From 0e37adc86acf9b5d3c2b428bfdc4306ba22e68c9 Mon Sep 17 00:00:00 2001
From: avsdev-cw <craig@avsdev.uk>
Date: Thu, 3 Sep 2020 16:32:06 +0100
Subject: [PATCH] Serialize to/from memory buffer, RData file, RObject (SEXP)

---
 src/Rmemory-object.c | 388 +++++++++++++++++++++++++++++++++++++++++++
 src/Rmemory-object.h |  21 +++
 2 files changed, 409 insertions(+)
 create mode 100644 src/Rmemory-object.c
 create mode 100644 src/Rmemory-object.h

diff --git a/src/Rmemory-object.c b/src/Rmemory-object.c
new file mode 100644
index 0000000..d00245b
--- /dev/null
+++ b/src/Rmemory-object.c
@@ -0,0 +1,388 @@
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+
+#include <R.h>
+#include <Rinternals.h>
+#include <Rembedded.h>
+
+#include "Rmagic.h"
+#include "Rmemory-object.h"
+
+
+int rdataToMemory(const char *filename, struct rmemoryobject_t *memObj)
+{
+  size_t iosz;
+  FILE *fp;
+  int magicSize;
+
+  // Open the file
+  fp = fopen(filename, "rb");
+  if (fp == 0) {
+    fprintf(stderr, "fopen: (%d) %s\n", errno, strerror(errno));
+    return errno;
+  }
+
+  // Read the magic from the file
+  memObj->magic = R_ReadMagic(fp);
+  if (memObj->magic == R_MAGIC_EMPTY || memObj->magic == R_MAGIC_CORRUPT) {
+    fprintf(stderr, "R_ReadMagic: (%d) Error reading magic/magic corrupted\n", memObj->magic);
+    fclose(fp);
+    return EINVAL;
+  }
+
+  // Get the current position (ie length of the magic)
+  magicSize = ftell(fp);
+  if (magicSize <= 0) {
+    fprintf(stderr, "ftell: (%d) %s\n", errno, strerror(errno));
+    fclose(fp);
+    return errno;
+  }
+
+  // Seek to the end of the file
+  if (fseek(fp, 0, SEEK_END) != 0) {
+    fprintf(stderr, "fseek: (%d) %s\n", errno, strerror(errno));
+    fclose(fp);
+    return errno;
+  }
+
+  // Get the current position (ie length of the file + magic)
+  memObj->bufsz = ftell(fp) - magicSize;
+  if (memObj->bufsz <= 0) {
+    fprintf(stderr, "ftell: (%d) %s\n", errno, strerror(errno));
+    fclose(fp);
+    return errno;
+  }
+
+  // Go back to the (nearly) the beginning of the file
+  if (fseek(fp, magicSize, SEEK_SET) != 0) {
+    fprintf(stderr, "fseek: (%d) %s\n", errno, strerror(errno));
+    fclose(fp);
+    return errno;
+  }
+
+  // Allocate a memory buffer for the file contents
+  memObj->buf = (char *)malloc((memObj->bufsz) * sizeof(char));
+  if (memObj->buf == 0) {
+    fprintf(stderr, "malloc: (%d) %s\n", errno, strerror(errno));
+    fclose(fp);
+    return errno;
+  }
+
+  // Read the file contents to the memory buffer
+  iosz = fread(memObj->buf, sizeof(char), memObj->bufsz, fp);
+  if (iosz == 0) {
+    fprintf(stderr, "fread: (%d) %s\n", errno, strerror(errno));
+    fclose(fp);
+    return errno;
+  }
+  if (iosz != memObj->bufsz) {
+    fprintf(stderr, "fread: Not enough bytes (got %lu, expected %lu)\n", iosz, memObj->bufsz);
+    fclose(fp);
+    return ENODATA;
+  }
+
+  // Close the file
+  if (fclose(fp) != 0) {
+    fprintf(stderr, "fclose: (%d) %s\n", errno, strerror(errno));
+    return errno;
+  }
+
+  // If you got here, well done, have a zero
+  return 0;
+}
+int memoryToRData(const char *filename, struct rmemoryobject_t memObj)
+{
+  size_t iosz;
+  FILE *fp;
+
+  // Open the file
+  fp = fopen(filename, "wb");
+  if (fp == 0) {
+    fprintf(stderr, "fopen: (%d) %s\n", errno, strerror(errno));
+    return errno;
+  }
+
+  // Write the R magic
+  if (R_WriteMagic(fp, memObj.magic) != 0) {
+    fprintf(stderr, "R_WriteMagic: (%d) %s\n", errno, strerror(errno));
+    fclose(fp);
+    return errno;
+  }
+
+  // Write the file contents from the memory buffer
+  iosz = fwrite(memObj.buf, sizeof(char), memObj.bufsz, fp);
+  if (iosz == 0) {
+    fprintf(stderr, "fwrite: (%d) %s\n", errno, strerror(errno));
+    fclose(fp);
+    return errno;
+  }
+  if (iosz != memObj.bufsz) {
+    fprintf(stderr, "fwrite: Not enough bytes (wrote %lu, expected %lu)\n", iosz, memObj.bufsz);
+    fclose(fp);
+    return ENODATA;
+  }
+
+  // Close the file
+  if (fclose(fp) != 0) {
+    fprintf(stderr, "fclose: (%d) %s\n", errno, strerror(errno));
+    return errno;
+  }
+
+  // If you got here, well done, have a zero
+  return 0;
+}
+
+
+SEXP memoryToRObject(struct rmemoryobject_t memObj)
+{
+  FILE *fp;
+  struct R_inpstream_st rin;
+  SEXP rObj;
+  int format;
+
+  switch (memObj.magic) {
+    case R_MAGIC_ASCII_V2:
+    case R_MAGIC_ASCII_V3:
+      format = R_pstream_ascii_format;
+      break;
+
+    case R_MAGIC_BINARY_V2:
+    case R_MAGIC_BINARY_V3:
+      format = R_pstream_binary_format;
+      break;
+
+    case R_MAGIC_XDR_V2:
+    case R_MAGIC_XDR_V3:
+      format = R_pstream_xdr_format;
+      break;
+
+    default:
+      fprintf(stderr, "Bad R magic: %d\n", memObj.magic);
+      return R_NilValue;
+  }
+
+  // Create a memory file device
+  fp = fmemopen(memObj.buf, memObj.bufsz, "r");
+  if (fp == NULL) {
+    fprintf(stderr, "fmemopen: (%d) %s\n", errno, strerror(errno));
+    return R_NilValue;
+  }
+
+  // Read the stream
+  R_InitFileInPStream(&rin, fp, format, NULL, NULL);
+  rObj = Rf_protect(R_Unserialize(&rin));
+
+  // Close the in-memory file device
+  if (fclose(fp) != 0) {
+    fprintf(stderr, "fclose: (%d) %s\n", errno, strerror(errno));
+  }
+
+  // All done
+  Rf_unprotect(1);
+  return rObj;
+}
+struct rmemoryobject_t *robjectToMemory(SEXP rObj, int magic)
+{
+  FILE *fp;
+  int version;
+  int format;
+  struct R_outpstream_st rout;
+  struct rmemoryobject_t memObj;
+  struct rmemoryobject_t *memObjPtr;
+
+  // Get version and format from the R magic header
+  switch (magic) {
+    case R_MAGIC_ASCII_V2:
+    case R_MAGIC_BINARY_V2:
+    case R_MAGIC_XDR_V2:
+      version = 2;
+      break;
+
+    case R_MAGIC_ASCII_V3:
+    case R_MAGIC_BINARY_V3:
+    case R_MAGIC_XDR_V3:
+      version = 3;
+      break;
+
+    default:
+      fprintf(stderr, "Bad R magic: %d\n", magic);
+      return NULL;
+  }
+  switch (magic) {
+    case R_MAGIC_ASCII_V2:
+    case R_MAGIC_ASCII_V3:
+      format = R_pstream_ascii_format;
+      break;
+
+    case R_MAGIC_BINARY_V2:
+    case R_MAGIC_BINARY_V3:
+      format = R_pstream_binary_format;
+      break;
+
+    case R_MAGIC_XDR_V2:
+    case R_MAGIC_XDR_V3:
+      format = R_pstream_xdr_format;
+      break;
+
+    default:
+      fprintf(stderr, "Bad R magic: %d\n", magic);
+      return NULL;
+  }
+  memObj.magic = magic;
+
+  // Create an in-memory file
+  fp = open_memstream(&(memObj.buf), &(memObj.bufsz));
+  if (fp == NULL) {
+    fprintf(stderr, "open_memstream: (%d) %s\n", errno, strerror(errno));
+    return NULL;
+  }
+
+  // Write to in-memory file
+  R_InitFileOutPStream(&rout, fp, format, version, NULL, NULL);
+  R_Serialize(rObj, &rout);
+
+  // Close the in-memory file
+  if (fclose(fp) != 0) {
+    fprintf(stderr, "fclose: (%d) %s\n", errno, strerror(errno));
+    return NULL;
+  }
+
+  // All done
+  memObjPtr = (struct rmemoryobject_t *)malloc(sizeof(struct rmemoryobject_t));
+  memcpy((void *)memObjPtr, (void *)&memObj, sizeof(struct rmemoryobject_t));
+
+  return memObjPtr;
+}
+
+
+SEXP rdataToRObject(const char *filename)
+{
+  size_t iosz;
+  FILE *fp;
+  int magic;
+  struct R_inpstream_st rin;
+  int format;
+  SEXP rObj;
+
+  // Open the file
+  fp = fopen(filename, "rb");
+  if (fp == 0) {
+    fprintf(stderr, "fopen: (%d) %s\n", errno, strerror(errno));
+    return R_NilValue;
+  }
+
+  // Read the magic from the file
+  magic = R_ReadMagic(fp);
+  if (magic == R_MAGIC_EMPTY || magic == R_MAGIC_CORRUPT) {
+    fprintf(stderr, "R_ReadMagic: (%d) Error reading magic/magic corrupted\n", magic);
+    fclose(fp);
+    return R_NilValue;
+  }
+  switch (magic) {
+    case R_MAGIC_ASCII_V2:
+    case R_MAGIC_ASCII_V3:
+      format = R_pstream_ascii_format;
+      break;
+
+    case R_MAGIC_BINARY_V2:
+    case R_MAGIC_BINARY_V3:
+      format = R_pstream_binary_format;
+      break;
+
+    case R_MAGIC_XDR_V2:
+    case R_MAGIC_XDR_V3:
+      format = R_pstream_xdr_format;
+      break;
+
+    default:
+      fprintf(stderr, "Bad R magic: %d\n", magic);
+      return R_NilValue;
+  }
+
+  // Read the stream
+  R_InitFileInPStream(&rin, fp, format, NULL, NULL);
+  rObj = Rf_protect(R_Unserialize(&rin));
+
+  // Close the in-memory file device
+  if (fclose(fp) != 0) {
+    fprintf(stderr, "fclose: (%d) %s\n", errno, strerror(errno));
+  }
+
+  // If you got here, well done
+  return rObj;
+}
+int robjectToRData(const char *filename, SEXP rObj, int magic)
+{
+  size_t iosz;
+  FILE *fp;
+  int version;
+  int format;
+  struct R_outpstream_st rout;
+
+  // Get version and format from the R magic
+  switch (magic) {
+    case R_MAGIC_ASCII_V2:
+    case R_MAGIC_BINARY_V2:
+    case R_MAGIC_XDR_V2:
+      version = 2;
+      break;
+
+    case R_MAGIC_ASCII_V3:
+    case R_MAGIC_BINARY_V3:
+    case R_MAGIC_XDR_V3:
+      version = 3;
+      break;
+
+    default:
+      fprintf(stderr, "Bad R magic: %d\n", magic);
+      return EINVAL;
+  }
+  switch (magic) {
+    case R_MAGIC_ASCII_V2:
+    case R_MAGIC_ASCII_V3:
+      format = R_pstream_ascii_format;
+      break;
+
+    case R_MAGIC_BINARY_V2:
+    case R_MAGIC_BINARY_V3:
+      format = R_pstream_binary_format;
+      break;
+
+    case R_MAGIC_XDR_V2:
+    case R_MAGIC_XDR_V3:
+      format = R_pstream_xdr_format;
+      break;
+
+    default:
+      fprintf(stderr, "Bad R magic: %d\n", magic);
+      return EINVAL;
+  }
+
+  // Open the file
+  fp = fopen(filename, "wb");
+  if (fp == 0) {
+    fprintf(stderr, "fopen: (%d) %s\n", errno, strerror(errno));
+    return errno;
+  }
+
+  // Write the R magic
+  if (R_WriteMagic(fp, magic) != 0) {
+    fprintf(stderr, "R_WriteMagic: (%d) %s\n", errno, strerror(errno));
+    fclose(fp);
+    return errno;
+  }
+
+  // Write to file
+  R_InitFileOutPStream(&rout, fp, format, version, NULL, NULL);
+  R_Serialize(rObj, &rout);
+
+  // Close the file
+  if (fclose(fp) != 0) {
+    fprintf(stderr, "fclose: (%d) %s\n", errno, strerror(errno));
+    return errno;
+  }
+
+  // If you got here, well done, have a zero
+  return 0;
+}
\ No newline at end of file
diff --git a/src/Rmemory-object.h b/src/Rmemory-object.h
new file mode 100644
index 0000000..4c6c212
--- /dev/null
+++ b/src/Rmemory-object.h
@@ -0,0 +1,21 @@
+#ifndef __R_MEMORY_OBJECT_H__
+#define __R_MEMORY_OBJECT_H__
+
+#include <Rinternals.h>
+
+struct rmemoryobject_t {
+  char *buf;
+  size_t bufsz;
+  int magic;
+};
+
+int rdataToMemory(const char *filename, struct rmemoryobject_t *objMem);
+int memoryToRData(const char *filename, struct rmemoryobject_t objMem);
+
+SEXP memoryToRObject(struct rmemoryobject_t objMem);
+struct rmemoryobject_t *robjectToMemory(SEXP rObj, int magic);
+
+SEXP rdataToRObject(const char *filename);
+int robjectToRData(const char *filename, SEXP rObj, int magic);
+
+#endif // __R_MEMORY_OBJECT_H__
\ No newline at end of file