mirror of
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243 lines
5.9 KiB
C
243 lines
5.9 KiB
C
/* go-caller.c -- look up function/file/line/entry info
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Copyright 2009 The Go Authors. All rights reserved.
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Use of this source code is governed by a BSD-style
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license that can be found in the LICENSE file. */
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/* Implement runtime.Caller. */
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#include <stdint.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "backtrace.h"
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#include "runtime.h"
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/* Get the function name, file name, and line number for a PC value.
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We use the backtrace library to get this. */
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/* Data structure to gather file/line information. */
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struct caller
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{
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String fn;
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String file;
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intgo line;
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intgo index;
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};
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/* Collect file/line information for a PC value. If this is called
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more than once, due to inlined functions, we use the last call, as
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that is usually the most useful one. */
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static int
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callback (void *data, uintptr_t pc __attribute__ ((unused)),
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const char *filename, int lineno, const char *function)
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{
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struct caller *c = (struct caller *) data;
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/* The libbacktrace library says that these strings might disappear,
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but with the current implementation they won't. We can't easily
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allocate memory here, so for now assume that we can save a
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pointer to the strings. */
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c->fn = runtime_gostringnocopy ((const byte *) function);
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c->file = runtime_gostringnocopy ((const byte *) filename);
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c->line = lineno;
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if (c->index == 0)
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return 1;
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if (c->index > 0)
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--c->index;
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return 0;
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}
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/* The error callback for backtrace_pcinfo and backtrace_syminfo. */
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static void
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error_callback (void *data __attribute__ ((unused)),
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const char *msg, int errnum)
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{
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if (errnum == -1)
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return;
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if (errnum > 0)
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runtime_printf ("%s errno %d\n", msg, errnum);
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runtime_throw (msg);
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}
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/* The backtrace library state. */
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static void *back_state;
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/* A lock to control creating back_state. */
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static uint32 back_state_lock;
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/* The program arguments. */
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extern Slice runtime_get_args(void);
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/* Fetch back_state, creating it if necessary. */
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struct backtrace_state *
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__go_get_backtrace_state ()
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{
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uint32 set;
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/* We may not have a g here, so we can't use runtime_lock. */
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set = 0;
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while (!__atomic_compare_exchange_n (&back_state_lock, &set, 1, false, __ATOMIC_ACQUIRE, __ATOMIC_RELAXED))
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{
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runtime_osyield ();
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set = 0;
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}
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if (back_state == NULL)
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{
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Slice args;
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const char *filename;
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struct stat s;
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args = runtime_get_args();
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filename = NULL;
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if (args.__count > 0)
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filename = (const char*)((String*)args.__values)[0].str;
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/* If there is no '/' in FILENAME, it was found on PATH, and
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might not be the same as the file with the same name in the
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current directory. */
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if (filename != NULL && __builtin_strchr (filename, '/') == NULL)
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filename = NULL;
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/* If the file is small, then it's not the real executable.
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This is specifically to deal with Docker, which uses a bogus
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argv[0] (http://gcc.gnu.org/PR61895). It would be nice to
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have a better check for whether this file is the real
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executable. */
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if (filename != NULL && (stat (filename, &s) < 0 || s.st_size < 1024))
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filename = NULL;
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back_state = backtrace_create_state (filename, 1, error_callback, NULL);
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}
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__atomic_store_n (&back_state_lock, 0, __ATOMIC_RELEASE);
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return back_state;
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}
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/* Return function/file/line information for PC. The index parameter
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is the entry on the stack of inlined functions; -1 means the last
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one. */
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static _Bool
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__go_file_line (uintptr pc, int index, String *fn, String *file, intgo *line)
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{
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struct caller c;
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struct backtrace_state *state;
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runtime_memclr (&c, sizeof c);
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c.index = index;
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runtime_xadd (&__go_runtime_in_callers, 1);
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state = __go_get_backtrace_state ();
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runtime_xadd (&__go_runtime_in_callers, -1);
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backtrace_pcinfo (state, pc, callback, error_callback, &c);
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*fn = c.fn;
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*file = c.file;
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*line = c.line;
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// If backtrace_pcinfo didn't get the function name from the debug
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// info, try to get it from the symbol table.
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if (fn->len == 0)
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backtrace_syminfo (state, pc, __go_syminfo_fnname_callback,
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error_callback, fn);
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return c.file.len > 0;
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}
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/* Collect symbol information. */
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static void
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syminfo_callback (void *data, uintptr_t pc __attribute__ ((unused)),
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const char *symname __attribute__ ((unused)),
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uintptr_t address, uintptr_t size __attribute__ ((unused)))
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{
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uintptr_t *pval = (uintptr_t *) data;
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*pval = address;
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}
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/* Set *VAL to the value of the symbol for PC. */
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static _Bool
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__go_symbol_value (uintptr pc, uintptr *val)
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{
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struct backtrace_state *state;
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*val = 0;
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runtime_xadd (&__go_runtime_in_callers, 1);
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state = __go_get_backtrace_state ();
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runtime_xadd (&__go_runtime_in_callers, -1);
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backtrace_syminfo (state, pc, syminfo_callback,
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error_callback, val);
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return *val != 0;
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}
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/* The values returned by runtime.Caller. */
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struct caller_ret
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{
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uintptr_t pc;
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String file;
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intgo line;
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_Bool ok;
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};
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struct caller_ret Caller (intgo n) __asm__ (GOSYM_PREFIX "runtime.Caller");
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/* Implement runtime.Caller. */
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struct caller_ret
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Caller (intgo skip)
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{
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struct caller_ret ret;
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Location loc;
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int32 n;
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runtime_memclr (&ret, sizeof ret);
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n = runtime_callers (skip + 1, &loc, 1, false);
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if (n < 1 || loc.pc == 0)
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return ret;
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ret.pc = loc.pc;
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ret.file = loc.filename;
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ret.line = loc.lineno;
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ret.ok = 1;
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return ret;
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}
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/* Look up the function name, file name, and line number for a PC. */
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struct funcfileline_return
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runtime_funcfileline (uintptr targetpc, int32 index)
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{
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struct funcfileline_return ret;
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if (!__go_file_line (targetpc, index, &ret.retfn, &ret.retfile,
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&ret.retline))
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runtime_memclr (&ret, sizeof ret);
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return ret;
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}
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/* Return the entry point of a function. */
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uintptr runtime_funcentry(uintptr)
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__asm__ (GOSYM_PREFIX "runtime.funcentry");
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uintptr
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runtime_funcentry (uintptr pc)
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{
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uintptr val;
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if (!__go_symbol_value (pc, &val))
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return 0;
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return val;
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}
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