Command logging wrapper to help analyze what commands scripts call and how.

1 files changed, 76 insertions, 0 deletions

diff --git a/toys/example/logwrapper.c b/toys/example/logwrapper.c
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+++ b/toys/example/logwrapper.c
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+/* logwrapper.c - Record commands called out of $PATH to a log
+ *
+ * Copyright 2019 Rob Landley <rob@landley.net>
+ *
+ * I made it up. Must be built standalone to work. (Is its own multiplexer.)
+
+USE_LOGWRAPPER(NEWTOY(logwrapper, 0, TOYFLAG_NOHELP|TOYFLAG_USR|TOYFLAG_BIN))
+
+config LOGWRAPPER
+  bool "logwrapper"
+  default n
+  help
+    usage: logwrapper ...
+
+    Append command line to $WRAPLOG, then call second instance
+    of command in $PATH.
+*/
+
+#define FOR_logwrapper
+#include "toys.h"
+
+void logwrapper_main(void)
+{
+  char *log = getenv("WRAPLOG"), *omnom = basename(*toys.argv),
+       *s, *ss, *sss;
+  struct string_list *list;
+  int i, len;
+
+  // Log the command line
+  if (!log) error_exit("no $WRAPLOG");
+  len = strlen(omnom)+2;
+  for (i = 1; i<toys.optc; i++) len += 2*strlen(toys.argv[i])+3;
+  ss = stpcpy(s = xmalloc(len), omnom);
+
+  // Copy arguments surrounded by quotes with \ escapes for " \ or \n
+  for (i = 0; i<toys.optc; i++) {
+    *(ss++) = ' ';
+    *(ss++) = '"';
+    for (sss = toys.optargs[i]; *sss; sss++) {
+      if (-1 == (len = stridx("\n\\\"", *sss))) *(ss++) = *sss;
+      else {
+        *(ss++) = '\\';
+        *(ss++) = "n\\\""[len];
+      }
+    }
+    *(ss++) = '"';
+  }
+  *(ss++) = '\n';
+
+  // Atomically append to log and free buffer
+  i = xcreate(log, O_RDWR|O_CREAT|O_APPEND, 0644);
+  xwrite(i, s, ss-s);
+  close(i);
+  free(s);
+
+  // Run next instance in $PATH after this one. If we were called via absolute
+  // path search for this instance, otherwise assume we're first instance
+  list = find_in_path(getenv("PATH"), omnom);
+  if (**toys.argv == '/') {
+    if (!readlink0("/proc/self/exe", s = toybuf, sizeof(toybuf)))
+      perror_exit("/proc/self/exe");
+
+    while (list) {
+      if (!strcmp(list->str, s)) break;
+      free(llist_pop(&list));
+    }
+  }
+
+  // Skip first instance and try to run next one, until out of instances.
+  for (;;) {
+    if (list) free(llist_pop(&list));
+    if (!list) error_exit("no %s after logwrapper in $PATH", omnom);
+    *toys.argv = list->str;
+    execve(list->str, toys.argv, environ);
+  }
+}