| /* Copyright (C) 1991-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <stdlib.h> |
| #include <unistd.h> |
| #include <string.h> |
| #include <limits.h> |
| #include <stdbool.h> |
| #include <sys/param.h> |
| #include <sys/uio.h> |
| #include <errno.h> |
| |
| |
| static void |
| ifree (char **ptrp) |
| { |
| free (*ptrp); |
| } |
| |
| /* Read data from file descriptor FD, and put the result in the |
| buffers described by VECTOR, which is a vector of COUNT 'struct iovec's. |
| The buffers are filled in the order specified. |
| Operates just like 'read' (see <unistd.h>) except that data are |
| put in VECTOR instead of a contiguous buffer. */ |
| ssize_t |
| __libc_readv (int fd, const struct iovec *vector, int count) |
| { |
| /* Find the total number of bytes to be read. */ |
| size_t bytes = 0; |
| for (int i = 0; i < count; ++i) |
| { |
| /* Check for ssize_t overflow. */ |
| if (SSIZE_MAX - bytes < vector[i].iov_len) |
| { |
| __set_errno (EINVAL); |
| return -1; |
| } |
| bytes += vector[i].iov_len; |
| } |
| |
| /* Allocate a temporary buffer to hold the data. We should normally |
| use alloca since it's faster and does not require synchronization |
| with other threads. But we cannot if the amount of memory |
| required is too large. */ |
| char *buffer; |
| char *malloced_buffer __attribute__ ((__cleanup__ (ifree))) = NULL; |
| if (__libc_use_alloca (bytes)) |
| buffer = (char *) __alloca (bytes); |
| else |
| { |
| malloced_buffer = buffer = (char *) malloc (bytes); |
| if (buffer == NULL) |
| return -1; |
| } |
| |
| /* Read the data. */ |
| ssize_t bytes_read = __read (fd, buffer, bytes); |
| if (bytes_read < 0) |
| return -1; |
| |
| /* Copy the data from BUFFER into the memory specified by VECTOR. */ |
| bytes = bytes_read; |
| for (int i = 0; i < count; ++i) |
| { |
| size_t copy = MIN (vector[i].iov_len, bytes); |
| |
| (void) memcpy ((void *) vector[i].iov_base, (void *) buffer, copy); |
| |
| buffer += copy; |
| bytes -= copy; |
| if (bytes == 0) |
| break; |
| } |
| |
| return bytes_read; |
| } |
| #ifndef __libc_readv |
| strong_alias (__libc_readv, __readv) |
| weak_alias (__libc_readv, readv) |
| #endif |