watch: execute command thru shell, not fork/exec. Other fixes

git-svn-id: svn://busybox.net/trunk/busybox@16417 69ca8d6d-28ef-0310-b511-8ec308f3f277

2 files changed, 54 insertions, 32 deletions

diff --git a/coreutils/watch.c b/coreutils/watch.c
index b1a7d9086..e3e9e06bb 100644
--- a/coreutils/watch.c
+++ b/coreutils/watch.c
@@ -13,45 +13,66 @@
 
 #include "busybox.h"
 
+// procps 2.0.18:
+// watch [-d] [-n seconds]
+//   [--differences[=cumulative]] [--interval=seconds] command
+//
+// procps-3.2.3:
+// watch [-dt] [-n seconds]
+//   [--differences[=cumulative]] [--interval=seconds] [--no-title] command
+//
+// (procps 3.x and procps 2.x are forks, not newer/older versions of the same)
 
 int watch_main(int argc, char **argv)
 {
-        int width, len;
+        unsigned opt;
         unsigned period = 2;
-        char **watched_argv, *header;
+        unsigned cmdlen = 1; // 1 for terminal NUL
+        char *header = NULL;
+        char *cmd;
+        char *tmp;
+        char **p;
 
-        if (argc < 2) bb_show_usage();
+        opt_complementary = "-1"; // at least one param please
+        opt = getopt32(argc, argv, "+dtn:", &tmp);
+        //if (opt & 0x1) // -d (ignore)
+        //if (opt & 0x2) // -t
+        if (opt & 0x4) period = xatou(tmp);
+        argv += optind;
 
-        get_terminal_width_height(STDOUT_FILENO, &width, 0);
-        header = xzalloc(width--);
-
-        /* don't use getopt, because it permutes the arguments */
-        ++argv;
-        if ((argc > 3) && argv[0][0] == '-' && argv[0][1] == 'n') {
-                period = xatou(argv[1]);
-                argv += 2;
+        p = argv;
+        while (*p)
+                cmdlen += strlen(*p++) + 1;
+        tmp = cmd = xmalloc(cmdlen);
+        while (*argv) {
+                tmp += sprintf(tmp, " %s", *argv);
+                argv++;
         }
-        watched_argv = argv;
-
-        /* create header */
-        len = snprintf(header, width, "Every %ds:", period);
-        while (*argv && len<width)
-                snprintf(header+len, width-len, " %s", *(argv++));
+        cmd++; // skip initial space
 
         while (1) {
-                char *thyme;
-                time_t t;
-
-                time(&t);
-                thyme = ctime(&t);
-                len = strlen(thyme);
-                if (len < width)
-                        header[width-len] = 0;
-                bb_printf("\033[H\033[J%s %s\n", header, thyme);
+                printf("\033[H\033[J");
+                if (!(opt & 0x2)) { // no -t
+                        int width, len;
+                        char *thyme;
+                        time_t t;
 
-                waitpid(xspawn(watched_argv),0,0);
+                        get_terminal_width_height(STDOUT_FILENO, &width, 0);
+                        header = xrealloc(header, width--);
+                        // We pad with spaces entire length
+                        snprintf(header, width, "Every %ds: %-*s", period, width, cmd);
+                        time(&t);
+                        thyme = ctime(&t);
+                        len = strlen(thyme);
+                        if (len < width)
+                                strcpy(header + width - len, thyme);
+                        puts(header);
+                }
+                fflush(stdout);
+                // TODO: 'real' watch pipes cmd's output to itself
+                // and does not allow it to overflow the screen
+                // (taking into account linewrap!)
+                system(cmd);
                 sleep(period);
         }
-        if (ENABLE_FEATURE_CLEAN_UP)
-                free(header);
 }
diff --git a/include/usage.h b/include/usage.h
index f9597763e..9a6febf46 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -3296,11 +3296,12 @@ USE_FEATURE_START_STOP_DAEMON_FANCY( \
         "\t-a\tLock all VTs"
 
 #define watch_trivial_usage \
-        "[-n <seconds>] COMMAND..."
+        "[-n <seconds>] [-t] COMMAND..."
 #define watch_full_usage \
-        "Executes a program periodically.\n" \
+        "Executes a program periodically\n\n" \
         "Options:\n" \
-        "\t-n\tLoop period in seconds - default is 2"
+        "\t-n\tLoop period in seconds - default is 2\n"
+        "\t-t\tDon't print header"
 #define watch_example_usage \
         "$ watch date\n" \
         "Mon Dec 17 10:31:40 GMT 2000\n" \