During port of libbacktrace code from gcc compiler I found that I need to be able to read a.out or similar file in runtime. This library try to read original executable file and parse it for functions addresses/etc, as a part of garbage collection for golang (it parse call stack in some specific way using gcc-specific calls).
I have to port to genode the following code from src/lib/gcc/libbacktrace/fileline.c:
for (pass = 0; pass < 5; ++pass) { int does_not_exist;
switch (pass) { case 0: filename = state->filename; break; case 1: filename = getexecname (); break; case 2: filename = "/proc/self/exe"; break; case 3: filename = "/proc/curproc/file"; break; case 4: snprintf (buf, sizeof (buf), "/proc/%ld/object/a.out", (long) getpid ()); filename = buf; break; default: abort (); }
best idea is to implement library call getexecname(), e.g. as a part of libc.
Anyway, this is complex question, because we need to be able to open it and read a content later. How to configure this in run file?
PS for better understanding why I need this - call stack where it is called, from gdb:
#0 fileline_initialize (state=0x29000, error_callback=0x1198543 <error_callback>, data=0x405fe770) at /var/services/homes/admin/gen/21.02/contrib/libbacktrace-cabcd83bc903137f607eda3a65eb09feaa5f507e/src/lib/gcc/libbacktrace/fileline.c:102 #1 0x000000000119a9a5 in backtrace_pcinfo (state=0x29000, pc=0x1198610, callback=0x119808e <callback>, error_callback=0x1198543 <error_callback>, data=0x405fe770) at /var/services/homes/admin/gen/21.02/contrib/libbacktrace-cabcd83bc903137f607eda3a65eb09feaa5f507e/src/lib/gcc/libbacktrace/fileline.c:177 #2 0x000000000119accc in unwind (context=0x405fe420, vdata=0x405fe700) at /var/services/homes/admin/gen/21.02/contrib/libbacktrace-cabcd83bc903137f607eda3a65eb09feaa5f507e/src/lib/gcc/libbacktrace/backtrace.c:91 #3 0x00000000011a87e9 in _Unwind_Backtrace (trace=0x119abfc <unwind>, trace_argument=0x405fe700) at /genodelabs-genode-2491eee/contrib/gcc-3cade18cf9defeefa714aa91de3b157fbad4aa18/src/noux-pkg/gcc/libgcc/unwind.inc:307 #4 0x000000000119ada2 in backtrace_full (state=0x29000, skip=0x0, callback=0x119808e <callback>, error_callback=0x1198543 <error_callback>, data=0x405fe770) at /var/services/homes/admin/gen/21.02/contrib/libbacktrace-cabcd83bc903137f607eda3a65eb09feaa5f507e/src/lib/gcc/libbacktrace/backtrace.c:127 #5 0x0000000001198611 in runtime_callers (skip=0x2, locbuf=0xc42000e8d8, m=0x20, keep_thunks=0x0) at /var/services/homes/admin/gen/21.02/contrib/libgo-281260d9bdc27fefb62c00310025c54e1e629a2e/src/lib/gcc/libgo/runtime/go-callers.c:207 #6 0x00000000010fdf28 in runtime.callers (skip=0x1, locbuf=...) at /var/services/homes/admin/gen/21.02/contrib/libgo-281260d9bdc27fefb62c00310025c54e1e629a2e/src/lib/gcc/libgo/go/runtime/traceback_gccgo.go:56 #7 0x00000000010d8f7d in runtime.mcommoninit (mp=0xc42000e800) at /var/services/homes/admin/gen/21.02/contrib/libgo-281260d9bdc27fefb62c00310025c54e1e629a2e/src/lib/gcc/libgo/go/runtime/proc.go:546 #8 0x00000000010db6c5 in runtime.allocm (_p_=0xc420008000, fn=0x121e298 <runtime.mspinning..f>, allocatestack=0x0) at /var/services/homes/admin/gen/21.02/contrib/libgo-281260d9bdc27fefb62c00310025c54e1e629a2e/src/lib/gcc/libgo/go/runtime/proc.go:1466 #9 0x00000000010dbdb2 in runtime.newm (fn=0x121e298 <runtime.mspinning..f>, _p_=0xc420008000) at /var/services/homes/admin/gen/21.02/contrib/libgo-281260d9bdc27fefb62c00310025c54e1e629a2e/src/lib/gcc/libgo/go/runtime/proc.go:1769 #10 0x00000000010dc360 in runtime.startm (_p_=0xc420008000, spinning=0x1) at /var/services/homes/admin/gen/21.02/contrib/libgo-281260d9bdc27fefb62c00310025c54e1e629a2e/src/lib/gcc/libgo/go/runtime/proc.go:1925 #11 0x00000000010dc702 in runtime.wakep () at /var/services/homes/admin/gen/21.02/contrib/libgo-281260d9bdc27fefb62c00310025c54e1e629a2e/src/lib/gcc/libgo/go/runtime/proc.go:2006 #12 0x00000000010dfabf in __go_go (fn=0x10d72f2, arg=0x0) at /var/services/homes/admin/gen/21.02/contrib/libgo-281260d9bdc27fefb62c00310025c54e1e629a2e/src/lib/gcc/libgo/go/runtime/proc.go:3144