Allow libtrace preload library to use for trace output a logfile specified by the environment variable FIREJAIL_TRACEFILE or as the RUN_TRACE_FILE if it exists ortherwise use the console as before.

1 files changed, 19 insertions, 8 deletions

diff --git a/src/libtrace/libtrace.c b/src/libtrace/libtrace.c
index 745dd2260..b3f040e8f 100644
--- a/src/libtrace/libtrace.c
+++ b/src/libtrace/libtrace.c
@@ -32,7 +32,7 @@
 #include <sys/stat.h>
 #include <syslog.h>
 #include <dirent.h>
-#include <limits.h>
+#include "../include/rundefs.h"
 
 #define tprintf(fp, args...) \
     do { \
@@ -46,6 +46,8 @@ typedef FILE *(*orig_fopen_t)(const char *pathname, const char *mode);
 static orig_fopen_t orig_fopen = NULL;
 typedef FILE *(*orig_fopen64_t)(const char *pathname, const char *mode);
 static orig_fopen64_t orig_fopen64 = NULL;
+typedef int (*orig_access_t)(const char *pathname, int mode);
+static orig_access_t orig_access = NULL;
 
 //
 // library constructor/destructor
@@ -65,14 +67,24 @@ void init(void) {
                 return;
 
         orig_fopen = (orig_fopen_t)dlsym(RTLD_NEXT, "fopen");
-
-        // tty
+        orig_access = (orig_access_t)dlsym(RTLD_NEXT, "access");
+
+        // allow environment variable to override defaults
+        char *logfile = getenv("FIREJAIL_TRACEFILE");
+        if (!logfile) {
+                // if exists, log to trace file
+                logfile = RUN_TRACE_FILE;
+                if (orig_access(logfile, F_OK))
 #ifdef PRINTF_DEVTTY
-        ftty = orig_fopen("/dev/tty", "w");
+                        // else log to associated tty
+                        logfile = "/dev/tty";
 #else
-        ftty = stderr;
+                        logfile = "/proc/self/fd/2";
 #endif
-        tprintf(ftty, "=== tracelib init() === \n");
+        }
+        
+        // logfile
+        ftty = orig_fopen(logfile, "a");
 
         // pid
         mypid = getpid();
@@ -92,6 +104,7 @@ void init(void) {
         if (ptr)
                 *ptr = '\0';
 
+        tprintf(ftty, "=== tracelib init() [%d:%s] === \n", mypid, myname);
         fclose(fp);
         free(fname);
 }
@@ -483,8 +496,6 @@ DIR *opendir(const char *pathname) {
 }
 
 // access
-typedef int (*orig_access_t)(const char *pathname, int mode);
-static orig_access_t orig_access = NULL;
 int access(const char *pathname, int mode) {
         if (!orig_access)
                 orig_access = (orig_access_t)dlsym(RTLD_NEXT, "access");