digitalmars.D.learn - std.conv.to!string refuses to convert a char* to string.
- Venkat (45/45) Dec 08 2017 I am trying out the DJni library
- Neia Neutuladh (5/12) Dec 08 2017 I've got no idea, but can you verify that you can print it with
- Venkat (2/2) Dec 08 2017 Thanks for the quick response. std.string.fromStringz did the
- Mike Parker (9/11) Dec 09 2017 Be careful with fromStringz. It doesn't allocate a new string, so
- Venkat (4/4) Dec 09 2017 Thank you, core.runtime.Runtime.initialize() fixed the issue. I
I am trying out the DJni library (https://github.com/Monnoroch/DJni). For some reason std.conv.to!string doesn't want to convert a char* to a string.The lines below are taken from the log. I see that the last frame is at gc_qalloc. I am not sure why it failed there. Can anybody elaborate on what is going on here ? Thanks in advance. 91 92 93 Stack: [0x00007f749dfd9000,0x00007f749e0da000], sp=0x00007f749e0d8600, free space=1021k 94 Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code) 95 C [libPrompt.so+0x6b0cc] gc_qalloc+0x2c 96 C [libPrompt.so+0x7bf18] _D2rt8lifetime12__arrayAllocFNaNbmxC8TypeInfoxQlZS4core6memory8BlkInfo_+0xec 97 C [libPrompt.so+0x6c2fa] _d_newarrayU+0x86 98 C [libPrompt.so+0x593a7] _D6object__T4_dupTxaTaZQlFNaNbAxaZAa+0x1f 99 C [libPrompt.so+0x59384] _D6object__T11_trustedDupTxaTaZQtFNaNbNeAxaZAa+0x20 100 C [libPrompt.so+0x59360] _D6object__T3dupTaZQhFNaNbNdNfAxaZAa+0x20 101 C [libPrompt.so+0x5932a] _D3std4conv__T6toImplTAyaTPxaZQqFQhZ9__lambda2MFNaNbZQBf+0x3e 102 C [libPrompt.so+0x592ea] _D3std4conv__T6toImplTAyaTPxaZQqFNaNbQlZQs+0x16 103 C [libPrompt.so+0x592d1] _D3std4conv__T2toTAyaZ__TQlTPxaZQsFNaNbQlZQy+0x9 104 C [libPrompt.so+0x59289] Java_Prompt_getLine+0x61 105 j Prompt.getLine(Ljava/lang/String;)Ljava/lang/String;+0 106 j Prompt.main([Ljava/lang/String;)V+11 107 v ~StubRoutines::call_stub 108 V [libjvm.so+0x690c66] JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*)+0x1056 109 V [libjvm.so+0x6d2072] jni_invoke_static(JNIEnv_*, JavaValue*, _jobject*, JNICallType, _jmethodID*, JNI_ArgumentPusher*, Thread*)+0x362 110 V [libjvm.so+0x6ee8da] jni_CallStaticVoidMethod+0x17a 111 C [libjli.so+0x7bdf] JavaMain+0x81f 112 C [libpthread.so.0+0x8184] start_thread+0xc4 113 114 Java frames: (J=compiled Java code, j=interpreted, Vv=VM code) 115 j Prompt.getLine(Ljava/lang/String;)Ljava/lang/String;+0 116 j Prompt.main([Ljava/lang/String;)V+11
Dec 08 2017
On Saturday, 9 December 2017 at 05:55:21 UTC, Venkat wrote:I am trying out the DJni library (https://github.com/Monnoroch/DJni). For some reason std.conv.to!string doesn't want to convert a char* to a string.The lines below are taken from the log. I see that the last frame is at gc_qalloc. I am not sure why it failed there. Can anybody elaborate on what is going on here ? Thanks in advance.I've got no idea, but can you verify that you can print it with printf? Can you allocate other GC memory? Can you try using fromStringz instead of to!string and see what that does? Just shots in the dark...
Dec 08 2017
Thanks for the quick response. std.string.fromStringz did the trick. I am not sure what was the deal with to!string.
Dec 08 2017
On Saturday, 9 December 2017 at 06:14:36 UTC, Venkat wrote:Thanks for the quick response. std.string.fromStringz did the trick. I am not sure what was the deal with to!string.Be careful with fromStringz. It doesn't allocate a new string, so the returned string can easily become corrupted if the C string it's referencing falls off the stack. As for your problem with to!string, it isn't actually to!string that's the issue. It appears to have something to do with the memory allocated from the GC. I assume this is a shared library. Random thoughts -- Have you initialized DRuntime? Have you registered the calling thread with the GC?
Dec 09 2017
Thank you, core.runtime.Runtime.initialize() fixed the issue. I am now able to use to!string as well. I found your posts and Ali Çehreli's posts on this subject. I think I have some understanding now.
Dec 09 2017