Squashed commit of the following:

Author: Gregory Nutt <gnutt@nuttx.org>

    TODO:  Remove 'Missing fscanf()' bug
    Clean up remaining complaints for tools/nxstyle
    Apply tools/detab, rmcr, convert-comments, lowhex, and indent.sh to the new and highly modified files.

Author: Johannes <nivus.entwicklung@gmail.com>

    - Move vscanf logic to lib_sscanf.c  Switched to stream interface (tricky, because the old implementation used massive read ahead, which isn't suitable for streams, chars already read are gone).
    - Added scanf and fscanf
    - Added hh, h, and ll modifiers
    - Fixes for standard compliance in scanf
    - Fixes for standard compliance in strto... function family (don't consume single '-' or '+', allow sign in strotul(l))

TODO

@@ -1,4 +1,4 @@
-NuttX TODO List (Last updated February 9, 2019)
+NuttX TODO List (Last updated February 14, 2019)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 This file summarizes known NuttX bugs, limitations, inconsistencies with
@@ -22,7 +22,7 @@ nuttx/:
  (18)  Network (net/, drivers/net)
   (4)  USB (drivers/usbdev, drivers/usbhost)
   (2)  Other drivers (drivers/)
- (12)  Libraries (libs/libc/, libs/libm/)
+ (11)  Libraries (libs/libc/, libs/libm/)
  (12)  File system/Generic drivers (fs/, drivers/)
  (10)  Graphics Subsystem (graphics/)
   (1)  Build system / Toolchains
@@ -2049,16 +2049,6 @@ o Libraries (libs/libc/, libs/libm/)
   Status:      Open
   Priority:    Low
 
-  Title:       MISSING fscanf()
-  Description: The standard C library function fscanf() has not been
-               implement.  This should be pretty straight forward feature
-               to implement using input streams as defined in
-               include/nuttx/streams.h analogous to the same way that output
-               streams were used in lib_vsprintf() to support both sprintf()
-               and fprintf().
-  Status:      Open
-  Priority:    Low
-
 o File system / Generic drivers (fs/, drivers/)
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

include/nuttx/streams.h

@@ -459,6 +459,19 @@ int lib_sprintf(FAR struct lib_outstream_s *obj,
 int lib_vsprintf(FAR struct lib_outstream_s *obj,
                  FAR const IPTR char *src, va_list ap);
 
+/****************************************************************************
+ * Name: lib_sscanf and lib_vsscanf
+ *
+ * Description:
+ *  Stream-oriented versions of sscanf and vsscanf.
+ *
+ ****************************************************************************/
+
+int lib_sscanf(FAR struct lib_instream_s *obj,
+                FAR const IPTR char *fmt, ...);
+int lib_vsscanf(FAR struct lib_instream_s *obj, FAR int *lastc,
+                 FAR const IPTR char *src, va_list ap);
+
 #undef EXTERN
 #if defined(__cplusplus)
 }

include/stdio.h

@@ -168,6 +168,7 @@ FAR char *gets_s(FAR char *s, rsize_t n);
 void   setbuf(FAR FILE *stream, FAR char *buf);
 int    setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size);
 int    ungetc(int c, FAR FILE *stream);
+int    fscanf(FAR FILE *stream, FAR const IPTR char *format, ...);
 
 /* Operations on the stdout stream, buffers, paths, and the whole printf-family */
 
@@ -178,7 +179,7 @@ int    sprintf(FAR char *buf, FAR const IPTR char *format, ...);
 int    asprintf (FAR char **ptr, FAR const IPTR char *fmt, ...);
 int    snprintf(FAR char *buf, size_t size,
          FAR const IPTR char *format, ...);
-int    sscanf(FAR const char *buf, FAR const char *fmt, ...);
+int    sscanf(FAR const char *buf, FAR const IPTR char *fmt, ...);
 void   perror(FAR const char *s);
 
 int    vprintf(FAR const IPTR FAR char *format, va_list ap);
@@ -189,6 +190,9 @@ int    vasprintf(FAR char **ptr, FAR const IPTR char *fmt, va_list ap);
 int    vsnprintf(FAR char *buf, size_t size, FAR const IPTR char *format,
          va_list ap);
 int    vsscanf(FAR const char *buf, FAR const char *s, va_list ap);
+int    scanf(FAR const IPTR char *format, ...);
+int    vfscanf(FAR FILE *stream, FAR const IPTR char *format,
+         va_list ap);
 
 /* Operations on file descriptors including:
  *

libs/libc/stdio/Make.defs

@@ -43,7 +43,7 @@ CSRCS += lib_vsnprintf.c lib_dprintf.c lib_vdprintf.c
 CSRCS += lib_meminstream.c lib_memoutstream.c lib_memsistream.c
 CSRCS += lib_memsostream.c lib_lowoutstream.c
 CSRCS += lib_zeroinstream.c lib_nullinstream.c lib_nulloutstream.c
-CSRCS += lib_sscanf.c lib_libnoflush.c lib_libsnoflush.c
+CSRCS += lib_sscanf.c lib_libsscanf.c lib_libnoflush.c lib_libsnoflush.c
 
 ifeq ($(CONFIG_NANO_PRINTF),y)
 
@@ -78,7 +78,7 @@ CSRCS += lib_rdflush.c lib_wrflush.c lib_fputc.c lib_puts.c lib_fputs.c
 CSRCS += lib_ungetc.c lib_vprintf.c lib_fprintf.c lib_vfprintf.c
 CSRCS += lib_stdinstream.c lib_stdoutstream.c lib_stdsistream.c
 CSRCS += lib_stdsostream.c lib_perror.c lib_feof.c lib_ferror.c
-CSRCS += lib_clearerr.c
+CSRCS += lib_clearerr.c lib_scanf.c lib_fscanf.c lib_vfscanf.c
 
 endif
 

libs/libc/stdio/lib_fscanf.c

@@ -0,0 +1,62 @@
+/****************************************************************************
+ * libs/libc/stdio/lib_fscanf.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Johannes Schock
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stdio.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: fscanf
+ ****************************************************************************/
+
+int fscanf(FAR FILE *stream, FAR const IPTR char *fmt, ...)
+{
+  va_list ap;
+  int n;
+
+  /* vfprintf into the stream */
+
+  va_start(ap, fmt);
+  n = vfscanf(stream, fmt, ap);
+  va_end(ap);
+
+  return n;
+}

libs/libc/stdio/lib_scanf.c

@@ -0,0 +1,61 @@
+/****************************************************************************
+ * libs/libc/stdio/lib_scanf.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Johannes Schock
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stdio.h>
+#include "libc.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: scanf
+ ****************************************************************************/
+
+int scanf(FAR const IPTR char *fmt, ...)
+{
+  va_list ap;
+  int ret;
+
+  va_start(ap, fmt);
+  ret = vfscanf(stdin, fmt, ap);
+  va_end(ap);
+
+  return ret;
+}

libs/libc/stdio/lib_vfscanf.c

@@ -0,0 +1,85 @@
+/****************************************************************************
+ * libs/libc/stdio/lib_vfscanf.c
+ *
+ *   Copyright (C) 2019 Gregory Nutt. All rights reserved.
+ *   Author: Johannes Shock
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdio.h>
+#include <semaphore.h>
+
+#include "libc.h"
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+int vfscanf(FAR FILE *stream, FAR const IPTR char *fmt, va_list ap)
+{
+  struct lib_stdinstream_s stdinstream;
+  int n = ERROR;
+  int lastc;
+
+  if (stream)
+    {
+      /* Wrap the stream in a stream object and let lib_vsscanf do the work. */
+
+      lib_stdinstream(&stdinstream, stream);
+
+      /* Hold the stream semaphore throughout the lib_vsscanf call so that
+       * this thread can get its entire message out before being pre-empted by
+       * the next thread.
+       */
+
+      lib_take_semaphore(stream);
+
+      n = lib_vsscanf(&stdinstream.public, &lastc, fmt, ap);
+
+      /* The lib_vsscanf function reads always one character more, this
+       * character needs to be written back.
+       */
+
+      if (lastc != EOF)
+        {
+          ungetc(lastc, stream);
+        }
+
+      lib_give_semaphore(stream);
+    }
+
+  return n;
+}

libs/libc/stdlib/lib_strtol.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * libs/libc/stdlib/lib_strtol.c
  *
- *   Copyright (C) 2007, 2009, 2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009, 2011, 2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -45,10 +45,6 @@
 
 #include "libc.h"
 
-/****************************************************************************
- * Private Functions
- ****************************************************************************/
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -74,7 +70,8 @@
 long strtol(FAR const char *nptr, FAR char **endptr, int base)
 {
   unsigned long accum = 0;
-  bool negate = false;
+  long retval = 0;
+  char sign = 0;
 
   if (nptr)
     {
@@ -84,13 +81,9 @@ long strtol(FAR const char *nptr, FAR char **endptr, int base)
 
       /* Check for leading + or - */
 
-      if (*nptr == '-')
-        {
-          negate = true;
-          nptr++;
-        }
-      else if (*nptr == '+')
+      if (*nptr == '-' || *nptr == '+')
         {
+          sign = *nptr;
           nptr++;
         }
 
@@ -100,25 +93,46 @@ long strtol(FAR const char *nptr, FAR char **endptr, int base)
 
       /* Correct the sign of the result and check for overflow */
 
-      if (negate)
+      if (sign == '-')
         {
           const unsigned long limit = ((unsigned long)-(LONG_MIN + 1)) + 1;
 
           if (accum > limit)
             {
               set_errno(ERANGE);
-              return LONG_MIN;
+              retval = LONG_MIN;
+            }
+          else
+            {
+              retval = (accum == limit) ? LONG_MIN : -(long)accum;
             }
-
-          return (accum == limit) ? LONG_MIN : -(long)accum;
         }
-
-      if (accum > LONG_MAX)
+      else
         {
-          set_errno(ERANGE);
-          return LONG_MAX;
+          if (accum > LONG_MAX)
+            {
+              set_errno(ERANGE);
+              retval = LONG_MAX;
+            }
+          else
+            {
+              retval = accum;
+            }
         }
     }
 
-  return (long)accum;
+  /* Return the final pointer to the unused value */
+
+  if (endptr)
+    {
+      if (sign)
+        {
+          if (*((*endptr) - 1) == sign)
+            {
+              (*endptr)--;
+            }
+        }
+    }
+
+  return retval;
 }

libs/libc/stdlib/lib_strtoll.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * libs/libc/stdlib/lib_strtoll.c
  *
- *   Copyright (C) 2009, 2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2009, 2011, 2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -47,10 +47,6 @@
 
 #ifdef CONFIG_HAVE_LONG_LONG
 
-/****************************************************************************
- * Private Functions
- ****************************************************************************/
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -76,7 +72,8 @@
 long long strtoll(FAR const char *nptr, FAR char **endptr, int base)
 {
   unsigned long long accum = 0;
-  bool negate = false;
+  long long retval = 0;
+  char sign = 0;
 
   if (nptr)
     {
@@ -86,13 +83,9 @@ long long strtoll(FAR const char *nptr, FAR char **endptr, int base)
 
       /* Check for leading + or - */
 
-      if (*nptr == '-')
-        {
-          negate = true;
-          nptr++;
-        }
-      else if (*nptr == '+')
+      if (*nptr == '-' || *nptr == '+')
         {
+          sign = *nptr;
           nptr++;
         }
 
@@ -102,27 +95,49 @@ long long strtoll(FAR const char *nptr, FAR char **endptr, int base)
 
       /* Correct the sign of the result and check for overflow */
 
-      if (negate)
+      if (sign == '-')
         {
-          const unsigned long long limit = ((unsigned long long)-(LLONG_MIN + 1)) + 1;
+          const unsigned long long limit =
+            ((unsigned long long)-(LLONG_MIN + 1)) + 1;
 
           if (accum > limit)
             {
               set_errno(ERANGE);
-              return LLONG_MIN;
+              retval = LLONG_MIN;
+            }
+          else
+            {
+              retval = (accum == limit) ? LLONG_MIN : -(long long)accum;
             }
-
-          return (accum == limit) ? LLONG_MIN : -(long long)accum;
         }
-
-      if (accum > LLONG_MAX)
+      else
         {
-          set_errno(ERANGE);
-          return LLONG_MAX;
+          if (accum > LLONG_MAX)
+            {
+              set_errno(ERANGE);
+              return LLONG_MAX;
+            }
+          else
+            {
+              retval = accum;
+            }
         }
     }
 
-  return (long long)accum;
+  /* Return the final pointer to the unused value */
+
+  if (endptr)
+    {
+      if (sign)
+        {
+          if (*((*endptr) - 1) == sign)
+            {
+              (*endptr)--;
+            }
+        }
+    }
+
+  return retval;
 }
 
 #endif

libs/libc/stdlib/lib_strtoul.c

@@ -1,7 +1,8 @@
 /****************************************************************************
  * /libs/libc/stdlib/lib_strtoul.c
  *
- *   Copyright (C) 2007, 2009, 2011, 2016-2017 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009, 2011, 2016-2017, 2019 Gregory Nutt.
+ *   All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -70,6 +71,7 @@ unsigned long strtoul(FAR const char *nptr, FAR char **endptr, int base)
   unsigned long accum = 0;
   unsigned long prev;
   int value;
+  char sign = 0;
 
   if (nptr)
     {
@@ -77,6 +79,14 @@ unsigned long strtoul(FAR const char *nptr, FAR char **endptr, int base)
 
       lib_skipspace(&nptr);
 
+      /* Check for leading + or - already done for strtol */
+
+      if (*nptr == '-' || *nptr == '+')
+        {
+          sign = *nptr;
+          nptr++;
+        }
+
       /* Check for unspecified or incorrect base */
 
       base = lib_checkbase(base, &nptr);
@@ -84,33 +94,47 @@ unsigned long strtoul(FAR const char *nptr, FAR char **endptr, int base)
       if (base < 0)
         {
           set_errno(EINVAL);
-          return 0;
+          accum = 0;
         }
-
-      /* Accumulate each "digit" */
-
-      while (lib_isbasedigit(*nptr, base, &value))
+      else
         {
-          prev  = accum;
-          accum = accum*base + value;
-          nptr++;
+          /* Accumulate each "digit" */
 
-          /* Check for overflow */
-
-          if (accum < prev)
+          while (lib_isbasedigit(*nptr, base, &value))
             {
-              set_errno(ERANGE);
-              accum = ULONG_MAX;
-              break;
+              prev = accum;
+              accum = accum * base + value;
+              nptr++;
+
+              /* Check for overflow */
+
+              if (accum < prev)
+                {
+                  set_errno(ERANGE);
+                  accum = ULONG_MAX;
+                  break;
+                }
+            }
+
+          if (sign == '-')
+            {
+              accum = (~accum) + 1;
             }
         }
+    }
 
-      /* Return the final pointer to the unused value */
+  /* Return the final pointer to the unused value */
 
-      if (endptr)
+  if (endptr)
+    {
+      if (sign)
         {
-          *endptr = (FAR char *)nptr;
+          if (*(nptr - 1) == sign)
+            {
+              nptr--;
+            }
         }
+      *endptr = (FAR char *)nptr;
     }
 
   return accum;

libs/libc/stdlib/lib_strtoull.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * /libs/libc/stdlib/lib_strtoull.c
  *
- *   Copyright (C) 2009, 2010, 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2009, 2010, 2016, 2019 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -73,6 +73,7 @@ unsigned long long strtoull(FAR const char *nptr, FAR char **endptr, int base)
   unsigned long long accum = 0;
   unsigned long long prev;
   int value;
+  char sign = 0;
 
   if (nptr)
     {
@@ -80,40 +81,62 @@ unsigned long long strtoull(FAR const char *nptr, FAR char **endptr, int base)
 
       lib_skipspace(&nptr);
 
-      /* Check for unspecified base */
+      /* Check for leading + or - already done for strtol */
+
+      if (*nptr == '-' || *nptr == '+')
+        {
+          sign = *nptr;
+          nptr++;
+        }
+
+      /* Check for unspecified or incorrect base */
 
       base = lib_checkbase(base, &nptr);
 
       if (base < 0)
         {
           set_errno(EINVAL);
-          return 0;
+          accum = 0;
         }
-
-      /* Accumulate each "digit" */
-
-      while (lib_isbasedigit(*nptr, base, &value))
+      else
         {
-          prev  = accum;
-          accum = accum*base + value;
-          nptr++;
+          /* Accumulate each "digit" */
 
-          /* Check for overflow */
-
-          if (accum < prev)
+          while (lib_isbasedigit(*nptr, base, &value))
             {
-              set_errno(ERANGE);
-              accum = ULLONG_MAX;
-              break;
+              prev = accum;
+              accum = accum * base + value;
+              nptr++;
+
+              /* Check for overflow */
+
+              if (accum < prev)
+                {
+                  set_errno(ERANGE);
+                  accum = ULLONG_MAX;
+                  break;
+                }
+            }
+
+          if (sign == '-')
+            {
+              accum = (~accum) + 1;
             }
         }
+    }
 
-      /* Return the final pointer to the unused value */
+  /* Return the final pointer to the unused value */
 
-      if (endptr)
+  if (endptr)
+    {
+      if (sign)
         {
-          *endptr = (char *)nptr;
+          if (*(nptr - 1) == sign)
+            {
+              nptr--;
+            }
         }
+      *endptr = (FAR char *)nptr;
     }
 
   return accum;