Patch from Jason Schoon to add optional SIGUSR1 support to dd.

diff --git a/coreutils/Config.in b/coreutils/Config.in
index 4eb3db0..6841ec9 100644 (file)
--- a/coreutils/Config.in
+++ b/coreutils/Config.in
@@ -115,6 +115,18 @@ config CONFIG_DD
          by default) using specific input and output blocksizes,
          while optionally performing conversions on it.
 
+config CONFIG_FEATURE_DD_SIGNAL_HANDLING
+       bool "Enable DD signal handling for status reporting"
+       default y
+       depends on CONFIG_DD
+       help
+         sending a SIGUSR1 signal to a running `dd' process makes it 
+         print to standard error the number of records read and written 
+         so far, then to resume copying.
+
+         $ dd if=/dev/zero of=/dev/null& pid=$! $ kill -USR1 $pid; sleep 1; kill $pid 
+         10899206+0 records in 10899206+0 records out
+
 config CONFIG_DF
        bool "df"
        default n

diff --git a/coreutils/dd.c b/coreutils/dd.c
index ce8bcc6..378e212 100644 (file)
--- a/coreutils/dd.c
+++ b/coreutils/dd.c
@@ -15,9 +15,9 @@
 #include <unistd.h>
 #include <string.h>
 #include <fcntl.h>
+#include <signal.h>  // For FEATURE_DD_SIGNAL_HANDLING
 #include "busybox.h"
 
-
 static const struct suffix_mult dd_suffixes[] = {
        { "c", 1 },
        { "w", 2 },
@@ -31,12 +31,20 @@ static const struct suffix_mult dd_suffixes[] = {
        { NULL, 0 }
 };
 
+static size_t out_full;
+static size_t out_part;
+static size_t in_full;
+static size_t in_part;
+
+static void dd_output_status(int cur_signal)
+{
+       fprintf(stderr, "%ld+%ld records in\n%ld+%ld records out\n",
+                       (long)in_full, (long)in_part,
+                       (long)out_full, (long)out_part);
+}
+
 int dd_main(int argc, char **argv)
 {
-       size_t out_full = 0;
-       size_t out_part = 0;
-       size_t in_full = 0;
-       size_t in_part = 0;
        size_t count = -1;
        size_t bs = 512;
        ssize_t n;
@@ -53,6 +61,17 @@ int dd_main(int argc, char **argv)
        const char *outfile = NULL;
        char *buf;
 
+       if (ENABLE_FEATURE_DD_SIGNAL_HANDLING)
+       {
+               struct sigaction sa;
+
+               memset(&sa, 0, sizeof(sa));
+               sa.sa_handler = dd_output_status; 
+               sa.sa_flags = SA_RESTART;
+               sigemptyset(&sa.sa_mask);
+               sigaction(SIGUSR1, &sa, 0); 
+       }
+
        for (i = 1; i < argc; i++) {
                if (strncmp("bs=", argv[i], 3) == 0)
                        bs = bb_xparse_number(argv[i]+3, dd_suffixes);
@@ -180,9 +199,7 @@ int dd_main(int argc, char **argv)
                bb_perror_msg_and_die("%s", outfile);
        }
 
-       fprintf(stderr, "%ld+%ld records in\n%ld+%ld records out\n",
-                       (long)in_full, (long)in_part,
-                       (long)out_full, (long)out_part);
+       dd_output_status(0);
 
        return EXIT_SUCCESS;
 }