Use fstat() to determine file size.

This allows us to get the file size even when the input file is passed
via stdin. This fixes `--content-size` not working in situations like

    $ lz4 -v --content-size < /tmp/test > /tmp/test.lz4
    Warning : cannot determine input content size

With this change, it works.

Also helps with #904.

2 files changed, 28 insertions, 3 deletions

diff --git a/programs/lz4io.c b/programs/lz4io.c
index 7926b20..0f3507e 100644
--- a/programs/lz4io.c
+++ b/programs/lz4io.c
@@ -680,7 +680,7 @@ LZ4IO_compressFilename_extRess(LZ4IO_prefs_t* const io_prefs, cRess_t ress,
     prefs.frameInfo.contentChecksumFlag = (LZ4F_contentChecksum_t)io_prefs->streamChecksum;
     prefs.favorDecSpeed = io_prefs->favorDecSpeed;
     if (io_prefs->contentSizeFlag) {
-      U64 const fileSize = UTIL_getFileSize(srcFileName);
+      U64 const fileSize = UTIL_getOpenFileSize(srcFile);
       prefs.frameInfo.contentSize = fileSize;   /* == 0 if input == stdin */
       if (fileSize==0)
           DISPLAYLEVEL(3, "Warning : cannot determine input content size \n");
@@ -1472,7 +1472,7 @@ LZ4IO_getCompressedFileInfo(LZ4IO_cFileInfo_t* cfinfo, const char* input_filenam
     LZ4IO_infoResult result = LZ4IO_format_not_known;  /* default result (error) */
     unsigned char buffer[LZ4F_HEADER_SIZE_MAX];
     FILE* const finput = LZ4IO_openSrcFile(input_filename);
-    cfinfo->fileSize = UTIL_getFileSize(input_filename);
+    cfinfo->fileSize = (finput == NULL) ? 0 : UTIL_getOpenFileSize(finput);
 
     while (!feof(finput)) {
         LZ4IO_frameInfo_t frameInfo = LZ4IO_INIT_FRAMEINFO;
diff --git a/programs/util.h b/programs/util.h
index 8e361ca..4b2c09a 100644
--- a/programs/util.h
+++ b/programs/util.h
@@ -33,7 +33,7 @@ extern "C" {
 #include <stddef.h>       /* size_t, ptrdiff_t */
 #include <stdlib.h>       /* malloc */
 #include <string.h>       /* strlen, strncpy */
-#include <stdio.h>        /* fprintf */
+#include <stdio.h>        /* fprintf, fileno */
 #include <assert.h>
 #include <sys/types.h>    /* stat, utime */
 #include <sys/stat.h>     /* stat */
@@ -357,6 +357,31 @@ UTIL_STATIC U32 UTIL_isDirectory(const char* infilename)
 }
 
 
+UTIL_STATIC U64 UTIL_getOpenFileSize(FILE* file)
+{
+    int r;
+    int fd = fileno(file);
+    if (fd < 0) {
+        perror("fileno");
+        exit(1);
+    }
+#if defined(_MSC_VER)
+    struct __stat64 statbuf;
+    r = _fstat64(fd, &statbuf);
+    if (r || !(statbuf.st_mode & S_IFREG)) return 0;   /* No good... */
+#elif defined(__MINGW32__) && defined (__MSVCRT__)
+    struct _stati64 statbuf;
+    r = _fstati64(fd, &statbuf);
+    if (r || !(statbuf.st_mode & S_IFREG)) return 0;   /* No good... */
+#else
+    struct stat statbuf;
+    r = fstat(fd, &statbuf);
+    if (r || !S_ISREG(statbuf.st_mode)) return 0;   /* No good... */
+#endif
+    return (U64)statbuf.st_size;
+}
+
+
 UTIL_STATIC U64 UTIL_getFileSize(const char* infilename)
 {
     int r;