simpleLog add redirection of stdout/stderr to custom FDs (#32)

Author: sy-c

include/Common/SimpleLog.h

@@ -26,6 +26,9 @@ class SimpleLog {
   // \param logFilePath Path to log file. If NULL, using stdout/stderr.
   int setLogFile(const char* logFilePath=NULL);
 
+  // Change file descriptors used for stdout/stderr with provided ones
+  // They must be valid for the lifetime of this object (or until overwritten), and are not closed.
+  void setFileDescriptors(int fdStdout, int fdStderr);
 
   enum FormatOption : int {
     ShowTimeStamp = 0x1,

src/SimpleLog.cxx

@@ -2,6 +2,7 @@
 
 #include <time.h>
 #include <sys/time.h>
+#include <unistd.h>
 
 class SimpleLog::Impl {
   public:
@@ -24,7 +25,9 @@ class SimpleLog::Impl {
   protected: 
   FILE *fp; // descriptor to be used. If NULL, using stdout/stderr.
   int formatOptions;
-  
+  int fdStdout;
+  int fdStderr;
+
   friend class SimpleLog;
 };
 
@@ -33,6 +36,8 @@ SimpleLog::Impl::Impl() {
   formatOptions =   SimpleLog::FormatOption::ShowTimeStamp
                   | SimpleLog::FormatOption::ShowSeveritySymbol
                   | SimpleLog::FormatOption::ShowMessage;
+  fdStdout = fileno(stdout);
+  fdStderr = fileno(stderr);
 }
 
 SimpleLog::Impl::~Impl() {
@@ -46,7 +51,7 @@ SimpleLog::Impl::~Impl() {
 int SimpleLog::Impl::logV(SimpleLog::Impl::Severity s, const char *message, va_list ap)
 {
   char buffer[1024] = "";
-  size_t len = sizeof(buffer);
+  size_t len = sizeof(buffer) - 2;
   size_t ix = 0;
 
   if (formatOptions & SimpleLog::FormatOption::ShowTimeStamp) {  
@@ -95,20 +100,23 @@ int SimpleLog::Impl::logV(SimpleLog::Impl::Severity s, const char *message, va_l
    ix+=vsnprintf(&buffer[ix], len-ix, message, ap);
    if (ix>len) { ix=len; } 
   }
-  
+
+  buffer[ix] = '\n';
+  ix++;
   buffer[ix]=0;
 
-  FILE *fpOut=stdout;
-  
-  if (fp==NULL) {
+  int fd;
+  if (fp != NULL) {
+    fd = fileno(fp);
+  } else {
     if (s==Severity::Error) {
-      fpOut=stderr;
+      fd = fdStderr;
+    } else {
+      fd = fdStdout;
     }
-  } else {
-    fpOut=fp;
   }
-  fprintf(fpOut,"%s\n", buffer);
-  fflush(fpOut);
+  write(fd, buffer, ix);
+
   return 0;
 }
 
@@ -182,4 +190,10 @@ void SimpleLog::setOutputFormat(int opts) {
   pImpl->formatOptions=opts;
 }
 
+void SimpleLog::setFileDescriptors(int fdStdout, int fdStderr)
+{
+  pImpl->fdStdout = fdStdout;
+  pImpl->fdStderr = fdStderr;
+}
+
 /// \todo: thread to flush output every 1 second