
 
@@ -2985,10 +2994,7 @@ read1 (Lisp_Object readcharfun, int *pch, bool first_in_list)
 	    if (end - p < MAX_MULTIBYTE_LENGTH)
 	      {
 		ptrdiff_t offset = p - read_buffer;
-		if (min (PTRDIFF_MAX, SIZE_MAX) / 2 < read_buffer_size)
-		  memory_full (SIZE_MAX);
-		read_buffer = xrealloc (read_buffer, read_buffer_size * 2);
-		read_buffer_size *= 2;
+		grow_read_buffer ();
 		p = read_buffer + offset;
 		end = read_buffer + read_buffer_size;
 	      }
@@ -3119,10 +3125,7 @@ read1 (Lisp_Object readcharfun, int *pch, bool first_in_list)
 	      if (end - p < MAX_MULTIBYTE_LENGTH)
 		{
 		  ptrdiff_t offset = p - read_buffer;
-		  if (min (PTRDIFF_MAX, SIZE_MAX) / 2 < read_buffer_size)
-		    memory_full (SIZE_MAX);
-		  read_buffer = xrealloc (read_buffer, read_buffer_size * 2);
-		  read_buffer_size *= 2;
+		  grow_read_buffer ();
 		  p = read_buffer + offset;
 		  end = read_buffer + read_buffer_size;
 		}
@@ -3149,10 +3152,7 @@ read1 (Lisp_Object readcharfun, int *pch, bool first_in_list)
 	  if (p == end)
 	    {
 	      ptrdiff_t offset = p - read_buffer;
-	      if (min (PTRDIFF_MAX, SIZE_MAX) / 2 < read_buffer_size)
-		memory_full (SIZE_MAX);
-	      read_buffer = xrealloc (read_buffer, read_buffer_size * 2);
-	      read_buffer_size *= 2;
+	      grow_read_buffer ();
 	      p = read_buffer + offset;
 	      end = read_buffer + read_buffer_size;
 	    }
diff --git a/src/macros.c b/src/macros.c
index d963838069b..7c6ab2efc30 100644
--- a/src/macros.c
+++ b/src/macros.c
@@ -184,16 +184,11 @@ store_kbd_macro_char (Lisp_Object c)
     {
       if (kb->kbd_macro_ptr - kb->kbd_macro_buffer == kb->kbd_macro_bufsize)
 	{
-	  ptrdiff_t ptr_offset, end_offset, nbytes;
-
-	  ptr_offset = kb->kbd_macro_ptr - kb->kbd_macro_buffer;
-	  end_offset = kb->kbd_macro_end - kb->kbd_macro_buffer;
-	  if (min (PTRDIFF_MAX, SIZE_MAX) / sizeof *kb->kbd_macro_buffer / 2
-	      < kb->kbd_macro_bufsize)
-	    memory_full (SIZE_MAX);
-	  nbytes = kb->kbd_macro_bufsize * (2 * sizeof *kb->kbd_macro_buffer);
-	  kb->kbd_macro_buffer = xrealloc (kb->kbd_macro_buffer, nbytes);
-	  kb->kbd_macro_bufsize *= 2;
+	  ptrdiff_t ptr_offset = kb->kbd_macro_ptr - kb->kbd_macro_buffer;
+	  ptrdiff_t end_offset = kb->kbd_macro_end - kb->kbd_macro_buffer;
+	  kb->kbd_macro_buffer = xpalloc (kb->kbd_macro_buffer,
+					  &kb->kbd_macro_bufsize,
+					  1, -1, sizeof *kb->kbd_macro_buffer);
 	  kb->kbd_macro_ptr = kb->kbd_macro_buffer + ptr_offset;
 	  kb->kbd_macro_end = kb->kbd_macro_buffer + end_offset;
 	}
diff --git a/src/minibuf.c b/src/minibuf.c
index 31b69461bde..727a70b166f 100644
--- a/src/minibuf.c
+++ b/src/minibuf.c
@@ -229,12 +229,7 @@ read_minibuf_noninteractive (Lisp_Object map, Lisp_Object initial,
 	  if (hide_char)
 	    fprintf (stdout, "%c", hide_char);
 	  if (len == size)
-	    {
-	      if (STRING_BYTES_BOUND / 2 < size)
-		memory_full (SIZE_MAX);
-	      size *= 2;
-	      line = xrealloc (line, size);
-	    }
+	    line = xpalloc (line, &size, 1, -1, sizeof *line);
 	  line[len++] = c;
 	}
     }
diff --git a/src/term.c b/src/term.c
index 9b1e7cad4b2..245712ecfc4 100644
--- a/src/term.c
+++ b/src/term.c
@@ -537,10 +537,10 @@ encode_terminal_code (struct glyph *src, int src_len,
   required = src_len;
   required *= MAX_MULTIBYTE_LENGTH;
   if (encode_terminal_src_size < required)
-    {
-      encode_terminal_src = xrealloc (encode_terminal_src, required);
-      encode_terminal_src_size = required;
-    }
+    encode_terminal_src = xpalloc (encode_terminal_src,
+				   &encode_terminal_src_size,
+				   required - encode_terminal_src_size,
+				   -1, sizeof *encode_terminal_src);
 
   charset_list = coding_charset_list (coding);
 
diff --git a/src/xrdb.c b/src/xrdb.c
index ce6e7d21edb..10bc76986e6 100644
--- a/src/xrdb.c
+++ b/src/xrdb.c
@@ -177,12 +177,8 @@ magic_db (const char *string, ptrdiff_t string_len, const char *class,
 
       /* Do we have room for this component followed by a '\0'?  */
       if (path_size - path_len <= next_len)
-	{
-	  if (min (PTRDIFF_MAX, SIZE_MAX) / 2 - 1 - path_len < next_len)
-	    memory_full (SIZE_MAX);
-	  path_size = (path_len + next_len + 1) * 2;
-	  path = xrealloc (path, path_size);
-	}
+	path = xpalloc (path, &path_size, path_len - path_size + next_len + 1,
+			-1, sizeof *path);
 
       memcpy (path + path_len, next, next_len);
       path_len += next_len;