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-rw-r--r--toys/example/logwrapper.c76
1 files changed, 76 insertions, 0 deletions
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);
+ }
+}