Add _pdfioStringPrintf function and support for using a string buffer to collect an object's value (Issue #101)

pdfio-private.h

@@ -277,9 +277,11 @@ typedef struct _pdfio_objmap_s		// PDF object map
 typedef struct _pdfio_strbuf_s		// PDF string buffer
 {
   struct _pdfio_strbuf_s *next;		// Next string buffer
+  pdfio_file_t	*pdf;			// PDF file
   bool		bufused;		// Is this string buffer being used?
-  char		buffer[PDFIO_MAX_STRING + 32];
+  char		buffer[PDFIO_MAX_STRING + 32],
 					// String buffer
+		*bufptr;		// Pointer into buffer
 } _pdfio_strbuf_t;
 
 struct _pdfio_file_s			// PDF file structure
@@ -468,9 +470,10 @@ extern bool		_pdfioObjWriteHeader(pdfio_obj_t *obj) _PDFIO_INTERNAL;
 extern pdfio_stream_t	*_pdfioStreamCreate(pdfio_obj_t *obj, pdfio_obj_t *length_obj, size_t cbsize, pdfio_filter_t compression) _PDFIO_INTERNAL;
 extern pdfio_stream_t	*_pdfioStreamOpen(pdfio_obj_t *obj, bool decode) _PDFIO_INTERNAL;
 
-extern char		*_pdfioStringAllocBuffer(pdfio_file_t *pdf);
+extern char		*_pdfioStringAllocBuffer(pdfio_file_t *pdf, _pdfio_strbuf_t **bptr);
 extern void		_pdfioStringFreeBuffer(pdfio_file_t *pdf, char *buffer);
 extern bool		_pdfioStringIsAllocated(pdfio_file_t *pdf, const char *s) _PDFIO_INTERNAL;
+extern bool		_pdfioStringPrintf(_pdfio_strbuf_t *bptr, const char *format, ...) _PDFIO_INTERNAL;
 
 extern void		_pdfioTokenClear(_pdfio_token_t *tb) _PDFIO_INTERNAL;
 extern void		_pdfioTokenFlush(_pdfio_token_t *tb) _PDFIO_INTERNAL;

pdfio-string.c

@@ -674,7 +674,8 @@ _pdfio_vsnprintf(pdfio_file_t *pdf,	// I - PDF file
 
 char *					// O - Buffer or `NULL` on error
 _pdfioStringAllocBuffer(
-    pdfio_file_t *pdf)			// I - PDF file
+    pdfio_file_t    *pdf,		// I - PDF file
+    _pdfio_strbuf_t **bptr)		// O - String buffer pointer
 {
   _pdfio_strbuf_t	*current;	// Current string buffer
 
@@ -683,21 +684,34 @@ _pdfioStringAllocBuffer(
   for (current = pdf->strbuffers; current; current = current->next)
   {
     if (!current->bufused)
-    {
-      current->bufused = true;
-      return (current->buffer);
-    }
+      goto done;
   }
 
   // Didn't find one, allocate a new one...
   if ((current = calloc(1, sizeof(_pdfio_strbuf_t))) == NULL)
+  {
+    if (bptr)
+      *bptr = NULL;
+
     return (NULL);
+  }
 
   // Add to the linked list of string buffers...
-  current->next    = pdf->strbuffers;
+  current->pdf    = pdf;
+  current->next   = pdf->strbuffers;
+  pdf->strbuffers = current;
+
+  // Claim and return the free string buffer...
+  done:
+
   current->bufused = true;
 
-  pdf->strbuffers = current;
+  if (bptr)
+  {
+    *bptr              = current;
+    current->buffer[0] = '\0';
+    current->bufptr    = current->buffer;
+  }
 
   return (current->buffer);
 }
@@ -857,6 +871,36 @@ _pdfioStringIsAllocated(
 }
 
 
+//
+// '_pdfioStringPrintf()' - Append a formatted string to a string buffer.
+//
+
+bool					// O - `true` on success, `false` on failure
+_pdfioStringPrintf(
+    _pdfio_strbuf_t *bptr,		// I - String buffer
+    const char      *format,		// I - Format string
+    ...)				// I - Additional arguments as needed
+{
+  va_list	ap;			// Pointer to additional arguments
+  size_t	remaining;		// Remaining bytes
+  ssize_t	bytes;			// Formatted bytes
+
+
+  // Format the string in the buffer...
+  va_start(ap, format);
+
+  remaining = sizeof(bptr->buffer) - (size_t)(bptr->bufptr - bptr->buffer);
+  bytes     = _pdfio_vsnprintf(bptr->pdf, bptr->bufptr, remaining, format, ap);
+
+  va_end(ap);
+
+  // Advance the current position in the buffer and return.
+  bptr->bufptr += strlen(bptr->bufptr);
+
+  return (bytes < (ssize_t)remaining && bytes >= 0);
+}
+
+
 //
 // 'find_string()' - Find an element in the array.
 //

pdfio-value.c

@@ -160,7 +160,7 @@ _pdfioValueDecrypt(pdfio_file_t   *pdf,	// I - PDF file
 	  _pdfioFileError(pdf, "Unable to read encrypted binary string - too long.");
 	  return (false);
 	}
-	else if ((temp = (uint8_t *)_pdfioStringAllocBuffer(pdf)) == NULL)
+	else if ((temp = (uint8_t *)_pdfioStringAllocBuffer(pdf, /*bptr*/NULL)) == NULL)
 	{
 	  _pdfioFileError(pdf, "Unable to read encrypted binary string - out of memory.");
 	  return (false);
@@ -191,7 +191,7 @@ _pdfioValueDecrypt(pdfio_file_t   *pdf,	// I - PDF file
 	  _pdfioFileError(pdf, "Unable to read encrypted string - too long.");
 	  return (false);
 	}
-	else if ((temp = (uint8_t *)_pdfioStringAllocBuffer(pdf)) == NULL)
+	else if ((temp = (uint8_t *)_pdfioStringAllocBuffer(pdf, /*bptr*/NULL)) == NULL)
 	{
 	  _pdfioFileError(pdf, "Unable to read encrypted binary string - out of memory.");
 	  return (false);
@@ -341,7 +341,7 @@ _pdfioValueRead(pdfio_file_t   *pdf,	// I - PDF file
                 size_t         depth)	// I - Depth of value
 {
   _pdfio_value_t *ret = NULL;		// Return value
-  char		*token = _pdfioStringAllocBuffer(pdf);
+  char		*token = _pdfioStringAllocBuffer(pdf, /*bptr*/NULL);
 					// Token buffer
   time_t	timeval;		// Date/time value
 #ifdef DEBUG
@@ -638,7 +638,7 @@ _pdfioValueWrite(
 	      _pdfioFileError(obj->pdf, "Unable to write encrypted binary string - too long.");
 	      return (false);
             }
-            else if ((temp = (uint8_t *)_pdfioStringAllocBuffer(obj->pdf)) == NULL)
+            else if ((temp = (uint8_t *)_pdfioStringAllocBuffer(obj->pdf, /*bptr*/NULL)) == NULL)
             {
 	      _pdfioFileError(obj->pdf, "Unable to write encrypted binary string - out of memory.");
 	      return (false);
@@ -764,7 +764,7 @@ _pdfioValueWrite(
             _pdfioFileError(obj->pdf, "Unable to write encrypted string - too long.");
             return (false);
           }
-          else if ((temp = (uint8_t *)_pdfioStringAllocBuffer(obj->pdf)) == NULL)
+          else if ((temp = (uint8_t *)_pdfioStringAllocBuffer(obj->pdf, /*bptr*/NULL)) == NULL)
           {
             _pdfioFileError(obj->pdf, "Unable to write encrypted string - out of memory.");
             return (false);