png conversion is no longer done in a separate process.

Signed-off-by: Mattias Andrée <maandree@member.fsf.org>

7 files changed, 323 insertions, 243 deletions

diff --git a/src/kern-linux.c b/src/kern-linux.c
index fdae636..00930f1 100644
--- a/src/kern-linux.c
+++ b/src/kern-linux.c
@@ -19,6 +19,7 @@
 #include "common.h"
 #include "kern.h"
 #include "pnm.h"
+#include "png.h"
 
 
 
@@ -128,8 +129,8 @@ measure (int fbno, char *restrict fbpath, long *restrict width, long *restrict h
  * @return              Zero on success, -1 on error.
  */
 int
-convert_fb (FILE *restrict file, const char *restrict buf,
-	    size_t n, size_t *restrict adjustment)
+convert_fb_to_pnm (FILE *restrict file, const char *restrict buf,
+		   size_t n, size_t *restrict adjustment)
 {
   const uint32_t *restrict pixel;
   int r, g, b;
@@ -144,7 +145,7 @@ convert_fb (FILE *restrict file, const char *restrict buf,
       g = (*pixel >> 8) & 255;
       b = (*pixel >> 0) & 255;
       
-      if (SAVE_PIXEL (file, r, g, b) < 0)
+      if (SAVE_PNM_PIXEL (file, r, g, b) < 0)
 	goto fail;
     }
   
@@ -154,3 +155,50 @@ convert_fb (FILE *restrict file, const char *restrict buf,
   return -1;
 }
 
+
+/**
+ * Convert read data from a framebuffer to PNG pixel data.
+ * 
+ * @param   file        The output image file.
+ * @param   buf         Buffer with read data.
+ * @param   n           The number of read characters.
+ * @param   width3      The width of the image multipled by 3.
+ * @param   adjustment  Set to zero if all bytes were converted
+ *                      (a whole number of pixels where available,)
+ *                      otherwise, set to the number of bytes a
+ *                      pixel is encoded.
+ * @param   state       Use this to keep track of where in the you
+ *                      stopped. It will be 0 on the first call.
+ * @return              Zero on success, -1 on error.
+ */
+int convert_fb_to_png (png_struct *pngbuf, png_byte *restrict pixbuf, const char *restrict buf,
+		       size_t n, long width3, size_t *restrict adjustment, long *restrict state)
+{
+  const uint32_t *restrict pixel;
+  int r, g, b;
+  size_t off;
+  long x3 = *state;
+  
+  for (off = 0; off < n; off += 4)
+    {
+      /* A pixel in the framebuffer is formatted as `%{blue}%{green}%{red}%{x}`
+	 in big-endian binary, or `%{x}%{red}%{green}%{blue}` in little-endian binary. */
+      pixel = (const uint32_t *)(buf + off);
+      r = (*pixel >> 16) & 255;
+      g = (*pixel >> 8) & 255;
+      b = (*pixel >> 0) & 255;
+      
+      SAVE_PNG_PIXEL (pixbuf, x3, r, g, b);
+      x3 += 3;
+      if (x3 == width3)
+	{
+	  SAVE_PNG_ROW (pngbuf, pixbuf);
+	  x3 = 0;
+	}
+    }
+  
+  *adjustment = (off != n ? 4 : 0);
+  *state = x3;
+  return 0;
+}
+
diff --git a/src/kern.h b/src/kern.h
index 45f692a..8c2adf0 100644
--- a/src/kern.h
+++ b/src/kern.h
@@ -16,6 +16,15 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#ifdef __GNUC__
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wpadded"
+#endif
+#include <png.h>
+#ifdef __GNUC__
+# pragma GCC diagnostic pop
+#endif
+
 
 
 /**
@@ -65,6 +74,24 @@ int measure (int fbno, char *restrict fbpath, long *restrict width, long *restri
  *                      pixel is encoded.
  * @return              Zero on success, -1 on error.
  */
-int convert_fb (FILE *restrict file, const char *restrict buf,
-		size_t n, size_t *restrict adjustment);
+int convert_fb_to_pnm (FILE *restrict file, const char *restrict buf,
+		       size_t n, size_t *restrict adjustment);
+
+/**
+ * Convert read data from a framebuffer to PNG pixel data.
+ * 
+ * @param   file        The output image file.
+ * @param   buf         Buffer with read data.
+ * @param   n           The number of read characters.
+ * @param   width3      The width of the image multipled by 3.
+ * @param   adjustment  Set to zero if all bytes were converted
+ *                      (a whole number of pixels where available,)
+ *                      otherwise, set to the number of bytes a
+ *                      pixel is encoded.
+ * @param   state       Use this to keep track of where in the you
+ *                      stopped. It will be 0 on the first call.
+ * @return              Zero on success, -1 on error.
+ */
+int convert_fb_to_png (png_struct *pngbuf, png_byte *restrict pixbuf, const char *restrict buf,
+		       size_t n, long width3, size_t *restrict adjustment, long *restrict state);
 
diff --git a/src/png.c b/src/png.c
index 0944f18..b0da466 100644
--- a/src/png.c
+++ b/src/png.c
@@ -18,11 +18,7 @@
  */
 #include "common.h"
 #include "png.h"
-
-#ifdef __GNUC__
-# pragma GCC diagnostic ignored "-Wpadded"
-#endif
-#include <png.h>
+#include "kern.h"
 
 
 /*
@@ -30,50 +26,37 @@
  * 
  *   Users want their files in PNG (most often), not PNM.
  *   Calling an external program for conversion poses
- *   potential security risks, and is slower.
+ *   potential security risks, and is significantly slower.
  */
 
 
 /**
- * Convert an image from PNM to PNG.
- * 
- * This is a very limited conversion implementation.
- * It is not generally reusable. It makes assumptions
- * that are true only necessarily for this program.
+ * Create an PNG file.
  * 
- * @param   fdin   The file descriptor for the image to convert (PNM).
- * @param   fdout  The file descriptor for the output image (PNG).
- * @return         Zero on success, -1 on error.
+ * @param   fbfd    The file descriptor connected to framebuffer device.
+ * @param   width   The width of the image.
+ * @param   height  The height of the image.
+ * @param   imgfd   The file descriptor connected to conversion process's stdin.
+ * @return          Zero on success, -1 on error.
  */
 int
-convert (int fdin, int fdout)
+save_png (int fbfd, long width, long height, int imgfd)
 {
-#define SCAN(...)  do { if (fscanf(in, __VA_ARGS__) != 1)  goto fail; } while (0)
-
-  FILE *in = NULL;
-  FILE *out = NULL;
-  long height, width, width3;
-  long y, x, r, g, b;
-  png_byte   *pixbuf = 0;
+  char buf[8 << 10];
+  FILE *file = NULL;
+  ssize_t got, off;
+  size_t adjustment;
+  png_byte   *restrict pixbuf = NULL;
   png_struct *pngbuf = NULL;
   png_info   *pnginfo = NULL;
-  int saved_errno = 0, rc, c;
+  long width3, state = 0;
+  int rc, saved_errno;
   
-  /* Get a FILE * for the input, we want to use fscanf, there is no dscanf. */
-  in = fdopen (fdin, "r");
-  if (in == NULL)
-    goto fail;
   /* Get a FILE * for the output, libpng wants a FILE *, not a file descriptor. */
-  out = fdopen (fdout, "w");
-  if (out == NULL)
+  file = fdopen (imgfd, "w");
+  if (file == NULL)
     goto fail;
   
-  /* Read head. */
-  do c = fgetc(in); while ((c != '\n') && (c != EOF));
-  SCAN ("%li ", &width);
-  SCAN ("%li\n", &height);
-  do c = fgetc(in); while ((c != '\n') && (c != EOF));
-  
   /* Allocte structures for the PNG. */
   width3 = width * 3;
   pixbuf = malloc ((size_t)width3 * sizeof (png_byte));
@@ -89,28 +72,45 @@ convert (int fdin, int fdout)
   /* Initialise PNG write, and write head. */
   if (setjmp (png_jmpbuf(pngbuf))) /* Failing libpng calls jump here. */
     goto fail;
-  png_init_io (pngbuf, out);
+  png_init_io (pngbuf, file);
   png_set_IHDR (pngbuf, pnginfo, (png_uint_32)width, (png_uint_32)height,
 		8 /* bit depth */, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE,
 		PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
   png_write_info (pngbuf, pnginfo);
   
-  /* Read and convert body. */
-  for (y = 0; y < height; y++)
+  /* TODO (maybe) The image shall be packed. That is, if 24 bits per pixel is
+   *              unnecessary, less shall be used. 6 bits is often sufficient. */
+  
+  /* Convert raw framebuffer data into a PNG image (body). */
+  for (off = 0;;)
     {
-      for (x = 0; x < width3; x += 3)
+      /* Read data from the framebuffer, we may have up to 3 bytes buffered. */
+      got = read (fbfd, buf + off, sizeof (buf) - (size_t)off * sizeof (char));
+      if (got < 0)
+	goto fail;
+      if (got == 0)
+	break;
+      got += off;
+      
+      /* Convert read pixels. */
+      if (convert_fb_to_png (pngbuf, pixbuf, buf, (size_t)got,
+			     width3, &adjustment, &state) < 0)
+	goto fail;
+      
+      /* If we read a whole number of pixels, reset the buffer, otherwise,
+         move the unconverted bytes to the beginning of the buffer. */
+      if (adjustment)
 	{
-	  SCAN ("%li\n", &r);
-	  SCAN ("%li\n", &g);
-	  SCAN ("%li\n", &b);
-	  pixbuf[x + 0] = (png_byte)r;
-	  pixbuf[x + 1] = (png_byte)g;
-	  pixbuf[x + 2] = (png_byte)b;
+	  off -= (ssize_t)adjustment;
+	  memcpy (buf, buf + off, (size_t)(got - off) * sizeof (char));
+	  off = got - off;
 	}
-      png_write_row (pngbuf, pixbuf);
+      else
+	off = 0;
     }
-  png_write_end (pngbuf, pnginfo);
   
+  /* Done! */
+  png_write_end (pngbuf, pnginfo);
   rc = 0;
   goto cleanup;
  fail:
@@ -120,11 +120,13 @@ convert (int fdin, int fdout)
   
  cleanup: 
   png_destroy_write_struct (&pngbuf, (pnginfo ? &pnginfo : NULL));
-  if (in != NULL)
-    fclose (in);
-  if (out != NULL)
-    fclose (out);
+  if (file != NULL)
+    {
+      fflush (file);
+      fclose (file);
+    }
   free (pixbuf);
-  return errno = saved_errno, rc;
+  errno = saved_errno;
+  return rc;
 }
 
diff --git a/src/png.h b/src/png.h
index 02a6223..b621234 100644
--- a/src/png.h
+++ b/src/png.h
@@ -16,14 +16,50 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#ifdef __GNUC__
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wpadded"
+#endif
+#include <png.h>
+#ifdef __GNUC__
+# pragma GCC diagnostic pop
+#endif
+
+
+
+/**
+ * Store a pixel to a PNG row buffer.
+ * 
+ * @param  PIXBUF:png_byte *  The pixel buffer for the row.
+ * @param  X3:long            The column of the pixel multipled by 3.
+ * @param  R:int              The [0, 255]-value on the red subpixel.
+ * @param  G:int              The [0, 255]-value on the green subpixel.
+ * @param  B:int              The [0, 255]-value on the blue subpixel.
+ */
+#define SAVE_PNG_PIXEL(PIXBUF, X3, R, G, B)	\
+  ((PIXBUF)[(X3) + 0] = (png_byte)(R),		\
+   (PIXBUF)[(X3) + 1] = (png_byte)(G),		\
+   (PIXBUF)[(X3) + 2] = (png_byte)(B))
+
+/**
+ * Store a row to a PNG image.
+ * 
+ * @param  PNGBUF:png_struct *  The PNG image structure.
+ * @param  PIXBUF:png_byte *    The pixel buffer for the row.
+ */
+#define SAVE_PNG_ROW(PNGBUF, PIXBUF)  \
+  png_write_row (PNGBUF, PIXBUF)
 
 
 /**
- * Convert an image from PNM to PNG.
+ * Create an PNG file.
  * 
- * @param   fdin   The file descriptor for the image to convert (PNM).
- * @param   fdout  The file descriptor for the output image (PNG).
- * @return         Zero on success, -1 on error.
+ * @param   fbfd    The file descriptor connected to framebuffer device.
+ * @param   width   The width of the image.
+ * @param   height  The height of the image.
+ * @param   imgfd   The file descriptor connected to conversion process's stdin.
+ * @return          Zero on success, -1 on error.
  */
-int convert (int fdin, int fdout);
+int
+save_png (int fbfd, long width, long height, int imgfd);
 
diff --git a/src/pnm.c b/src/pnm.c
new file mode 100644
index 0000000..da9dd3a
--- /dev/null
+++ b/src/pnm.c
@@ -0,0 +1,118 @@
+/**
+ * scrotty — Screenshot program for Linux's TTY
+ * 
+ * Copyright © 2014, 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "common.h"
+#include "pnm.h"
+#include "kern.h"
+
+
+
+#define LIST_0_9(P)  P"0\n", P"1\n", P"2\n", P"3\n", P"4\n", P"5\n", P"6\n", P"7\n", P"8\n", P"9\n"
+/**
+ * [0, 255]-integer-to-text convertion lookup table for faster conversion from
+ * raw framebuffer data to the PNM format. The values have a whitespace at the
+ * end for even faster conversion.
+ * Lines should not be longer than 70 (although most programs will probably
+ * work even if there are longer lines), therefore the selected whitespace
+ * is LF (new line).
+ * 
+ * ASCII has wider support than binary, and is create for version control,
+ * especifially with one datum per line.
+ */
+const char* inttable[] =
+  {
+    LIST_0_9(""),  LIST_0_9("1"), LIST_0_9("2"), LIST_0_9("3"), LIST_0_9("4"),
+    LIST_0_9("5"), LIST_0_9("6"), LIST_0_9("7"), LIST_0_9("8"), LIST_0_9("9"),
+    
+    LIST_0_9("10"), LIST_0_9("11"), LIST_0_9("12"), LIST_0_9("13"), LIST_0_9("14"),
+    LIST_0_9("15"), LIST_0_9("16"), LIST_0_9("17"), LIST_0_9("18"), LIST_0_9("19"),
+    
+    LIST_0_9("20"), LIST_0_9("21"), LIST_0_9("22"), LIST_0_9("23"), LIST_0_9("24"),
+    "250\n", "251\n", "252\n", "253\n", "254\n", "255\n"
+  };
+
+
+
+/**
+ * Create an PNM file.
+ * 
+ * @param   fbfd    The file descriptor connected to framebuffer device.
+ * @param   width   The width of the image.
+ * @param   height  The height of the image.
+ * @param   imgfd   The file descriptor connected to conversion process's stdin.
+ * @return          Zero on success, -1 on error.
+ */
+int
+save_pnm (int fbfd, long width, long height, int imgfd)
+{
+  char buf[8 << 10];
+  FILE *file = NULL;
+  ssize_t got, off;
+  size_t adjustment;
+  int saved_errno;
+  
+  /* Create a FILE *, for writing, for the image file. */
+  file = fdopen (imgfd, "w");
+  if (file == NULL)
+    goto fail;
+  
+  /* The PNM image should begin with `P3\n%{width} %{height}\n%{colour max=255}\n`.
+     ('\n' and ' ' can be exchanged at will.) */
+  if (fprintf (file, "P3\n%li %li\n255\n", width, height) < 0)
+    goto fail;
+  
+  /* Convert raw framebuffer data into a PNM image. */
+  for (off = 0;;)
+    {
+      /* Read data from the framebuffer, we may have up to 3 bytes buffered. */
+      got = read (fbfd, buf + off, sizeof (buf) - (size_t)off * sizeof (char));
+      if (got < 0)
+	goto fail;
+      if (got == 0)
+	break;
+      got += off;
+      
+      /* Convert read pixels. */
+      if (convert_fb_to_pnm (file, buf, (size_t)got, &adjustment) < 0)
+	goto fail;
+      
+      /* If we read a whole number of pixels, reset the buffer, otherwise,
+         move the unconverted bytes to the beginning of the buffer. */
+      if (adjustment)
+	{
+	  off -= (ssize_t)adjustment;
+	  memcpy (buf, buf + off, (size_t)(got - off) * sizeof (char));
+	  off = got - off;
+	}
+      else
+	off = 0;
+    }
+  
+  /* Close file and return successfully. */
+  fflush (file);
+  fclose (file);
+  return 0;
+  
+ fail:
+  saved_errno = errno;
+  if (file != NULL)
+    fclose (file);
+  errno = saved_errno;
+  return -1;
+}
+
diff --git a/src/pnm.h b/src/pnm.h
index 172e3cb..9721d4c 100644
--- a/src/pnm.h
+++ b/src/pnm.h
@@ -16,11 +16,10 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
-#include <stdio.h>
 
 
 /**
- * Store a pixel to an PNM image.
+ * Store a pixel to a PNM image.
  * 
  * A pixel in the PNM image is formatted as `%{red} %{green} %{blue} ` in text.
  * 
@@ -30,7 +29,7 @@
  * @param   B:int     The [0, 255]-value on the blue subpixel.
  * @return            Positive on success (not zero!), -1 on error.
  */
-#define SAVE_PIXEL(F, R, G, B)  \
+#define SAVE_PNM_PIXEL(F, R, G, B)  \
   fprintf (F, "%s%s%s", inttable[R], inttable[G], inttable[B])
 
 
@@ -47,3 +46,15 @@
  */
 extern const char* inttable[];
 
+
+/**
+ * Create an PNM file.
+ * 
+ * @param   fbfd    The file descriptor connected to framebuffer device.
+ * @param   width   The width of the image.
+ * @param   height  The height of the image.
+ * @param   imgfd   The file descriptor connected to conversion process's stdin.
+ * @return          Zero on success, -1 on error.
+ */
+int save_pnm (int fbfd, long width, long height, int imgfd);
+
diff --git a/src/scrotty.c b/src/scrotty.c
index c076fa4..4bc6982 100644
--- a/src/scrotty.c
+++ b/src/scrotty.c
@@ -42,31 +42,6 @@
 #define LIST_DISPLAY_VARS  X(DISPLAY) X(MDS_DISPLAY) X(MIR_DISPLAY) X(WAYLAND_DISPLAY) X(PREFERRED_DISPLAY)
 
 
-#define LIST_0_9(P)  P"0\n", P"1\n", P"2\n", P"3\n", P"4\n", P"5\n", P"6\n", P"7\n", P"8\n", P"9\n"
-/**
- * [0, 255]-integer-to-text convertion lookup table for faster conversion from
- * raw framebuffer data to the PNM format. The values have a whitespace at the
- * end for even faster conversion.
- * Lines should not be longer than 70 (although most programs will probably
- * work even if there are longer lines), therefore the selected whitespace
- * is LF (new line).
- * 
- * ASCII has wider support than binary, and is create for version control,
- * especifially with one datum per line.
- */
-const char* inttable[] =
-  {
-    LIST_0_9(""),  LIST_0_9("1"), LIST_0_9("2"), LIST_0_9("3"), LIST_0_9("4"),
-    LIST_0_9("5"), LIST_0_9("6"), LIST_0_9("7"), LIST_0_9("8"), LIST_0_9("9"),
-    
-    LIST_0_9("10"), LIST_0_9("11"), LIST_0_9("12"), LIST_0_9("13"), LIST_0_9("14"),
-    LIST_0_9("15"), LIST_0_9("16"), LIST_0_9("17"), LIST_0_9("18"), LIST_0_9("19"),
-    
-    LIST_0_9("20"), LIST_0_9("21"), LIST_0_9("22"), LIST_0_9("23"), LIST_0_9("24"),
-    "250\n", "251\n", "252\n", "253\n", "254\n", "255\n"
-  };
-
-
 
 /**
  * `argv[0]` from `main`.
@@ -89,85 +64,6 @@ static int try_alt_fbpath = 0;
 
 
 /**
- * Create an PNM-file that is sent to a conversion process,
- * or directly to a file.
- * 
- * @param   fbname  The framebuffer device.
- * @param   width   The width of the image.
- * @param   height  The height of the image.
- * @param   fd      The file descriptor connected to conversion process's stdin.
- * @return          Zero on success, -1 on error.
- */
-static int
-save_pnm (const char *fbpath, long width, long height, int fd)
-{
-  char buf[8 << 10];
-  FILE *file = NULL;
-  int fbfd = 1;
-  ssize_t got, off;
-  int saved_errno;
-  size_t adjustment;
-  
-  /* Open the framebuffer device for reading. */
-  fbfd = open (fbpath, O_RDONLY);
-  if (fbfd == -1)
-    goto fail;
-  
-  /* Create a FILE *, for writing, for the image file. */
-  file = fdopen (fd, "w");
-  if (file == NULL)
-    goto fail;
-  
-  /* The PNM image should begin with `P3\n%{width} %{height}\n%{colour max=255}\n`.
-     ('\n' and ' ' can be exchanged at will.) */
-  if (fprintf (file, "P3\n%li %li\n255\n", width, height) < 0)
-    goto fail;
-  
-  /* Convert raw framebuffer data into an PNM image. */
-  for (off = 0;;)
-    {
-      /* Read data from the framebuffer, we may have up to 3 bytes buffered. */
-      got = read (fbfd, buf + off, sizeof (buf) - (size_t)off * sizeof (char));
-      if (got < 0)
-	goto fail;
-      if (got == 0)
-	break;
-      got += off;
-      
-      /* Convert read pixels. */
-      if (convert_fb (file, buf, (size_t)got, &adjustment) < 0)
-	goto fail;
-      
-      /* If we read a whole number of pixels, reset the buffer, otherwise,
-         move the unconverted bytes to the beginning of the buffer. */
-      if (adjustment)
-	{
-	  off -= (ssize_t)adjustment;
-	  memcpy (buf, buf + off, (size_t)(got - off) * sizeof (char));
-	  off = got - off;
-	}
-      else
-	off = 0;
-    }
-  
-  /* Close files and return successfully. */
-  fflush (file);
-  fclose (file);
-  close (fbfd);
-  return 0;
-  
- fail:
-  saved_errno = errno;
-  if (file != NULL)
-    fclose (file);
-  if (fbfd >= 0)
-    close (fbfd);
-  errno = saved_errno;
-  return -1;
-}
-
-
-/**
  * Create an image of a framebuffer.
  * 
  * @param   fbname    The framebuffer device.
@@ -180,92 +76,34 @@ save_pnm (const char *fbpath, long width, long height, int fd)
 static int
 save (const char *fbpath, const char *imgpath, long width, long height, int raw)
 {
-  int pipe_rw[2] = { -1, -1 };
-  pid_t pid;
-  int status;
-  int fd = -1;
+  int imgfd = -1, fbfd;
   int saved_errno;
   
-  if (raw)
-    goto no_convert;
-  
-  
-  /* Create a pipe that for sending data into the conversion process program. */
-  if (pipe (pipe_rw) < 0)
-    goto fail;
-  
-  /* Fork the process, the child will become the conversion process. */
-  pid = fork ();
-  if (pid == -1)
-    goto fail;
-  
-  
-  /* Child process: */
-  if (pid == 0)
-    {
-      /* Close the write-end of the pipe. */
-      close (pipe_rw[1]);
-      
-      /* Open file descriptor for the output image. */
-      fd = open (imgpath, O_WRONLY | O_CREAT | O_TRUNC,
-		 S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
-      if (fd == -1)
-	goto child_fail;
-      
-      /* Convert the PNM-image we create to a compressed image, namely in PNG. */
-      if (convert (pipe_rw[0], fd) < 0)
-	goto child_fail;
-      
-      _exit(0);
-    child_fail:
-      perror(execname);
-      _exit(1);
-    }
-  
-  
-  /* Parent process: */
-  
-  /* Close the read-end of the pipe. */
-  close (pipe_rw[0]), pipe_rw[0] = -1;
-  
-  /* Create a PNM-image of the framebuffer. */
-  if (save_pnm (fbpath, width, height, pipe_rw[1]) < 0)
-    goto fail;
-  
-  /* Close the write-end of the pipe. */
-  close (pipe_rw[1]), pipe_rw[1] = -1;
-  
-  /* Wait for conversion process to exit. */
-  if (waitpid (pid, &status, 0) < 0)
-    goto fail;
-  
-  /* Return successfully if and only if conversion did. */
-  return status == 0 ? 0 : -1;
-  
-  
-  /* Conversion shall not take place: */
-  
- no_convert:
   /* Open output file. */
-  if (fd = open (imgpath, O_WRONLY | O_CREAT | O_TRUNC,
-		 S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH), fd == -1)
+  imgfd = open (imgpath, O_WRONLY | O_CREAT | O_TRUNC,
+		S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+  if (imgfd == -1)
     FILE_FAILURE (imgpath);
   
+  /* Open the framebuffer device for reading. */
+  fbfd = open (fbpath, O_RDONLY);
+  if (fbfd == -1)
+    FILE_FAILURE (fbpath);
+  
   /* Save image. */
-  if (save_pnm (fbpath, width, height, fd) < 0)
+  if ((raw ? save_pnm : save_png) (fbfd, width, height, imgfd) < 0)
     goto fail;
   
-  close (fd);
+  close (fbfd);
+  close (imgfd);
   return 0;
   
  fail:
   saved_errno = errno;
-  if (pipe_rw[0] >= 0)
-    close (pipe_rw[0]);
-  if (pipe_rw[1] >= 0)
-    close (pipe_rw[1]);
-  if (fd >= 0)
-    close (fd);
+  if (fbfd >= 0)
+    close (fbfd);
+  if (imgfd >= 0)
+    close (imgfd);
   errno = saved_errno;
   return -1;
 }