From 7f975c0c2881c1f6b2523fdc64489cda280c6de1 Mon Sep 17 00:00:00 2001
From: Yi Jin <yijin@fb.com>
Date: Thu, 13 Dec 2018 15:42:55 -0800
Subject: [PATCH 01/10] create simple_compressionCCtx.c out of
 simple_compression.c, to be worked on

---
 examples/simple_compressionCCtx.c | 69 +++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 examples/simple_compressionCCtx.c

diff --git a/examples/simple_compressionCCtx.c b/examples/simple_compressionCCtx.c
new file mode 100644
index 000000000..0193dd40f
--- /dev/null
+++ b/examples/simple_compressionCCtx.c
@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#include <stdlib.h>    // malloc, free, exit
+#include <stdio.h>     // fprintf, perror, fopen, etc.
+#include <string.h>    // strlen, strcat, memset, strerror
+#include <errno.h>     // errno
+#include <sys/stat.h>  // stat
+#include <zstd.h>      // presumes zstd library is installed
+#include "utils.h"
+
+static void compress_orDie(const char* fname, const char* oname)
+{
+    size_t fSize;
+    void* const fBuff = loadFile_orDie(fname, &fSize);
+    size_t const cBuffSize = ZSTD_compressBound(fSize);
+    void* const cBuff = malloc_orDie(cBuffSize);
+
+    size_t const cSize = ZSTD_compress(cBuff, cBuffSize, fBuff, fSize, 1);
+    if (ZSTD_isError(cSize)) {
+        fprintf(stderr, "error compressing %s : %s \n", fname, ZSTD_getErrorName(cSize));
+        exit(8);
+    }
+
+    saveFile_orDie(oname, cBuff, cSize);
+
+    /* success */
+    printf("%25s : %6u -> %7u - %s \n", fname, (unsigned)fSize, (unsigned)cSize, oname);
+
+    free(fBuff);
+    free(cBuff);
+}
+
+static char* createOutFilename_orDie(const char* filename)
+{
+    size_t const inL = strlen(filename);
+    size_t const outL = inL + 5;
+    void* const outSpace = malloc_orDie(outL);
+    memset(outSpace, 0, outL);
+    strcat(outSpace, filename);
+    strcat(outSpace, ".zst");
+    return (char*)outSpace;
+}
+
+int main(int argc, const char** argv)
+{
+    const char* const exeName = argv[0];
+
+    if (argc!=2) {
+        printf("wrong arguments\n");
+        printf("usage:\n");
+        printf("%s FILE\n", exeName);
+        return 1;
+    }
+
+    const char* const inFilename = argv[1];
+
+    char* const outFilename = createOutFilename_orDie(inFilename);
+    compress_orDie(inFilename, outFilename);
+    free(outFilename);
+    return 0;
+}

From 193fbd30f236ddee04d85aece12465b13aa10335 Mon Sep 17 00:00:00 2001
From: Yi Jin <yijin@fb.com>
Date: Thu, 13 Dec 2018 22:51:35 -0800
Subject: [PATCH 02/10] WIP

---
 examples/simple_compressionCCtx.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/examples/simple_compressionCCtx.c b/examples/simple_compressionCCtx.c
index 0193dd40f..17255cba2 100644
--- a/examples/simple_compressionCCtx.c
+++ b/examples/simple_compressionCCtx.c
@@ -62,6 +62,17 @@ int main(int argc, const char** argv)
 
     const char* const inFilename = argv[1];
 
+    /** copied code
+    ZSTD_CCtx* const cctx = ZSTD_createCCtx();
+    if (cctx==NULL) { fprintf(stderr, "ZSTD_createCCtx() error \n"); exit(10); } 
+    size_t const cSize = ZSTD_compress_usingCDict(cctx, cBuff, cBuffSize, fBuff, fSize, cdict);
+    if (ZSTD_isError(cSize)) { 
+        fprintf(stderr, "error compressing %s : %s \n", fname, ZSTD_getErrorName(cSize));
+        exit(7);
+    }
+    **/
+
+
     char* const outFilename = createOutFilename_orDie(inFilename);
     compress_orDie(inFilename, outFilename);
     free(outFilename);

From 04d06ad8850c77f60e936e6a1c8eb0de6146a8cc Mon Sep 17 00:00:00 2001
From: Yi Jin <yijin@fb.com>
Date: Fri, 14 Dec 2018 18:12:05 -0800
Subject: [PATCH 03/10] refactor utils.h and implement simple_compressionCCtx.c

---
 examples/.gitignore                 |  1 +
 examples/Makefile                   |  6 +++
 examples/dictionary_compression.c   |  4 +-
 examples/dictionary_decompression.c |  4 +-
 examples/simple_compression.c       |  2 +-
 examples/simple_compressionCCtx.c   | 75 ++++++++++++++++-----------
 examples/simple_decompression.c     |  2 +-
 examples/utils.h                    | 80 +++++++++++++++++------------
 8 files changed, 106 insertions(+), 68 deletions(-)

diff --git a/examples/.gitignore b/examples/.gitignore
index 280feb36e..c92c69897 100644
--- a/examples/.gitignore
+++ b/examples/.gitignore
@@ -1,6 +1,7 @@
 #build
 simple_compression
 simple_decompression
+simple_compressionCCtx
 dictionary_compression
 dictionary_decompression
 streaming_compression
diff --git a/examples/Makefile b/examples/Makefile
index 96af41b54..7bcbd120b 100644
--- a/examples/Makefile
+++ b/examples/Makefile
@@ -17,6 +17,7 @@ LIB = ../lib/libzstd.a
 default: all
 
 all: simple_compression simple_decompression \
+	simple_compressionCCtx\
 	dictionary_compression dictionary_decompression \
 	streaming_compression streaming_decompression \
 	multiple_streaming_compression streaming_memory_usage
@@ -30,6 +31,9 @@ simple_compression : simple_compression.c $(LIB)
 simple_decompression : simple_decompression.c $(LIB)
 	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
 
+simple_compressionCCtx : simple_compressionCCtx.c $(LIB)
+	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+
 dictionary_compression : dictionary_compression.c $(LIB)
 	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
 
@@ -51,6 +55,7 @@ streaming_memory_usage : streaming_memory_usage.c $(LIB)
 clean:
 	@rm -f core *.o tmp* result* *.zst \
         simple_compression simple_decompression \
+	simple_compressionCCtx \
         dictionary_compression dictionary_decompression \
         streaming_compression streaming_decompression \
         multiple_streaming_compression streaming_memory_usage
@@ -62,6 +67,7 @@ test: all
 	@echo -- Simple compression tests
 	./simple_compression tmp
 	./simple_decompression tmp.zst
+	./simple_compressionCCtx *.c
 	./streaming_decompression tmp.zst > /dev/null
 	@echo -- Streaming memory usage
 	./streaming_memory_usage
diff --git a/examples/dictionary_compression.c b/examples/dictionary_compression.c
index 511b35676..2a3d61562 100644
--- a/examples/dictionary_compression.c
+++ b/examples/dictionary_compression.c
@@ -21,7 +21,7 @@ static ZSTD_CDict* createCDict_orDie(const char* dictFileName, int cLevel)
 {
     size_t dictSize;
     printf("loading dictionary %s \n", dictFileName);
-    void* const dictBuffer = loadFile_orDie(dictFileName, &dictSize);
+    void* const dictBuffer = loadFile_orDie(dictFileName, &dictSize, 0, 0);
     ZSTD_CDict* const cdict = ZSTD_createCDict(dictBuffer, dictSize, cLevel);
     if (!cdict) {
         fprintf(stderr, "ZSTD_createCDict error \n");
@@ -35,7 +35,7 @@ static ZSTD_CDict* createCDict_orDie(const char* dictFileName, int cLevel)
 static void compress(const char* fname, const char* oname, const ZSTD_CDict* cdict)
 {
     size_t fSize;
-    void* const fBuff = loadFile_orDie(fname, &fSize);
+    void* const fBuff = loadFile_orDie(fname, &fSize, 0, 0);
     size_t const cBuffSize = ZSTD_compressBound(fSize);
     void* const cBuff = malloc_orDie(cBuffSize);
 
diff --git a/examples/dictionary_decompression.c b/examples/dictionary_decompression.c
index 69f56d56b..36d20c1b1 100644
--- a/examples/dictionary_decompression.c
+++ b/examples/dictionary_decompression.c
@@ -25,7 +25,7 @@ static ZSTD_DDict* createDict_orDie(const char* dictFileName)
 {
     size_t dictSize;
     printf("loading dictionary %s \n", dictFileName);
-    void* const dictBuffer = loadFile_orDie(dictFileName, &dictSize);
+    void* const dictBuffer = loadFile_orDie(dictFileName, &dictSize, 0, 0);
     ZSTD_DDict* const ddict = ZSTD_createDDict(dictBuffer, dictSize);
     if (ddict==NULL) { fprintf(stderr, "ZSTD_createDDict error \n"); exit(5); }
     free(dictBuffer);
@@ -35,7 +35,7 @@ static ZSTD_DDict* createDict_orDie(const char* dictFileName)
 static void decompress(const char* fname, const ZSTD_DDict* ddict)
 {
     size_t cSize;
-    void* const cBuff = loadFile_orDie(fname, &cSize);
+    void* const cBuff = loadFile_orDie(fname, &cSize, 0, 0);
     unsigned long long const rSize = ZSTD_findDecompressedSize(cBuff, cSize);
     if (rSize==ZSTD_CONTENTSIZE_ERROR) {
         fprintf(stderr, "%s : it was not compressed by zstd.\n", fname);
diff --git a/examples/simple_compression.c b/examples/simple_compression.c
index 0193dd40f..7f1fa6cc6 100644
--- a/examples/simple_compression.c
+++ b/examples/simple_compression.c
@@ -19,7 +19,7 @@
 static void compress_orDie(const char* fname, const char* oname)
 {
     size_t fSize;
-    void* const fBuff = loadFile_orDie(fname, &fSize);
+    void* const fBuff = loadFile_orDie(fname, &fSize, 0, 0);
     size_t const cBuffSize = ZSTD_compressBound(fSize);
     void* const cBuff = malloc_orDie(cBuffSize);
 
diff --git a/examples/simple_compressionCCtx.c b/examples/simple_compressionCCtx.c
index 17255cba2..a5447f069 100644
--- a/examples/simple_compressionCCtx.c
+++ b/examples/simple_compressionCCtx.c
@@ -16,14 +16,14 @@
 #include <zstd.h>      // presumes zstd library is installed
 #include "utils.h"
 
-static void compress_orDie(const char* fname, const char* oname)
+/* compress with pre-allocated context (ZSTD_CCtx) and input/output buffers*/
+static void compressExpress_orDie(const char* fname, const char* oname,
+                                   ZSTD_CCtx* cctx, void* cBuff, size_t cBuffSize, void* fBuff, size_t fBuffSize)
 {
     size_t fSize;
-    void* const fBuff = loadFile_orDie(fname, &fSize);
-    size_t const cBuffSize = ZSTD_compressBound(fSize);
-    void* const cBuff = malloc_orDie(cBuffSize);
+    loadFile_orDie(fname, &fSize, fBuff, fBuffSize);
 
-    size_t const cSize = ZSTD_compress(cBuff, cBuffSize, fBuff, fSize, 1);
+    size_t const cSize = ZSTD_compressCCtx(cctx, cBuff, cBuffSize, fBuff, fBuffSize, 1);
     if (ZSTD_isError(cSize)) {
         fprintf(stderr, "error compressing %s : %s \n", fname, ZSTD_getErrorName(cSize));
         exit(8);
@@ -33,48 +33,65 @@ static void compress_orDie(const char* fname, const char* oname)
 
     /* success */
     printf("%25s : %6u -> %7u - %s \n", fname, (unsigned)fSize, (unsigned)cSize, oname);
-
-    free(fBuff);
-    free(cBuff);
 }
 
-static char* createOutFilename_orDie(const char* filename)
+static void getOutFilename(const char* const filename, char* const outFilename)
 {
-    size_t const inL = strlen(filename);
-    size_t const outL = inL + 5;
-    void* const outSpace = malloc_orDie(outL);
-    memset(outSpace, 0, outL);
-    strcat(outSpace, filename);
-    strcat(outSpace, ".zst");
-    return (char*)outSpace;
+    memset(outFilename, 0, 1);
+    strcat(outFilename, filename);
+    strcat(outFilename, ".zst");
 }
 
 int main(int argc, const char** argv)
 {
     const char* const exeName = argv[0];
 
-    if (argc!=2) {
+    if (argc<2) {
         printf("wrong arguments\n");
         printf("usage:\n");
-        printf("%s FILE\n", exeName);
+        printf("%s FILE(s)\n", exeName);
         return 1;
     }
 
-    const char* const inFilename = argv[1];
+    /* pre-calculate buffer sizes needed to handle all files */
+    size_t maxFileNameLength=0;
+    size_t maxFileSize = 0;
+    size_t maxCBufferSize = 0;
 
-    /** copied code
-    ZSTD_CCtx* const cctx = ZSTD_createCCtx();
-    if (cctx==NULL) { fprintf(stderr, "ZSTD_createCCtx() error \n"); exit(10); } 
-    size_t const cSize = ZSTD_compress_usingCDict(cctx, cBuff, cBuffSize, fBuff, fSize, cdict);
-    if (ZSTD_isError(cSize)) { 
-        fprintf(stderr, "error compressing %s : %s \n", fname, ZSTD_getErrorName(cSize));
-        exit(7);
+    int argNb;
+    for (argNb = 1; argNb < argc; argNb++) {
+      const char* const fileName = argv[argNb];
+      size_t const fileNameLength = strlen(fileName);
+      size_t const fileSize = fsize_orDie(fileName);
+
+      if (fileNameLength > maxFileNameLength) maxFileNameLength = fileNameLength;
+      if (fileSize > maxFileSize) maxFileSize = fileSize;
     }
-    **/
+    maxCBufferSize = ZSTD_compressBound(maxFileSize);
 
+    /* allocate memory for output file name, input/output buffers for all compression tasks */
+    char* const outFilename = (char*)malloc_orDie(maxFileNameLength + 5);
+    void* const fBuffer = malloc_orDie(maxFileSize);
+    void* const cBuffer = malloc_orDie(maxCBufferSize);
 
-    char* const outFilename = createOutFilename_orDie(inFilename);
-    compress_orDie(inFilename, outFilename);
+    /* create a compression context (ZSTD_CCtx) for all compression tasks */
+    ZSTD_CCtx* const cctx = ZSTD_createCCtx();
+    if (cctx==NULL) { fprintf(stderr, "ZSTD_createCCtx() error \n"); exit(10); }
+
+    /* compress files with shared context, input and output buffers */
+    for (argNb = 1; argNb < argc; argNb++) {
+      const char* const inFilename = argv[argNb];
+      getOutFilename(inFilename, outFilename);
+      compressExpress_orDie(inFilename, outFilename, cctx, cBuffer, maxCBufferSize, fBuffer, maxFileSize);
+    }
+
+    /* free momery resources */
     free(outFilename);
+    free(fBuffer);
+    free(cBuffer);
+    ZSTD_freeCCtx(cctx);   /* never fails */
+
+    printf("compressed %i files \n", argc-1);
+
     return 0;
 }
diff --git a/examples/simple_decompression.c b/examples/simple_decompression.c
index ee055dd67..00e020954 100644
--- a/examples/simple_decompression.c
+++ b/examples/simple_decompression.c
@@ -20,7 +20,7 @@
 static void decompress(const char* fname)
 {
     size_t cSize;
-    void* const cBuff = loadFile_orDie(fname, &cSize);
+    void* const cBuff = loadFile_orDie(fname, &cSize, 0, 0);
     unsigned long long const rSize = ZSTD_findDecompressedSize(cBuff, cSize);
     if (rSize==ZSTD_CONTENTSIZE_ERROR) {
         fprintf(stderr, "%s : it was not compressed by zstd.\n", fname);
diff --git a/examples/utils.h b/examples/utils.h
index 55a329e23..506cc1ab4 100644
--- a/examples/utils.h
+++ b/examples/utils.h
@@ -9,7 +9,7 @@
  */
 
 /*
- * This header file has common utility functions used in examples. 
+ * This header file has common utility functions used in examples.
  */
 #ifndef UTILS_H
 #define UTILS_H
@@ -21,7 +21,7 @@
 #include <sys/stat.h>  // stat
 
 /*
- * Define the returned error code from utility functions. 
+ * Define the returned error code from utility functions.
  */
 typedef enum {
     ERROR_fsize = 1,
@@ -35,21 +35,33 @@ typedef enum {
     ERROR_largeFile = 9,
 } UTILS_ErrorCode;
 
-/*! fsize_orDie() : 
+/*! fsize_orDie() :
  * Get the size of a given file path.
- * 
+ *
  * @return The size of a given file path.
  */
-static off_t fsize_orDie(const char *filename)
+static size_t fsize_orDie(const char *filename)
 {
     struct stat st;
-    if (stat(filename, &st) == 0) return st.st_size;
-    /* error */
-    perror(filename);
-    exit(ERROR_fsize);
+    if (stat(filename, &st) != 0) {
+        /* error */
+        perror(filename);
+        exit(ERROR_fsize);
+    }
+
+    off_t const fileSize = st.st_size;
+    size_t const size = (size_t)fileSize;
+    /* if off_t -> size_t conversion causes discrepancy, the file size is
+     * too big for at least 1 type to handle
+     */
+    if (size != fileSize) {   /* narrowcast overflow */
+        fprintf(stderr, "%s : filesize too large \n", filename);
+        exit(ERROR_largeFile);
+    }
+    return size;
 }
 
-/*! fopen_orDie() : 
+/*! fopen_orDie() :
  * Open a file using given file path and open option.
  *
  * @return If successful this function will return a FILE pointer to an
@@ -64,7 +76,7 @@ static FILE* fopen_orDie(const char *filename, const char *instruction)
     exit(ERROR_fopen);
 }
 
-/*! fclose_orDie() : 
+/*! fclose_orDie() :
  * Close an opened file using given FILE pointer.
  */
 static void fclose_orDie(FILE* file)
@@ -75,11 +87,11 @@ static void fclose_orDie(FILE* file)
     exit(ERROR_fclose);
 }
 
-/*! fread_orDie() : 
- * 
+/*! fread_orDie() :
+ *
  * Read sizeToRead bytes from a given file, storing them at the
  * location given by buffer.
- * 
+ *
  * @return The number of bytes read.
  */
 static size_t fread_orDie(void* buffer, size_t sizeToRead, FILE* file)
@@ -93,12 +105,12 @@ static size_t fread_orDie(void* buffer, size_t sizeToRead, FILE* file)
 }
 
 /*! fwrite_orDie() :
- *  
+ *
  * Write sizeToWrite bytes to a file pointed to by file, obtaining
  * them from a location given by buffer.
  *
  * Note: This function will send an error to stderr and exit if it
- * cannot write data to the given file pointer. 
+ * cannot write data to the given file pointer.
  *
  * @return The number of bytes written.
  */
@@ -113,7 +125,7 @@ static size_t fwrite_orDie(const void* buffer, size_t sizeToWrite, FILE* file)
 
 /*! malloc_orDie() :
  * Allocate memory.
- * 
+ *
  * @return If successful this function returns a pointer to allo-
  * cated memory.  If there is an error, this function will send that
  * error to stderr and exit.
@@ -128,39 +140,41 @@ static void* malloc_orDie(size_t size)
 }
 
 /*! loadFile_orDie() :
- * Read size bytes from a file.
- * 
+ * Read size bytes from a file. If buffer is not provided (i.e., buffer == null),
+ * malloc will be called to allocate one.
+ *
  * Note: This function will send an error to stderr and exit if it
  * cannot read data from the given file path.
- * 
+ *
  * @return If successful this function will return a pointer to read
  * data otherwise it will printout an error to stderr and exit.
  */
-static void* loadFile_orDie(const char* fileName, size_t* size)
+static void* loadFile_orDie(const char* fileName, size_t* size, void* buffer, int bufferSize)
 {
-    off_t const fileSize = fsize_orDie(fileName);
-    size_t const buffSize = (size_t)fileSize;
-    if ((off_t)buffSize < fileSize) {   /* narrowcast overflow */
-        fprintf(stderr, "%s : filesize too large \n", fileName);
-        exit(ERROR_largeFile);
-    }
+    size_t const fileSize = fsize_orDie(fileName);
     FILE* const inFile = fopen_orDie(fileName, "rb");
-    void* const buffer = malloc_orDie(buffSize);
-    size_t const readSize = fread(buffer, 1, buffSize, inFile);
-    if (readSize != (size_t)buffSize) {
+    if (!buffer) {
+        buffer = malloc_orDie(fileSize);
+    }
+    else if (bufferSize < fileSize) {
+        fprintf(stderr, "%s : filesize bigger than provided buffer.\n", fileName);
+
+    }
+    size_t const readSize = fread(buffer, 1, fileSize, inFile);
+    if (readSize != (size_t)fileSize) {
         fprintf(stderr, "fread: %s : %s \n", fileName, strerror(errno));
         exit(ERROR_fread);
     }
     fclose(inFile);  /* can't fail, read only */
-    *size = buffSize;
+    *size = fileSize;
     return buffer;
 }
 
 /*! saveFile_orDie() :
- *  
+ *
  * Save buffSize bytes to a given file path, obtaining them from a location pointed
  * to by buff.
- * 
+ *
  * Note: This function will send an error to stderr and exit if it
  * cannot write to a given file.
  */

From 0d14153cfb52fb8d24fcfe956498edc50a02764d Mon Sep 17 00:00:00 2001
From: Yi Jin <yijinru@gmail.com>
Date: Fri, 14 Dec 2018 22:10:31 -0800
Subject: [PATCH 04/10] formatting

---
 examples/simple_compressionCCtx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/simple_compressionCCtx.c b/examples/simple_compressionCCtx.c
index a5447f069..d3dd67cc7 100644
--- a/examples/simple_compressionCCtx.c
+++ b/examples/simple_compressionCCtx.c
@@ -18,7 +18,7 @@
 
 /* compress with pre-allocated context (ZSTD_CCtx) and input/output buffers*/
 static void compressExpress_orDie(const char* fname, const char* oname,
-                                   ZSTD_CCtx* cctx, void* cBuff, size_t cBuffSize, void* fBuff, size_t fBuffSize)
+                                  ZSTD_CCtx* cctx, void* cBuff, size_t cBuffSize, void* fBuff, size_t fBuffSize)
 {
     size_t fSize;
     loadFile_orDie(fname, &fSize, fBuff, fBuffSize);

From cce0842c607de31320a4fd37c1218fd40ac9b011 Mon Sep 17 00:00:00 2001
From: Yi Jin <yijinru@gmail.com>
Date: Sun, 16 Dec 2018 15:36:28 -0800
Subject: [PATCH 05/10] Factor out allocMemory_orDIe(...) in
 simple_compressionCCtx.c, and amend Makefile to account for dependency on
 utils.h

---
 examples/Makefile                 | 34 ++++++++---------
 examples/simple_compressionCCtx.c | 62 ++++++++++++++++++++-----------
 examples/utils.h                  |  4 +-
 3 files changed, 59 insertions(+), 41 deletions(-)

diff --git a/examples/Makefile b/examples/Makefile
index 7bcbd120b..7af6176b1 100644
--- a/examples/Makefile
+++ b/examples/Makefile
@@ -25,32 +25,32 @@ all: simple_compression simple_decompression \
 $(LIB) :
 	$(MAKE) -C ../lib libzstd.a
 
-simple_compression : simple_compression.c $(LIB)
-	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+simple_compression : simple_compression.c utils.h $(LIB)
+	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
-simple_decompression : simple_decompression.c $(LIB)
-	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+simple_decompression : simple_decompression.c utils.h $(LIB)
+	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
-simple_compressionCCtx : simple_compressionCCtx.c $(LIB)
-	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+simple_compressionCCtx : simple_compressionCCtx.c utils.h $(LIB)
+	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
-dictionary_compression : dictionary_compression.c $(LIB)
-	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+dictionary_compression : dictionary_compression.c utils.h $(LIB)
+	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
-dictionary_decompression : dictionary_decompression.c $(LIB)
-	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+dictionary_decompression : dictionary_decompression.c utils.h $(LIB)
+	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
-streaming_compression : streaming_compression.c $(LIB)
-	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+streaming_compression : streaming_compression.c utils.h $(LIB)
+	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
-multiple_streaming_compression : multiple_streaming_compression.c $(LIB)
-	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+multiple_streaming_compression : multiple_streaming_compression.c utils.h $(LIB)
+	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
-streaming_decompression : streaming_decompression.c $(LIB)
-	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+streaming_decompression : streaming_decompression.c utils.h $(LIB)
+	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
 streaming_memory_usage : streaming_memory_usage.c $(LIB)
-	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
+	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
 clean:
 	@rm -f core *.o tmp* result* *.zst \
diff --git a/examples/simple_compressionCCtx.c b/examples/simple_compressionCCtx.c
index d3dd67cc7..00279e4e6 100644
--- a/examples/simple_compressionCCtx.c
+++ b/examples/simple_compressionCCtx.c
@@ -23,7 +23,7 @@ static void compressExpress_orDie(const char* fname, const char* oname,
     size_t fSize;
     loadFile_orDie(fname, &fSize, fBuff, fBuffSize);
 
-    size_t const cSize = ZSTD_compressCCtx(cctx, cBuff, cBuffSize, fBuff, fBuffSize, 1);
+    size_t const cSize = ZSTD_compressCCtx(cctx, cBuff, cBuffSize, fBuff, fSize, 1);
     if (ZSTD_isError(cSize)) {
         fprintf(stderr, "error compressing %s : %s \n", fname, ZSTD_getErrorName(cSize));
         exit(8);
@@ -42,6 +42,32 @@ static void getOutFilename(const char* const filename, char* const outFilename)
     strcat(outFilename, ".zst");
 }
 
+/* allocate memory for buffers big enough to compress all files
+ * as well as memory for output file names (outFileName)
+ */
+void allocMemory_orDie(int argc, const char** argv, char** outFilename,
+                       void** cBuffer, size_t* cBufferSize, void** fBuffer, size_t* fBufferSize) {
+    size_t maxFilenameLength=0;
+    size_t maxFileSize = 0;
+
+    int argNb;
+    for (argNb = 1; argNb < argc; argNb++) {
+      const char* const filename = argv[argNb];
+      size_t const filenameLength = strlen(filename);
+      size_t const fileSize = fsize_orDie(filename);
+
+      if (filenameLength > maxFilenameLength) maxFilenameLength = filenameLength;
+      if (fileSize > maxFileSize) maxFileSize = fileSize;
+    }
+    *cBufferSize = ZSTD_compressBound(maxFileSize);
+    *fBufferSize = maxFileSize;
+
+    /* allocate memory for output file name, input/output buffers for all compression tasks */
+    *outFilename = (char*)malloc_orDie(maxFilenameLength + 5);
+    *cBuffer = malloc_orDie(*cBufferSize);
+    *fBuffer = malloc_orDie(*fBufferSize);
+}
+
 int main(int argc, const char** argv)
 {
     const char* const exeName = argv[0];
@@ -53,36 +79,28 @@ int main(int argc, const char** argv)
         return 1;
     }
 
-    /* pre-calculate buffer sizes needed to handle all files */
-    size_t maxFileNameLength=0;
-    size_t maxFileSize = 0;
-    size_t maxCBufferSize = 0;
-
-    int argNb;
-    for (argNb = 1; argNb < argc; argNb++) {
-      const char* const fileName = argv[argNb];
-      size_t const fileNameLength = strlen(fileName);
-      size_t const fileSize = fsize_orDie(fileName);
-
-      if (fileNameLength > maxFileNameLength) maxFileNameLength = fileNameLength;
-      if (fileSize > maxFileSize) maxFileSize = fileSize;
-    }
-    maxCBufferSize = ZSTD_compressBound(maxFileSize);
-
-    /* allocate memory for output file name, input/output buffers for all compression tasks */
-    char* const outFilename = (char*)malloc_orDie(maxFileNameLength + 5);
-    void* const fBuffer = malloc_orDie(maxFileSize);
-    void* const cBuffer = malloc_orDie(maxCBufferSize);
+    /* allocate memory for buffers big enough to compress all files
+     * as well as memory for output file name (outFileName)
+     *    fBuffer - buffer for input file data
+     *    cBuffer - buffer for compressed data 
+     */
+    char* outFilename;
+    void* fBuffer;
+    void* cBuffer;
+    size_t fBufferSize;
+    size_t cBufferSize;
+    allocMemory_orDie(argc, argv, &outFilename, &cBuffer, &cBufferSize, &fBuffer, &fBufferSize); 
 
     /* create a compression context (ZSTD_CCtx) for all compression tasks */
     ZSTD_CCtx* const cctx = ZSTD_createCCtx();
     if (cctx==NULL) { fprintf(stderr, "ZSTD_createCCtx() error \n"); exit(10); }
 
     /* compress files with shared context, input and output buffers */
+    int argNb;
     for (argNb = 1; argNb < argc; argNb++) {
       const char* const inFilename = argv[argNb];
       getOutFilename(inFilename, outFilename);
-      compressExpress_orDie(inFilename, outFilename, cctx, cBuffer, maxCBufferSize, fBuffer, maxFileSize);
+      compressExpress_orDie(inFilename, outFilename, cctx, cBuffer, cBufferSize, fBuffer, fBufferSize);
     }
 
     /* free momery resources */
diff --git a/examples/utils.h b/examples/utils.h
index 506cc1ab4..2df52be74 100644
--- a/examples/utils.h
+++ b/examples/utils.h
@@ -51,8 +51,8 @@ static size_t fsize_orDie(const char *filename)
 
     off_t const fileSize = st.st_size;
     size_t const size = (size_t)fileSize;
-    /* if off_t -> size_t conversion causes discrepancy, the file size is
-     * too big for at least 1 type to handle
+    /* if off_t -> size_t type conversion results in discrepancy,
+     * the file size is too big for at least one type to handle.
      */
     if (size != fileSize) {   /* narrowcast overflow */
         fprintf(stderr, "%s : filesize too large \n", filename);

From ea4859ec7194e1439d1e102f8dee583cbe8cd81b Mon Sep 17 00:00:00 2001
From: Yi Jin <yijinru@gmail.com>
Date: Sun, 16 Dec 2018 20:45:43 -0800
Subject: [PATCH 06/10] add multiple_simple_compression.c

---
 examples/multiple_simple_compression.c | 115 +++++++++++++++++++++++++
 examples/utils.h                       |   7 +-
 2 files changed, 119 insertions(+), 3 deletions(-)
 create mode 100644 examples/multiple_simple_compression.c

diff --git a/examples/multiple_simple_compression.c b/examples/multiple_simple_compression.c
new file mode 100644
index 000000000..ab128bbb3
--- /dev/null
+++ b/examples/multiple_simple_compression.c
@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#include <stdlib.h>    // malloc, free, exit
+#include <stdio.h>     // fprintf, perror, fopen, etc.
+#include <string.h>    // strlen, strcat, memset, strerror
+#include <errno.h>     // errno
+#include <sys/stat.h>  // stat
+#include <zstd.h>      // presumes zstd library is installed
+#include "utils.h"
+
+typedef struct {
+    void* fBuffer;
+    void* cBuffer;
+    size_t fBufferSize;
+    size_t cBufferSize;
+    ZSTD_CCtx* cctx;
+} resources;
+
+/*
+ * allocate memory for buffers big enough to compress all files
+ * as well as memory for output file name (outFilename)
+ */
+static resources createResources_orDie(int argc, const char** argv, char **outFilename)
+{
+    size_t maxFilenameLength=0;
+    size_t maxFileSize = 0;
+
+    int argNb;
+    for (argNb = 1; argNb < argc; argNb++) {
+      const char* const filename = argv[argNb];
+      size_t const filenameLength = strlen(filename);
+      size_t const fileSize = fsize_orDie(filename);
+
+      if (filenameLength > maxFilenameLength) maxFilenameLength = filenameLength;
+      if (fileSize > maxFileSize) maxFileSize = fileSize;
+    }
+
+    resources ress;
+    ress.fBufferSize = maxFileSize;
+    ress.cBufferSize = ZSTD_compressBound(maxFileSize);
+
+    *outFilename = (char*)malloc_orDie(maxFilenameLength + 5);
+    ress.fBuffer = malloc_orDie(ress.fBufferSize);
+    ress.cBuffer = malloc_orDie(ress.cBufferSize);
+    ress.cctx = ZSTD_createCCtx();
+    if (ress.cctx==NULL) { fprintf(stderr, "ZSTD_createCCtx() error \n"); exit(10); }
+    return ress;
+}
+
+static void freeResources(resources ress, char *outFilename)
+{
+    free(ress.fBuffer);
+    free(ress.cBuffer);
+    ZSTD_freeCCtx(ress.cctx);   /* never fails */
+    free(outFilename);
+}
+
+/* compress with pre-allocated context (ZSTD_CCtx) and input/output buffers*/
+static void compressFile_orDie(resources ress, const char* fname, const char* oname)
+{
+    size_t fSize;
+    loadFile_orDie(fname, &fSize, ress.fBuffer, ress.fBufferSize);
+
+    size_t const cSize = ZSTD_compressCCtx(ress.cctx, ress.cBuffer, ress.cBufferSize, ress.fBuffer, fSize, 1);
+    if (ZSTD_isError(cSize)) {
+        fprintf(stderr, "error compressing %s : %s \n", fname, ZSTD_getErrorName(cSize));
+        exit(8);
+    }
+
+    saveFile_orDie(oname, ress.cBuffer, cSize);
+
+    /* success */
+    printf("%25s : %6u -> %7u - %s \n", fname, (unsigned)fSize, (unsigned)cSize, oname);
+}
+
+int main(int argc, const char** argv)
+{
+    const char* const exeName = argv[0];
+
+    if (argc<2) {
+        printf("wrong arguments\n");
+        printf("usage:\n");
+        printf("%s FILE(s)\n", exeName);
+        return 1;
+    }
+
+    /* memory allocation for outFilename and resources */
+    char* outFilename;
+    resources ress = createResources_orDie(argc, argv, &outFilename); 
+
+    /* compress files with shared context, input and output buffers */
+    int argNb;
+    for (argNb = 1; argNb < argc; argNb++) {
+        const char* const inFilename = argv[argNb];
+        memset(outFilename, 0, 1);
+        strcat(outFilename, inFilename);
+        strcat(outFilename, ".zst");
+        compressFile_orDie(ress, inFilename, outFilename);
+    }
+
+    /* free momery */
+    freeResources(ress,outFilename);
+
+    printf("compressed %i files \n", argc-1);
+
+    return 0;
+}
diff --git a/examples/utils.h b/examples/utils.h
index 2df52be74..d722d3cef 100644
--- a/examples/utils.h
+++ b/examples/utils.h
@@ -51,10 +51,11 @@ static size_t fsize_orDie(const char *filename)
 
     off_t const fileSize = st.st_size;
     size_t const size = (size_t)fileSize;
-    /* if off_t -> size_t type conversion results in discrepancy,
-     * the file size is too big for at least one type to handle.
+    /* 1. fileSize should be non-negative,
+     * 2. if off_t -> size_t type conversion results in discrepancy,
+     *    the file size is too large for type size_t.
      */
-    if (size != fileSize) {   /* narrowcast overflow */
+    if ((fileSize < 0) || (fileSize != (off_t)size)) { 
         fprintf(stderr, "%s : filesize too large \n", filename);
         exit(ERROR_largeFile);
     }

From 595401e4c7bcd90e6cf8eeefdd0d39302d8840b7 Mon Sep 17 00:00:00 2001
From: Yi Jin <yijinru@gmail.com>
Date: Sun, 16 Dec 2018 21:09:21 -0800
Subject: [PATCH 07/10] edit README.md and remove simple_compressionCCtx.c

---
 examples/.gitignore               |   2 +-
 examples/Makefile                 |   8 +--
 examples/README.md                |  10 ++-
 examples/simple_compressionCCtx.c | 115 ------------------------------
 4 files changed, 13 insertions(+), 122 deletions(-)
 delete mode 100644 examples/simple_compressionCCtx.c

diff --git a/examples/.gitignore b/examples/.gitignore
index c92c69897..d682cae38 100644
--- a/examples/.gitignore
+++ b/examples/.gitignore
@@ -1,7 +1,7 @@
 #build
 simple_compression
 simple_decompression
-simple_compressionCCtx
+multiple_simple_compression
 dictionary_compression
 dictionary_decompression
 streaming_compression
diff --git a/examples/Makefile b/examples/Makefile
index 7af6176b1..25a0a62c2 100644
--- a/examples/Makefile
+++ b/examples/Makefile
@@ -17,7 +17,7 @@ LIB = ../lib/libzstd.a
 default: all
 
 all: simple_compression simple_decompression \
-	simple_compressionCCtx\
+	multiple_simple_compression\
 	dictionary_compression dictionary_decompression \
 	streaming_compression streaming_decompression \
 	multiple_streaming_compression streaming_memory_usage
@@ -31,7 +31,7 @@ simple_compression : simple_compression.c utils.h $(LIB)
 simple_decompression : simple_decompression.c utils.h $(LIB)
 	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
-simple_compressionCCtx : simple_compressionCCtx.c utils.h $(LIB)
+multiple_simple_compression : multiple_simple_compression.c utils.h $(LIB)
 	$(CC) $(CPPFLAGS) $(CFLAGS) $< $(LIB) $(LDFLAGS) -o $@
 
 dictionary_compression : dictionary_compression.c utils.h $(LIB)
@@ -55,7 +55,7 @@ streaming_memory_usage : streaming_memory_usage.c $(LIB)
 clean:
 	@rm -f core *.o tmp* result* *.zst \
         simple_compression simple_decompression \
-	simple_compressionCCtx \
+        multiple_simple_compression \
         dictionary_compression dictionary_decompression \
         streaming_compression streaming_decompression \
         multiple_streaming_compression streaming_memory_usage
@@ -67,7 +67,7 @@ test: all
 	@echo -- Simple compression tests
 	./simple_compression tmp
 	./simple_decompression tmp.zst
-	./simple_compressionCCtx *.c
+	./multiple_simple_compression *.c
 	./streaming_decompression tmp.zst > /dev/null
 	@echo -- Streaming memory usage
 	./streaming_memory_usage
diff --git a/examples/README.md b/examples/README.md
index eba50c999..0bff7ac19 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -11,8 +11,14 @@ Zstandard library : usage examples
   Result remains in memory.
   Introduces usage of : `ZSTD_decompress()`
 
+- [Multiple simple compression](multiple_simple_compression.c) :
+  Compress multiple files (in simple mode) in a single command line.
+  Demonstrates memory preservation technique that
+  minimizes malloc()/free() calls by re-using existing resources.
+  Introduces usage of : `ZSTD_compressCCtx()`
+
 - [Streaming memory usage](streaming_memory_usage.c) :
-  Provides amount of memory used by streaming context
+  Provides amount of memory used by streaming context.
   Introduces usage of : `ZSTD_sizeof_CStream()`
 
 - [Streaming compression](streaming_compression.c) :
@@ -20,7 +26,7 @@ Zstandard library : usage examples
   Introduces usage of : `ZSTD_compressStream()`
 
 - [Multiple Streaming compression](multiple_streaming_compression.c) :
-  Compress multiple files in a single command line.
+  Compress multiple files (in streaming mode) in a single command line.
   Introduces memory usage preservation technique,
   reducing impact of malloc()/free() and memset() by re-using existing resources.
 
diff --git a/examples/simple_compressionCCtx.c b/examples/simple_compressionCCtx.c
deleted file mode 100644
index 00279e4e6..000000000
--- a/examples/simple_compressionCCtx.c
+++ /dev/null
@@ -1,115 +0,0 @@
-/*
- * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under both the BSD-style license (found in the
- * LICENSE file in the root directory of this source tree) and the GPLv2 (found
- * in the COPYING file in the root directory of this source tree).
- * You may select, at your option, one of the above-listed licenses.
- */
-
-#include <stdlib.h>    // malloc, free, exit
-#include <stdio.h>     // fprintf, perror, fopen, etc.
-#include <string.h>    // strlen, strcat, memset, strerror
-#include <errno.h>     // errno
-#include <sys/stat.h>  // stat
-#include <zstd.h>      // presumes zstd library is installed
-#include "utils.h"
-
-/* compress with pre-allocated context (ZSTD_CCtx) and input/output buffers*/
-static void compressExpress_orDie(const char* fname, const char* oname,
-                                  ZSTD_CCtx* cctx, void* cBuff, size_t cBuffSize, void* fBuff, size_t fBuffSize)
-{
-    size_t fSize;
-    loadFile_orDie(fname, &fSize, fBuff, fBuffSize);
-
-    size_t const cSize = ZSTD_compressCCtx(cctx, cBuff, cBuffSize, fBuff, fSize, 1);
-    if (ZSTD_isError(cSize)) {
-        fprintf(stderr, "error compressing %s : %s \n", fname, ZSTD_getErrorName(cSize));
-        exit(8);
-    }
-
-    saveFile_orDie(oname, cBuff, cSize);
-
-    /* success */
-    printf("%25s : %6u -> %7u - %s \n", fname, (unsigned)fSize, (unsigned)cSize, oname);
-}
-
-static void getOutFilename(const char* const filename, char* const outFilename)
-{
-    memset(outFilename, 0, 1);
-    strcat(outFilename, filename);
-    strcat(outFilename, ".zst");
-}
-
-/* allocate memory for buffers big enough to compress all files
- * as well as memory for output file names (outFileName)
- */
-void allocMemory_orDie(int argc, const char** argv, char** outFilename,
-                       void** cBuffer, size_t* cBufferSize, void** fBuffer, size_t* fBufferSize) {
-    size_t maxFilenameLength=0;
-    size_t maxFileSize = 0;
-
-    int argNb;
-    for (argNb = 1; argNb < argc; argNb++) {
-      const char* const filename = argv[argNb];
-      size_t const filenameLength = strlen(filename);
-      size_t const fileSize = fsize_orDie(filename);
-
-      if (filenameLength > maxFilenameLength) maxFilenameLength = filenameLength;
-      if (fileSize > maxFileSize) maxFileSize = fileSize;
-    }
-    *cBufferSize = ZSTD_compressBound(maxFileSize);
-    *fBufferSize = maxFileSize;
-
-    /* allocate memory for output file name, input/output buffers for all compression tasks */
-    *outFilename = (char*)malloc_orDie(maxFilenameLength + 5);
-    *cBuffer = malloc_orDie(*cBufferSize);
-    *fBuffer = malloc_orDie(*fBufferSize);
-}
-
-int main(int argc, const char** argv)
-{
-    const char* const exeName = argv[0];
-
-    if (argc<2) {
-        printf("wrong arguments\n");
-        printf("usage:\n");
-        printf("%s FILE(s)\n", exeName);
-        return 1;
-    }
-
-    /* allocate memory for buffers big enough to compress all files
-     * as well as memory for output file name (outFileName)
-     *    fBuffer - buffer for input file data
-     *    cBuffer - buffer for compressed data 
-     */
-    char* outFilename;
-    void* fBuffer;
-    void* cBuffer;
-    size_t fBufferSize;
-    size_t cBufferSize;
-    allocMemory_orDie(argc, argv, &outFilename, &cBuffer, &cBufferSize, &fBuffer, &fBufferSize); 
-
-    /* create a compression context (ZSTD_CCtx) for all compression tasks */
-    ZSTD_CCtx* const cctx = ZSTD_createCCtx();
-    if (cctx==NULL) { fprintf(stderr, "ZSTD_createCCtx() error \n"); exit(10); }
-
-    /* compress files with shared context, input and output buffers */
-    int argNb;
-    for (argNb = 1; argNb < argc; argNb++) {
-      const char* const inFilename = argv[argNb];
-      getOutFilename(inFilename, outFilename);
-      compressExpress_orDie(inFilename, outFilename, cctx, cBuffer, cBufferSize, fBuffer, fBufferSize);
-    }
-
-    /* free momery resources */
-    free(outFilename);
-    free(fBuffer);
-    free(cBuffer);
-    ZSTD_freeCCtx(cctx);   /* never fails */
-
-    printf("compressed %i files \n", argc-1);
-
-    return 0;
-}

From a951ee9fe1f157f0e2d611ef9152c146abe1f5bb Mon Sep 17 00:00:00 2001
From: Yi Jin <yijinru@gmail.com>
Date: Sun, 16 Dec 2018 21:27:52 -0800
Subject: [PATCH 08/10] comment out printf() to make output terse

---
 examples/multiple_simple_compression.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/multiple_simple_compression.c b/examples/multiple_simple_compression.c
index ab128bbb3..2401a99b6 100644
--- a/examples/multiple_simple_compression.c
+++ b/examples/multiple_simple_compression.c
@@ -78,7 +78,7 @@ static void compressFile_orDie(resources ress, const char* fname, const char* on
     saveFile_orDie(oname, ress.cBuffer, cSize);
 
     /* success */
-    printf("%25s : %6u -> %7u - %s \n", fname, (unsigned)fSize, (unsigned)cSize, oname);
+    // printf("%25s : %6u -> %7u - %s \n", fname, (unsigned)fSize, (unsigned)cSize, oname);
 }
 
 int main(int argc, const char** argv)

From 452689678bf4d956308dc0ad9d3c75440496b4b9 Mon Sep 17 00:00:00 2001
From: Yi Jin <yijinru@gmail.com>
Date: Sun, 16 Dec 2018 22:44:27 -0800
Subject: [PATCH 09/10] bug fix in loadFile_orDie(): exit with error code if
 filesize is bigger than provided buffer

---
 examples/utils.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/utils.h b/examples/utils.h
index d722d3cef..7968d436f 100644
--- a/examples/utils.h
+++ b/examples/utils.h
@@ -159,7 +159,7 @@ static void* loadFile_orDie(const char* fileName, size_t* size, void* buffer, in
     }
     else if (bufferSize < fileSize) {
         fprintf(stderr, "%s : filesize bigger than provided buffer.\n", fileName);
-
+        exit(ERROR_largeFile);
     }
     size_t const readSize = fread(buffer, 1, fileSize, inFile);
     if (readSize != (size_t)fileSize) {

From bc4dc606de284c65162ee8fb9de5c50ab2dfc233 Mon Sep 17 00:00:00 2001
From: Yi Jin <yijin@fb.com>
Date: Mon, 17 Dec 2018 16:54:55 -0800
Subject: [PATCH 10/10] break loadFile_orDie() into 2: loadFile_orDie() loads
 file into a pre-allocated memory buffer, mallocAndLoadFile_orDie() allocates
 memory first, then calls loadFile_orDie()

---
 examples/dictionary_compression.c      |  4 +--
 examples/dictionary_decompression.c    |  4 +--
 examples/multiple_simple_compression.c | 20 +++++++-------
 examples/simple_compression.c          |  2 +-
 examples/simple_decompression.c        |  2 +-
 examples/utils.h                       | 37 +++++++++++++++++---------
 6 files changed, 41 insertions(+), 28 deletions(-)

diff --git a/examples/dictionary_compression.c b/examples/dictionary_compression.c
index 2a3d61562..3c4a5bd1e 100644
--- a/examples/dictionary_compression.c
+++ b/examples/dictionary_compression.c
@@ -21,7 +21,7 @@ static ZSTD_CDict* createCDict_orDie(const char* dictFileName, int cLevel)
 {
     size_t dictSize;
     printf("loading dictionary %s \n", dictFileName);
-    void* const dictBuffer = loadFile_orDie(dictFileName, &dictSize, 0, 0);
+    void* const dictBuffer = mallocAndLoadFile_orDie(dictFileName, &dictSize);
     ZSTD_CDict* const cdict = ZSTD_createCDict(dictBuffer, dictSize, cLevel);
     if (!cdict) {
         fprintf(stderr, "ZSTD_createCDict error \n");
@@ -35,7 +35,7 @@ static ZSTD_CDict* createCDict_orDie(const char* dictFileName, int cLevel)
 static void compress(const char* fname, const char* oname, const ZSTD_CDict* cdict)
 {
     size_t fSize;
-    void* const fBuff = loadFile_orDie(fname, &fSize, 0, 0);
+    void* const fBuff = mallocAndLoadFile_orDie(fname, &fSize);
     size_t const cBuffSize = ZSTD_compressBound(fSize);
     void* const cBuff = malloc_orDie(cBuffSize);
 
diff --git a/examples/dictionary_decompression.c b/examples/dictionary_decompression.c
index 36d20c1b1..243e22236 100644
--- a/examples/dictionary_decompression.c
+++ b/examples/dictionary_decompression.c
@@ -25,7 +25,7 @@ static ZSTD_DDict* createDict_orDie(const char* dictFileName)
 {
     size_t dictSize;
     printf("loading dictionary %s \n", dictFileName);
-    void* const dictBuffer = loadFile_orDie(dictFileName, &dictSize, 0, 0);
+    void* const dictBuffer = mallocAndLoadFile_orDie(dictFileName, &dictSize);
     ZSTD_DDict* const ddict = ZSTD_createDDict(dictBuffer, dictSize);
     if (ddict==NULL) { fprintf(stderr, "ZSTD_createDDict error \n"); exit(5); }
     free(dictBuffer);
@@ -35,7 +35,7 @@ static ZSTD_DDict* createDict_orDie(const char* dictFileName)
 static void decompress(const char* fname, const ZSTD_DDict* ddict)
 {
     size_t cSize;
-    void* const cBuff = loadFile_orDie(fname, &cSize, 0, 0);
+    void* const cBuff = mallocAndLoadFile_orDie(fname, &cSize);
     unsigned long long const rSize = ZSTD_findDecompressedSize(cBuff, cSize);
     if (rSize==ZSTD_CONTENTSIZE_ERROR) {
         fprintf(stderr, "%s : it was not compressed by zstd.\n", fname);
diff --git a/examples/multiple_simple_compression.c b/examples/multiple_simple_compression.c
index 2401a99b6..65c775bfa 100644
--- a/examples/multiple_simple_compression.c
+++ b/examples/multiple_simple_compression.c
@@ -26,9 +26,9 @@ typedef struct {
 
 /*
  * allocate memory for buffers big enough to compress all files
- * as well as memory for output file name (outFilename)
+ * as well as memory for output file name (ofn)
  */
-static resources createResources_orDie(int argc, const char** argv, char **outFilename)
+static resources createResources_orDie(int argc, const char** argv, char **ofn, int* ofnBufferLen)
 {
     size_t maxFilenameLength=0;
     size_t maxFileSize = 0;
@@ -47,7 +47,8 @@ static resources createResources_orDie(int argc, const char** argv, char **outFi
     ress.fBufferSize = maxFileSize;
     ress.cBufferSize = ZSTD_compressBound(maxFileSize);
 
-    *outFilename = (char*)malloc_orDie(maxFilenameLength + 5);
+    *ofnBufferLen = maxFilenameLength + 5;
+    *ofn = (char*)malloc_orDie(*ofnBufferLen);
     ress.fBuffer = malloc_orDie(ress.fBufferSize);
     ress.cBuffer = malloc_orDie(ress.cBufferSize);
     ress.cctx = ZSTD_createCCtx();
@@ -66,8 +67,7 @@ static void freeResources(resources ress, char *outFilename)
 /* compress with pre-allocated context (ZSTD_CCtx) and input/output buffers*/
 static void compressFile_orDie(resources ress, const char* fname, const char* oname)
 {
-    size_t fSize;
-    loadFile_orDie(fname, &fSize, ress.fBuffer, ress.fBufferSize);
+    size_t fSize = loadFile_orDie(fname, ress.fBuffer, ress.fBufferSize);
 
     size_t const cSize = ZSTD_compressCCtx(ress.cctx, ress.cBuffer, ress.cBufferSize, ress.fBuffer, fSize, 1);
     if (ZSTD_isError(cSize)) {
@@ -94,15 +94,17 @@ int main(int argc, const char** argv)
 
     /* memory allocation for outFilename and resources */
     char* outFilename;
-    resources ress = createResources_orDie(argc, argv, &outFilename); 
+    int outFilenameBufferLen;
+    resources const ress = createResources_orDie(argc, argv, &outFilename, &outFilenameBufferLen); 
 
     /* compress files with shared context, input and output buffers */
     int argNb;
     for (argNb = 1; argNb < argc; argNb++) {
         const char* const inFilename = argv[argNb];
-        memset(outFilename, 0, 1);
-        strcat(outFilename, inFilename);
-        strcat(outFilename, ".zst");
+        int inFilenameLen = strlen(inFilename);
+        assert(inFilenameLen + 5 <= outFilenameBufferLen);
+        memcpy(outFilename, inFilename, inFilenameLen);
+        memcpy(outFilename+inFilenameLen, ".zst", 5);
         compressFile_orDie(ress, inFilename, outFilename);
     }
 
diff --git a/examples/simple_compression.c b/examples/simple_compression.c
index 7f1fa6cc6..829cbd7d8 100644
--- a/examples/simple_compression.c
+++ b/examples/simple_compression.c
@@ -19,7 +19,7 @@
 static void compress_orDie(const char* fname, const char* oname)
 {
     size_t fSize;
-    void* const fBuff = loadFile_orDie(fname, &fSize, 0, 0);
+    void* const fBuff = mallocAndLoadFile_orDie(fname, &fSize);
     size_t const cBuffSize = ZSTD_compressBound(fSize);
     void* const cBuff = malloc_orDie(cBuffSize);
 
diff --git a/examples/simple_decompression.c b/examples/simple_decompression.c
index 00e020954..e7949376c 100644
--- a/examples/simple_decompression.c
+++ b/examples/simple_decompression.c
@@ -20,7 +20,7 @@
 static void decompress(const char* fname)
 {
     size_t cSize;
-    void* const cBuff = loadFile_orDie(fname, &cSize, 0, 0);
+    void* const cBuff = mallocAndLoadFile_orDie(fname, &cSize);
     unsigned long long const rSize = ZSTD_findDecompressedSize(cBuff, cSize);
     if (rSize==ZSTD_CONTENTSIZE_ERROR) {
         fprintf(stderr, "%s : it was not compressed by zstd.\n", fname);
diff --git a/examples/utils.h b/examples/utils.h
index 7968d436f..6d1360457 100644
--- a/examples/utils.h
+++ b/examples/utils.h
@@ -18,6 +18,7 @@
 #include <stdio.h>     // fprintf, perror, fopen, etc.
 #include <string.h>    // strlen, strcat, memset, strerror
 #include <errno.h>     // errno
+#include <assert.h>    // assert
 #include <sys/stat.h>  // stat
 
 /*
@@ -141,33 +142,43 @@ static void* malloc_orDie(size_t size)
 }
 
 /*! loadFile_orDie() :
- * Read size bytes from a file. If buffer is not provided (i.e., buffer == null),
- * malloc will be called to allocate one.
+ * load file into buffer (memory).
  *
  * Note: This function will send an error to stderr and exit if it
  * cannot read data from the given file path.
  *
- * @return If successful this function will return a pointer to read
- * data otherwise it will printout an error to stderr and exit.
+ * @return If successful this function will load file into buffer and
+ * return file size, otherwise it will printout an error to stderr and exit.
  */
-static void* loadFile_orDie(const char* fileName, size_t* size, void* buffer, int bufferSize)
+static size_t loadFile_orDie(const char* fileName, void* buffer, int bufferSize)
 {
     size_t const fileSize = fsize_orDie(fileName);
+    assert(fileSize <= bufferSize);
+
     FILE* const inFile = fopen_orDie(fileName, "rb");
-    if (!buffer) {
-        buffer = malloc_orDie(fileSize);
-    }
-    else if (bufferSize < fileSize) {
-        fprintf(stderr, "%s : filesize bigger than provided buffer.\n", fileName);
-        exit(ERROR_largeFile);
-    }
     size_t const readSize = fread(buffer, 1, fileSize, inFile);
     if (readSize != (size_t)fileSize) {
         fprintf(stderr, "fread: %s : %s \n", fileName, strerror(errno));
         exit(ERROR_fread);
     }
     fclose(inFile);  /* can't fail, read only */
-    *size = fileSize;
+    return fileSize;
+}
+
+/*! mallocAndLoadFile_orDie() :
+ * allocate memory buffer and then load file into it.
+ *
+ * Note: This function will send an error to stderr and exit if memory allocation
+ * fails or it cannot read data from the given file path.
+ *
+ * @return If successful this function will return buffer and bufferSize(=fileSize),
+ * otherwise it will printout an error to stderr and exit.
+ */
+static void* mallocAndLoadFile_orDie(const char* fileName, size_t* bufferSize) {
+    size_t const fileSize = fsize_orDie(fileName);
+    *bufferSize = fileSize;
+    void* const buffer = malloc_orDie(*bufferSize);
+    loadFile_orDie(fileName, buffer, *bufferSize);
     return buffer;
 }