Replace fmemopen.
A new implementation starting from the FreeBSD fmemopen rather than the
OpenBSD one we used to use.
The tests were arrived at by translating each sentence in
http://pubs.opengroup.org/onlinepubs/9699919799/functions/fmemopen.html,
plus http://man7.org/linux/man-pages/man3/fmemopen.3.html for historical
GNU bugs.
Bug: http://b/31304889
Test: ran tests
Change-Id: Id8b168c9ecde638e9cdedbc3b8a0982fc83c7048
diff --git a/libc/stdio/fmemopen.cpp b/libc/stdio/fmemopen.cpp
new file mode 100644
index 0000000..9d8c41f
--- /dev/null
+++ b/libc/stdio/fmemopen.cpp
@@ -0,0 +1,156 @@
+/*-
+ * 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>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "local.h"
+
+// See http://pubs.opengroup.org/onlinepubs/9699919799/functions/fmemopen.html
+// and http://man7.org/linux/man-pages/man3/fmemopen.3.html for documentation.
+
+struct fmemopen_cookie {
+ char* buf;
+ char* allocation;
+ size_t capacity;
+ size_t size;
+ size_t offset;
+ bool append;
+};
+
+static int fmemopen_read(void* cookie, char* buf, int n) {
+ fmemopen_cookie* ck = static_cast<fmemopen_cookie*>(cookie);
+
+ if (static_cast<size_t>(n) > ck->size - ck->offset) n = ck->size - ck->offset;
+
+ if (n > 0) {
+ memmove(buf, ck->buf + ck->offset, n);
+ ck->offset += n;
+ }
+ return n;
+}
+
+static int fmemopen_write(void* cookie, const char* buf, int n) {
+ fmemopen_cookie* ck = static_cast<fmemopen_cookie*>(cookie);
+
+ // We don't need to add the trailing NUL if there's already a trailing NUL
+ // in the data we're writing.
+ size_t space_for_null = (n > 0 && buf[n - 1] != '\0') ? 1 : 0;
+
+ // Undo any seeking/reading on an append-only stream.
+ if (ck->append) ck->offset = ck->size;
+
+ // How much can we actually fit?
+ if (static_cast<size_t>(n) + space_for_null > ck->capacity - ck->offset) {
+ n = ck->capacity - ck->offset - space_for_null;
+ // Give up if we don't even have room for one byte of userdata.
+ if (n <= 0) {
+ errno = ENOSPC;
+ return -1;
+ }
+ }
+
+ if (n > 0) {
+ memmove(ck->buf + ck->offset, buf, n);
+ ck->offset += n;
+ // Is this the furthest we've ever been?
+ if (ck->offset >= ck->size) {
+ if (buf[n - 1] != '\0') ck->buf[ck->offset] = '\0';
+ ck->size = ck->offset;
+ }
+ }
+ return n;
+}
+
+static fpos_t fmemopen_seek(void* cookie, fpos_t offset, int whence) {
+ fmemopen_cookie* ck = static_cast<fmemopen_cookie*>(cookie);
+
+ if (whence == SEEK_SET && (offset >= 0 && static_cast<size_t>(offset) <= ck->capacity)) {
+ return (ck->offset = offset);
+ } else if (whence == SEEK_CUR && (ck->offset + offset <= ck->capacity)) {
+ return (ck->offset += offset);
+ } else if (whence == SEEK_END && (offset <= 0 && static_cast<size_t>(-offset) <= ck->size)) {
+ return (ck->offset = ck->size + offset);
+ }
+ errno = EINVAL;
+ return -1;
+}
+
+static int fmemopen_close(void* cookie) {
+ fmemopen_cookie* ck = static_cast<fmemopen_cookie*>(cookie);
+ free(ck->allocation);
+ free(ck);
+ return 0;
+}
+
+FILE* fmemopen(void* buf, size_t capacity, const char* mode) {
+ int flags;
+ if (__sflags(mode, &flags) == 0) {
+ errno = EINVAL;
+ return nullptr;
+ }
+
+ fmemopen_cookie* ck = static_cast<fmemopen_cookie*>(calloc(sizeof(fmemopen_cookie), 1));
+ if (ck == nullptr) return nullptr;
+
+ ck->buf = static_cast<char*>(buf);
+ ck->capacity = capacity;
+
+ if (ck->buf == nullptr) ck->buf = ck->allocation = static_cast<char*>(calloc(capacity, 1));
+ if (ck->buf == nullptr) {
+ free(ck);
+ return nullptr;
+ }
+
+ FILE* fp = funopen(ck,
+ (flags & O_WRONLY) ? nullptr : fmemopen_read,
+ (flags & O_RDONLY) ? nullptr : fmemopen_write,
+ fmemopen_seek,
+ fmemopen_close);
+ if (fp == nullptr) {
+ fmemopen_close(ck);
+ return nullptr;
+ }
+
+ if (mode[0] == 'a') {
+ ck->size = strnlen(ck->buf, ck->capacity);
+ ck->offset = ck->size;
+ ck->append = true;
+ } else if (mode[0] == 'r') {
+ ck->size = capacity;
+ ck->offset = 0;
+ } else if (mode[0] == 'w') {
+ ck->size = 0;
+ ck->offset = 0;
+ ck->buf[0] = '\0';
+ }
+
+ return fp;
+}