qemu-file: Move stdio implementation to qemu-file-stdio.c

Separate the QEMUFile interface from the stdio-specific implementation,
to reduce dependencies from code using QEMUFile.

The code that is being moved is similar to the one that was on savevm.c before
it was moved in commit 093c455a8c6d8f715eabd8c8d346f08f17d686ec, except for
some changes done by Markus, Juan, and myself. So, I am using the copyright and
license header from savevm.c, but CCing Juan and Markus so they can review the
copyright/license header.

Cc: Markus Armbruster <armbru@redhat.com>
Cc: Juan Quintela <quintela@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

1 files changed, 194 insertions, 0 deletions

diff --git a/qemu-file-stdio.c b/qemu-file-stdio.c
new file mode 100644
index 0000000000..285068b303
--- /dev/null
+++ b/qemu-file-stdio.c
@@ -0,0 +1,194 @@
+/*
+ * QEMU System Emulator
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "qemu-common.h"
+#include "block/coroutine.h"
+#include "migration/qemu-file.h"
+
+typedef struct QEMUFileStdio {
+    FILE *stdio_file;
+    QEMUFile *file;
+} QEMUFileStdio;
+
+static int stdio_get_fd(void *opaque)
+{
+    QEMUFileStdio *s = opaque;
+
+    return fileno(s->stdio_file);
+}
+
+static int stdio_put_buffer(void *opaque, const uint8_t *buf, int64_t pos,
+                            int size)
+{
+    QEMUFileStdio *s = opaque;
+    int res;
+
+    res = fwrite(buf, 1, size, s->stdio_file);
+
+    if (res != size) {
+        return -errno;
+    }
+    return res;
+}
+
+static int stdio_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
+{
+    QEMUFileStdio *s = opaque;
+    FILE *fp = s->stdio_file;
+    int bytes;
+
+    for (;;) {
+        clearerr(fp);
+        bytes = fread(buf, 1, size, fp);
+        if (bytes != 0 || !ferror(fp)) {
+            break;
+        }
+        if (errno == EAGAIN) {
+            yield_until_fd_readable(fileno(fp));
+        } else if (errno != EINTR) {
+            break;
+        }
+    }
+    return bytes;
+}
+
+static int stdio_pclose(void *opaque)
+{
+    QEMUFileStdio *s = opaque;
+    int ret;
+    ret = pclose(s->stdio_file);
+    if (ret == -1) {
+        ret = -errno;
+    } else if (!WIFEXITED(ret) || WEXITSTATUS(ret) != 0) {
+        /* close succeeded, but non-zero exit code: */
+        ret = -EIO; /* fake errno value */
+    }
+    g_free(s);
+    return ret;
+}
+
+static int stdio_fclose(void *opaque)
+{
+    QEMUFileStdio *s = opaque;
+    int ret = 0;
+
+    if (qemu_file_is_writable(s->file)) {
+        int fd = fileno(s->stdio_file);
+        struct stat st;
+
+        ret = fstat(fd, &st);
+        if (ret == 0 && S_ISREG(st.st_mode)) {
+            /*
+             * If the file handle is a regular file make sure the
+             * data is flushed to disk before signaling success.
+             */
+            ret = fsync(fd);
+            if (ret != 0) {
+                ret = -errno;
+                return ret;
+            }
+        }
+    }
+    if (fclose(s->stdio_file) == EOF) {
+        ret = -errno;
+    }
+    g_free(s);
+    return ret;
+}
+
+static const QEMUFileOps stdio_pipe_read_ops = {
+    .get_fd =     stdio_get_fd,
+    .get_buffer = stdio_get_buffer,
+    .close =      stdio_pclose
+};
+
+static const QEMUFileOps stdio_pipe_write_ops = {
+    .get_fd =     stdio_get_fd,
+    .put_buffer = stdio_put_buffer,
+    .close =      stdio_pclose
+};
+
+QEMUFile *qemu_popen_cmd(const char *command, const char *mode)
+{
+    FILE *stdio_file;
+    QEMUFileStdio *s;
+
+    if (mode == NULL || (mode[0] != 'r' && mode[0] != 'w') || mode[1] != 0) {
+        fprintf(stderr, "qemu_popen: Argument validity check failed\n");
+        return NULL;
+    }
+
+    stdio_file = popen(command, mode);
+    if (stdio_file == NULL) {
+        return NULL;
+    }
+
+    s = g_malloc0(sizeof(QEMUFileStdio));
+
+    s->stdio_file = stdio_file;
+
+    if (mode[0] == 'r') {
+        s->file = qemu_fopen_ops(s, &stdio_pipe_read_ops);
+    } else {
+        s->file = qemu_fopen_ops(s, &stdio_pipe_write_ops);
+    }
+    return s->file;
+}
+
+static const QEMUFileOps stdio_file_read_ops = {
+    .get_fd =     stdio_get_fd,
+    .get_buffer = stdio_get_buffer,
+    .close =      stdio_fclose
+};
+
+static const QEMUFileOps stdio_file_write_ops = {
+    .get_fd =     stdio_get_fd,
+    .put_buffer = stdio_put_buffer,
+    .close =      stdio_fclose
+};
+
+QEMUFile *qemu_fopen(const char *filename, const char *mode)
+{
+    QEMUFileStdio *s;
+
+    if (qemu_file_mode_is_not_valid(mode)) {
+        return NULL;
+    }
+
+    s = g_malloc0(sizeof(QEMUFileStdio));
+
+    s->stdio_file = fopen(filename, mode);
+    if (!s->stdio_file) {
+        goto fail;
+    }
+
+    if (mode[0] == 'w') {
+        s->file = qemu_fopen_ops(s, &stdio_file_write_ops);
+    } else {
+        s->file = qemu_fopen_ops(s, &stdio_file_read_ops);
+    }
+    return s->file;
+fail:
+    g_free(s);
+    return NULL;
+}