system/dd: emit status messages to stderr (not stdout)

Previously `dd` clobbered its output by writing status messages (e.g.
transfer statistics) to stdout.

Now all status messages are written to stderr.

Signed-off-by: Lars Kruse <devel@sumpfralle.de>

Author: sumpfralle

system/dd/dd_main.c

@@ -110,7 +110,8 @@ static int dd_write(FAR struct dd_s *dd)
       nbytes = write(dd->outfd, buffer, dd->nbytes - written);
       if (nbytes < 0)
         {
-          printf("%s: failed to write: %s\n", g_dd, strerror(errno));
+          fprintf(stderr, "%s: failed to write: %s\n", g_dd,
+              strerror(errno));
           return ERROR;
         }
 
@@ -142,7 +143,7 @@ static int dd_read(FAR struct dd_s *dd)
               continue;
             }
 
-          printf("%s: failed to read: %s\n", g_dd, strerror(errno));
+          fprintf(stderr, "%s: failed to read: %s\n", g_dd, strerror(errno));
           return ERROR;
         }
 
@@ -174,7 +175,8 @@ static inline int dd_infopen(FAR const char *name, FAR struct dd_s *dd)
   dd->infd = open(name, O_RDONLY);
   if (dd->infd < 0)
     {
-      printf("%s: failed to open '%s': %s\n", g_dd, name, strerror(errno));
+      fprintf(stderr, "%s: failed to open '%s': %s\n", g_dd, name,
+          strerror(errno));
       return ERROR;
     }
 
@@ -196,7 +198,8 @@ static inline int dd_outfopen(FAR const char *name, FAR struct dd_s *dd)
   dd->outfd = open(name, dd->oflags, 0644);
   if (dd->outfd < 0)
     {
-      printf("%s: failed to open '%s': %s\n", g_dd, name, strerror(errno));
+      fprintf(stderr, "%s: failed to open '%s': %s\n", g_dd, name,
+          strerror(errno));
       return ERROR;
     }
 
@@ -212,15 +215,17 @@ static int dd_verify(FAR struct dd_s *dd)
   ret = lseek(dd->infd, dd->skip ? dd->skip * dd->sectsize : 0, SEEK_SET);
   if (ret < 0)
     {
-      printf("%s: failed to infd lseek: %s\n", g_dd, strerror(errno));
+      fprintf(stderr, "%s: failed to infd lseek: %s\n", g_dd,
+          strerror(errno));
       return ret;
     }
 
   dd->eof = 0;
   ret = lseek(dd->outfd, 0, SEEK_SET);
   if (ret < 0)
     {
-      printf("%s: failed to outfd lseek: %s\n", g_dd, strerror(errno));
+      fprintf(stderr, "%s: failed to outfd lseek: %s\n", g_dd,
+          strerror(errno));
       return ret;
     }
 
@@ -241,7 +246,7 @@ static int dd_verify(FAR struct dd_s *dd)
       ret = read(dd->outfd, buffer, dd->nbytes);
       if (ret != dd->nbytes)
         {
-          printf("%s: failed to outfd read: %d\n",
+          fprintf(stderr, "%s: failed to outfd read: %d\n",
                  g_dd, ret < 0 ? errno : ret);
           break;
         }
@@ -255,7 +260,8 @@ static int dd_verify(FAR struct dd_s *dd)
           snprintf(msg, sizeof(msg), "\noutfile sector %d", sector);
           lib_dumpbuffer(msg, buffer, dd->nbytes);
 #else
-          printf("%s: sector %d differs unexpectedly\n", g_dd, sector);
+          fprintf(stderr, "%s: sector %d differs unexpectedly\n", g_dd,
+              sector);
 #endif
           ret = ERROR;
           break;
@@ -266,7 +272,7 @@ static int dd_verify(FAR struct dd_s *dd)
 
   if (ret < 0)
     {
-      printf("%s: failed to dd verify: %d\n", g_dd, ret);
+      fprintf(stderr, "%s: failed to dd verify: %d\n", g_dd, ret);
     }
 
   free(buffer);
@@ -277,10 +283,10 @@ static int dd_verify(FAR struct dd_s *dd)
  * Name: print_usage
  ****************************************************************************/
 
-static void print_usage(void)
+static void print_usage(FAR FILE *stream)
 {
-  printf("usage:\n");
-  printf("  %s [if=<infile>] [of=<outfile>] [bs=<sectsize>] "
+  fprintf(stream, "usage:\n");
+  fprintf(stream, "  %s [if=<infile>] [of=<outfile>] [bs=<sectsize>] "
          "[count=<sectors>] [skip=<sectors>] [seek=<sectors>] [verify] "
          "[conv=<nocreat,notrunc>]\n", g_dd);
 }
@@ -360,7 +366,7 @@ int main(int argc, FAR char **argv)
                 }
               else
                 {
-                  printf("%s: unknown conversion '%.*s'\n", g_dd,
+                  fprintf(stderr, "%s: unknown conversion '%.*s'\n", g_dd,
                          (int)len, cur);
                   goto errout_with_paths;
                 }
@@ -375,7 +381,7 @@ int main(int argc, FAR char **argv)
         }
       else
         {
-          print_usage();
+          print_usage(stderr);
           goto errout_with_paths;
         }
     }
@@ -384,8 +390,9 @@ int main(int argc, FAR char **argv)
 
   if ((dd.oflags & O_RDONLY) && (infile == NULL || outfile == NULL))
     {
-      printf("%s: invalid parameters: %s\n", g_dd, strerror(EINVAL));
-      print_usage();
+      fprintf(stderr, "%s: invalid parameters: %s\n", g_dd,
+          strerror(EINVAL));
+      print_usage(stderr);
       goto errout_with_paths;
     }
 
@@ -394,7 +401,7 @@ int main(int argc, FAR char **argv)
   dd.buffer = malloc(dd.sectsize);
   if (!dd.buffer)
     {
-      printf("%s: failed to malloc: %s\n", g_dd, strerror(errno));
+      fprintf(stderr, "%s: failed to malloc: %s\n", g_dd, strerror(errno));
       goto errout_with_paths;
     }
 
@@ -419,7 +426,8 @@ int main(int argc, FAR char **argv)
       ret = lseek(dd.infd, dd.skip * dd.sectsize, SEEK_SET);
       if (ret < 0)
         {
-          printf("%s: failed to lseek: %s\n", g_dd, strerror(errno));
+          fprintf(stderr, "%s: failed to lseek: %s\n", g_dd,
+              strerror(errno));
           ret = ERROR;
           goto errout_with_outf;
         }
@@ -430,7 +438,7 @@ int main(int argc, FAR char **argv)
       ret = lseek(dd.outfd, dd.seek * dd.sectsize, SEEK_SET);
       if (ret < 0)
         {
-          printf("%s: failed to lseek on output: %s\n",
+          fprintf(stderr, "%s: failed to lseek on output: %s\n",
                  g_dd, strerror(errno));
           ret = ERROR;
           goto errout_with_outf;
@@ -483,9 +491,9 @@ int main(int argc, FAR char **argv)
   elapsed -= (((uint64_t)ts0.tv_sec * NSEC_PER_SEC) + ts0.tv_nsec);
   elapsed /= NSEC_PER_USEC; /* usec */
 
-  printf("%" PRIu64 " bytes (%" PRIu32 " blocks) copied, %u usec, ",
+  fprintf(stderr, "%" PRIu64 " bytes (%" PRIu32 " blocks) copied, %u usec, ",
          total, sector, (unsigned int)elapsed);
-  printf("%u KB/s\n" ,
+  fprintf(stderr, "%u KB/s\n" ,
          (unsigned int)(((double)total / 1024)
          / ((double)elapsed / USEC_PER_SEC)));
 #endif
@@ -501,7 +509,8 @@ int main(int argc, FAR char **argv)
       dd.outfd = close(dd.outfd);
       if (dd.outfd < 0)
         {
-          printf("%s failed to close outfd:%s\n", g_dd, strerror(errno));
+          fprintf(stderr, "%s failed to close outfd:%s\n", g_dd,
+              strerror(errno));
         }
     }
 
@@ -511,7 +520,8 @@ int main(int argc, FAR char **argv)
       dd.infd = close(dd.infd);
       if (dd.infd < 0)
         {
-          printf("%s failed to close infd:%s\n", g_dd, strerror(errno));
+          fprintf(stderr, "%s failed to close infd:%s\n", g_dd,
+              strerror(errno));
         }
     }