SoW-2019-0002: Dynamic Snapshot

[lttng-tools.git] / src / common / filter / memstream.h

diff --git a/src/common/filter/memstream.h b/src/common/filter/memstream.h
new file mode 100644 (file)
index 0000000..cd246ee
--- /dev/null
+++ b/src/common/filter/memstream.h
@@ -0,0 +1,87 @@
+/*
+ * Copyright 2012 (C) Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+#ifndef _LTTNG_CTL_MEMSTREAM_H
+#define _LTTNG_CTL_MEMSTREAM_H
+
+#ifdef LTTNG_HAVE_FMEMOPEN
+#include <stdio.h>
+
+static inline
+FILE *lttng_fmemopen(void *buf, size_t size, const char *mode)
+{
+       return fmemopen(buf, size, mode);
+}
+
+#else /* LTTNG_HAVE_FMEMOPEN */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+/*
+ * Fallback for systems which don't have fmemopen. Copy buffer to a
+ * temporary file, and use that file as FILE * input.
+ */
+static inline
+FILE *lttng_fmemopen(void *buf, size_t size, const char *mode)
+{
+       char tmpname[PATH_MAX];
+       size_t len;
+       FILE *fp;
+       int ret;
+
+       /*
+        * Support reading only.
+        */
+       if (strcmp(mode, "rb") != 0) {
+               return NULL;
+       }
+       strncpy(tmpname, "/tmp/lttng-tmp-XXXXXX", PATH_MAX);
+       ret = mkstemp(tmpname);
+       if (ret < 0) {
+               return NULL;
+       }
+       /*
+        * We need to write to the file.
+        */
+       fp = fdopen(ret, "w+");
+       if (!fp) {
+               goto error_unlink;
+       }
+       /* Copy the entire buffer to the file */
+       len = fwrite(buf, sizeof(char), size, fp);
+       if (len != size) {
+               goto error_close;
+       }
+       ret = fseek(fp, 0L, SEEK_SET);
+       if (ret < 0) {
+               PERROR("fseek");
+               goto error_close;
+       }
+       /* We keep the handle open, but can unlink the file on the VFS. */
+       ret = unlink(tmpname);
+       if (ret < 0) {
+               PERROR("unlink");
+       }
+       return fp;
+
+error_close:
+       ret = fclose(fp);
+       if (ret < 0) {
+               PERROR("close");
+       }
+error_unlink:
+       ret = unlink(tmpname);
+       if (ret < 0) {
+               PERROR("unlink");
+       }
+       return NULL;
+}
+
+#endif /* LTTNG_HAVE_FMEMOPEN */
+
+#endif /* _LTTNG_CTL_MEMSTREAM_H */