[hackers] [farbfeld] Refactor jpg2ff || FRIGN

[git]

commit ff5bbfae5214d8291c8eb93670233909ded5b722
Author:     FRIGN <d...@frign.de>
AuthorDate: Wed Jan 6 12:30:17 2016 +0100
Commit:     FRIGN <d...@frign.de>
CommitDate: Wed Jan 6 12:32:48 2016 +0100

    Refactor jpg2ff
    
    Remove some kitchen sink comments (the jpg boilerplate is already
    horrible enough) and flush the output buffer manually to detect write
    errors.
    Also improve error reporting.

diff --git a/jpg2ff.c b/jpg2ff.c
index 52b4928..acf66b3 100644
--- a/jpg2ff.c
+++ b/jpg2ff.c
@@ -1,34 +1,22 @@
 /* See LICENSE file for copyright and license details. */
 #include <arpa/inet.h>
+
 #include <errno.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-
 #include <setjmp.h>
-#include <jpeglib.h>
 
-char *argv0;
-
-static jmp_buf setjmp_buffer;
+#include <jpeglib.h>
 
-static void
-usage(void)
-{
-       fprintf(stderr, "usage: %s\n", argv0);
-       exit(1);
-}
+static jmp_buf error_jump;
 
 METHODDEF(void)
-if_jpeg_error(j_common_ptr cinfo)
+jpeg_error(j_common_ptr cinfo)
 {
-       /* Always display the message. */
-       /* We could postpone this until after returning, if we chose. */
-       (*cinfo->err->output_message) (cinfo);
-
-       /* Return control to the setjmp point */
-       longjmp(setjmp_buffer, 1);
+       (*cinfo->err->output_message)(cinfo);
+       longjmp(error_jump, 1);
 }
 
 int
@@ -42,18 +30,16 @@ main(int argc, char *argv[])
        int ret = 1;
        JSAMPARRAY buffer; /* output row buffer */
 
-       argv0 = argv[0];
-       if (argc > 1)
-               usage();
+       if (argc > 1) {
+               fprintf(stderr, "usage: %s\n", argv[0]);
+               return 1;
+       }
 
-       /* load jpeg */
+       /* load jpg */
        cinfo.err = jpeg_std_error(&jerr);
 
-       jerr.error_exit = if_jpeg_error;
-       /* Establish the setjmp return context for my_error_exit to use. */
-       if (setjmp(setjmp_buffer)) {
-               /* If we get here, the JPEG code has signaled an error.
-               * We need to clean up the JPEG object, close the input file, 
and return. */
+       jerr.error_exit = jpeg_error;
+       if (setjmp(error_jump)) {
                goto cleanup;
        }
 
@@ -64,23 +50,23 @@ main(int argc, char *argv[])
        width = cinfo.image_width;
        height = cinfo.image_height;
 
-       /* change output for farbfeld */
-       cinfo.output_components = 3;     /* # of color components per pixel */
-       cinfo.out_color_space = JCS_RGB; /* colorspace of input image */
+       /* set output format */
+       cinfo.output_components = 3;     /* color components per pixel */
+       cinfo.out_color_space = JCS_RGB; /* input color space */
 
        jpeg_start_decompress(&cinfo);
        jpeg_row_len = width * cinfo.output_components;
 
-       /* Make a one-row-high sample array that will go away when done with 
image */
-       buffer = (*cinfo.mem->alloc_sarray)
-                ((j_common_ptr) &cinfo, JPOOL_IMAGE, jpeg_row_len, 1);
-       ff_row_len = strlen("RRGGBBAA") * width;
+       /* create output buffers */
+       buffer = (*cinfo.mem->alloc_sarray)((j_common_ptr)&cinfo,
+                                           JPOOL_IMAGE, jpeg_row_len, 1);
+       ff_row_len = strlen("RGBA") * sizeof(uint16_t) * width;
        if(!(ff_row = malloc(ff_row_len))) {
-               fprintf(stderr, "Can't malloc\n");
+               fprintf(stderr, "%s: malloc: out of memory\n", argv[0]);
                return 1;
        }
 
-       /* write header with big endian width and height-values */
+       /* write header */
        fprintf(stdout, "farbfeld");
        val_be = htonl(width);
        fwrite(&val_be, sizeof(uint32_t), 1, stdout);
@@ -91,7 +77,7 @@ main(int argc, char *argv[])
                /* jpeg_read_scanlines expects an array of pointers to 
scanlines.
                 * Here the array is only one element long, but you could ask 
for
                 * more than one scanline at a time if that's more convenient. 
*/
-               (void)jpeg_read_scanlines(&cinfo, buffer, 1);
+               jpeg_read_scanlines(&cinfo, buffer, 1);
 
                for(i = 0, dx = 0, sx = 0; i < width; i++, sx += 3, dx += 4) {
                        ff_row[dx]   = htons(buffer[0][sx]   * 257);
@@ -102,13 +88,25 @@ main(int argc, char *argv[])
 
                /* write data */
                if (fwrite(ff_row, 1, ff_row_len, stdout) != ff_row_len) {
-                       fprintf(stderr, "fwrite() failed\n");
+                       fprintf(stderr, "%s: fwrite: ");
+                       perror(NULL);
                        goto cleanup;
                }
        }
        jpeg_finish_decompress(&cinfo);
        ret = 0;
 
+       /* flush output */
+        if (fflush(stdout)) {
+                fprintf(stderr, "%s: fflush stdout: ", argv[0]);
+                perror(NULL);
+                ret = 1;
+        }
+        if (fclose(stdout) && !ret) {
+                fprintf(stderr, "%s: fclose stdout: ", argv[0]);
+                perror(NULL);
+                ret = 1;
+        }
 cleanup:
        free(ff_row);
        jpeg_destroy_decompress(&cinfo);