From a242b5be0b486fb1137c45c87e2867aef2e1fcb3 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Wed, 30 Jan 2019 16:16:07 -0600
Subject: Command logging wrapper to help analyze what commands scripts call
 and how.

---
 scripts/record-commands   | 33 ++++++++++++++++++++
 toys/example/logwrapper.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 109 insertions(+)
 create mode 100755 scripts/record-commands
 create mode 100644 toys/example/logwrapper.c

diff --git a/scripts/record-commands b/scripts/record-commands
new file mode 100755
index 00000000..0201ac31
--- /dev/null
+++ b/scripts/record-commands
@@ -0,0 +1,33 @@
+#!/bin/bash
+
+# Set up command recording wrapper
+
+[ -z "$WRAPDIR" ] && WRAPDIR="$PWD"/record-commands
+[ -z "$WRAPLOG" ] && export WRAPLOG="$PWD"/log.txt && CLEANUP=1
+
+if [ $# -eq 0 ]
+then
+  echo "Usage: WRAPDIR=dir WRAPLOG=log.txt record-commands command..."
+  echo "Then examine log.txt"
+  exit 1
+fi
+
+if [ ! -x "$WRAPDIR/logwrapper" ]
+then
+  make logwrapper
+  mkdir -p "$WRAPDIR" && mv logwrapper "$WRAPDIR" || exit 1
+
+  echo "$PATH" | tr : '\n' | while read DIR
+  do
+    ls "$DIR/" | while read FILE
+    do
+      ln -s logwrapper "$WRAPDIR/$FILE" 2>/dev/null
+    done
+  done
+fi
+
+PATH="$WRAPDIR:$PATH" "$@"
+X=$?
+[ ! -z "$CLEANUP" ] && rm -rf "$WRAPDIR"
+
+exit $X
diff --git a/toys/example/logwrapper.c b/toys/example/logwrapper.c
new file mode 100644
index 00000000..0f87df24
--- /dev/null
+++ b/toys/example/logwrapper.c
@@ -0,0 +1,76 @@
+/* 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);
+  }
+}
-- 
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