Manually load required symbols.

2 files changed, 24 insertions, 7 deletions

diff --git a/extra/systrace/build b/extra/systrace/build
index c023ffc8..d3578d15 100644
--- a/extra/systrace/build
+++ b/extra/systrace/build
@@ -1,3 +1,3 @@
-clang tracy_systrace.c -s -Os -ffunction-sections -fdata-sections -Wl,--gc-sections -fno-stack-protector -Wl,-z,norelro -Wl,--build-id=none -nostdlib -lc
+clang tracy_systrace.c -s -Os -ffunction-sections -fdata-sections -Wl,--gc-sections -fno-stack-protector -Wl,-z,norelro -Wl,--build-id=none -nostdlib -ldl
 strip --strip-all -R .note.gnu.gold-version -R .comment -R .note -R .note.gnu.build-id -R .note.ABI-tag -R .eh_frame -R .eh_frame_hdr -R .gnu.hash -R .gnu.version -R .got a.out
 sstrip -z a.out			(elfkickers)
diff --git a/extra/systrace/tracy_systrace.c b/extra/systrace/tracy_systrace.c
index 56b7df49..530f05f5 100644
--- a/extra/systrace/tracy_systrace.c
+++ b/extra/systrace/tracy_systrace.c
@@ -6,15 +6,32 @@
 #include <stdlib.h>
 #include <time.h>
 #include <unistd.h>
+#include <dlfcn.h>
 
 enum { BufSize = 64*1024 };
 
+typedef int (*open_t)( const char*, int, ... );
+typedef void (*exit_t)( int );
+typedef int (*poll_t)( struct pollfd*, nfds_t, int timeout );
+typedef int (*nanosleep_t)( const struct timespec*, struct timespec* );
+typedef ssize_t (*read_t)( int, void*, size_t );
+typedef ssize_t (*write_t)( int, const void*, size_t );
+
 void _start()
 {
+    void* libc = dlopen( "libc.so", RTLD_LAZY );
+
+    open_t sym_open = dlsym( libc, "open" );
+    exit_t sym_exit = dlsym( libc, "exit" );
+    poll_t sym_poll = dlsym( libc, "poll" );
+    nanosleep_t sym_nanosleep = dlsym( libc, "nanosleep" );
+    read_t sym_read = dlsym( libc, "read" );
+    write_t sym_write = dlsym( libc, "write" );
+
     char buf[BufSize];
 
-    int kernelFd = open( "/sys/kernel/debug/tracing/trace_pipe", O_RDONLY );
-    if( kernelFd < 0 ) exit( 0 );
+    int kernelFd = sym_open( "/sys/kernel/debug/tracing/trace_pipe", O_RDONLY );
+    if( kernelFd < 0 ) sym_exit( 0 );
 
     struct pollfd pfd;
     pfd.fd = kernelFd;
@@ -26,11 +43,11 @@ void _start()
 
     for(;;)
     {
-        while( poll( &pfd, 1, 0 ) <= 0 ) nanosleep( &sleepTime, NULL );
-        const int rd = read( kernelFd, buf, BufSize );
+        while( sym_poll( &pfd, 1, 0 ) <= 0 ) sym_nanosleep( &sleepTime, NULL );
+        const int rd = sym_read( kernelFd, buf, BufSize );
         if( rd <= 0 ) break;
-        write( STDOUT_FILENO, buf, rd );
+        sym_write( STDOUT_FILENO, buf, rd );
     }
 
-    exit( 0 );
+    sym_exit( 0 );
 }