Improve the function that gets the cursor position

Remove the now useless xread utility function and try to do it faster.

3 files changed, 21 insertions, 44 deletions

diff --git a/smenu.c b/smenu.c
index 7948823..c3e57d0 100644
--- a/smenu.c
+++ b/smenu.c
@@ -1415,14 +1415,19 @@ int
 get_cursor_position(int * const r, int * const c)
 {
   char   buf[32];
-  size_t i     = 0;
-  int    count = 64;
-  int    v;
-  int    rc = 1;
+  char * s;
+
+  int count = 64;
+  int v;
+  int rc = 1;
+
+  int ask; /* Number of asked characters.    */
+  int got; /* Number of characters obtained. */
+
+  int buf_size = sizeof(buf);
 
   /* Report cursor location. */
   /* """"""""""""""""""""""" */
-  errno = 0;
   while ((v = write(STDOUT_FILENO, "\x1b[6n", 4)) == -1 && count)
   {
     if (errno == EINTR)
@@ -1443,17 +1448,20 @@ read:
 
   /* Read the response: ESC [ rows ; cols R. */
   /* """"""""""""""""""""""""""""""""""""""" */
-  while (i < sizeof(buf) - 1)
-  {
-    if (xread(STDIN_FILENO, buf + i, 1) != 1)
-      break;
+  *(s = buf) = 0;
 
-    i++;
+  do
+  {
+    ask = buf_size - 1 - (s - buf);
+    got = read(STDIN_FILENO, s, ask);
 
-    if (buf[i - 1] == 'R')
+    if (got < 0 && errno == EINTR)
+      got = 0;
+    else if (got == 0)
       break;
-  }
-  buf[i] = '\0';
+
+    s += got;
+  } while (strchr(buf, 'R') == 0);
 
   /* Parse it. */
   /* """"""""" */
diff --git a/utils.c b/utils.c
index c2ce1c6..add1346 100644
--- a/utils.c
+++ b/utils.c
@@ -326,31 +326,3 @@ is_integer(const char * const s)
   strtol(s, &end, 10);
   return (*end == '\0');
 }
-
-/* ========= */
-/* Safe read */
-/* ========= */
-ssize_t
-xread(int fd, void * buf, size_t n)
-{
-  size_t  rem = n;
-  ssize_t r;
-  char *  ptr = buf;
-
-  while (rem > 0)
-  {
-    if ((r = read(fd, ptr, rem)) < 0)
-    {
-      if (errno == EINTR)
-        r = 0;
-      else
-        return -1;
-    }
-    else if (r == 0)
-      break; /* EOF */
-
-    rem -= r;
-    ptr += r;
-  }
-  return (n - rem);
-}
diff --git a/utils.h b/utils.h
index 8d108a3..4519ad0 100644
--- a/utils.h
+++ b/utils.h
@@ -68,7 +68,4 @@ xwcscasecmp(const wchar_t * w1s, const wchar_t * w2s);
 int
 is_integer(const char * const s);
 
-ssize_t
-xread(int fd, void * buf, size_t n);
-
 #endif