Trivial updates from review of vecto I/O logic.

include/limits.h

@@ -134,13 +134,19 @@
 
 #ifdef CONFIG_SMALL_MEMORY
 
+#define _POSIX_SIZE_MAX       65535         /* See sys/types.h */
+#define _POSIX_SIZE_MIN       0
+
 #define _POSIX_SSIZE_MAX      32767         /* See sys/types.h */
 #define _POSIX_SSIZE_MIN      -32768
 
 #else /* CONFIG_SMALL_MEMORY */
 
-#define _POSIX_SSIZE_MAX      2147483647  /* See sys/types.h */
+#define _POSIX_SIZE_MAX       4294967295L   /* See sys/types.h */
-#define _POSIX_SSIZE_MIN      -2147483648
+#define _POSIX_SIZE_MIN       0
+
+#define _POSIX_SSIZE_MAX      2147483647UL  /* See sys/types.h */
+#define _POSIX_SSIZE_MIN      -2147483648UL
 
 #endif /* CONFIG_SMALL_MEMORY */
 
@@ -205,6 +211,8 @@
 #define OPEN_MAX       _POSIX_OPEN_MAX
 #define PATH_MAX       _POSIX_PATH_MAX
 #define PIPE_BUF       _POSIX_PIPE_BUF
+#define SIZE_MAX       _POSIX_SIZE_MAX
+#define SIZE_MIN       _POSIX_SIZE_MIN
 #define SSIZE_MAX      _POSIX_SSIZE_MAX
 #define SSIZE_MIN      _POSIX_SSIZE_MIN
 #define STREAM_MAX     _POSIX_STREAM_MAX
@@ -237,6 +245,7 @@
 #define SEM_VALUE_MAX  _POSIX_SEM_VALUE_MAX
 
 /* Required for readv() and writev() */
+/* There really is no upper limit on the number of vectors */
 
 #define IOV_MAX        INT_MAX
 

include/sys/types.h

@@ -132,6 +132,8 @@ typedef unsigned int mode_t;
 /* size_t is used for sizes of memory objects.
  * ssize_t is used for a count of bytes or an error indication.
  *
+ * See also definitions of SIZE_MAX et al in limits.h.
+ *
  * REVISIT: size_t belongs in stddef.h
  */
 

include/sys/uio.h

@@ -38,14 +38,20 @@
 #ifndef __INCLUDE_SYS_UIO_H
 #define __INCLUDE_SYS_UIO_H
 
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <sys/types.h>
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
 
 struct iovec
 {
-  FAR void *iov_base;
+  FAR void *iov_base;  /* Base address of I/O memory region */
-  size_t    iov_len;
+  size_t    iov_len;   /* Size of the memory pointed to by iov_base */
 };
 
 /****************************************************************************
@@ -57,17 +63,17 @@ struct iovec
  *
  * Description:
  *   The readv() function is equivalent to read(), except as described below.
- *   The readv() function places the input data into the iovcnt buffers
+ *   The readv() function places the input data into the 'iovcnt' buffers
- *   specified by the members of the iov array: iov[0], iov[1], ...,
+ *   specified by the members of the 'iov' array: iov[0], iov[1], ...,
- *   iov[iovcnt-1].  The iovcnt argument is valid if greater than 0 and less
+ *   iov['iovcnt'-1].  The 'iovcnt' argument is valid if greater than 0 and
- *   than or equal to IOV_MAX as defined in limits.h.
+ *   less than or equal to IOV_MAX as defined in limits.h.
  *
  *   Each iovec entry specifies the base address and length of an area in
  *   memory where data should be placed.  The readv() function will always
  *   fill an area completely before proceeding to the next.
  *
- *   Upon successful completion, readv() will mark for update the st_atime
+ *   TODO: pon successful completion, readv() will mark for update the
- *   field of the file.
+ *   st_atime field of the file.
  *
  * Input Parameters:
  *   filedes - The open file descriptor for the file to be read
@@ -77,7 +83,14 @@ struct iovec
  * Returned Value:
  *   Upon successful completion, readv() will return a non-negative integer
  *   indicating the number of bytes actually read.  Otherwise, the functions
- *   will return -1 and set errno to indicate the error.  See read().
+ *   will return -1 and set errno to indicate the error.  See read() for the
+ *   list of returned errno values.  In addition, the readv() function will
+ *   fail if:
+ *
+ *    EINVAL.
+ *      The sum of the iov_len values in the iov array overflowed an ssize_t
+ *      or The 'iovcnt' argument was less than or equal to 0, or greater than
+ *      IOV_MAX (Not implemented).
  *
  ****************************************************************************/
 
@@ -88,20 +101,20 @@ ssize_t readv(int fildes, FAR const struct iovec *iov, int iovcnt);
  *
  * Description:
  *   The writev() function is equivalent to write(), except as described
- *   below. The writev() function will gather output data from the iovcnt
+ *   below. The writev() function will gather output data from the 'iovcnt'
- *   buffers specified by the members of the iov array: iov[0], iov[1], ...,
+ *   buffers specified by the members of the 'iov' array: iov[0], iov[1], ...,
- *   iov[iovcnt-1]. The iovcnt argument is valid if greater than 0 and less
+ *   iov[iovcnt-1]. The 'iovcnt' argument is valid if greater than 0 and less
  *   than or equal to IOV_MAX, as defined in limits.h.
  *
  *   Each iovec entry specifies the base address and length of an area in
  *   memory from which data should be written. The writev() function always
  *   writes a complete area before proceeding to the next.
  *
- *   If fildes refers to a regular file and all of the iov_len members in
+ *   If 'filedes' refers to a regular file and all of the iov_len members in
  *   the array pointed to by iov are 0, writev() will return 0 and have no
  *   other effect. For other file types, the behavior is unspecified.
  *
- *   If the sum of the iov_len values is greater than SSIZE_MAX, the
+ *   TODO: If the sum of the iov_len values is greater than SSIZE_MAX, the
  *   operation will fail and no data will be transferred.
  *
  * Input Parameters:
@@ -113,7 +126,13 @@ ssize_t readv(int fildes, FAR const struct iovec *iov, int iovcnt);
  *   Upon successful completion, writev() shall return the number of bytes
  *   actually written. Otherwise, it shall return a value of -1, the file-
  *   pointer shall remain unchanged, and errno shall be set to indicate an
- *   error.
+ *   error. See write for the list of returned errno values. In addition,
+ *   the readv() function will fail if:
+ *
+ *    EINVAL.
+ *      The sum of the iov_len values in the iov array overflowed an ssize_t
+ *      or The 'iovcnt' argument was less than or equal to 0, or greater than
+ *      IOV_MAX (Not implemented).
  *
  ****************************************************************************/
 

libs/libc/uio/lib_readv.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * libs/libc/stdio/lib_readv.c
  *
- *   Copyright (C) 2017 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2017=-2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -50,17 +50,17 @@
  *
  * Description:
  *   The readv() function is equivalent to read(), except as described below.
- *   The readv() function places the input data into the iovcnt buffers
+ *   The readv() function places the input data into the 'iovcnt' buffers
- *   specified by the members of the iov array: iov[0], iov[1], ...,
+ *   specified by the members of the 'iov' array: iov[0], iov[1], ...,
- *   iov[iovcnt-1].  The iovcnt argument is valid if greater than 0 and less
+ *   iov['iovcnt'-1].  The 'iovcnt' argument is valid if greater than 0 and
- *   than or equal to IOV_MAX as defined in limits.h.
+ *   less than or equal to IOV_MAX as defined in limits.h.
  *
  *   Each iovec entry specifies the base address and length of an area in
  *   memory where data should be placed.  The readv() function will always
  *   fill an area completely before proceeding to the next.
  *
- *   Upon successful completion, readv() will mark for update the st_atime
+ *   TODO: pon successful completion, readv() will mark for update the
- *   field of the file.
+ *   st_atime field of the file.
  *
  * Input Parameters:
  *   filedes - The open file descriptor for the file to be read
@@ -70,7 +70,14 @@
  * Returned Value:
  *   Upon successful completion, readv() will return a non-negative integer
  *   indicating the number of bytes actually read.  Otherwise, the functions
- *   will return -1 and set errno to indicate the error.  See read().
+ *   will return -1 and set errno to indicate the error.  See read() for the
+ *   list of returned errno values.  In addition, the readv() function will
+ *   fail if:
+ *
+ *    EINVAL.
+ *      The sum of the iov_len values in the iov array overflowed an ssize_t
+ *      or The 'iovcnt' argument was less than or equal to 0, or greater than
+ *      IOV_MAX (Not implemented).
  *
  ****************************************************************************/
 

libs/libc/uio/lib_writev.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * libs/libc/stdio/lib_writev.c
  *
- *   Copyright (C) 2017 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2017-2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -51,20 +51,20 @@
  *
  * Description:
  *   The writev() function is equivalent to write(), except as described
- *   below. The writev() function will gather output data from the iovcnt
+ *   below. The writev() function will gather output data from the 'iovcnt'
- *   buffers specified by the members of the iov array: iov[0], iov[1], ...,
+ *   buffers specified by the members of the 'iov' array: iov[0], iov[1], ...,
- *   iov[iovcnt-1]. The iovcnt argument is valid if greater than 0 and less
+ *   iov[iovcnt-1]. The 'iovcnt' argument is valid if greater than 0 and less
  *   than or equal to IOV_MAX, as defined in limits.h.
  *
  *   Each iovec entry specifies the base address and length of an area in
  *   memory from which data should be written. The writev() function always
  *   writes a complete area before proceeding to the next.
  *
- *   If fildes refers to a regular file and all of the iov_len members in
+ *   If 'filedes' refers to a regular file and all of the iov_len members in
  *   the array pointed to by iov are 0, writev() will return 0 and have no
  *   other effect. For other file types, the behavior is unspecified.
  *
- *   If the sum of the iov_len values is greater than SSIZE_MAX, the
+ *   TODO: If the sum of the iov_len values is greater than SSIZE_MAX, the
  *   operation will fail and no data will be transferred.
  *
  * Input Parameters:
@@ -76,7 +76,13 @@
  *   Upon successful completion, writev() shall return the number of bytes
  *   actually written. Otherwise, it shall return a value of -1, the file-
  *   pointer shall remain unchanged, and errno shall be set to indicate an
- *   error.
+ *   error. See write for the list of returned errno values. In addition,
+ *   the readv() function will fail if:
+ *
+ *    EINVAL.
+ *      The sum of the iov_len values in the iov array overflowed an ssize_t
+ *      or The 'iovcnt' argument was less than or equal to 0, or greater than
+ *      IOV_MAX (Not implemented).
  *
  ****************************************************************************/