diff options
Diffstat (limited to 'lib/libc/stdio/fmemopen.c')
| -rw-r--r-- | lib/libc/stdio/fmemopen.c | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/lib/libc/stdio/fmemopen.c b/lib/libc/stdio/fmemopen.c new file mode 100644 index 0000000..581a91e --- /dev/null +++ b/lib/libc/stdio/fmemopen.c @@ -0,0 +1,258 @@ +/*- + * Copyright (C) 2013 Pietro Cerutti <gahr@FreeBSD.org> + * + * 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. + * + * THIS SOFTWARE IS PROVIDED BY AUTHOR 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 AUTHOR 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. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <fcntl.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <errno.h> +#include "local.h" + +struct fmemopen_cookie +{ + char *buf; /* pointer to the memory region */ + bool own; /* did we allocate the buffer ourselves? */ + char bin; /* is this a binary buffer? */ + size_t size; /* buffer length in bytes */ + size_t len; /* data length in bytes */ + size_t off; /* current offset into the buffer */ +}; + +static int fmemopen_read(void *cookie, char *buf, int nbytes); +static int fmemopen_write(void *cookie, const char *buf, int nbytes); +static fpos_t fmemopen_seek(void *cookie, fpos_t offset, int whence); +static int fmemopen_close(void *cookie); + +FILE * +fmemopen(void * __restrict buf, size_t size, const char * __restrict mode) +{ + struct fmemopen_cookie *ck; + FILE *f; + int flags, rc; + + /* + * Retrieve the flags as used by open(2) from the mode argument, and + * validate them. + */ + rc = __sflags(mode, &flags); + if (rc == 0) { + errno = EINVAL; + return (NULL); + } + + /* + * There's no point in requiring an automatically allocated buffer + * in write-only mode. + */ + if (!(flags & O_RDWR) && buf == NULL) { + errno = EINVAL; + return (NULL); + } + + ck = malloc(sizeof(struct fmemopen_cookie)); + if (ck == NULL) { + return (NULL); + } + + ck->off = 0; + ck->size = size; + + /* Check whether we have to allocate the buffer ourselves. */ + ck->own = ((ck->buf = buf) == NULL); + if (ck->own) { + ck->buf = malloc(size); + if (ck->buf == NULL) { + free(ck); + return (NULL); + } + } + + /* + * POSIX distinguishes between w+ and r+, in that w+ is supposed to + * truncate the buffer. + */ + if (ck->own || mode[0] == 'w') { + ck->buf[0] = '\0'; + } + + /* Check for binary mode. */ + ck->bin = strchr(mode, 'b') != NULL; + + /* + * The size of the current buffer contents is set depending on the + * mode: + * + * for append (text-mode), the position of the first NULL byte, or the + * size of the buffer if none is found + * + * for append (binary-mode), the size of the buffer + * + * for read, the size of the buffer + * + * for write, 0 + */ + switch (mode[0]) { + case 'a': + if (ck->bin) { + /* + * This isn't useful, since the buffer isn't allowed + * to grow. + */ + ck->off = ck->len = size; + } else + ck->off = ck->len = strnlen(ck->buf, ck->size); + break; + case 'r': + ck->len = size; + break; + case 'w': + ck->len = 0; + break; + } + + f = funopen(ck, + flags & O_WRONLY ? NULL : fmemopen_read, + flags & O_RDONLY ? NULL : fmemopen_write, + fmemopen_seek, fmemopen_close); + + if (f == NULL) { + if (ck->own) + free(ck->buf); + free(ck); + return (NULL); + } + + /* + * Turn off buffering, so a write past the end of the buffer + * correctly returns a short object count. + */ + setvbuf(f, NULL, _IONBF, 0); + + return (f); +} + +static int +fmemopen_read(void *cookie, char *buf, int nbytes) +{ + struct fmemopen_cookie *ck = cookie; + + if (nbytes > ck->len - ck->off) + nbytes = ck->len - ck->off; + + if (nbytes == 0) + return (0); + + memcpy(buf, ck->buf + ck->off, nbytes); + + ck->off += nbytes; + + return (nbytes); +} + +static int +fmemopen_write(void *cookie, const char *buf, int nbytes) +{ + struct fmemopen_cookie *ck = cookie; + + if (nbytes > ck->size - ck->off) + nbytes = ck->size - ck->off; + + if (nbytes == 0) + return (0); + + memcpy(ck->buf + ck->off, buf, nbytes); + + ck->off += nbytes; + + if (ck->off > ck->len) + ck->len = ck->off; + + /* + * We append a NULL byte if all these conditions are met: + * - the buffer is not binary + * - the buffer is not full + * - the data just written doesn't already end with a NULL byte + */ + if (!ck->bin && ck->off < ck->size && ck->buf[ck->off - 1] != '\0') + ck->buf[ck->off] = '\0'; + + return (nbytes); +} + +static fpos_t +fmemopen_seek(void *cookie, fpos_t offset, int whence) +{ + struct fmemopen_cookie *ck = cookie; + + + switch (whence) { + case SEEK_SET: + if (offset > ck->size) { + errno = EINVAL; + return (-1); + } + ck->off = offset; + break; + + case SEEK_CUR: + if (ck->off + offset > ck->size) { + errno = EINVAL; + return (-1); + } + ck->off += offset; + break; + + case SEEK_END: + if (offset > 0 || -offset > ck->len) { + errno = EINVAL; + return (-1); + } + ck->off = ck->len + offset; + break; + + default: + errno = EINVAL; + return (-1); + } + + return (ck->off); +} + +static int +fmemopen_close(void *cookie) +{ + struct fmemopen_cookie *ck = cookie; + + if (ck->own) + free(ck->buf); + + free(ck); + + return (0); +} |
